Pre-feedback phase locking device and method for locking carrier envelope phase offset frequency based on pre-feedback

Abstract

The invention relates to a front feedback phase locking device and a method for locking carrier envelope phase offset frequency based on front feedback. An exemplary pre-feedback phase locking apparatus includes: an oscillator to generate laser light; the laser beam splitting module is used for splitting the laser into a first light beam and a second light beam; the carrier envelope phase shift frequency measurement module is used for measuring the carrier envelope phase shift frequency of the first light beam; and the carrier envelope phase shift frequency locking module is used for locking the carrier envelope phase shift frequency of the second light beam.

Description

Technical Field

[0001] The present disclosure generally relates to the field of ultrafast laser technology, and in particular, to a pre-feedback phase locking device and a method for locking a carrier envelope phase offset frequency based on pre-feedback. Background Art

[0002] With the development of attosecond (as) science and frequency standard metrology, the control of pulse carrier-envelope phase offset (CEO) frequency, especially the few-cycle pulse CEO frequency, has become an important issue. Whether the CEO frequency is stable will greatly affect the oscillation mode and peak electric field strength of the electric field.

[0003] The CEO frequency of pulses in femtosecond lasers drifts due to the presence of dispersion elements and self-phase modulation in femtosecond lasers. In addition, environmental factors such as temperature, airflow, vibration, pump stability, and gain loss changes can also affect the CEO frequency of pulses in femtosecond lasers.

[0004] Compared with other gain media, Ti:sapphire has an extremely wide emission bandwidth and high thermal conductivity, making it an excellent gain crystal in the field of ultrafast laser technology. At present, the CEO frequency control method of conventional Ti:sapphire oscillators is generally locked by pump feedback. The specific method is to first use the f-2f or 0-f measurement method to obtain the CEO frequency (expressed as f CEO ) signal, and f CEO The signal is compared with the local signal to obtain an error signal, which is fed back to the acousto-optic modulator (AOM) of the oscillator pump source through a proportional-integral-derivative (PID) circuit. The oscillator cavity gain is changed by changing the power of the pump source, thereby changing the intracavity dispersion and achieving f CEO modulation.

[0005] However, the pump feedback solution has the following disadvantages. First, the pump feedback is easily affected by environmental noise, resulting in f CEO The oscillator is locked and cannot be locked for a long time. Secondly, it cannot be automatically rebuilt after losing the lock. Moreover, when adjusting the PID circuit, the oscillator mode locking is easily lost due to the influence of the dispersion in the oscillator cavity.

[0006] In addition, the f CEOThe locking method currently still uses the above-mentioned pump feedback scheme, f CEO The problem of long-term lock is difficult to solve. Summary of the invention

[0007] In a first aspect, a pre-feedback phase locking device is provided, comprising: an oscillator for generating laser; a laser beam splitting module for splitting the laser into a first light beam and a second light beam; a carrier-envelope phase offset frequency measurement module for measuring the carrier-envelope phase offset frequency of the first light beam; and a carrier-envelope phase offset frequency locking module for locking the carrier-envelope phase offset frequency of the second light beam.

[0008] In some embodiments, the oscillator is a titanium sapphire oscillator having a pair of wedges symmetrically arranged at a Brewster angle in an optical path for generating the laser.

[0009] In some embodiments, the pre-feedback phase locking device further comprises a feedback circuit, at least one of the pair of wedges is connected to the feedback circuit, and the feedback circuit is used to adjust the at least one wedge to stabilize the carrier envelope phase offset frequency of the laser.

[0010] In some embodiments, the laser beam splitting module includes: a half-wave plate for adjusting the polarization state of the laser; and a polarization beam splitter for splitting the laser with adjusted polarization state into p light with a polarization direction parallel to the incident plane and s light with a polarization direction perpendicular to the incident plane, the first light beam is the s light, and the second light beam is the p light.

[0011] In some embodiments, the carrier-envelope phase offset frequency measurement module is a self-difference frequency 0-f module or a self-reference f-2f module.

[0012] In some embodiments, the carrier-envelope phase offset frequency locking module has an acousto-optic modulator or an acousto-optic frequency shifter for generating -1 order diffraction light of the second light beam.

[0013] In a second aspect, a method for locking a carrier-envelope phase offset frequency based on pre-feedback is provided, comprising: using an oscillator to generate a laser; using a laser beam splitting module to split the laser into a first beam and a second beam; using a carrier-envelope phase offset frequency measurement module to measure the carrier-envelope phase offset frequency of the first beam; and using a carrier-envelope phase offset frequency locking module to lock the carrier-envelope phase offset frequency of the second beam.

[0014] In some embodiments, the oscillator is a titanium sapphire oscillator, and a pair of wedges are symmetrically arranged at the Brewster angle in the optical path generating the laser, at least one of the pair of wedges is connected to a feedback circuit, and the feedback circuit is used to adjust the at least one wedge to stabilize the carrier envelope phase offset frequency of the laser.

[0015] In some embodiments, the laser beam splitting module includes a half-wave plate and a polarization beam splitter. The half-wave plate is used to adjust the polarization state of the laser, and the polarization beam splitter is used to split the laser with adjusted polarization state into p light whose polarization direction is parallel to the incident plane and s light whose polarization direction is perpendicular to the incident plane. The first light beam is the s light, and the second light beam is the p light.

[0016] In some embodiments, the carrier-envelope phase offset frequency locking module has an acousto-optic modulator or an acousto-optic frequency shifter, and the acousto-optic modulator or the acousto-optic frequency shifter is used to generate the -1st order diffraction light of the second light beam.

[0017] The above and other features and advantages of the present disclosure will become apparent from the following description of specific embodiments with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 is a structural diagram of a forward feedback phase locking device according to an exemplary embodiment of the present disclosure.

[0019] Figure 2 The present invention is a flowchart of a method for locking a carrier envelope phase offset frequency based on forward feedback according to an exemplary embodiment of the present disclosure. DETAILED DESCRIPTION

[0020] Below, the example embodiments according to the present disclosure will be described in detail with reference to the accompanying drawings. Note that the accompanying drawings may not be drawn to scale. Obviously, the described embodiments are only part of the embodiments of the present disclosure, rather than all the embodiments of the present disclosure, and the present disclosure is not limited to the example embodiments described here.

[0021] Figure 1 is a structural diagram of a forward feedback phase locking device according to an exemplary embodiment of the present disclosure, wherein the optical route is represented by a dotted line and the circuit is represented by a solid line. Figure 1 As shown, the feedforward phase locking device according to an exemplary embodiment of the present disclosure may include an oscillator 100 and a feedforward phase locking module 200 .

[0022] The oscillator 100 can be used to generate laser. In some embodiments, the oscillator 100 can be a titanium sapphire oscillator. The power of the titanium sapphire oscillator can be, for example, 0.1mW-2000mW, for example, 200-1000mW, for example, 600mW. In some embodiments, the wavelength of the titanium sapphire oscillator 100 can be, for example, 515-1064nm, for example, 650-1064nm, for example, 750-850nm. In some embodiments, the titanium sapphire oscillator 100 can generate a few-cycle femtosecond pulse laser with a central wavelength in the 800nm ​​band, the wavelength bandwidth can be, for example, 600-1000nm, the average power can be 200-700mW, the pulse width can be 5-50fs, or the pulse width range can be 10-30fs.

[0023] The pre-feedback phase locking module 200 may include a laser beam splitting module 300 , a carrier envelope phase offset (CEO) frequency measurement module 400 , and a carrier envelope phase offset (CEO) frequency locking module 500 .

[0024] The laser beam splitting module 300 can split the laser generated by the oscillator 100 into a first beam and a second beam, wherein the first beam enters the CEO frequency measurement module 400, which can be used to measure the CEO frequency of the first beam, and the second beam enters the CEO frequency locking module 500, which can be used to lock the CEO frequency of the second beam.

[0025] In some embodiments, the laser beam splitting module 300 may include a half-wave plate 3 and a polarization beam splitter 4 in sequence on the optical path. The half-wave plate 3 may be used to adjust the polarization state of the laser light generated by the oscillator 100. For example, by rotating the half-wave plate 3, the polarization state of the laser light emitted by the titanium sapphire oscillator 100 may be changed. The polarization beam splitter 4 may be used to split the laser light whose polarization state is adjusted by the half-wave plate 3 into a p-light whose polarization direction is parallel to the incident plane and an s-light whose polarization direction is perpendicular to the incident plane, and the first light beam may be the s-light and the second light beam may be the p-light. In some embodiments, the laser beam splitting module 300 may split the laser light in a tunable ratio, wherein a small portion of the light is reflected into the CEO frequency measurement module 400 and most of the light is transmitted into the CEO frequency locking module 500. For example, the splitting ratio of the first light beam reflected by the polarization beam splitter 4 to the CEO frequency measurement module 400 and the second light beam transmitted to the CEO frequency locking module 500 may be, for example, 3:7.

[0026] In some embodiments, the CEO frequency measurement module 400 may be a self-difference frequency 0-f module or a self-reference f-2f module, for example, an f-2f interferometer, which may be used to obtain f CEO Signal. Figure 1As shown, the CEO frequency measurement module 400 may include a first reflector 5, a second reflector 6, a first half-wave plate 7, a first aspheric lens collimator 8, a photonic crystal fiber 9, a second aspheric lens collimator 10, a third reflector 11, a dichroic mirror 12, a fourth reflector 13, a fifth reflector 14, a first convex lens 15, a frequency doubling crystal 16, a second convex lens 17, a sixth reflector 18, a filter 19, a third convex lens 20, and an avalanche diode 21.

[0027] After the first light beam enters the CEO frequency measurement module 400, it is first reflected by the first reflector 5 and the second reflector 6. In some embodiments, the first reflector 5 and the second reflector 6 can be silver mirrors, and the size can be, for example, half an inch, for folding the optical path. In some embodiments, the first reflector 5 and the second reflector 6 can be chirped mirrors.

[0028] The first light beam reflected by the first reflector 5 and the second reflector 6 in sequence passes through the first half-wave plate 7 and enters the first aspheric lens collimator 8. The first aspheric lens collimator 8 is tunable, and the focal length can be, for example, 0.4-3.0 mm. The first aspheric lens collimator 8 can focus the first light beam into the photonic crystal fiber 9.

[0029] The photonic crystal fiber 9 can, for example, enable the first light beam to generate a supercontinuum spectrum in the 532-1064 nm band. After exiting the photonic crystal fiber 9 , the supercontinuum first light beam enters the second aspheric lens collimator 10 , which collimates the first light beam.

[0030] In some embodiments, the first light beam collimated by the second aspheric lens collimator 10 can be reflected by the third reflector 11 and enter the dichroic mirror 12. The third reflector 11 can be, for example, a silver mirror, and the dichroic mirror 12 can have a transmittance greater than 90% for light with a wavelength of 825-1300nm and a reflectance greater than 95% for light with a wavelength of 400-785nm. Thus, the dichroic mirror 12 can, for example, directly reflect the laser light with a wavelength less than 805nm in the first light beam to the fifth reflector 14, transmit the laser light with a wavelength greater than 805nm in the first light beam to the fourth reflector 13 at the rear, and the laser light with a wavelength greater than 805nm in the first light beam is reflected by the fourth reflector 13 to the fifth reflector 14. The fourth reflector 13 can be, for example, a silver mirror, and the fifth reflector 14 can be, for example, a square silver mirror.

[0031] Two paths of light, namely, the laser light with a wavelength less than 805nm in the first light beam and the laser light with a wavelength greater than 805nm in the first light beam, are reflected by the fifth reflector 14 and enter the first convex lens 15. The focal length of the first convex lens 15 may be, for example, 30mm, and the size may be, for example, half an inch, and may be used to converge the two paths of light to the frequency doubling crystal 16. The frequency doubling crystal 16 may be, for example, magnesium oxide-doped periodically poled lithium niobate, and its period may be, for example, 6.97 microns (μm), which can frequency double the light with a wavelength of 1064nm reflected by the fourth reflector 13 to 532nm, and completely transmit the laser light with a wavelength less than 805nm, so that the first light beam output by the frequency doubling crystal 16 includes the short-wave light with a wavelength less than 805nm divided by the dichroic mirror 12 and the frequency doubled light with a wavelength greater than 805nm doubled by the frequency doubling crystal 16.

[0032] The first light beam passing through the frequency doubling crystal 16 then enters the second convex lens 17, which can collimate the first light beam, and its focal length can be, for example, 30 mm, and its size can be, for example, half an inch. The first light beam collimated by the second convex lens 17 is reflected by the sixth reflector 18 and enters the filter 19. The sixth reflector 18 can be, for example, a silver mirror, and its size can be, for example, half an inch. The filter 19 can be, for example, a bandpass filter, and for example, has a transmittance greater than 90% for lasers with a wavelength of 532 nm.

[0033] The first light beam filtered by the filter 19 enters the third convex lens 20. The third convex lens 20 can focus the first light beam, and its focal length can be, for example, 30 mm, and its size can be, for example, half an inch.

[0034] Then, the short-wave light and the doubled frequency light of the first light beam enter the avalanche diode 21, and the avalanche diode 21 converts the optical signal into an electrical signal, generating a free-running f of the oscillator 100 on the probe of the avalanche diode 21. CEO The beat frequency signal, the f CEO The beat frequency signal contains the f CEO All noise information.

[0035] In some embodiments, the fifth reflector 14, the first convex lens 15, the frequency doubling crystal 16, the second convex lens 17, the sixth reflector 18, the filter 19, the third convex lens 20, and the avalanche diode 21 are on the same horizontal axis plane.

[0036] On the other hand, the CEO frequency locking module 500 may include a seventh reflector 22, an eighth reflector 23, an acoustic optic frequency shifter (AOFS) or an acoustic optic modulator (AOM) 24. The second light beam transmitted through the polarization beam splitter 4 is reflected by the seventh reflector 22 and the eighth reflector 23 in sequence and enters the AOFS or AOM 24. The seventh reflector 22 and the eighth reflector 23 may be, for example, silver mirrors.

[0037] In some embodiments, the pre-feedback phase locking device may further include a circuit module 600 , and the circuit module 600 may be respectively connected to the avalanche diode 21 , the AOFS or AOM 24 , and the oscillator 100 through circuits.

[0038] The f measured by the avalanche diode 21 CEO After the beat frequency signal is processed by the circuit module 600, a constant power will be output to drive the AOFS or AOM 24. For example, if the f measured by the avalanche diode 21 is CEO If the beat frequency signal is below -40dBm, the f CEO The beat signal is filtered, amplified, and mixed with a local signal of, for example, 60 MHz in the circuit module 600 to obtain a mixed signal of at least 10 mW to drive the acousto-optic driver in the circuit module 600. The circuit module 600 may have a first feedback circuit connected to the AOFS or AOM 24, so that the acousto-optic driver will output a signal of constant power to drive the AOFS or AOM 24. The second beam of laser light is introduced into the AOFS or AOM 24 to fine-tune the angle of the AOFS or AOM 24, and while obtaining the 0th order diffraction light 26, the -1st order diffraction light 25 is obtained. Thereafter, the AOFS or AOM 24 can be fixed at this angle without further adjustment.

[0039] The frequency of the laser generated by the oscillator 100 and entering the pre-feedback phase locking module 200 is f input , f input =nf rep +f CEO , where f rep is the repetition frequency in the CEO frequency locking module 500, n is a multiple, and can be a positive integer greater than or equal to 1. The signal frequency driving the AOFS or AOM 24 is f drive , f drive =f CEO +f lo , where f lois the frequency of the local signal of the circuit module 600. The frequency f of the -1st order diffracted light 25 is obtained by using the frequency shift function of the AOFS or AOM 24. -1 , f -1 =f input -f drive =nf rep +f CEO -(f CEO +f lo )=nf rep -f lo In this way, f CEO The signal is frequency-shifted to a low-noise local signal, and the -1 order diffraction light 25 is the locked f CEO The driving frequency f of AOFS or AOM 24 drive For example, it may be in the range of 60-100 MHz, for example, 80 MHz. The frequency f of the local signal lo For example, it may be in the range of 0.1-200 MHz, for example, in the range of 5-100 MHz, or for example, in the range of 20-60 MHz, or for example, 20 MHz, or for example, 60 MHz. The driving frequency f drive and the frequency f of the local signal lo It refers to a specific frequency rather than a range. The above-mentioned "in a certain range" refers to a specific frequency within the range.

[0040] In some embodiments, the oscillator 100 has a pair of wedges 1 and 2 symmetrically arranged at a Brewster's angle in the optical path of generating the laser, and the second feedback circuit in the circuit module 600 can be connected to at least one of the pair of wedges 1 and 2, and the second feedback circuit can be used to adjust at least one of the connected wedges to stabilize the CEO frequency of the laser.

[0041] The second feedback circuit may be, for example, a slow loop feedback circuit, for example, connected to the sharp wedge 1, and by controlling the insertion amount of the sharp wedge 1, f CEO The beat frequency signal is controlled at about 20MHz for a long time, so that the AOFS or AOM 24 is kept at the operating frequency for a long time, thereby obtaining a low-noise pulse laser that is locked for a long time. For example, the wedge 1 is placed on a translation stage controlled by a piezoelectric screw, and a slow loop feedback is applied to the piezoelectric screw to adjust the f CEO The long-term control is around 20MHz.

[0042] According to the forward feedback phase locking device of the exemplary embodiment of the present disclosure, the laser emitted by the oscillator 100 is placed in the forward direction by AOFS or AOM 24 for optical frequency shifting, thereby achieving f CEO of the actuator, so it can be called "forward feedback".

[0043] Figure 2 8 is a flow chart of a method 800 for locking a carrier envelope phase offset frequency based on forward feedback according to an exemplary embodiment of the present disclosure. Figure 2 The method 800 shown may be performed, for example, by using Figure 1 It is implemented by the forward feedback phase locking device shown.

[0044] like Figure 2 As shown, in operation 810, for example, an oscillator 100 can be used to generate a laser; in operation 820, for example, a laser beam splitting module 300 can be used to split the laser into a first light beam and a second light beam; in operation 830, a CEO frequency measurement module 400 can be used to measure the CEO frequency of the first light beam; and in operation 840, a CEO frequency locking module 500 can be used to lock the CEO frequency of the second light beam.

[0045] In some embodiments, the oscillator 100 can be a titanium sapphire oscillator, and a pair of wedges 1 and 2 can be symmetrically arranged at the Brewster angle in the optical path of the laser. At least one wedge in the pair of wedges 1 and 2, such as wedge 1, can be connected to a second feedback circuit in the circuit module 600, and the second feedback circuit can be used to adjust at least one wedge connected to the second feedback circuit, such as wedge 1, to stabilize the CEO frequency of the laser.

[0046] In some embodiments, the laser beam splitting module 300 may include a half-wave plate 3 and a polarization beam splitter 4. The half-wave plate 3 can be used to adjust the polarization state of the laser, and the polarization beam splitter 4 can be used to split the laser with adjusted polarization state into p light whose polarization direction is parallel to the incident plane and s light whose polarization direction is perpendicular to the incident plane. The first light beam can be s light, and the second light beam can be p light.

[0047] In some embodiments, the CEO frequency locking module 500 may have an AOM or an AOFS 24 , and the AOM or the AOFS 24 may be used to generate the −1 -order diffracted light 25 of the second light beam.

[0048] According to the forward feedback phase locking device of the exemplary embodiment of the present disclosure and the method for locking the CEO frequency based on forward feedback, a part of the light (for example, the first light beam mentioned above) is generated into a beat frequency signal through a self-difference frequency 0-f module or a self-reference f-2f module (for example, the CEO frequency measurement module 400 mentioned above), and then the light of the main optical path (for example, the second light beam mentioned above) is modulated by a forward feedback circuit (for example, the first feedback circuit applied to AOFS or AOM 24 in the aforementioned circuit module 600) and an acousto-optic modulator or an acousto-optic frequency shifter (for example, the aforementioned AOFS or AOM 24), thereby achieving the locking of the long-term carrier envelope phase, for example, the CEO frequency.

[0049] In addition, according to the pre-feedback phase locking device and the method for locking the CEO frequency based on pre-feedback of the exemplary embodiment of the present disclosure, the scheme for CEO frequency locking based on pre-feedback is used, which can not only adjust the frequency of the CEO after locking, but also realize the long-term CEO locking of the titanium sapphire laser by adding a slow-loop feedback circuit, such as the second feedback circuit applied to the wedge in the aforementioned circuit module 600. According to the pre-feedback phase locking device and the method for locking the CEO frequency based on pre-feedback of the exemplary embodiment of the present disclosure, it can be applied to a variety of femtosecond lasers, and can realize the fast locking of the CEO of a femtosecond laser with a few cycles, which can not only not change the laser state, but also realize the long-term carrier envelope phase, such as CEO frequency, locking.

[0050] Under the condition of achieving CEO locking, compared with the existing methods and devices, the forward feedback phase locking device and the method for locking the CEO frequency based on forward feedback according to the exemplary embodiments of the present disclosure are easy to rebuild after loss of lock, are not easily affected by environmental noise, and after applying slow-loop feedback to the sharp wedge in the oscillator, the CEO locking time can be greatly increased.

[0051] The basic principles of the present disclosure are described above in conjunction with specific embodiments. However, it should be noted that the advantages, strengths, effects, etc. mentioned in the present disclosure are only examples and not limitations, and it cannot be considered that these advantages, strengths, effects, etc. are required by each embodiment of the present disclosure. In addition, the specific details disclosed above are only for the purpose of illustration and ease of understanding, and are not limitations. The above details do not limit the present disclosure to the necessity of adopting the above specific details to be implemented.

[0052] The block diagrams of the devices, apparatuses, equipment and systems involved in the present disclosure are only illustrative examples and are not intended to require or imply that they must be connected, arranged and configured in the manner shown in the block diagram. As will be appreciated by those skilled in the art, these devices, apparatuses, equipment and systems can be connected, arranged and configured in any manner. Each block shown in the figure can be subdivided into multiple sub-blocks, and each sub-block can implement related functions or steps, so that multiple sub-blocks can realize the functions realized by a large block before subdivision. Alternatively, the multiple blocks shown in the figure can also be merged into one block, which can realize the functions of multiple blocks before merging. In the present disclosure, words such as "including", "comprising", "having" and the like are open words, referring to "including but not limited to", and can be used interchangeably with them. The words "or" and "and" used here refer to the words "and / or" and can be used interchangeably with them, unless the context clearly indicates otherwise. The words "such as" used here refer to the phrase "such as but not limited to", and can be used interchangeably with them.

[0053] It should be noted that in the apparatus, device and method of the present disclosure, each component or each step can be decomposed and / or recombined. Such decomposition and / or recombination should be regarded as equivalent solutions of the present disclosure.

[0054] The above description of the disclosed aspects is provided to enable any person skilled in the art to make or use the present disclosure. Various modifications to these aspects will be readily apparent to those skilled in the art, and the general principles defined herein may be applied to other aspects without departing from the scope of the present disclosure. Therefore, the present disclosure is not intended to be limited to the aspects shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

[0055] The above description has been given for the purpose of illustration and description. In addition, this description is not intended to limit the embodiments of the present disclosure to the forms disclosed herein. Although multiple example aspects and embodiments have been discussed above, those skilled in the art will recognize certain variations, modifications, changes, additions and sub-combinations thereof.

Claims

1. A pre-feedback phase locking device, comprising: Oscillator, used to generate laser light; A laser beam splitting module, used for splitting the laser into a first light beam and a second light beam; a carrier-envelope phase offset frequency measurement module, configured to measure the carrier-envelope phase offset frequency of the first light beam; and The carrier-envelope phase offset frequency locking module is used to lock the carrier-envelope phase offset frequency of the second light beam.

2. The pre-feedback phase locking device according to claim 1, wherein: The oscillator is a titanium sapphire oscillator, and has a pair of wedges symmetrically arranged at the Brewster angle on the optical path of generating the laser.

3. The pre-feedback phase locking device as described in claim 2 further has a feedback circuit, at least one of the pair of wedges is connected to the feedback circuit, and the feedback circuit is used to adjust the at least one wedge to stabilize the carrier envelope phase offset frequency of the laser.

4. The forward feedback phase locking device according to claim 1, wherein: The laser beam splitting module comprises: A half-wave plate, used to adjust the polarization state of the laser; and The polarization beam splitter is used to split the laser light with adjusted polarization state into p light with polarization direction parallel to the incident plane and s light with polarization direction perpendicular to the incident plane, the first light beam is the s light, and the second light beam is the p light.

5. The forward feedback phase locking device according to claim 1, wherein: The carrier envelope phase offset frequency measurement module is a self-difference frequency 0-f module or a self-reference f-2f module.

6. The forward feedback phase locking device according to any one of claims 1 to 5, wherein: The carrier-envelope phase offset frequency locking module has an acousto-optic modulator or an acousto-optic frequency shifter, which is used to generate -1 order diffraction light of the second light beam.

7. A method for locking a carrier envelope phase offset frequency based on pre-feedback, comprising: Use an oscillator to generate laser light; Using a laser beam splitting module to split the laser into a first beam and a second beam; Using a carrier-envelope phase offset frequency measurement module to measure the carrier-envelope phase offset frequency of the first light beam; and A carrier-envelope phase offset frequency locking module is used to lock the carrier-envelope phase offset frequency of the second light beam.

8. The method for locking the carrier envelope phase offset frequency as claimed in claim 7, wherein: The oscillator is a titanium sapphire oscillator, and a pair of wedges are symmetrically arranged at the Brewster angle on the optical path generating the laser. At least one of the pair of wedges is connected to a feedback circuit, and the feedback circuit is used to adjust the at least one wedge to stabilize the carrier envelope phase offset frequency of the laser.

9. The method for locking the carrier envelope phase offset frequency as claimed in claim 7, wherein: The laser beam splitting module includes a half-wave plate and a polarization beam splitter. The half-wave plate is used to adjust the polarization state of the laser, and the polarization beam splitter is used to split the laser with adjusted polarization state into p light with a polarization direction parallel to the incident plane and s light with a polarization direction perpendicular to the incident plane. The first light beam is the s light, and the second light beam is the p light.

10. The method for locking the carrier envelope phase offset frequency according to any one of claims 7 to 9, wherein: The carrier-envelope phase offset frequency locking module has an acousto-optic modulator or an acousto-optic frequency shifter, and uses the acousto-optic modulator or the acousto-optic frequency shifter to generate -1st order diffraction light of the second light beam.

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