阅读说明：本技术 一种光模块 (Optical module ) 是由 梅冬斌 于 2019-11-15 设计创作，主要内容包括：本申请提供的光模块电路板,设置在所述电路板上的微控制芯片和驱动芯片,其中,微控制芯片用于根据微控制芯片温度和预先存储的调制系数,计算调制电流值,其中,所述微控制芯片温度的精度可以达到1/256℃；驱动芯片,基于微控制芯片写入的调制电流值调整电流信号生成驱动电流,并输出所述驱动电流至激光器芯片。光模块运行的过程中,微控制芯片基于MCU温度和调制系数计算出调制电流值,由于MCU温度的精度可以达到1/256℃,使用微控制芯片温度计算出的调制电流值的精度较高,驱动芯片基于所述调制电流值调整电流信号生成的驱动电流的精度较高,将该驱动电流作用于激光器芯片,相应的激光器芯片采眼图测试光功率和消光比的稳定性均有所提升。(The optical module circuit board is provided with a micro control chip and a driving chip which are arranged on the circuit board, wherein the micro control chip is used for calculating a modulation current value according to the temperature of the micro control chip and a pre-stored modulation coefficient, and the precision of the temperature of the micro control chip can reach 1/256 ℃; and the driving chip adjusts the current signal to generate a driving current based on the modulation current value written by the micro-control chip and outputs the driving current to the laser chip. In the operation process of the optical module, the micro control chip calculates a modulation current value based on the temperature of the MCU and the modulation coefficient, the precision of the temperature of the MCU can reach 1/256 ℃, the precision of the modulation current value calculated by using the temperature of the micro control chip is higher, the precision of a driving current generated by the driving chip based on the modulation current value adjusting current signal is higher, the driving current acts on the laser chip, and the stability of the corresponding laser chip adopting an eye pattern to test the optical power and the extinction ratio is improved.)

1. A light module, comprising:

a circuit board having a signal circuit for providing a signal electrical connection;

the micro-control chip is arranged on the circuit board and used for calculating a modulation current value according to the temperature of the micro-control chip and a pre-stored modulation coefficient;

a port of the driving chip is connected with the micro control chip and is used for receiving the modulation current value written by the micro control chip; the other port is connected with the signal circuit and used for receiving a current signal transmitted by the signal circuit and adjusting the current signal to generate a driving current based on the modulation current value;

and the laser chip is electrically connected with the driving chip and used for sending out corresponding optical signals according to the driving current.

2. The light module of claim 1,

and one port of the micro control chip is connected with the laser chip and is used for receiving the extinction ratio reported by the laser chip, generating a modulation coefficient based on the extinction ratio and the temperature of the micro control chip and storing the modulation coefficient in a nonvolatile storage area in the micro control chip.

3. The optical module of claim 2, wherein the modulation factor comprises: a modulation slope and a modulation offset value;

the micro control chip is further used for calculating a modulation current value according to the following formula:

modulating current value (SLOPE × T + OFFSET); wherein, LOPE is the modulation slope, OFFSET is the modulation OFFSET value, and T is the temperature of the micro-control chip.

4. The optical module of claim 3, wherein the modulation slope comprises: a high temperature modulation slope and a low temperature modulation slope, the respective modulation offset values comprising: a low temperature modulation offset value and a high temperature modulation offset value.

5. The optical module according to claim 4, wherein the modulation factor is generated by:

the optical module is arranged in a control box at 25 ℃, and the micro control chip is used for adjusting the modulation current value written into the drive chip until receiving the extinction reported by the laser chipThe ratio falls within a range of 4.2dB to 4.6dB, and the modulation current value M at this time is recorded₂And micro-control chip temperature T₂；

The optical module is arranged in a control box at the temperature of minus 10 ℃, the micro control chip is used for adjusting the modulation current value written in the drive chip until the extinction ratio reported by the laser chip is within the range of 4.2dB to 4.6dB, and the modulation current value M at the moment is recorded₁And micro-control chip temperature T₁；

The micro control chip is used for calculating a low-temperature slope and a low-temperature offset value according to the following formula;

OFFSET1＝M₂-SLPE1*T₂(ii) a Wherein SLOPE1 is the low temperature SLOPE, and OFFSET1 is the low temperature OFFSET value.

6. The optical module according to claim 5, wherein when the micro control chip temperature is in the range of 10 ℃ to 50 ℃, the micro control chip calculates the modulation current value by using the low temperature slope and the low temperature offset value.

7. The optical module according to claim 4, wherein the modulation factor is generated by:

the optical module is arranged in a control box at 25 ℃, the micro control chip is used for adjusting the modulation current value written in the drive chip until the extinction ratio reported by the laser chip is within the range of 4.2 dB-4.6 dB, the modulation current value at the moment is recorded, and the modulation current value M at the moment is recorded₂And micro-control chip temperature T₂；

The optical module is placed in a control box at 55 ℃, the micro control chip is used for adjusting the modulation current value written in the drive chip until the extinction ratio reported by the laser chip is within the range of 4.2 dB-4.6 dB, the modulation current value at the moment is recorded, and the modulation current value M at the moment is recorded₃And micro-control chip temperature T₃；

Calculating a high-temperature slope and a high-temperature section deviation value according to the following formula;

OFFSET2＝M₂-SLPE1*T₂(ii) a Among them, SLOPE2 is a high temperature SLOPE, and OFFSET2 is a high temperature SLOPE.

8. The optical module according to claim 7, wherein when the micro control chip temperature is in the range of 50 ℃ to 80 ℃, the micro control chip calculates the modulation current value by using the high temperature slope and the high temperature offset value.

9. The optical module according to any one of claims 1 to 8, characterized in that the modulation factor is stored in a non-volatile storage area in a single-precision floating-point manner.

10. The optical module according to any of claims 1-8, characterized in that the accuracy of the micro control chip temperature is 1/256 ℃.

Technical Field

The embodiment of the application relates to the optical communication technology. And more particularly, to a light module.

Background

The optical module generally refers to an integrated module for photoelectric conversion, which is generally packaged by a light emitting module, a light receiving module and a Printed Circuit Board (PCB) for photoelectric signal conversion. The transmitter optical subassembly comprises a driving chip and a laser chip, wherein the driving chip outputs a modulation current value and a bias current to the laser chip to control the laser chip to emit light.

The cavity of the laser chip has two mirror surfaces which are semi-transparent and which serve to form the cavity in which photons are guided to emit new photons, on the one hand, and to emit light when a substantial proportion of the photons are transmitted from the mirror surfaces. The light transmitted by the front mirror, referred to as the primary light, becomes useful for transmission through the coupling of the transmitting optical fiber to the optical fiber. The light radiated off the rear reflecting mirror is also referred to as back light. A Transmitter Optical Subassembly (TOSA) converts the backlight into a backlight current, which is used to monitor the amount of the laser chip emitting power.

When the optical gain in the cavity of the laser chip exceeds the loss of the reflecting surface at the end of the cavity, the laser chip can emit a coherent optical signal. As the optical gain in the cavity of the laser chip decreases with increasing temperature, the laser chip requires a larger injection current to achieve coherent light output as the optical gain decreases within the cavity, and as a result, the threshold current of the laser chip increases. The output optical power is reduced due to the increase of the threshold current, and the driving chip must output a larger bias current if the optical power is to be kept constant. In order to compensate for the variation of the threshold of the laser chip, an Automatic Power Control (APC) circuit is required, and the APC circuit maintains the stability of the average optical power of the optical signal emitted from the laser chip by controlling the output bias current. In general, the proportional relationship between the bias current and the average optical power is linear, so that the average optical power of the laser chip is kept constant by keeping the bias current stable.

For a direct-current coupled optical module, both a bias current and a modulation current value affect optical power and an extinction ratio, and in the process of temperature change, the stability of the output optical power of a laser chip is kept, and the stability of the extinction ratio of the laser chip is also kept. Keeping the output optical power and extinction ratio stable is to adjust the bias current and modulation current values. The general method is to track the temperature change according to the temperature lookup table by using the MCU inside the optical module to simulate APC, so as to output the appropriate bias current and modulation current value. The method for determining the modulation current value adopts a table look-up method, specifically, a temperature-modulation current value preset table is stored in advance, the temperature is obtained in the working process of the MCU, then the temperature-modulation current value preset table is traversed, the modulation current value at the corresponding temperature is found out, and then the modulation current value is written into the driver, so that the modulation current value is generated, and the bias current method is the same. Usually, the temperature range of the micro-control chip ranges from-40 ℃ to +128 ℃, the temperature precision is 1/256 ℃, if the temperature-modulation current value preset table is set according to the precision of 1/256 ℃, a great number of registers are needed, the cost is not reasonable obviously, and the operation is troublesome, so the precision of the lookup table is usually set to be 2 ℃ or more, and the lookup table occupied by a single variable can be less than 128 bytes.

However, if the temperature precision setting value is 2 ℃ in the table look-up process, the output precision of the corresponding modulation current value will be poor, and the output precision of the modulation current value will be poor, so that the eye pattern will be unstable, and finally the problem of instability of the eye pattern test optical power and extinction ratio will be caused.

Disclosure of Invention

The first optical module in the embodiment of the application is used for solving the technical problems in the prior art.

A first aspect of an embodiment of the present application shows an optical module, including:

a circuit board having a signal circuit for providing a signal electrical connection and for carrying a photovoltaic device;

the micro control chip is arranged on the circuit board and used for calculating a modulation current value according to the temperature of the micro control chip and a pre-stored modulation coefficient, wherein the modulation current value is obtained by the micro control chip;

a port of the driving chip is connected with the micro control chip and is used for receiving the modulation current value written by the micro control chip; the other port is connected with the signal circuit and used for receiving a current signal transmitted by the signal circuit and adjusting the current signal to generate a driving current based on the modulation current value;

and the laser chip is electrically connected with the driving chip and used for sending out corresponding optical signals according to the driving current.

The optical module comprises a circuit board, a micro control chip and a driving chip, wherein the circuit board is provided with a signal circuit and is used for providing signal electric connection and bearing a photoelectric device; the micro control chip is arranged on the circuit board and used for calculating a modulation current value according to the temperature of the micro control chip and a pre-stored modulation coefficient, and the precision of the temperature of the micro control chip is high and can reach 1/256 ℃ generally; a port of the driving chip is connected with the micro control chip and is used for receiving the modulation current value written by the micro control chip; and the other port is connected with the signal circuit and used for receiving a current signal transmitted by the signal circuit, adjusting the current signal based on the modulation current value to generate a driving current and outputting the driving current to the laser chip. In the operation process of the optical module, the micro control chip calculates the modulation current value based on the temperature and the modulation coefficient of the MCU, and the precision of the modulation current value calculated by using the temperature of the micro control chip is higher because the precision of the temperature of the MCU is 1/256 ℃; the driving chip adjusts the received current signal based on the modulation current value, the precision of the corresponding generated driving current is higher, the driving current acts on the laser chip, and the stability of the eye pattern test optical power and the extinction ratio of the corresponding laser chip is improved.

Further, a modulation coefficient of a recording laser chip of a preset table in an optical module shown in the embodiment of the present application is: the modulation slope and the modulation offset value correspond to two groups of modulation coefficients corresponding to each laser chip, and in a modulation current value table controlled by temperature shown in the prior art, the modulation coefficient corresponding to each laser chip is at least hundreds, so that the data volume of the modulation coefficient recorded in the preset table of the application is far smaller than the data recorded in the modulation current value table controlled by temperature, the number of corresponding occupied registers is reduced, and the development cost is correspondingly reduced.

Drawings

In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings needed to be used in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present application, and it is obvious for those skilled in the art to obtain other drawings without creative efforts.

Fig. 1 is a schematic diagram of a connection relationship of an optical communication terminal;

fig. 2 is a schematic structural diagram of an optical network terminal;

fig. 3 is a schematic structural diagram of an optical module according to an embodiment of the present invention;

FIG. 4 is an exploded view of an optical module according to an embodiment of the present invention;

FIG. 5 is a schematic diagram of a circuit board according to an embodiment of the present invention;

FIG. 6 is a schematic diagram of a micro control chip according to an embodiment of the present invention;

FIG. 7 is a schematic diagram of a micro control chip according to an embodiment of the present invention;

fig. 8 is a schematic diagram of a micro control chip according to an embodiment of the present invention.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

One of the core links of optical fiber communication is the interconversion of optical and electrical signals. The optical fiber communication uses optical signals carrying information to transmit in information transmission equipment such as optical fibers/optical waveguides, and the information transmission with low cost and low loss can be realized by using the passive transmission characteristic of light in the optical fibers/optical waveguides; meanwhile, the information processing device such as a computer uses an electric signal, and in order to establish information connection between the information transmission device such as an optical fiber or an optical waveguide and the information processing device such as a computer, it is necessary to perform interconversion between the electric signal and the optical signal.

The optical module realizes the function of interconversion of optical signals and electrical signals in the technical field of optical fiber communication, and the interconversion of the optical signals and the electrical signals is the core function of the optical module. The optical module is electrically connected with an external upper computer through a golden finger on an internal circuit board of the optical module, and the main electrical connection comprises power supply, I2C signals, data signals, grounding and the like; the electrical connection mode realized by the gold finger has become the mainstream connection mode of the optical module industry, and on the basis of the mainstream connection mode, the definition of the pin on the gold finger forms various industry protocols/specifications.

Fig. 1 is a schematic diagram of connection relationship of an optical communication terminal. As shown in fig. 1, the connection of the optical communication terminal mainly includes the interconnection among the optical network terminal 100, the optical module 200, the optical fiber 101 and the network cable 103;

one end of the optical fiber 101 is connected with a far-end server, one end of the network cable 103 is connected with local information processing equipment, and the connection between the local information processing equipment and the far-end server is completed by the connection between the optical fiber 101 and the network cable 103; and the connection between the optical fiber 101 and the network cable 103 is made by the optical network terminal 100 having the optical module 200.

An optical port of the optical module 200 is externally accessed to the optical fiber 101, and establishes bidirectional optical signal connection with the optical fiber 101; an electrical port of the optical module 200 is externally connected to the optical network terminal 100, and establishes bidirectional electrical signal connection with the optical network terminal 100; the optical module realizes the interconversion of optical signals and electric signals, thereby realizing the establishment of information connection between the optical fiber and the optical network terminal; specifically, the optical signal from the optical fiber is converted into an electrical signal by the optical module and then input to the optical network terminal 100, and the electrical signal from the optical network terminal 100 is converted into an optical signal by the optical module and input to the optical fiber. The optical module 200 is a tool for realizing the mutual conversion of the photoelectric signals, and has no function of processing data, and in the photoelectric conversion process, information only changes in a transmission carrier, and information does not change.

The optical network terminal is provided with an optical module interface 102, which is used for accessing an optical module 200 and establishing bidirectional electric signal connection with the optical module 200; the optical network terminal is provided with a network cable interface 104, which is used for accessing the network cable 103 and establishing bidirectional electric signal connection with the network cable 103; the optical module 200 is connected to the network cable 103 through the optical network terminal 100, specifically, the optical network terminal transmits a signal from the optical module to the network cable and transmits the signal from the network cable to the optical module, and the optical network terminal serves as an upper computer of the optical module to monitor the operation of the optical module. Different from the optical module, the optical network terminal has certain information processing capability.

At this point, a bidirectional signal transmission channel is established between the remote server and the local information processing device through the optical fiber, the optical module, the optical network terminal and the network cable.

Common information processing apparatuses include routers, switches, electronic computers, and the like; the optical network terminal is an upper computer of the optical module, provides data signals for the optical module, and receives the data signals from the optical module, and the common upper computer of the optical module also comprises an optical line terminal and the like.

Fig. 2 is a schematic diagram of an optical network terminal structure. As shown in fig. 2, the optical network terminal 100 has a circuit board 105, and a cage 106 is disposed on a surface of the circuit board 105; an electric connector is arranged in the cage 106 and used for connecting an electric port of an optical module such as a golden finger; the cage 106 is provided with a heat sink 107, and the heat sink 107 has a projection such as a fin that increases a heat radiation area.

The optical module 200 is inserted into the optical network terminal, specifically, the electrical port of the optical module is inserted into the electrical connector inside the cage 106, and the optical port of the optical module is connected to the optical fiber 101.

The cage 106 is positioned on the circuit board, and the electrical connector on the circuit board is wrapped in the cage, so that the electrical connector is arranged in the cage; the optical module is inserted into the cage, held by the cage, and the heat generated by the optical module is conducted to the cage 106 and then diffused by the heat sink 107 on the cage.

Fig. 3 is a schematic diagram of an optical module according to an embodiment of the present invention, and fig. 4 is a schematic diagram of an optical module according to an embodiment of the present invention. As shown in fig. 3 and 4, an optical module 200 according to an embodiment of the present invention includes an upper housing 201, a lower housing 202, an unlocking member 203, a circuit board 300, and an optical transceiver 400;

the upper shell 201 is covered on the lower shell 202 to form a wrapping cavity with two openings; the outer contour of the wrapping cavity is generally a square body, and specifically, the lower shell comprises a main plate and two side plates which are positioned at two sides of the main plate and are perpendicular to the main plate; the upper shell comprises a cover plate, and the cover plate covers two side plates of the upper shell to form a wrapping cavity; the upper shell can also comprise two side walls which are positioned at two sides of the cover plate and are perpendicular to the cover plate, and the two side walls are combined with the two side plates to realize that the upper shell covers the lower shell.

The two openings may be two ends (204, 205) in the same direction, or two openings in different directions; one opening is an electric port 204, and a gold finger of the circuit board extends out of the electric port 204 and is inserted into an upper computer such as an optical network terminal; the other opening is an optical port 205 for external optical fiber access to connect with the optical transceiver 400 inside the optical module; the photoelectric devices such as the circuit board 300 and the optical transceiver 400 are positioned in the packaging cavity.

The assembly mode of combining the upper shell and the lower shell is adopted, so that the circuit board 300, the optical transceiver 400 and other devices can be conveniently installed in the shells, and the upper shell and the lower shell form the outermost packaging protection shell of the optical module; the upper shell and the lower shell are made of metal materials generally, so that electromagnetic shielding and heat dissipation are facilitated; generally, the housing of the optical module is not made into an integrated component, so that when devices such as a circuit board and the like are assembled, the positioning component, the heat dissipation component and the electromagnetic shielding component cannot be installed, and the production automation is not facilitated.

The unlocking component 203 is located on the outer wall of the wrapping cavity/lower shell 202, and is used for realizing the fixed connection between the optical module and the upper computer or releasing the fixed connection between the optical module and the upper computer.

The unlocking component 203 is provided with a clamping component matched with the upper computer cage; the end of the unlocking component can be pulled to enable the unlocking component to move relatively on the surface of the outer wall; the optical module is inserted into a cage of the upper computer, and the optical module is fixed in the cage of the upper computer by a clamping component of the unlocking component; by pulling the unlocking component, the clamping component of the unlocking component moves along with the unlocking component, so that the connection relation between the clamping component and the upper computer is changed, the clamping relation between the optical module and the upper computer is released, and the optical module can be drawn out from the cage of the upper computer.

Referring to fig. 5, the circuit board 300 is provided with circuit traces, electronic components (such as capacitors, resistors, triodes, and MOS transistors), and chips (such as the MCU1, the optical driver chip 2, the amplitude limiting amplifier chip, the clock data recovery CDR, the power management chip, and the data processing chip DSP).

The circuit board connects the electrical appliances in the optical module together according to the circuit design through circuit wiring to realize the functions of power supply, electrical signal transmission, grounding and the like.

The circuit board is generally a hard circuit board, and the hard circuit board can also realize a bearing effect due to the relatively hard material of the hard circuit board, for example, the hard circuit board can stably bear a chip; when the optical transceiver is positioned on the circuit board, the rigid circuit board can also provide stable bearing; the hard circuit board can also be inserted into an electric connector in the upper computer cage, and specifically, a metal pin/golden finger is formed on the surface of the tail end of one side of the hard circuit board and is used for being connected with the electric connector; these are not easily implemented with flexible circuit boards.

A flexible circuit board is also used in a part of the optical module to supplement a rigid circuit board; the flexible circuit board is generally used in combination with a rigid circuit board, for example, the rigid circuit board may be connected to the optical transceiver device through the flexible circuit board.

As can be seen from fig. 5, the main parts on the circuit board are a micro controller chip (MCU) 1, a driver chip 2, and a light emitting component (transmitter Optical Sub-Assembly) 3. The commonly used light emitting module is classified into two major types, one is a Transmitter Optical Subassembly (TOSA) packaged by a Light Emitting Diode (LED), and the other is a TOSA packaged by a semiconductor laser chip (LD). The former has wide spectrum line and low coupling efficiency, although the LED can emit light power of several milliwatts, the directivity is poor, the part which can be coupled into the optical fiber and is used for transmission only accounts for 1% -2%, but the cost is low, the service life is long, and the LED has little application under the conditions of low speed and short distance, is commonly used for short-distance data transmission in the hundred-mega Ethernet multimode optical fiber, and the wavelength is generally 1300 nm. The laser chip LD adopted by the optical module shown in the embodiment of the application. The cavity of the laser chip has two mirror surfaces which are semi-transparent and which serve to form the cavity in which photons are guided to emit new photons, on the one hand, and to emit light when a substantial proportion of the photons are transmitted from the mirror surfaces. The light transmitted by the front mirror, referred to as the primary light, becomes useful for transmission through the coupling of the transmitting optical fiber to the optical fiber. The light radiated off the rear reflecting mirror is also referred to as back light. The transmitter optical subassembly converts the backlight into a modulation current value, and the modulation current value can be used for monitoring the luminous power of the laser chip.

When the optical gain in the cavity of the laser chip exceeds the loss of the reflective surface at the end of the cavity, the laser chip will emit a coherent optical signal, and the current in the laser chip at the critical time is called the threshold current (Ith). As the optical gain in the cavity of the laser chip decreases with increasing temperature, the laser chip requires a larger injection current to achieve coherent light output as the optical gain decreases within the cavity, and as a result, the threshold current of the laser chip increases. The output optical power is reduced due to the increase in threshold current, and the driver has to output a larger bias current if the optical power is to be kept constant.

In order to compensate for the variation of the threshold of the laser chip, an Automatic Power Control (APC) circuit is required to be used inside the micro control chip 1, and a processor and a driver are arranged in the APC circuit, the processor monitors the backlight current of the laser chip 3, and the backlight current of the laser chip is kept stable by adjusting the larger bias current output by the driver. In general, the proportional relationship between the backlight current and the average optical power is linear, so that the average optical power of the laser chip is kept constant by keeping the backlight current stable.

Generally, as the temperature increases, the slope of the characteristic curve of the laser chip input current and output optical power becomes smaller, that is, the photoelectric conversion efficiency of the laser chip decreases. It is known that the laser chip measures the photoelectric conversion efficiency of the laser chip by using an extinction ratio Er of 10 × lg [ P1/P0], where P1 and P0 represent the output optical power of the laser chip when the digital logic signals are "1" and "0", respectively, and P1 and P0 represent the amplitude of the optical signal after modulation. Assuming that the output optical power is unchanged, the conversion slope decreases, and the effective output power of the corresponding laser chip decreases.

In the optical module, in addition to the stabilization of the output optical power of the laser chip, the extinction ratio of the laser chip is also kept stable during the temperature variation. Keeping the output optical power and extinction ratio stable is to adjust the modulation current value. The most common method for modulating current is to look up a table to determine the value of the modulation current at a certain temperature, and then to output the corresponding value of the modulation current by an internal driver by using the APC circuit to maintain the stability of the extinction ratio.

However, if the accuracy setting value of the temperature is 2 ℃ in the table lookup process, the output accuracy of the corresponding modulation current value is small, for example: in the temperature range of 16-80 ℃, the temperature is not increased by 2 ℃, and the corresponding modulation current value is increased by 3 units, so the precision of the modulation current value is smaller in the adjustment process, and the eye pattern is unstable when the precision of the modulation current value is small. Eventually leading to problems: when the extinction ratio approaches the limit, the extinction ratio of the eye pattern test is unstable.

Based on the above technical problem, the embodiment of the present application shows an optical module, and the basic structure of the optical module can refer to fig. 1 to 5, where the structure of the micro control chip can refer to fig. 6.

The processor 11 obtains the temperature of the micro control chip 1 (micro control chip temperature), and calls a modulation coefficient corresponding to the laser chip in a preset table, wherein the modulation coefficient includes a modulation slope and a modulation offset value. And the processor 11 calculates a modulation current value based on the temperature of the micro-control chip and the modulation coefficient in the preset table, and writes the modulation current value into the driving chip.

And a preset table 12A for recording the modulation factor corresponding to the laser chip. Table 1 is a preset table 1 shown according to a preferred embodiment.

TABLE 1

Register address	Hexadecimal storage mode	Modulation slope	Modulation offset value
				128	80	1.333333	16.666667

Multiple laser chips may be included in an optical module. In a preferred embodiment, the optical module may include 4 laser chips, but the application does not limit the number of the laser chips included in the optical module, and in the actual application process, the format of the laser chips included in the optical module may be configured according to actual requirements.

For convenience of distinction, four-way laser chips are defined as: the optical module comprises a laser chip 3A, a laser chip 3B, a laser chip 3C and a laser chip 3D, wherein 4 driving chips are correspondingly configured in the optical module and respectively serve as a driving chip 2A, a driving chip 2B, a driving chip 2C and a driving chip 2D. The modulation factor recorded in the corresponding preset table is: modulation slope1, modulation offset value 1; modulation slope2, modulation offset value 2; modulation slope 3, modulation offset value 3; modulation slope 4, modulation offset value 4.

Fig. 7 is a schematic diagram of a micro control chip of the optical module. The preset table 12A stores 4 sets of modulation coefficients.

The specific operation process is as follows: and the processor 11 determines the laser chip to be controlled, acquires the temperature of the micro-control chip 1 (micro-control chip temperature), and calls the modulation coefficient corresponding to the laser chip to be adjusted in a preset table. The process of determining the modulation coefficient corresponding to the laser chip to be adjusted may be to establish a correspondence between the laser chip and the modulation coefficient in advance, and when the laser chip to be controlled is determined, send the device information of the laser chip to be controlled to the processor 11; then, the processor 11 traverses a preset table based on the device information to screen out a modulation coefficient corresponding to the laser chip to be controlled, then, the processor 11 controls the digital potentiometer to output a corresponding modulation current value to a corresponding driving chip based on the modulation current value, and the laser chip controls the corresponding laser chip to emit light based on the modulation current value.

Further, the modulation factor can be recorded in a preset table by a single-precision floating point recording method.

The table 2 shows the conversion of the preset table shown in table 1 into the preset table converted by the single-precision floating point recording method.

TABLE 2

In the operation process of the optical module, the microcontroller acquires the temperature of the micro control chip, calculates the modulation current value according to the modulation coefficient stored in the preset table and the acquired temperature of the micro control chip, and writes the modulation current value into the driving chip. In the calculation process, the precision of the temperature reported by the MCU is 1/256 ℃, the control precision of the modulation current value is mainly the precision of the modulation current value, so that the obtained modulation current value has better precision, the corresponding modulation current value output to the laser chip has higher precision, and the stability of the eye pattern of the laser chip is correspondingly improved.

Further, a modulation coefficient of a recording laser chip of a preset table in an optical module shown in the embodiment of the present application is: the modulation slope and the modulation offset value correspond to two groups of modulation coefficients corresponding to each laser chip, and in a modulation current value table controlled by temperature shown in the prior art, the modulation coefficient corresponding to each laser chip is at least hundreds, so that the data volume of the modulation coefficient recorded in the preset table of the application is far smaller than the data recorded in the modulation current value table controlled by temperature, the number of corresponding occupied registers is reduced, and the development cost is correspondingly reduced.

Generally, there is a great difference between the variation trend of the modulation current value in the low temperature region and the variation trend of the modulation current value in the high temperature region, and in order to ensure the accuracy of the modulation slope and the modulation offset value, the technical solution shown in the embodiment of the present application calculates the modulation slope and the modulation offset value in a "sectional manner".

Specifically, the temperature range to which the optical module according to the embodiment of the present application is applied is 0 to 70 ℃ (the case temperature), the applicant refers to a case temperature range of 0 to 25 ℃ (corresponding to the micro control chip temperatures T1 to T2) as a low temperature range, and the applicant refers to a temperature range of 25 to 70 ℃ (corresponding to the micro control chip temperatures T2 to T3) as a high temperature range.

The modulation slope of the low temperature section may also be referred to as a low temperature slope in this embodiment, and the modulation offset value of the low temperature section may also be referred to as a low temperature offset value in this embodiment. Accordingly, the modulation slope of the high temperature segment may also be referred to as the high temperature slope in this embodiment, and the modulation offset value of the high temperature segment may also be referred to as the high temperature offset value in this embodiment.

The calculation process of the low-temperature slope and the low-temperature offset value is specifically as follows:

the optical module is placed in a temperature control box to ensure that the shell temperature is 25 ℃, the extinction ratio of the laser chip is adjusted to be in the range of 4.2 dB-4.6 dB by adjusting the modulation current value written in the drive chip at 25 ℃, and the modulation current value M at the moment is recorded₂And micro-control chip temperature T₂；

Adjusting the temperature of the temperature control box to 0 ℃ lower limit of the working temperature of the optical module, adjusting the extinction ratio of the laser chip to be within the range of 4.2 dB-4.6 dB by adjusting the modulation current value written in the drive chip at 0 ℃, and recording the extinction ratioModulation current value M of time₁And micro-control chip temperature T₁。

Calculating a low-temperature slope and a low-temperature offset value according to the following formula;

OFFSET1＝M₂-SLPE1*T₂

wherein M is₂For micro-control of chip temperature T₂Modulation current value of time, M₁For micro-control of chip temperature T₁The modulation current value at time, SLOPE1, is a low temperature SLOPE, and OFFSET1 is a low temperature OFFSET value.

And recording the low-temperature slope and the low-temperature offset value into a preset table.

The calculation process of the high-temperature slope and the high-temperature offset value is specifically as follows:

the optical module is placed in a temperature control box to ensure that the shell temperature is 25 ℃, the extinction ratio of the laser chip is adjusted to be in the range of 4.2 dB-4.6 dB by adjusting the modulation current value written in the drive chip at 25 ℃, and the modulation current value M at the moment is recorded₂And micro-control chip temperature T₂。

Adjusting the temperature of the temperature control box to 70 ℃ of the upper limit of the working temperature of the optical module, adjusting the extinction ratio of the laser chip to be within the range of 4.2dB to 4.6dB by adjusting the modulation current value written in the drive chip at 70 ℃, and recording the modulation current value M at the moment₃And micro-control chip temperature T₃；

Calculating a high-temperature slope and a high-temperature section deviation value according to the following formula;

OFFSET2＝M₂-SLPE1*T₂

wherein M is₂For micro-control of chip temperature T₂Modulation current value of time, M₃For micro-control of chip temperature T₃The modulation current value at time, SLOPE2, is a high temperature SLOPE, and OFFSET2 is a high temperature OFFSET value.

And recording the high-temperature slope and the high-temperature deviation value into a preset table.

The modulation current value control function calculates MOD based on MOD ═ SLOPE × (T) + OFFSET, where MOD is a modulation current value, SLOPE is a modulation SLOPE, OFFSET is a modulation OFFSET value, and T is a micro-control chip temperature. When the temperature of the micro-control chip is in a range of T2-T3, calculating a modulation current value by adopting a high-temperature slope and a high-temperature offset value; and when the temperature of the micro-control chip is in a range of T1-T2, calculating a modulation current value by adopting a low-temperature slope and a low-temperature offset value.

The performance of the optical module shown in the embodiment of the present application on cost saving is described in detail below with reference to specific examples: in a preferred embodiment, an optical module includes four laser chips: the optical module comprises a laser chip 3A, a laser chip 3B, a laser chip 3C and a laser chip 3D, wherein 4 driving chips are correspondingly configured in the optical module and respectively serve as a driving chip 2A, a driving chip 2B, a driving chip 2C and a driving chip 2D. The modulation factor recorded in the corresponding preset table is: modulation slope1, modulation offset value 1; modulation slope2, modulation offset value 2; modulation slope 3, modulation offset value 3; modulation slope 4, modulation offset value 4.

The operating temperature of the optical module is-40-150 ℃, and if the corresponding relation between the temperature and the modulation current value is recorded by adopting a temperature-modulation current value preset table shown in the prior art, the specific temperature-modulation current value preset table can refer to table 3

TABLE 3

From the above table 3, it can be seen that the modulation current value is searched by using a manner of searching the temperature-modulation current value preset table, on one hand, the temperature-modulation current value preset table occupies a large space, a single channel occupies 96 bytes, and 4 channels occupy 384 bytes. Meanwhile, the temperature precision is 2 ℃, the control precision of the corresponding modulation current value reaches 3 units, the output precision of the corresponding modulation current value is poor, and the situation of unstable eye pattern can occur when the output precision of the modulation current value is small. Eventually leading to the problem of unstable extinction ratio of eye pattern test.

In this embodiment, a schematic diagram of a micro control chip of an optical module can refer to fig. 8. By adopting the technical scheme shown in the embodiment of the present application, if the modulation coefficient recorded by the preset table shown in the embodiment of the present application is adopted, the specific modulation coefficient preset table can refer to table 4:

TABLE 4

From the table above, it can be seen that the total registers used by the four channels are 64 bytes, and the registers can be stored by using one table. In actual control, the modulation current value is calculated as follows: the modulation current value is SLOPE T + OFFSET, SLOPE is the modulation SLOPE of the corresponding temperature segment, OFFSET is the modulation OFFSET value of the corresponding temperature segment, the formula shows that the control accuracy of the modulation current value mainly depends on the reporting accuracy of the temperature of the micro-control chip, the reporting accuracy of the temperature of the micro-control chip is 1/256 ℃, and therefore the calculated modulation current value has better accuracy, the modulation current value is more stable, and the stability of an eye diagram is correspondingly improved.

Further, a modulation coefficient of a recording laser chip of a preset table in an optical module shown in the embodiment of the present application is: the modulation slope and the modulation offset value correspond to two groups of modulation coefficients corresponding to each laser chip, and in a modulation current value table controlled by temperature shown in the prior art, the modulation coefficient corresponding to each laser chip is at least hundreds, so that the data volume of the modulation coefficient recorded in the preset table of the application is far smaller than the data recorded in the modulation current value table controlled by temperature, the number of corresponding occupied registers is reduced, and the development cost is correspondingly reduced.

Finally, it should be noted that: the above examples are only intended to illustrate the technical solution of the present invention, but not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and the modifications or the substitutions do not make the essence of the corresponding technical solutions depart from the technology of the embodiments of the present invention.