CN215070853U - Single-frequency phase-locked laser amplifier - Google Patents
Single-frequency phase-locked laser amplifier Download PDFInfo
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- CN215070853U CN215070853U CN202121027945.4U CN202121027945U CN215070853U CN 215070853 U CN215070853 U CN 215070853U CN 202121027945 U CN202121027945 U CN 202121027945U CN 215070853 U CN215070853 U CN 215070853U
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Abstract
The utility model discloses a single-frequency phase-locked laser amplifier for further improving the power of a deep ultraviolet laser light source, which comprises an optical fiber beam splitter, an optical fiber amplitude modulator, a primary power amplifier, a phase modulator, a secondary power amplifier, a tertiary power amplifier, a pulse string output switch module and a closed-loop control module; the optical fiber beam splitter, the optical fiber amplitude modulator, the primary power amplifier, the phase modulator, the secondary power amplifier, the tertiary power amplifier and the pulse string output switch module are sequentially connected; the closed-loop control module is respectively in signal connection with the optical fiber amplitude modulator, the primary power amplifier, the phase modulator, the secondary power amplifier, the tertiary power amplifier and the pulse train output switch module. The utility model discloses it is simple relatively to have a technical route, and stability is higher, can realize commercial beneficial effect in batches.
Description
Technical Field
The utility model relates to a semiconductor photoetching light source field among the laser technology field specifically indicates a single-frequency lock phase laser amplifier.
Background
Photolithography is one of the most important process steps in semiconductor manufacturing, and a laser, i.e., a light source, is one of the core devices of a photolithography machine. The deep ultraviolet laser light source widely used at present is taken as an example, an excimer laser is adopted, and the wavelength can reach 193 nm. Meanwhile, research shows that the high-power extreme deep ultraviolet light source is the most important light source applied to the field of semiconductor lithography in the future process of semiconductor process upgrading, so that the technical difficulty needing to be broken through at present is also to further improve the power of the light source through the laser amplifier on the basis of the existing laser light source.
In the prior art, an excimer laser is generally adopted to bombard a metallic tin target material to further generate an ultra-deep ultraviolet light source with 13.5nm so as to improve the power of the light source. However, the inventor of the present application has found through research that the technical route involved in the method is very complex, the technical difficulty of further narrowing the wavelength and further increasing the power is very high, and the recently proposed mode of multiple interactions between the electron microbeam and the single-frequency laser to obtain the higher harmonic laser output is expected to provide a technical path of a higher-efficiency and higher-power euv light source, wherein the laser acting on the electron beam needs to use the laser amplifier described herein.
In summary, an amplifier which has a relatively simple technical route and higher stability and can realize batch commercial use and be used for further improving the power of the deep ultraviolet laser light source is absent at present.
SUMMERY OF THE UTILITY MODEL
The to-be-solved technical problem of the utility model is to provide a technical route is simple relatively, and stability is higher, can realize commercial single-frequency lock-in laser amplifier who is used for further improving deep ultraviolet laser light source's power in batches.
In order to solve the technical problem, the utility model provides a technical scheme does: a single-frequency phase-locked laser amplifier comprises an optical fiber beam splitter, an optical fiber amplitude modulator, a primary power amplifier, a phase modulator, a secondary power amplifier, a tertiary power amplifier, a pulse string output switch module and a closed-loop control module; the optical fiber beam splitter, the optical fiber amplitude modulator, the primary power amplifier, the phase modulator, the secondary power amplifier, the tertiary power amplifier and the pulse string output switch module are sequentially connected; the closed-loop control module is respectively in signal connection with the optical fiber amplitude modulator, the primary power amplifier, the phase modulator, the secondary power amplifier, the tertiary power amplifier and the pulse train output switch module; the optical fiber beam splitter is used for splitting input seed source laser into two parts, one part is injected into a rear-stage light path for laser amplification, and the other part is used as reference light to interfere with the amplified main laser in a pulse train output switch module at the tail end, so that the phase of the main laser is locked on the reference light; the optical fiber amplitude modulator is used for chopping continuous single-frequency seed laser into pulse laser with specific repetition frequency and pulse width; the phase modulator is used for modulating the phase of the main laser light path, and the control circuit controls the signal of the phase modulator by extracting an interference measurement signal in the final pulse train output module to achieve the purpose of phase locking; the pulse train output switch module is used for enabling the main laser to realize pulse train output and simultaneously generating a power control signal and a phase control signal; the closed-loop control module is used for generating a closed-loop control signal to control the optical fiber phase modulator to realize phase closed loop.
Preferably, the chopping pulse width of the optical fiber amplitude modulator is within 3 ns.
Preferably, the first-stage power amplifier is a single-mode fiber amplifier, and is used for increasing the average power of the pulsed laser to a level of 100 mW.
Preferably, the second-stage power amplifier adopts a large mode field optical fiber amplifier to increase the average power of the pulse laser to the magnitude of several watts.
Preferably, the three-stage power amplifier adopts an ultra-large mode field optical fiber amplifier, the average power of the pulse laser is further improved to hundreds of watts, and meanwhile, the peak power reaches tens of kilowatts.
Preferably, the pump source in the three-stage power amplifier comprises a high-power multimode diode laser and a plurality of butterfly diode lasers.
Preferably, the pulse train output switch module comprises a main laser output collimation head, a reference light output collimation head, a first polarization beam splitter, a second polarization beam splitter, a third polarization beam splitter, a fourth polarization beam splitter, an electro-optical switch, a waste light barrel, a first half glass sheet, a second half glass sheet, a first photoelectric detector and a second photoelectric detector; the main laser output collimation head is sequentially connected with the electro-optical switch, the second polarization beam splitter and the waste light barrel through the first polarization beam splitter; the first polarization beam splitter is also sequentially connected with the first half glass, the third polarization beam splitter, the second half glass and the fourth polarization beam splitter; the first photoelectric detector is connected with the third polarization beam splitter; and the reference light output collimation head and the second photoelectric detector are connected with the fourth polarization beam splitter.
Preferably, the heat dissipation is carried out by adopting a forced water cooling mode, and the water cooling temperature control precision is superior to 0.1 ℃.
Preferably, the splitting ratio of the optical fiber splitter is 90: 10.
After the structure is adopted, the utility model discloses following beneficial effect has: the method has the advantages that the interaction of the single-frequency laser and the electron micro-bunching in the electron annular accelerator is creatively utilized, the output of the ultra-deep ultraviolet laser is obtained through multiple modulation, the strict single frequency and phase locking of the laser are controlled in the process, and the phase can be kept consistent when the electrons and the laser interact for multiple times; the amplification efficiency and stability of the amplifier can be further improved according to various preference.
To sum up, the utility model provides a technical route is simple relatively, and stability is higher, can realize commercial single-frequency lock-in laser amplifier who is used for further improving deep ultraviolet laser light source's power in batches.
Drawings
Fig. 1 is a schematic structural diagram of a middle single-frequency phase-locked laser amplifier of the present invention.
Fig. 2 is the structure diagram of the pulse train output switch module in the middle single-frequency phase-locked laser amplifier of the present invention.
As shown in the figure: the single-frequency continuous laser seed source 101, the fiber splitter 102, the fiber amplitude modulator 103, the primary power amplifier 104, the phase modulator 105, the secondary power amplifier 106, the tertiary power amplifier 107, the pulse train output switch module 108 and the closed-loop control module 109, the main laser output collimation head 201, the reference light output collimation head 210, the first polarization beam splitter 202, the second polarization beam splitter 204, the third polarization beam splitter 207, the fourth polarization beam splitter 211, the electro-optical switch 203, the waste light barrel 205, the first half glass 206, the second half glass 209, the first photodetector 208 and the second photodetector 212.
Detailed Description
The present invention will be described in further detail with reference to the accompanying drawings.
The utility model discloses a single-frequency phase-locked laser amplifier, which comprises an optical fiber beam splitter 102, an optical fiber amplitude modulator 103, a primary power amplifier 104, a phase modulator 105, a secondary power amplifier 106, a tertiary power amplifier 107, a pulse string output switch module 108 and a closed-loop control module 109; the optical fiber beam splitter 102, the optical fiber amplitude modulator 103, the primary power amplifier 104, the phase modulator 105, the secondary power amplifier 106, the tertiary power amplifier 107 and the pulse train output switch module 108 are connected in sequence; the closed-loop control module 109 is in signal connection with the fiber amplitude modulator 103, the primary power amplifier 104, the phase modulator 105, the secondary power amplifier 106, the tertiary power amplifier 107 and the pulse train output switch module 108 respectively; the optical fiber beam splitter 102 is configured to split an input seed source laser into two parts, one part is injected into a post-stage optical path for laser amplification, and the other part is used as a reference light and interferes with the amplified main laser in a pulse train output switch module 108 at the end, so that the phase of the main laser is locked on the reference light; the optical fiber amplitude modulator 103 is used for chopping continuous single-frequency seed laser into pulse laser with specific repetition frequency and pulse width; the phase modulator 105 is used for modulating the phase of the main laser light path, and the control circuit controls the signal of the phase modulator by extracting an interference measurement signal in the final pulse train output module to achieve the purpose of phase locking; the pulse train output switch module 108 is used for enabling the main laser to realize pulse train output and simultaneously generating a power control signal and a phase control signal; the closed-loop control module 109 is configured to generate a closed-loop control signal to control the fiber phase modulator 105 to implement phase closed-loop. The pulse train output switch module 108 comprises a main laser output collimation head 201, a reference light output collimation head 210, a first polarization beam splitter 202, a second polarization beam splitter 204, a third polarization beam splitter 207, a fourth polarization beam splitter 211, an electro-optical switch 203, a waste light barrel 205, a first half glass 206, a second half glass 209, a first photoelectric detector 208 and a second photoelectric detector 212; the main laser output collimation head 201 is sequentially connected with an electro-optical switch 203, a second polarization beam splitter 204 and a waste light barrel 205 through a first polarization beam splitter 202; the first polarizing beam splitter 202 is also connected to a first half slide 206, a third polarizing beam splitter 207, a second half slide 209 and a fourth polarizing beam splitter 211 in sequence; the first photodetector 208 is connected to the third polarization beam splitter 207; the reference light output collimating head 210 and the second photodetector 212 are both connected to a fourth polarizing beam splitter 211.
Further combining with fig. 1 and fig. 2, in the specific implementation of the present application, the single-frequency continuous laser seed source 101 is used as an injection light source of an amplifier, the line width is required to be less than 10kHz to ensure a sufficiently long coherence length, and meanwhile, in order to ensure long-time stability, the interior of the seed source is required to lock the frequency, and at least, the frequency stability is ensured to be higher than 10-12Magnitude. The splitting ratio of the fiber splitter 102 is preferably 90:10, i.e. the main laser power enters the post-amplification path and the small amount is used as a referenceThe light enters the closed loop control module 109. The circuit driving of the pump sources used by the first-stage power amplifier 104, the second-stage power amplifier 106 and the third-stage power amplifier 107 should ensure high stability enough to make the power stability of the open loop better than 1%. The three-stage power amplifier 107 also has a pumping path except for finishing the power amplification of the final stage, and adopts butterfly-shaped single-mode pumping and user power closed-loop feedback. In the pulse train output switch module 108, in addition to ensuring that the high repetition frequency pulse laser forms a pulse train output, the main laser is sampled, and a part of the sampled laser interferes with the reference laser. The sampled laser and interfered laser signals are detected by a low noise photodetector and the signals enter the closed loop control module 109. As preferred, the laser amplifier in this patent application adopts the cooling mode of forced water-cooling to dispel the heat, and water-cooling temperature control precision is superior to 0.1 degree centigrade.
The main laser enters the pulse train output switch module 108 through the main laser output collimating head 201, is polarized by the first polarization beam splitter 202, and part of the vertical polarization component is reflected for monitoring. After the main laser is polarized, the electro-optical switch 203 receives timing control of the control circuit through the electro-optical switch 203. When the polarization state is consistent with the polarization direction of the second polarization beam splitter 204 at the output end, the laser is output, otherwise, the laser enters the waste light barrel 205.
The monitoring light rotates the polarization state through the first half-wave plate 206 to control the light to enter the first photodetector 208 after passing through the third polarization beam splitter 207, the first photodetector 208 is used for monitoring the power of the main laser, and a group of pumps of the three-stage power amplifier 107 is controlled through the closed-loop control module 109 to realize power closed-loop control. The laser power passing through the third polarization beam splitter 207 passes through the second half-wave plate 209, is polarized and combined with the reference light passing through the reference light output collimating head 210, and then enters the second photodetector 212, and the detected signal enters the closed-loop control module 109 to generate a closed-loop control signal to control the fiber phase modulator 105 to realize phase closed-loop.
The power closed loop may use a PID algorithm to lock the output power to some absolute value. The phase closed loop adopts an SPGD algorithm to lock the phase of the output main laser on the reference light source. The bandwidth of closed-loop locking is within 1MHz, and the closed-loop locking is mainly used for compensating amplifier noise introduced in an amplification process and noise caused by environmental vibration and thermal fluctuation.
The seed source of the single-frequency phase-locked laser amplifier has linewidth less than 10kHz and frequency stability superior to 10-12The high-stability single-frequency continuous laser. The single-frequency continuous laser can adopt an optical fiber single-frequency laser or a non-planar ring cavity (NPRO) and the like, and in order to further improve the long-time stability of the system, various closed-loop frequency stabilization measures can be adopted to control the long-time stability of the output laser to be 10-12The above.
The working principle of the patent application is briefly explained as follows: the fiber beam splitter divides the input single-frequency continuous laser seed source 101 into two parts, one part is injected into a rear-stage light path for laser amplification, and the other part is used as reference light to interfere with the amplified main laser in a pulse train output switch module at the tail end, so that the phase of the main laser is locked on the reference light. The fiber amplitude modulator is used for chopping the continuous single-frequency seed laser into pulse laser with specific repetition frequency and pulse width. If laser interaction with the electron beam is desired, the repetition rate of the laser should be closely matched to the cycle time of the electron microbeam in the storage ring. In order to suppress the Stimulated Brillouin Scattering (SBS) effect which may occur in the subsequent fiber laser amplification process of the single-frequency laser pulse, the chopping pulse width needs to be controlled within 3 ns. The average power of the single-frequency continuous seed laser is generally about 100mW, taking chopping pulse width 3ns and repetition frequency 6MHz as an example, the average power of the pulse is 1.8mW without considering loss. In order to achieve strong interaction between the laser and the electron beam, the laser is required to have a peak power of 10kW or more, and thus power boosting by a multi-stage power amplifier is required. The first-stage power amplifier adopts a single-mode fiber amplifier, and the average power of the pulse laser is improved to about 100 mW. The primary power amplifier outputs laser light to enter the fiber phase modulator. The phase modulator is used for modulating the phase of the main laser light path, and the control circuit controls the signal of the phase modulator by extracting an interference measurement signal in the final pulse train output module, so that the purpose of phase locking is realized. The secondary power amplifier adopts a large mode field optical fiber amplifier to increase the average power of the pulse laser to the magnitude of several watts. The three-stage power amplifier adopts an ultra-large mode field optical fiber amplifier, the average power of the pulse laser is further improved to hundreds of watts, and meanwhile, the peak power reaches tens of kilowatts. The three-stage power amplifier adopts a plurality of butterfly diode lasers as pumping sources for power closed loop besides a high-power multimode diode Laser (LD). The three-stage power amplifier outputs laser signals to enter a pulse train output switch module, and the module has three functions: 1) the main laser realizes pulse train output through an electro-optical switch in the module; 2) sampling and photoelectric detection are carried out on the main laser, the control module extracts power fluctuation information through detection signals, and generates power control signals after algorithm processing, and the power control signals are used for controlling the output power of a gain pump source in a three-stage power amplifier, so that the laser power stability is maintained; 3) interference beat frequency is carried out on a part of sampled main laser and reference light split by a seed source, a photoelectric detector is used for measuring beat frequency signals, a control circuit extracts the signals and processes the signals through an algorithm, and phase control signals are generated and used for controlling a phase modulator, so that phase stability is achieved. In consideration of system stability, the laser amplifier adopts a forced water cooling mode. In specific implementation, except for the seed source, the amplifier is affected by ambient temperature, vibration and pumping noise of the amplifier, and laser power and phase fluctuation can be caused, and the frequency of noise signals is basically within 1MHz, so that the control speed of the power closed loop and the phase closed loop can be about 1 MHz.
The present invention and the embodiments thereof have been described above, but the description is not limited thereto, and the embodiment shown in the drawings is only one of the embodiments of the present invention, and the actual structure is not limited thereto. In summary, those skilled in the art should understand that they should not be limited to the embodiments described above, and that they can design the similar structure and embodiments without departing from the spirit of the invention.
Claims (9)
1. A single frequency phase-locked laser amplifier, comprising: the fiber optic phase-locked loop power amplifier comprises a fiber splitter (102), a fiber amplitude modulator (103), a primary power amplifier (104), a phase modulator (105), a secondary power amplifier (106), a tertiary power amplifier (107), a pulse train output switch module (108) and a closed-loop control module (109); the optical fiber beam splitter (102), the optical fiber amplitude modulator (103), the primary power amplifier (104), the phase modulator (105), the secondary power amplifier (106), the tertiary power amplifier (107) and the pulse train output switch module (108) are connected in sequence; the closed-loop control module (109) is respectively in signal connection with the optical fiber amplitude modulator (103), the primary power amplifier (104), the phase modulator (105), the secondary power amplifier (106), the tertiary power amplifier (107) and the pulse train output switch module (108); the fiber beam splitter (102) is used for splitting input seed source laser into two parts, one part is injected into a rear-stage light path for laser amplification, and the other part is used as reference light to interfere with the amplified main laser in a pulse train output switch module (108) at the tail end, so that the phase of the main laser is locked on the reference light; the optical fiber amplitude modulator (103) is used for chopping continuous single-frequency seed laser into pulse laser with specific repetition frequency and pulse width; the phase modulator (105) is used for modulating the phase of a main laser light path, and the control circuit controls the signal of the phase modulator by extracting an interference measurement signal in a final-stage pulse train output module to achieve the purpose of phase locking; the pulse train output switch module (108) is used for enabling the main laser to realize pulse train output and simultaneously generating a power control signal and a phase control signal; the closed-loop control module (109) is used for generating a closed-loop control signal to control the optical fiber phase modulator (105) to realize phase closed loop.
2. The single frequency phase-locked laser amplifier of claim 1, wherein: the chopping pulse width of the optical fiber amplitude modulator (103) is within 3 ns.
3. The single frequency phase-locked laser amplifier of claim 1, wherein: the primary power amplifier (104) adopts a single-mode fiber amplifier and is used for increasing the average power of the pulse laser to 100mW level.
4. The single frequency phase-locked laser amplifier of claim 1, wherein: the secondary power amplifier (106) adopts a large mode field optical fiber amplifier to increase the average power of the pulse laser to the magnitude of several watts.
5. The single frequency phase-locked laser amplifier of claim 1, wherein: the three-stage power amplifier (107) adopts an ultra-large mode field optical fiber amplifier, the average power of the pulse laser is further improved to hundreds of watts, and meanwhile, the peak power reaches tens of kilowatts.
6. The single frequency phase-locked laser amplifier of claim 5, wherein: the pumping source in the three-stage power amplifier (107) comprises a high-power multimode diode laser and a plurality of butterfly diode lasers.
7. The single frequency phase-locked laser amplifier of claim 1, wherein: the pulse train output switch module (108) comprises a main laser output collimation head (201), a reference light output collimation head (210), a first polarization beam splitter (202), a second polarization beam splitter (204), a third polarization beam splitter (207), a fourth polarization beam splitter (211), an electro-optical switch (203), a waste light barrel (205), a first half glass sheet (206), a second half glass sheet (209), a first photoelectric detector (208) and a second photoelectric detector (212); the main laser output collimation head (201) is sequentially connected with the electro-optical switch (203), the second polarization beam splitter (204) and the waste light barrel (205) through the first polarization beam splitter (202); the first polarization beam splitter (202) is also connected with a first half glass (206), a third polarization beam splitter (207), a second half glass (209) and a fourth polarization beam splitter (211) in sequence; the first photodetector (208) is connected with the third polarization beam splitter (207); the reference light output collimating head (210) and the second photodetector (212) are both connected to a fourth polarizing beam splitter (211).
8. The single frequency phase-locked laser amplifier of claim 1, wherein: the heat dissipation is carried out by adopting a forced water cooling mode, and the water cooling temperature control precision is superior to 0.1 ℃.
9. The single frequency phase-locked laser amplifier of claim 1, wherein: the beam splitting ratio of the optical fiber beam splitter (102) is 90: 10.
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| Application Number | Priority Date | Filing Date | Title |
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| CN202121027945.4U CN215070853U (en) | 2021-05-14 | 2021-05-14 | Single-frequency phase-locked laser amplifier |
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| Application Number | Priority Date | Filing Date | Title |
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| CN202121027945.4U CN215070853U (en) | 2021-05-14 | 2021-05-14 | Single-frequency phase-locked laser amplifier |
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