阅读说明：本技术 一种低电压独立加压式电光q开关 (Low-voltage independent pressurization type electro-optical Q switch ) 是由 商继芳 孙军 杨金凤 周娅玲 郝好山 于 2021-07-12 设计创作，主要内容包括：本发明提供了一种低电压独立加压式电光Q开关,属于晶体材料在光电技术领域中的应用。本发明是由铌酸锂或者钽酸锂晶体按照一定的设计切型制成的一种电光Q开关器件,用于YAG激光器及其他激光器中作电光调Q使用。本发明的电光Q开关能够独立进行加压式电光调Q,既规避了传统加压式电光调Q需要额外使用偏振元件,进而导致的插入损耗大、激光器结构不够紧凑稳定的弊端,又保留了加压式工作对调Q驱动源要求低、Q开关寿命长等优点。同时,本发明的电光Q开关半波电压得到有效降低,器件更加容易制备。(The invention provides a low-voltage independent pressurization type electro-optical Q switch, belonging to the application of crystal materials in the field of photoelectric technology. The invention relates to an electro-optical Q-switch device which is made by cutting lithium niobate or lithium tantalate crystals according to a certain design and is used for electro-optical Q-switching in YAG lasers and other lasers. The electro-optical Q switch can independently perform pressurized electro-optical Q switching, overcomes the defects that the traditional pressurized electro-optical Q switching needs an additional polarizing element, so that the insertion loss is large, and the laser structure is not compact and stable enough, and also keeps the advantages of low requirement of pressurized work on Q switching drive sources, long service life of the Q switch and the like. Meanwhile, the half-wave voltage of the electro-optical Q-switch is effectively reduced, and the device is easier to prepare.)

1. A low-voltage independent pressurization type electro-optical Q switch is characterized in that: the electro-optic crystal is cut at a special angle intoWhereiny、zThe axes represent the respective crystal axes of the electro-optic crystal,brepresenting the width direction of the cut crystal,θthe angle is acute.

2. The low voltage, independently pressurized electro-optic Q-switch of claim 1, wherein the low voltage, independently pressurized electro-optic Q-switch is characterized byθThe angle satisfies the relation:wherein, in the step (A),，Lthe length of the light-transmitting direction is,n _oandn _eis the natural birefringence of the electro-optic crystal,λis the laser wavelength.

3. The low voltage, independently pressurized electro-optic Q-switch of claim 1, wherein: the electro-optic crystal is a lithium niobate crystal or a lithium tantalate crystal.

4. The low voltage, independently pressurized electro-optic Q-switch of claim 1, wherein: the length direction of the electro-optic crystal is the light passing direction, and two end faces are polished and plated with laser antireflection films.

5. The low voltage, independently pressurized electro-optic Q-switch of claim 1, wherein: an electric field is applied along the thickness direction of the crystal, and two crystal faces in the thickness direction are plated with metal films.

6. The low voltage, independently pressurized electro-optic Q-switch according to any of claims 1-5, characterized in that: the cutting type can also beOrWhereinx、zThe axes represent the respective crystal axes of the electro-optic crystal,l、brespectively representing the length and width directions of the cut crystal.

7. The low voltage, independently pressurized electro-optic Q-switch of claim 6, wherein: the electro-optical Q switch independently realizes the pressurized electro-optical Q-switching under the condition of not adding 1/4 wave plates or analyzers.

8. The use of a low voltage independently pressurized electro-optic Q-switch as claimed in claim 7 in a laser resonator.

9. Use according to claim 8, characterized in that: when the laser resonator is applied, laser is incident perpendicular to a light-passing surface, and the thickness or width direction of a crystal and the transmission direction of a polarizer form an angle of 45 degrees.

Technical Field

The invention relates to the field of laser devices, in particular to a low-voltage independent pressurization type electro-optical Q switch.

Background

In the field of laser technology, the Q-switching technology is one of the most important ways to obtain high-peak-power narrow-pulse-width laser at present, and the Q-switching technology modulates the loss in a laser resonant cavity periodically by a certain method, so that energy is stored in a laser working substance in a large amount during the high loss period, when the energy is accumulated to the maximum value, the loss in the cavity is suddenly reduced to the minimum, at the moment, laser oscillation is rapidly established, and a large amount of energy is rapidly released in a very short time, thereby realizing the output of the high-peak-power narrow-pulse-width laser.

The existing Q-switching technology mainly comprises electro-optic Q-switching, acousto-optic Q-switching, passive Q-switching, mechanical Q-switching and the like. Compared with other Q-switching technologies, the electro-optical Q-switching has the advantages of high switching rate, strong turn-off capability, active controllability and the like, and is more favorable for obtaining stable and controllable high-peak-power short pulse laser, so that the electro-optical Q-switching technology is widely applied to the field of laser, and electro-optical Q-switching devices are widely applied to pulse lasers.

At present, the practical electro-optical Q-switch device is mainly composed of potassium dideuterium phosphate (KD)₂PO₄DKDP), lithium niobate (LiNbO)₃LN), rubidium titanyl phosphate (RbTiOPO)₄RTP) and the like, and the switch configuration mainly adopts a so-called tangential mode, i.e. a light-passing direction and a power-on direction are respectively along a certain main axis of the crystal. When the electro-optical Q switch with the structure works in a pressurized Q-switching mode, a quarter-wave plate or an analyzer must be additionally used, on one hand, the intra-cavity loss is increased, the compactness and the stability of a laser are not facilitated, and on the other hand, the cost and the debugging difficulty are increased. When the Q-switching is applied during voltage relief, although a polarizing element is not required to be added, the service life of a Q-switching device is shortened due to the long-time action of high voltage, and the preparation difficulty of the voltage relief type electro-optical driving power supply is higher. In addition, some crystals have piezoelectric and elasto-optical effects, and the Q-switching performance of the crystals is seriously affected or even cannot work when the crystals are applied in a decompression mode.

In the early days, we designed and developed an electro-optical Q-switch with complex functions (patent of "a complex function electro-optical Q-switch (CN 108767650B)") which could realize the Q-switched operation in the pressurized mode without adding a quarter-wave plate or an analyzer, and combined the advantages of the Q-switched operation in the pressurized mode and the Q-switched operation in the decompressed mode, however, the half-wave voltage of the LN electro-optical Q-switch with this configuration and the traditional onezThe LN electro-optical Q-switches are equal and the drive voltage is still relatively high. In addition, the switch is cut intoThere is a certain difficulty in processing and preparation.

Disclosure of Invention

The invention provides a low-voltage independent pressurization type electro-optic Q switch, which solves the defects that the prior art can not take the advantages of pressurization type electro-optic Q switch and voltage-relief type electro-optic Q switch into consideration, the half-wave voltage of the switch is high, the preparation difficulty is high and the like. The electro-optical Q switch device provided not only combines the advantages of the pressurization type and the decompression type, but also can independently realize the Q-switching of the pressurization type electro-optical Q switch, and meanwhile, the half-wave voltage is lower, and the processing and debugging difficulty is smaller.

The technical scheme for realizing the invention is as follows:

a low-voltage independent-pressurizing electro-optical Q switch is characterized in that an electro-optical crystal is cut at a special angle in a shape ofWhereiny、zThe axes represent the respective crystal axes of the electro-optic crystal,brepresenting the width direction of the cut crystal,θthe angle is acute.

The above-mentionedθThe angle satisfies the relation:wherein, in the step (A),，Lthe length of the light-transmitting direction is,n _oandn _eis the natural birefringence of the electro-optic crystal,λis the laser wavelength.

The electro-optic crystal is a lithium niobate crystal or a lithium tantalate crystal.

The length direction of the electro-optic crystal is the light passing direction, and two end faces are polished and plated with laser antireflection films.

An electric field is applied along the thickness direction of the crystal, and two crystal faces in the thickness direction are plated with metal films.

The cutting type can also beOrWhereinx、zThe axes represent the respective crystal axes of the electro-optic crystal,l、brespectively representing the length and width directions of the cut crystal.

The half-wave voltage of the electro-optical Q switch is reduced by more than 1 kV.

When the laser resonator is applied, laser is incident perpendicular to a light-passing surface, and the thickness or width direction of a crystal and the transmission direction of a polarizer form an angle of 45 degrees.

The invention has the beneficial effects that:

(1) compared with the traditional tangent electro-optical Q switch, the electro-optical Q switch can independently realize the pressurized electro-optical Q switching under the condition of not adding 1/4 wave plates or analyzers, and simultaneously combines the advantages of the pressurized Q switching work and the voltage-releasing Q switching work, so that a laser is more compact and stable, the debugging difficulty and the cost are lower, the service life of a device is longer, and the requirement on an electro-optical Q switching driving power supply is lower.

(2) Andcompared with a cut LN electro-optical Q switch, the invention optimizes the best crystal cut and modulation mode by analyzing and calculating the electro-optical effect when the power is applied along any direction and combining the electro-optical Q-switching theory, the half-wave voltage of the designed electro-optical Q switch is greatly reduced, and the voltage can be reduced by more than 1 kV; meanwhile, the crystal cut of the electro-optical Q switch only involves one-time rotation, and the electro-optical Q switch is easier to process and prepare.

(3) The invention relates to an electro-optical Q-switch device which is made by cutting lithium niobate or lithium tantalate crystals according to a certain design and is used for electro-optical Q-switching in YAG lasers and other lasers. The electro-optical Q switch can independently carry out pressurized electro-optical Q switching, overcomes the defects that the traditional pressurized electro-optical Q switching needs to additionally use a polarizing element, and further causes large insertion loss and an insufficiently compact and stable laser structure, and also keeps the advantages of low requirement of pressurized work on Q-switching driving sources, long service life of the Q switch and the like. Meanwhile, the half-wave voltage of the electro-optical Q-switch is effectively reduced, and the device is easier to prepare.

Drawings

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

Fig. 1 is a schematic diagram of an electro-optical Q-switch of the present invention. In the drawingsx、y、zThe axes represent the respective crystal axes of the electro-optic crystal,l、b、 trespectively representing the length, width and thickness directions of the cut crystal.

Detailed Description

The technical solutions of the present invention will be described clearly and completely with reference to the following embodiments of the present invention, and it should be understood 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 obtained by a person skilled in the art without inventive effort based on the embodiments of the present invention, are within the scope of the present invention.

Example 1

The low-voltage independent pressurization type electro-optical Q switch is prepared by LN crystal, and the size of the Q switch is designed to be 9 mm multiplied by 18.8 mm (thickness)tX widthbX lengthl) The method is applied to lasers with laser wavelength of 1064 nm. By the formulaGet itk=5, substituting the corresponding parameter to obtainθAt a value of 2.5 DEG, the LN crystal is set in accordance withCutting, polishing and plating both end faces in the length directionAnd plating Au/Ti electrodes on two crystal faces of the anti-reflection film with the thickness direction of 1064 nm.

When the Q-switch is applied to a laser, laser is incident perpendicular to the end face of a crystal, and the thickness and width directions of the Q-switch and the transmission direction of a polarizer in the laser are arranged at an angle of 45 degrees. From FIG. 1, it can be seen that the angle between the laser propagation direction and the crystal optical axis isθI.e. 2.5 deg., the azimuth angle of the propagation direction is-90 deg..

When no voltage is applied, the phase difference generated by natural birefringence after laser passes through the Q switch is 11p/2, the intrinsic polarization direction respectively follows the thickness direction and the width direction, namely the direction of the transmission of the polarizer forms 45 degrees, the laser is reflected by the full-reflection mirror and then passes through the Q switch again to generate the phase difference of 11p/2, so the total phase difference is 11p, at the moment, the polarization direction of the laser just rotates 90 degrees relative to the original polarization direction, the laser cannot pass through the polarizer again, the Q switch is in a turn-off state, the cavity loss is maximum, and the Q value is minimum.

When 1/4 wave voltage is applied to the Q switch, the phase difference generated after the laser passes through the Q switch is changed into 5p, the total phase difference is 10p after the laser passes through the crystal twice in a reciprocating mode, the polarization direction of the laser is still the same as the original polarization direction, the Q switch can be in an open state through the polarizer, the cavity loss is minimum, and the Q value is highest.

When the electro-optical Q switch is applied to an Nd-YAG laser, a light path can be completely cut off when no voltage is applied, stable pulse laser output is obtained when 1/4-wave Q-switching high voltage is applied, when the repetition frequency is 10Hz, the single-pulse output energy is 200mJ, and the pulse width is 7ns, namely the independent pressurization type electro-optical Q-switching is realized, and a 1/4 wave plate or an analyzer is not required to be used in a resonant cavity. The 1/4 wave voltage is 1650V, and compared with an electro-optical Q switch (invention patent of a functional composite electro-optical Q switch (CN 108767650B)) with a cut shape of (xztw) -1.2 degrees/1.2 degrees, the half-wave voltage is reduced by 1100V.

Example 2

The low-voltage independent pressurization type electro-optical Q switch is prepared by LN crystal, and the size of the Q switch is designed to be 9 mm multiplied by 18.8 mm (thickness)tX widthbX lengthl) The method is applied to lasers with laser wavelength of 1064 nm. By the formulaGet itk=4, substituting the corresponding parameter to obtainθA value of 2.3 DEG, and an LN crystal according toCutting, polishing two end faces along the length direction, plating an antireflection film of 1064 nm, and plating Au/Ti electrodes on two crystal faces along the thickness direction.

When the Q-switch is applied to a laser, laser is made to enter perpendicular to the end face of a crystal, and the thickness and width directions of the Q-switch and the transmission direction of a polarizer in the laser are arranged at an angle of 45 degrees. Thus, in the crystal axis coordinate system, the included angle between the laser propagation direction and the crystal optical axis isθI.e. 2.3 deg., the azimuth angle of the propagation direction is 30 deg..

When no voltage is applied, the phase difference generated by natural birefringence after laser passes through the Q switch is 9p/2, the intrinsic polarization direction respectively follows the thickness direction and the width direction, namely the direction of the transmission of the polarizer forms 45 degrees, the laser is reflected by the full-reflection mirror and then passes through the Q switch again to generate the phase difference of 9p/2, so the total phase difference is 9p, at the moment, the polarization direction of the laser just rotates 90 degrees relative to the original polarization direction, the laser cannot pass through the polarizer again, the Q switch is in a turn-off state, the cavity loss is maximum, and the Q value is minimum.

When 1/4 wave voltage is applied to the Q switch, the phase difference generated after the laser passes through the Q switch is changed into 4p, the total phase difference is 8p after the laser passes through the crystal twice in a reciprocating mode, the polarization direction of the laser is still the same as the original polarization direction, the Q switch can be in an open state through the polarizer, the cavity loss is minimum, and the Q value is highest.

When the electro-optical Q switch is applied to an Nd: YAG laser, the light path can be completely cut off when no voltage is applied. When 1/4 wave Q-switching high voltage is applied, stable pulse laser output is obtained, when the repetition frequency is 10Hz, the single pulse output energy is 200mJ, the pulse width is 7ns, namely, the independent pressurization type electro-optic Q-switching is realized, and a 1/4 wave plate or an analyzer is not needed to be used in a resonant cavity. 1/4 wave voltage is 1750V, and compared with an electro-optical Q switch (invention patent "a function composite electro-optical Q switch (CN 108767650B)") with a cut shape of (xztw) -1.2 degrees/1.2 degrees designed in the earlier stage, half-wave voltage is reduced by 900V.

Example 3:

the low-voltage independent pressurization type electro-optical Q switch is prepared by LN crystal, and the size of the Q switch is designed to be 9 mm multiplied by 18.8 mm (thickness)tX widthbX lengthl) The method is applied to lasers with laser wavelength of 1064 nm. By the formulaGet itk=6, substituting the corresponding parameter to obtainθA value of 2.7 DEG, and an LN crystal according toCutting, polishing two end faces along the length direction, plating an antireflection film of 1064 nm, and plating Au/Ti electrodes on two crystal faces along the thickness direction.

When the Q-switch is applied to a laser, laser is made to enter perpendicular to the end face of a crystal, and the thickness and width directions of the Q-switch and the transmission direction of a polarizer in the laser are arranged at an angle of 45 degrees. Thus, in the crystal axis coordinate system, the included angle between the laser propagation direction and the crystal optical axis isθI.e. 2.7 deg., the azimuth angle of the propagation direction is 150 deg..

When no voltage is applied, the phase difference generated by natural birefringence after laser passes through the Q switch is 13p/2, the intrinsic polarization direction respectively follows the thickness direction and the width direction, namely the direction of the transmission of the polarizer forms 45 degrees, the laser is reflected by the full-reflection mirror and then passes through the Q switch again to generate the phase difference of 13p/2, so the total phase difference is 13p, at the moment, the polarization direction of the laser just rotates 90 degrees relative to the original polarization direction, the laser cannot pass through the polarizer again, the Q switch is in a turn-off state, the cavity loss is maximum, and the Q value is minimum.

When 1/4 wave voltage is applied to the Q switch, the phase difference generated after the laser passes through the Q switch is changed into 6p, the total phase difference is 12p after the laser passes through the crystal twice in a reciprocating mode, the polarization direction of the laser is still the same as the original polarization direction, the Q switch can be in an open state through the polarizer, the cavity loss is minimum, and the Q value is highest.

When the electro-optical Q switch is applied to an Nd: YAG laser, the light path can be completely cut off when no voltage is applied. When 1/4 wave Q-switching high voltage is applied, stable pulse laser output is obtained, when the repetition frequency is 10Hz, the single pulse output energy is 200mJ, the pulse width is 7ns, namely, the independent pressurization type electro-optic Q-switching is realized, and a 1/4 wave plate or an analyzer is not needed to be used in a resonant cavity. 1/4 wave voltage is 1600V, compared with the electro-optical Q-switch (patent of invention, a function composite electro-optical Q-switch (CN 108767650B) with the cut shape of (xztw) -1.2 °/1.2 °), half-wave voltage is reduced by 1200V.

The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like that fall within the spirit and principle of the present invention are intended to be included therein.