阅读说明：本技术 一种小型化低成本大频率调谐范围稳频激光器系统及方法 (Miniaturized low-cost large-frequency tuning range frequency-stabilized laser system and method ) 是由 李荟 于佳晨 熊炜 陈徐宗 于 2018-08-27 设计创作，主要内容包括：本发明公开了一种小型化低成本大频率调谐范围稳频激光器系统及方法。本发明采用双激光器结构,尺寸为50mm×25mm×20mm；成本低,在6000元人民币量级；采用VCSEL激光器控制频率,通过电流调制(调制频率连续可调)可调出两个边带,即可做到在两倍10GHz的大范围内连续调谐频率,调制信号线宽为赫兹量级,激光线宽为兆赫兹量级,调制信号对激光线宽的增宽可忽略；通过改变调制信号频率就能对激光器进行调谐且不影响其稳定性；单模激光器输出功率高,成本低,易获得；整个激光器系统由零温漂微晶玻璃实现,可靠性高；本发明的方法可以广泛应用在激光精密测量、原子钟、原子干涉仪以及超冷原子实验技术研究等基础研究和精密测量技术领域。(The invention discloses a miniaturized low-cost frequency-stabilized laser system with a large frequency tuning range and a method. The invention adopts a double-laser structure, and the size is 50mm multiplied by 25mm multiplied by 20 mm; the cost is low, and is in the 6000 yuan RMB level; the frequency is controlled by a VCSEL laser, two sidebands can be adjusted through current modulation (modulation frequency is continuously adjustable), the frequency can be continuously tuned in a large range of two times of 10GHz, the line width of a modulation signal is in a Hertz magnitude, the line width of a laser is in a megahertz magnitude, and the broadening of the modulation signal to the line width of the laser can be ignored; the laser can be tuned by changing the frequency of the modulation signal without influencing the stability of the laser; the single-mode laser has high output power, low cost and easy acquisition; the whole laser system is realized by the zero-temperature-drift microcrystalline glass, and the reliability is high; the method can be widely applied to the technical fields of basic research and precision measurement such as laser precision measurement, atomic clocks, atomic interferometers, supercooled atomic experimental technology research and the like.)

1. A miniaturized, low-cost, large frequency tuning range, frequency stabilized laser system, said laser system comprising: the device comprises a modulation signal, a vertical cavity surface emitting VCSEL laser, a single-mode laser, an optical fiber, an atomic gas chamber, a photoelectric detector and first to fourth light splitting lenses; the modulation signal is loaded on a power supply of the VCSEL laser, and the current of the VCSEL laser is modulated, so that seed light is output, the seed light has a carrier and two sidebands, and the frequency difference between the carrier and the sidebands is equal to the frequency of the modulation signal; the seed light output by the VCSEL laser is divided into two beams by a first spectroscope, a reflected light beam is coupled into an optical fiber by a lens, a transmitted light beam passes through a free space, the two light beams are combined by a second spectroscope, a self-differencing beat frequency signal is formed due to optical path difference, and the line width of the seed light is compressed from a hundred megahertz magnitude to a megahertz magnitude; the combined beam is divided into two beams by a second beam splitter, one beam of light passes through a third beam splitter and enters an atomic gas chamber as pumping light, reflected light of a rear window of the atomic gas chamber is used as detection light, a saturated absorption spectrum is generated in the atomic gas chamber, and the saturated absorption spectrum has transmission peaks at an atomic resonance frequency point and at a frequency point of the atomic resonance frequency point plus a modulation signal frequency; the detection light returns along the original path and is reflected by the third beam splitting lens again to enter the photoelectric detector, the photoelectric detector detects the saturated absorption spectrum to obtain the position of a transmission peak, the position of the transmission peak is fed back to a power supply of the VCSEL laser to lock the laser center frequency, and the laser center frequency can be locked at the transmission peak of the saturated absorption spectrum; the other beam of light passing through the second beam splitting lens enters the single-mode laser after being reflected by the fourth beam splitting lens, the single-mode laser is injected and locked, and the mode selection is carried out by adjusting the temperature and the current of the single-mode laser, so that the frequency of the single-mode laser is equal to the frequency of the carrier wave of the VCSEL laser, and all other modes are suppressed; the single-mode laser outputs the laser after mode selection, and the laser is output through the fourth light splitting lens.

2. The laser system of claim 1, wherein the frequency of the modulation signal is continuously adjustable between 10MHz and 10 GHz.

3. The laser system of claim 2, wherein the VCSEL laser is capable of continuous tuning in the range of two times 10GHz after being locked.

4. The laser system of claim 1, wherein the single mode laser has an output power on the order of hundreds of milliwatts of laser light.

5. The laser system of claim 1, wherein the single mode laser is a compact laser, a G-package single mode laser, or a C-package single mode laser.

6. The laser system as claimed in claim 1, wherein the first to third dichroic mirrors are dichroic plates, and the fourth dichroic mirror is a polarization beam splitter prism.

7. A control method for a miniaturized low-cost large-frequency tuning range frequency-stabilized laser system is characterized by comprising the following steps:

1) loading a modulation signal on a power supply of a VCSEL laser, and modulating the current of the VCSEL laser so as to output seed light, wherein the seed light has a carrier and two sidebands, and the frequency difference between the carrier and the sidebands is equal to the frequency of the modulation signal;

2) the seed light output by the VCSEL laser is divided into two beams by a first spectroscope, a reflected light beam is coupled into an optical fiber by a lens, a transmitted light beam passes through a free space, the two light beams are combined by a second spectroscope, a self-differencing beat signal is formed due to optical path difference, the self-differencing beat signal contains phase noise of laser, a phase discrimination signal generated by the self-differencing beat signal and a modulation signal is fed back to the VCSEL laser, the frequency of the VCSEL laser is adjusted, and the line width of the seed light is compressed from the hundred MHz level to the MHz level;

3) the combined beam is divided into two beams by a second beam splitter, one beam of light passes through a third beam splitter and enters an atomic gas chamber as pumping light, reflected light of a rear window of the atomic gas chamber is used as detection light, a saturated absorption spectrum is generated in the atomic gas chamber, and the saturated absorption spectrum has transmission peaks at an atomic resonance frequency point and at a frequency point of the atomic resonance frequency point plus a modulation signal frequency;

4) the detection light returns along the original path and enters the photoelectric detector after being reflected by the third beam splitting mirror again, the photoelectric detector detects the saturated absorption spectrum to obtain the position of a transmission peak, the position is fed back to a power supply of the VCSEL laser to lock the laser central frequency, the laser central frequency can be locked at the transmission peak of the saturated absorption spectrum, the frequency corresponding to the transmission peak of the saturated absorption spectrum is the frequency of an atomic hyperfine energy interstage transition frequency shift modulation signal, and the modulation signal frequency is continuously adjustable, so that the VCSEL laser can be continuously tuned within the range of 10GHz of twice the maximum modulation signal frequency after being locked;

5) the other beam of light passing through the second beam splitting lens enters the single-mode laser after being reflected by the polarization beam splitting prism, the single-mode laser is injected and locked, and the mode selection is carried out by adjusting the temperature and the current of the single-mode laser, so that the frequency of the single-mode laser is equal to the frequency of the carrier wave of the VCSEL laser, and all other modes are suppressed;

6) the single-mode laser outputs the laser after mode selection, and the laser is output through the fourth light splitting lens.

8. The control method according to claim 7, wherein in step 1), the modulation signal frequency is continuously adjustable in a range of 10MHz to 10 GHz.

9. The control method of claim 7, wherein in step 4), the VCSEL laser can be continuously tuned within 10GHz, which is twice the maximum modulation signal frequency, after being locked, since the modulation signal frequency is continuously tunable within 10MHz to 10 GHz.

Technical Field

The invention relates to the photoelectron technology, in particular to a miniaturized low-cost frequency-stabilized laser system with a large frequency tuning range and a method.

Background

In the fundamental experimental research of atomic interferometer, atomic gravimeter, atomic gyroscope and atomic and molecular manipulation, a frequency stabilized laser is an indispensable device, and such a laser needs to have the following characteristics: 1. the system has a GHz tuning range and can lock all frequency points in the tuning range; 2. relative frequency stability of more than 10^-10(ii) a 3. The output power is in the order of hundreds of milliwatts.

Generally, a frequency stabilized laser can be locked to an optical cavity reference or an atomic or molecular frequency reference. The optical resonant cavity is influenced by temperature change and stress release, and the relative drift can be more than 10^-10(ii) a The frequency stabilized laser locked on the atomic and molecular frequency reference can only be locked at a few fixed resonance frequency points, and an external modulator is required to assist in completing tuning, such as an acousto-optic modulator, an electro-optic modulator and the like.

Existing miniaturized laser solutions that meet the above applications are: 1. the external cavity semiconductor laser has a complex structure, is greatly influenced by temperature and vibration, is volatile and locked, has low reliability, has the cost of 16000 RMB magnitude and the size of 150mm multiplied by 100mm multiplied by 120mm magnitude; 2, DFB laser linewidth is at megahertz magnitude, so do not need external cavity further to compress the linewidth, it is less influenced by shaking, the reliability is good, the cost is in 23000 yuan RMB magnitude, the size is in 40mm x 70mm magnitude. Neither of these two lasers can independently realize that all frequency points in the tuning range can be locked.

Disclosure of Invention

Aiming at the problems in the prior art, the invention provides a miniaturized low-cost large-frequency tuning range frequency-stabilized laser system and a method, the size of the laser system is 50mm multiplied by 25mm multiplied by 20mm, the cost is 6000 yuan RMB level, the laser system can be locked at any frequency point in the tuning range, and the frequency stability is better than 10^-10And the output power can reach hundreds of milliwatts.

One object of the present invention is to provide a miniaturized, low-cost, large-frequency tuning range frequency-stabilized laser system.

The miniaturized low-cost large-frequency tuning range frequency-stabilized laser system comprises: a modulation signal, a Vertical Cavity Surface Emitting Laser (VCSEL) Laser, a single-mode Laser, an optical fiber, an atomic gas chamber, a photodetector, and first to fourth spectroscope lenses; the modulation signal is loaded on a power supply of the VCSEL laser, and the current of the VCSEL laser is modulated, so that seed light is output, the seed light has a carrier and two sidebands, and the frequency difference between the carrier and the sidebands is equal to the frequency of the modulation signal; the seed light output by the VCSEL laser is divided into two beams by a first spectroscope, a reflected light beam is coupled into an optical fiber by a lens, a transmitted light beam passes through a free space, the two light beams are combined by a second spectroscope, a self-differencing beat frequency signal is formed due to optical path difference, and the line width of the seed light is compressed from a hundred megahertz magnitude to a megahertz magnitude; the combined beam is divided into two beams by a second beam splitter, one beam of light passes through a third beam splitter and enters an atomic gas chamber as pumping light, reflected light of a rear window of the atomic gas chamber is used as detection light, a saturated absorption spectrum is generated in the atomic gas chamber, and the saturated absorption spectrum has transmission peaks at an atomic resonance frequency point and at a frequency point of the atomic resonance frequency point plus a modulation signal frequency; the detection light returns along the original path and is reflected by the third beam splitting lens again to enter the photoelectric detector, the photoelectric detector detects the saturated absorption spectrum to obtain the position of a transmission peak, the position of the transmission peak is fed back to a power supply of the VCSEL laser to lock the laser center frequency, and the laser center frequency can be locked at the transmission peak of the saturated absorption spectrum; the other beam of light passing through the second beam splitting lens enters the single-mode laser after being reflected by the fourth beam splitting lens, the single-mode laser is injected and locked, and the mode selection is carried out by adjusting the temperature and the current of the single-mode laser, so that the frequency of the single-mode laser is equal to the frequency of the carrier wave of the VCSEL laser, and all other modes are suppressed; the single-mode laser outputs the laser after mode selection, and the laser is output through the fourth light splitting lens.

The frequency of the modulation signal is continuously adjustable between 10MHz and 10GHz, so that the VCSEL laser can be continuously tuned within the range of two times 10GHz after being locked. The output power of the single-mode laser is hundreds of milliwatts of laser light.

The single-mode laser adopts a miniaturized laser, and adopts a G-packaged single-mode laser or a C-packaged single-mode laser.

The back window of the atomic gas chamber is a concave lens, and the focal length of the concave lens is half of the length of the atomic gas chamber, so that optical feedback is reduced.

The first to third light splitting lenses adopt light splitting flat plates, and the fourth light splitting lens adopts a polarization beam splitter prism.

Another object of the present invention is to provide a method for controlling a small-sized, low-cost, large-frequency tuning range frequency-stabilized laser system.

The invention discloses a control method of a miniaturized low-cost large-frequency tuning range frequency-stabilized laser system, which comprises the following steps:

1) loading a modulation signal on a power supply of a VCSEL laser, and modulating the current of the VCSEL laser so as to output seed light, wherein the seed light has a carrier and two sidebands, and the frequency difference between the carrier and the sidebands is equal to the frequency of the modulation signal;

2) the seed light output by the VCSEL laser is divided into two beams by a first spectroscope, a reflected light beam is coupled into an optical fiber by a lens, a transmitted light beam passes through a free space, the two light beams are combined by a second spectroscope, a self-differencing beat signal is formed due to optical path difference, the self-differencing beat signal contains phase noise of laser, a phase discrimination signal generated by the self-differencing beat signal and a modulation signal is fed back to the VCSEL laser, the frequency of the VCSEL laser is adjusted, and the line width of the seed light is compressed from the hundred MHz level to the MHz level;

3) the combined beam is divided into two beams by a second beam splitter, one beam of light passes through a third beam splitter and enters an atomic gas chamber as pumping light, reflected light of a rear window of the atomic gas chamber is used as detection light, a saturated absorption spectrum is generated in the atomic gas chamber, and the saturated absorption spectrum has transmission peaks at an atomic resonance frequency point and at a frequency point of the atomic resonance frequency point plus a modulation signal frequency;

4) the detection light returns along the original path and enters the photoelectric detector after being reflected by the third beam splitting mirror again, the photoelectric detector detects the saturated absorption spectrum to obtain the position of a transmission peak, the position is fed back to a power supply of the VCSEL laser to lock the laser central frequency, the laser central frequency can be locked at the transmission peak of the saturated absorption spectrum, the frequency corresponding to the transmission peak of the saturated absorption spectrum is the frequency of an atomic hyperfine energy interstage transition frequency shift modulation signal, and the modulation signal frequency is continuously adjustable, so that the VCSEL laser can be continuously tuned within the range of 10GHz of twice the maximum modulation signal frequency after being locked;

5) the other beam of light passing through the second beam splitting lens enters the single-mode laser after being reflected by the polarization beam splitting prism, the single-mode laser is injected and locked, and the mode selection is carried out by adjusting the temperature and the current of the single-mode laser, so that the frequency of the single-mode laser is equal to the frequency of the carrier wave of the VCSEL laser, and all other modes are suppressed;

6) the single-mode laser outputs the laser after mode selection, and the laser is output through the fourth light splitting lens.

In the step 1), the frequency of the modulation signal is continuously adjustable within the range of 10MHz to 10 GHz.

In step 4), since the modulation signal frequency is continuously adjustable in the range of 10MHz to 10GHz, the VCSEL laser can be continuously tuned in the range of 10GHz which is twice the maximum modulation signal frequency after being locked.

The working principle of the miniaturized low-cost large-frequency tuning range frequency-stabilized laser system comprises the following steps: 1. because the tube core size of the VCSEL laser is small, the junction capacitance is small, and a modulation signal with the frequency within 10GHz can be loaded on the laser; the linewidth of the VCSEL laser is in the order of hundred megahertz, and the linewidth of an atomic saturation spectrum is lower than ten megahertz, so that the linewidth of the laser needs to be narrowed; the output power of the VCSEL laser is in the milliwatt level, so that the laser output of hundreds of milliwatt level power is required to be realized by injection locking; 4, after the current frequency modulation, the VCSEL laser can generate two side bands except the central frequency, the side bands also resonate with atoms and generate a saturated absorption spectrum, and the frequency of the side bands directly depends on the current modulation frequency which can be continuously adjusted, so that the transmission peak of the saturated absorption spectrum can realize seamless coverage spectrum, and any frequency point of the laser can be locked in a large range when the frequency is changed; 5. when injected into the lock, the temperature and current of the single-mode laser are adjusted to restrain all other sidebands so that the carrier wave can be surpassed in competition, and the laser finally outputs single-mode laser with the frequency capable of being tuned in a large range and locked.

The invention has the advantages that:

the invention 1 adopts a double-laser structure, and the size is 50mm multiplied by 25mm multiplied by 20 mm; 2. the cost is low, and is in the 6000 yuan RMB level; 3. the frequency is controlled by a VCSEL laser, two sidebands can be adjusted through current modulation (modulation frequency is continuously adjustable), the frequency can be continuously tuned in a large range of two times of 10GHz, the line width of a modulation signal is in a Hertz magnitude, the line width of a laser is in a megahertz magnitude, and the broadening of the modulation signal to the line width of the laser can be ignored; 4. the laser can be tuned by changing the frequency of the modulation signal without influencing the stability of the laser; 5. the single-mode laser has high output power, low cost and easy acquisition; 6. the whole laser system is realized by the zero-temperature-drift microcrystalline glass, and the reliability is high; the method can be widely applied to the technical fields of basic research and precision measurement such as laser precision measurement, atomic clocks, atomic interferometers, supercooled atomic experimental technology research and the like.

Drawings

FIG. 1 is a schematic block diagram of an optical path of an embodiment of a miniaturized low-cost large-frequency tuning range frequency stabilized laser of the present invention;

fig. 2 is a top view of one embodiment of a miniaturized, low-cost, large frequency tuning range frequency stabilized laser of the present invention.

Detailed Description

The invention will be further elucidated by means of specific embodiments in the following with reference to the drawing.

As shown in fig. 1, the miniaturized, low-cost, large-frequency tuning range frequency stabilized laser of the present embodiment includes: the device comprises a modulation signal, a VCSEL laser, a G-packaged single-mode laser, optical fibers, an atomic gas chamber, a photoelectric detector, first to third beam splitting plane plates M1-M3 and a polarization beam splitter prism M4; the modulation signal is loaded on a power supply of the VCSEL laser, the frequency of the modulation signal is continuously adjustable between 10MHz and 10GHz, the current of the VCSEL laser is modulated, and therefore seed light is output, the seed light has a carrier and two sidebands, and the frequency difference between the carrier and the sidebands is equal to the frequency of the modulation signal; seed light output by the VCSEL laser is divided into two beams through a first beam splitter M1, a reflected light beam is coupled into an optical fiber through a lens, a transmitted light beam passes through a free space, the two light beams are combined in a second beam splitter M2, a self-differential beat signal is formed due to optical path difference, the self-differential beat signal contains phase noise of laser, and a phase discrimination signal generated by the self-differential beat signal and a modulation signal is fed back to the VCSEL laser to adjust the frequency of the VCSEL laser, so that the line width of the seed light is compressed from a hundred megahertz level to a megahertz level; the combined beam is divided into two beams by the second beam splitter, one beam of light passes through the third beam splitter M3 to be used as pumping light to enter the atomic gas chamber, reflected light of a rear window of the atomic gas chamber is used as detection light, a saturated absorption spectrum is generated in the atomic gas chamber, and the saturated absorption spectrum has transmission peaks at an atomic resonance frequency point and at a frequency point of the atomic resonance frequency point plus a modulation signal frequency; the detection light returns along the original path and enters the photoelectric detector after being reflected by the third beam splitter again, the photoelectric detector detects the saturated absorption spectrum to obtain the position of a transmission peak, the position is fed back to a power supply of the VCSEL laser to lock the laser center frequency, the laser center frequency can be locked at the transmission peak of the saturated absorption spectrum, the frequency corresponding to the transmission peak of the saturated absorption spectrum is the frequency of the atomic hyperfine energy interstage transition frequency offset modulation signal, and the modulation signal frequency is continuously adjustable within the range of 10MHz to 10GHz, so that the VCSEL laser can be continuously tuned within the range of two times of 10GHz after being locked; the other beam of light passing through the second beam splitter plate enters the G-packaged single-mode laser after being reflected by the polarization beam splitter prism M4, the G-packaged single-mode laser is injected and locked, and the mode selection is carried out by adjusting the temperature and the current of the G-packaged single-mode laser, so that the frequency of the G-packaged single-mode laser is equal to the frequency of the carrier wave of the VCSEL laser, and all other modes are suppressed; the G-packaged single-mode laser outputs laser after mode selection, the laser is output through the polarization beam splitter prism, and the output power of the G-packaged single-mode laser is hundreds of milliwatts.

As shown in fig. 2, the overall size of the miniaturized, low-cost, large-frequency tuning range frequency-stabilized laser system of the present embodiment is: 50mm long, 25mm wide and 20mm high. The sizes of the VCSEL laser and the G-packaged single-mode laser are both in millimeter level; the diameter of the atomic gas chamber is 12mm, and the length of the atomic gas chamber is 15 mm; the laser, the optical fiber, the light splitting lens, the atomic gas chamber and the photoelectric detector are all fixed on the zero-temperature-drift glass ceramics.

Finally, it is noted that the disclosed embodiments are intended to aid in further understanding of the invention, but those skilled in the art will appreciate that: various substitutions and modifications are possible without departing from the spirit and scope of the invention and the appended claims. Therefore, the invention should not be limited to the embodiments disclosed, but the scope of the invention is defined by the appended claims.