Laser frequency division method and device

Abstract

The invention relates to a laser frequency division method, which is realized through a laser frequency division device, and the laser frequency division device comprises a Pockels cell and a polaroid. The laser frequency division method comprises the steps that the Pockels cell and the polaroid are placed on a laser light path needing light splitting, and the polaroid is arranged behind the Pockels cell in the light path direction; and applying a half-wave voltage pulse to the Pockels cell, and enabling the laser needing to be split to pass through the Pockels cell and the polaroid in sequence, so as to realize the splitting of the laser. A beam of high-frequency linearly polarized light can be divided into two beams of low-frequency laser, the monopulse energy of the two beams of laser after light splitting is equal to the monopulse energy of the laser before light splitting, and the energy requirement for a light source laser is low.

Description

Technical Field

[0001] This application relates to the technical field of lasers, and particularly to a laser frequency division method and device. Background Art

[0002] In the design and debugging of lasers, it is often necessary to split a beam of pulsed laser light. For example, split the local oscillator laser generated by a seed source to obtain two beams of seed light for amplification respectively, or split the high-energy laser generated by a laser for non-linear frequency conversion to achieve multi-band output. Currently, two common splitting methods are polarization splitting and semi-transmissive and semi-reflective splitting. In semi-transmissive and semi-reflective splitting, a beam of laser light is irradiated on a semi-transmissive and semi-reflective mirror, with half of the energy passing through the mirror and half of the energy being reflected at the mirror. This splitting method requires the laser intensity before splitting to be the sum of the required laser intensities after splitting. Due to the transmittance and placement angle of the mirror, it is difficult to ensure that the intensities of the two beams of laser light after splitting are the same. Polarization splitting uses a polarization beam splitter to split natural light, partially polarized light, or circularly polarized light into two beams of laser light. This splitting method has requirements for the polarization state of the laser light before splitting, and also requires the laser intensity before splitting to be the sum of the required laser intensities after splitting. Both of these methods have relatively high requirements for the laser energy before splitting, and the design and debugging of lasers are more difficult. Summary of the Invention

[0003] This application provides a laser frequency division method and device to solve the problems in the above background art.

[0004] In a first aspect, this application provides a laser frequency division method, which is implemented through a laser frequency division device. The laser frequency division device includes a Pockels cell and a polarizer; the laser frequency division method includes:

[0005] Place the Pockels cell and the polarizer on the laser light path that needs to be split, and the polarizer is arranged behind the Pockels cell along the light path direction;

[0006] Apply a half-wave voltage pulse to the Pockels cell, so that the laser light that needs to be split passes through the Pockels cell and the polarizer in sequence, to achieve splitting of the laser light.

[0007] Further, the laser frequency division device further includes a driver; applying the half-wave voltage pulse to the Pockels cell includes:

[0008] Connect the output end of the driver to both ends of the Pockels cell, so that the driver outputs high voltage to apply a half-wave voltage pulse to the Pockels cell.

[0009] Further, after making the driver output high voltage to apply a half-wave voltage pulse to the Pockels cell, it further includes:

[0010] Adjust the frequency and delay of the high voltage output by the driver so that the frequency of the high voltage output by the driver is half of the laser frequency before beam splitting, and each high voltage pulse contains one laser pulse.

[0011] Further, the laser frequency division method further includes:

[0012] Control the waveform of the high voltage output by the driver to control the code patterns of the two beams of laser after beam splitting.

[0013] Further, the laser frequency division method further includes:

[0014] Control the frequency and pulse width of the high voltage applied by the driver to the Pockels cell to obtain two beams of laser with different frequencies or pulse encodings after beam splitting.

[0015] Further, the laser frequency division method further includes:

[0016] Perform beam splitting on the laser after beam splitting again and through non - linear frequency conversion to achieve multi - band laser output.

[0017] In a second aspect, the present application provides a laser frequency division device, including a Pockels cell, a polarizer and a driver; the laser frequency division device is used to implement the laser frequency division method as described above.

[0018] Further, the Pockels cell includes an electro - optic crystal, an insulating package and an exposed electrode, and the exposed electrode is connected to both ends of the electro - optic crystal;

[0019] The exposed electrode is used to be connected to the output end of the driver to apply a voltage to both ends of the electro - optic crystal; the electro - optic crystal is used to change the polarization state of the transmitted laser when a half - wave voltage is applied.

[0020] Further, the driver includes a power input terminal, a signal input terminal and an output terminal;

[0021] The power input terminal is used to provide a driving voltage for the driver, the signal input terminal is used to provide a clock signal for the driver, and the output terminal is used to output high voltage.

[0022] Further, the polarizer is used to transmit p - polarized light and reflect s - polarized light.

[0023] The above - mentioned technical solution of the present application has the following advantages:

[0024] The laser frequency division method provided in the first aspect of the present application places the Pockels cell and the polarizer on the laser light path that needs to be split, and the polarizer is arranged behind the Pockels cell along the light path direction. A half-wave voltage pulse is applied to the Pockels cell, so that the laser that needs to be split passes through the Pockels cell and the polarizer in sequence, so as to realize the splitting of the laser. It can split a high-frequency linearly polarized light into two low-frequency lasers. The single-pulse energy of the two lasers after splitting is equal to the single-pulse energy of the laser before splitting, and the energy requirement for the light source laser is low.

[0025] It can be understood that the beneficial effects of the above second aspect can be referred to the relevant descriptions in the above first aspect, and will not be elaborated here. Description of the Drawings

[0026] In order to more clearly illustrate the specific embodiments of the present application or the technical solutions in the prior art, the following will briefly introduce the drawings required for the description of the specific embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present application. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0027] Figure 1 It is a schematic diagram of the laser frequency division device provided by the present application. Detailed Embodiments

[0028] In the following description, for the purpose of illustration rather than limitation, specific details such as specific system structures and technologies are put forward in order to thoroughly understand the embodiments of the present application. However, those skilled in the art should clearly understand that the present application can also be implemented in other embodiments without these specific details. In other cases, the detailed descriptions of well-known systems, devices, circuits and methods are omitted to avoid unnecessary details from interfering with the description of the present application.

[0029] It should be understood that when used in the description of the present application specification and the appended claims, the term "comprising" indicates the presence of the described features, wholes, steps, operations, elements and / or components, but does not exclude the presence or addition of one or more other features, wholes, steps, operations, elements, components and / or their combinations.

[0030] In addition, in the description of the present application specification and the appended claims, the terms "first", "second", "third", etc. are only used for distinguishing descriptions, and cannot be understood as indicating or implying relative importance.

[0031] As described in the specification of this application, references to "one embodiment" or "some embodiments" etc. mean that in one or more embodiments of this application, specific features, structures or characteristics described in connection with that embodiment are included. Thus, statements such as "in one embodiment", "in some embodiments", "in other some embodiments", "in still other embodiments" etc. that appear in different places in this specification do not necessarily all refer to the same embodiment, but mean "one or more but not all of the embodiments", unless otherwise specifically emphasized in other ways. The terms "comprise", "include", "have" and their variants all mean "include but not limited to", unless otherwise specifically emphasized in other ways. "Plurality" means "two or more".

[0032] To solve the deficiencies of the prior art, this application proposes a laser frequency division method and device, which divides a beam of high-frequency linearly polarized light into two beams of low-frequency lasers, and the single-pulse energy of the two lasers after beam splitting is equal to the single-pulse energy of the laser before beam splitting.

[0033] The following will further describe in detail the specific implementation manners of this application in conjunction with the accompanying drawings and embodiments. The following embodiments are used to illustrate this application, but are not used to limit the scope of this application.

[0034] The embodiment of this application provides a laser frequency division method, which is implemented through a laser frequency division device, as Figure 1 shown, the laser frequency division device includes a Pockels cell and a polarizer; the laser frequency division method includes: placing the Pockels cell and the polarizer on the laser light path that needs to be split, and the polarizer is arranged behind the Pockels cell along the light path direction; applying a half-wave voltage pulse to the Pockels cell, so that the laser that needs to be split passes through the Pockels cell and the polarizer in sequence, so as to realize the splitting of the laser.

[0035] In some embodiments, the laser frequency division device further includes a driver; applying the half-wave voltage pulse to the Pockels cell includes: connecting the output end of the driver to both ends of the Pockels cell, so that the driver outputs high voltage, so as to realize applying a half-wave voltage pulse to the Pockels cell.

[0036] In some embodiments, after making the driver output high voltage to realize applying a half-wave voltage pulse to the Pockels cell, it further includes: adjusting the frequency and delay of the high voltage output by the driver, so that the frequency of the high voltage output by the driver is half of the laser frequency before beam splitting, and each high voltage pulse time contains one laser pulse.

[0037] In some embodiments, the laser frequency division method further includes: controlling the waveform of the high voltage output by the driver, so as to realize controlling the code patterns of the two lasers after beam splitting.

[0038] In some embodiments, the laser frequency division method further includes: controlling the frequency and pulse width of the high voltage applied by the driver to the Pockels cell, so as to obtain two lasers with different frequencies or pulse codes after beam splitting.

[0039] In some embodiments, the laser frequency division method further includes: splitting the laser after beam splitting again and performing non-linear frequency conversion to achieve multi-band laser output.

[0040] The Pockels cell includes an electro-optic crystal, an insulating package and exposed electrodes. The exposed electrodes are connected to both ends of the electro-optic crystal, and a voltage can be applied to both ends of the crystal through the exposed electrodes. When the voltage applied to the electro-optic crystal is the half-wave voltage, the phase delay of the incident laser changes by π when passing through the electro-optic crystal, thereby changing the polarization state of the light passing through the electro-optic crystal.

[0041] The driver has a power input, a signal input and a high voltage output. The power input provides a driving voltage for the entire driver. The signal input is synchronized with the high voltage output, and each time a signal clock is input, there is a corresponding high voltage output. The high voltage output is connected to the exposed electrodes of the Pockels cell. By controlling the clock signal input to the driver, precise control of the polarization state of the incident laser by the Pockels cell can be achieved.

[0042] The polarizer is a lens made according to the principle of light polarization, which realizes beam splitting of two lasers with different polarization states. The p-polarized light can pass through the polarizer, and the s-polarized light will be reflected at the polarizer. By selecting polarizers with different parameters, the direction of the output laser can be controlled.

[0043] Under the action of the driver, after the Pockels cell is applied with the half-wave voltage, the polarization state of the incident laser is changed, and the p-polarized pulsed laser can be converted into an s-polarized pulsed laser, or the s-polarized pulsed laser can be converted into a p-polarized pulsed laser. When the device is working, the previous incident p-polarized pulsed laser directly passes through the Pockels cell without the half-wave voltage applied to the Pockels cell and the polarization state remains unchanged, and then enters the polarizer. Since it is p-polarized, this laser passes through the polarizer and is output; the latter incident p-polarized pulsed laser passes through the Pockels cell and the polarization state becomes s-polarized after the Pockels cell is applied with the half-wave voltage, and then enters the polarizer. Since it is s-polarized, this laser is reflected by the polarizer and output. In this way, it alternates in a cycle to achieve splitting a high-frequency laser into two low-frequency lasers.

[0044] If two lasers with different frequencies or pulse codes are needed, it can be achieved by controlling the frequency and pulse width of the high voltage applied by the driver to the Pockels cell.

[0045] The embodiment of the present application also provides a laser frequency division device, such as Figure 1As shown, it includes a Pockels cell, a polarizer, and a driver; the laser frequency division device is used to implement the laser frequency division method as described above.

[0046] In some embodiments, the Pockels cell includes an electro-optic crystal, an insulating package, and exposed electrodes, and the exposed electrodes are connected to both ends of the electro-optic crystal; the exposed electrodes are used to connect to the output end of the driver to apply a voltage across the electro-optic crystal; the electro-optic crystal is used to change the polarization state of the transmitted laser when a half-wave voltage is applied.

[0047] In some embodiments, the driver includes a power input terminal, a signal input terminal, and an output terminal; the power input terminal is used to provide a driving voltage for the driver, the signal input terminal is used to provide a clock signal for the driver, and the output terminal is used to output a high voltage.

[0048] In some embodiments, the polarizer is used to transmit p-polarized light and reflect s-polarized light.

[0049] In application, place the Pockels cell on the laser light path that needs to be frequency-divided, and place the polarizer behind the Pockels cell to ensure that the laser that needs to be frequency-divided first passes through the Pockels cell and then through the polarizer. The high voltage output by the driver should be the half-wave voltage of the Pockels cell, and connect the output terminal of the driver to both ends of the Pockels cell. Adjust the frequency and delay of the high voltage output by the driver so that the frequency of the high voltage output by the driver is half of the frequency of the laser before frequency division, and each high voltage pulse time contains one laser pulse. For the previous incident p-polarized pulsed laser, without applying a half-wave voltage to the Pockels cell, it directly passes through the Pockels cell and the polarization state remains unchanged, and then it is incident on the polarizer. Since it is p-polarized, this laser passes through the polarizer and is output; for the latter incident p-polarized pulsed laser, when a half-wave voltage is applied to the Pockels cell, after passing through the Pockels cell, the polarization state becomes s-polarized, and then it is incident on the polarizer. Since it is s-polarized, this laser is reflected by the polarizer and output. By alternating in this way, a high-frequency laser beam is frequency-divided into two low-frequency laser beams, and the single-pulse energy of the laser is equal to that before frequency division. The laser obtained after frequency division can be frequency-divided again and through non-linear frequency conversion, multi-band laser output can be realized.

[0050] The laser frequency division method and device provided by the embodiments of the present application frequency-divide a pulsed laser beam in the time dimension, divide a high-frequency laser beam into two low-frequency laser beams, and can control the code patterns of the two low-frequency laser beams by controlling the waveform of the high voltage output by the driver. The single-pulse energy of the two low-frequency laser beams is equal to the single-pulse energy of the laser before frequency division, and the energy requirement for the light source laser is low.

[0051] Those skilled in the art can clearly understand that, for the convenience and brevity of description, only the above-mentioned division of each functional unit and module is used as an example. In actual applications, the above functions can be allocated to different functional units and modules according to needs, that is, the internal structure of the device is divided into different functional units or modules to complete all or part of the functions described above. Each functional unit and module in the embodiments can be integrated into a processing unit, or each unit can exist physically alone, or two or more units can be integrated into one unit. In addition, the specific names of the functional units and modules are only for the convenience of mutual distinction and do not limit the protection scope of the present application.

[0052] The above-described embodiments are only used to illustrate the technical solutions of the present application, rather than to limit it; although the present application has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements for some of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present application, and should all be included in the protection scope of the present application.

Claims

1. A laser frequency division method, characterized in that: The method is realized by a laser frequency division device, wherein the laser frequency division device comprises a Pockels cell and a polarizer; the laser frequency division method comprises: Placing the Pockels cell and the polarizer on the laser light path that needs to be split, and the polarizer is arranged after the Pockels cell along the light path direction; A half-wave voltage pulse is applied to the Pockels cell, so that the laser light to be split passes through the Pockels cell and the polarizer successively, so as to achieve splitting of the laser light.

2. The laser frequency division method according to claim 1, characterized in that: The laser frequency division device further includes a driver; the step of applying a half-wave voltage pulse to the Pockels cell includes: The output end of the driver is connected to the two ends of the Pockels cell so that the driver outputs a high voltage, thereby applying a half-wave voltage pulse to the Pockels cell.

3. The laser frequency division method according to claim 2, characterized in that: After the driver is caused to output a high voltage to implement the application of a half-wave voltage pulse to the Pockels cell, the method further comprises: The frequency and delay of the high voltage output by the driver are adjusted so that the frequency of the high voltage output by the driver is half of the laser frequency before splitting, and each high voltage pulse contains a laser pulse.

4. The laser frequency division method according to claim 2, characterized in that: The laser frequency division method further includes: The driver is controlled to output a high voltage waveform to achieve the control of the code type of the two laser beams after the splitting.

5. The laser frequency division method according to claim 2, characterized in that: The laser frequency division method further includes: The frequency and pulse width of the high voltage applied by the driver to the Pockels cell are controlled to obtain two laser beams with different frequencies or pulse codes after light splitting.

6. The laser frequency division method according to claim 1, characterized in that: The laser frequency division method further includes: The split laser is split again and multi-band laser output is achieved through nonlinear frequency conversion.

7. A laser frequency division device, characterized in that: It comprises a Pockels cell, a polarizer and a driver; the laser frequency division device is used to implement the laser frequency division method according to any one of claims 1 to 6.

8. The laser frequency division device according to claim 7, characterized in that: The Pockels cell comprises an electro-optical crystal, an insulating package and exposed electrodes, wherein the exposed electrodes are connected to two ends of the electro-optical crystal; The exposed electrode is used to be connected to the output end of the driver so as to apply voltage to both ends of the electro-optical crystal; the electro-optical crystal is used to change the polarization state of the passing laser when a half-wave voltage is applied thereto.

9. The laser frequency division device according to claim 7, characterized in that: The driver comprises a power input terminal, a signal input terminal and an output terminal; The power input terminal is used to provide a driving voltage for the driver, the signal input terminal is used to provide a clock signal for the driver, and the output terminal is used to output a high voltage.

10. The laser frequency division device according to claim 7, characterized in that: The polarizer is used to transmit p-polarized light and reflect s-polarized light.

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