A method and device for preparing chromium atom lithography grating based on optical frequency comb bias frequency locking wavelength

Abstract

The invention discloses a method and device for preparing a chromium atomic lithography grating based on an optical frequency comb bias frequency locking wavelength, and relates to the technical field of atomic lithography. In the device, the output end of the optical frequency comb is connected to a frequency doubling optical path; the output end of a continuously tunable laser is connected to an input end of a polarization-maintaining optical fiber beam splitter; the frequency doubling optical path and a first output end of the polarization-maintaining optical fiber beam splitter are respectively connected to an input end of an optical fiber combiner; the output end of the polarization-maintaining optical fiber combiner is connected to an input end of a beat frequency detection optical path; the output end of the beat frequency detection optical path is connected to an input end of a power divider through a photoelectric receiver; the input end of a frequency counter is connected to a first output end of the power divider; the input end of a bias frequency locking system is connected to a second output end of the power divider; and the output end of the bias frequency locking system is connected to a control input end of a continuously tunable laser. The invention ensures high diffraction efficiency of the grating while achieving size expansion of the atomic lithography grating.

Description

Technical Field

[0001] The present invention relates to the field of atomic lithography technology, and in particular to a method and device for preparing a chromium atomic lithography grating based on the frequency-offset locking wavelength of an optical frequency comb. Background Art

[0002] Nanotechnology studies the material world in the nanoscale range and manufactures products with specific functions by manipulating atoms and molecules. Almost all innovations and technological advancements in modern scientific fields are inseparable from nanotechnology. In the field of nanomanufacturing, nanogratings play an important role in precision displacement measurement, instrument calibration, etc., and are one of the basic supports for nanoscale ultra-precision measurement. Gratings with cross-scale periodic accuracy, structural uniformity, and high line density are urgently needed for the development of ultra-precision grating interferometric displacement measurement systems.

[0003] Atomic lithography technology mainly uses the dipole force of a laser standing wave field to manipulate the motion of atoms, so that the cooled chromium atom beam forms a periodic grating structure on the substrate after passing through the laser standing wave field. Since the atomic deposition position strictly corresponds to the wave valley or wave peak position of the laser standing wave field, the period of this structure strictly originates from the laser wavelength, with extremely high accuracy and consistency. Taking a one-dimensional chromium atomic lithography grating as an example, the one-dimensional chromium atomic lithography grating with a period of 212.8 nm has been verified to have an accuracy and consistency of about 0.001 nm, and the chromium atomic lithography grating interferometer has demonstrated sub-nanometer ultra-precision displacement measurement capabilities.

[0004] However, the small area of the atomic lithography grating structure severely restricts its application scope in key industries. Taking a one-dimensional chromium atomic lithography grating as an example again, limited by the atomic flux of the evaporation and leakage type atomic furnace tube, the single preparation area is only about 2 mm × 0.25 mm. Although stitching atomic lithography solves the problem of expanding the atomic lithography grating in the standing wave field direction, the existing atomic lithography technology using fluorescence frequency stabilization technology cannot meet the requirement of long-term high-stability locking of the 425.5 nm continuous laser frequency for the growth and preparation of large-area atomic lithography gratings, severely restricting the number of experiments using stitching atomic lithography, resulting in difficulties in the preparation of large-area chromium atomic lithography gratings. At the same time, the poor fluorescence frequency stabilization effect also leads to an unsatisfactory grating morphology, thus affecting the grating diffraction efficiency.

[0005] Based on the above situation, since the existing methods are difficult to meet the requirements of the laser frequency for the preparation of large-area chromium atomic lithography gratings, it is extremely necessary to develop a method for preparing atomic lithography gratings based on long-term high-stability laser frequency stabilization technology. Summary of the Invention

[0006] To solve the above problems, the present application provides a method and device for preparing a chromium atomic lithography grating based on the bias frequency locking wavelength of an optical frequency comb, with the goal of improving the laser frequency stabilization effect of the existing atomic lithography technology, and aims to provide a method for preparing a chromium atomic lithography grating based on the bias frequency locking wavelength of an optical frequency comb, which has simple operation, high preparation efficiency, and fine control of the grating morphology.

[0007] In the present application, a chromium atomic lithography grating preparation device based on optical frequency comb bias frequency locking wavelength is provided, including an optical frequency comb, a continuously tunable laser, a frequency doubling optical path, a polarization-maintaining fiber beam splitter, a polarization-maintaining fiber beam combiner, a beat frequency detection optical path, a power divider, a frequency counter, a bias frequency locking system, and an atomic lithography deposition system;

[0008] The output end of the optical frequency comb is connected to the frequency doubling optical path;

[0009] The output end of the continuously tunable laser is connected to the input end of the polarization-maintaining optical fiber beam splitter;

[0010] A second half-wave plate and a second coupler are sequentially arranged on one side of the output end of the continuously tunable laser;

[0011] The frequency doubling optical path and the first output end of the polarization-maintaining optical fiber beam splitter are respectively connected to the input end of the optical fiber combiner;

[0012] The output end of the polarization-maintaining optical fiber combiner is connected to the input end of the beat frequency detection optical path;

[0013] The output end of the beat frequency detection optical path is connected to the input end of the power divider through a photoelectric receiver;

[0014] The input end of the frequency counter is connected to the first output end of the power divider;

[0015] The input end of the offset frequency locking system is connected to the second output end of the power divider;

[0016] The output end of the bias frequency locking system is connected to the control input end of the continuously tunable laser.

[0017] Preferably, the atomic lithography deposition system heats the metal powder to a sublimation state in a vacuum environment and draws out a chromium atomic beam in a leakage manner, and collimates the chromium atomic beam. The collimated chromium atomic beam is subjected to spatial periodic distribution regulation by a laser converging standing wave field, and the atoms are periodically arranged and deposited on the substrate to form an atomic lithography grating structure.

[0018] The atomic lithography deposition system realizes the collimation of the chromium atomic beam through a slit or a transverse laser light field;

[0019] The atomic lithography deposition system has a light-cutting ratio of 10% to 50% for the focused light and the substrate;

[0020] The substrate used in the atomic lithography deposition system includes single crystal silicon, microcrystalline glass or indium phosphide material.

[0021] Preferably, the frequency doubling optical path includes a filter, a first half-wave plate, a first convex lens, a frequency doubling crystal PPLN, a second convex lens and a first coupler;

[0022] The output end of the optical frequency comb is connected to the input end of the filter;

[0023] The output end of the filter is connected to the input end of the first half-wave plate;

[0024] The output end of the first half-wave plate is connected to the input end of the frequency doubling crystal PPLN;

[0025] A first convex lens and a second convex lens are disposed at two ends of the frequency doubling crystal PPLN so that the light beam is focused inside the frequency doubling crystal PPLN.

[0026] Preferably, the beat frequency detection optical path includes a third coupler, a reflector, a third half-wave plate, a polarization beam splitter prism and a diffraction grating;

[0027] The optical path output end of the polarization-maintaining fiber combiner is connected to the input end of the photoelectric receiver after passing through the third coupler, the reflector, the third half-wave plate, the polarization beam splitter prism and the diffraction grating in sequence.

[0028] Preferably, the optical frequency comb output band covers 851±2 nm, the output power is greater than 10 mW, and the reference source is a high-stability time-frequency signal.

[0029] Preferably, the continuously tunable laser has an output band covering 425.5±1.0 nm, and a frequency tuning module is provided at the input end.

[0030] Preferably, a low-pass filter is provided between the photoelectric receiver and the offset frequency locking system.

[0031] The present application also provides a method for preparing a chromium atom lithography grating based on an optical frequency comb bias frequency locking wavelength, comprising the following steps:

[0032] S1. Based on the bias frequency locking technology, build a beat frequency optical path and develop a bias frequency locking system to strictly lock the 425.5nm continuous laser to an optical frequency comb that can be traced back to a high-precision time and frequency reference;

[0033] S2, fixedly changing the bias frequency locking value, based on the atomic lithography technology, using the interaction between the chromium atomic beam and the laser convergence standing wave field, performing an atomic lithography on the substrate to obtain an atomic lithography grating template;

[0034] S3, loop and execute S2 several times;

[0035] S4. By characterizing the morphology of each sample, the optimal laser bias frequency locking value for the atomic lithography experiment is determined, and a large-area atomic lithography grating with high diffraction efficiency is prepared by combining the splicing atomic lithography grating method.

[0036] In summary, the present invention is a method and device for preparing a chromium atomic lithography grating based on the frequency-locked wavelength of an optical frequency comb. Compared with the traditional atomic lithography technology, the present application can achieve the expansion of the atomic lithography grating size while ensuring the high diffraction efficiency of the grating. When the quality of the standing wave field allows, based on the long-term high-stability laser, multiple splicing can be achieved, and the standing wave field direction of the self-traceable grating has a large expansion space.

[0037] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 A schematic diagram of a chromium atom lithography grating preparation device based on optical frequency comb bias frequency locking wavelength of the present invention;

[0039] Figure 2 A schematic diagram of a one-dimensional chromium atom lithography process of a method and device for preparing a chromium atom lithography grating based on an optical frequency comb bias frequency locking wavelength according to the present invention;

[0040] Figure 3 This is a comparison diagram of the chromium atomic beam fluorescence detection image before and after cooling of a chromium atomic lithography grating preparation method and device based on the optical frequency comb bias frequency locking wavelength of the present invention;

[0041] Figure 4 This is a diagram showing the 3-hour stability effect of a 425.5nm continuous laser in a method and device for preparing a chromium atom lithography grating based on an optical frequency comb bias-frequency locked wavelength according to the present invention.

[0042] Reference numerals:

[0043] 1. Optical frequency comb; 2. Filter; 3. First half-wave plate; 4. First convex lens; 5. Frequency doubling crystal PPLN; 6. Second convex lens; 7. First coupler; 8. Continuously tunable laser; 9. Second half-wave plate; 10. Second coupler; 11. Polarization-maintaining fiber beam splitter; 12. Converging light; 13. Polarization-maintaining fiber combiner; 14. Third coupler; 15. Reflector; 16. Third half-wave plate; 17. Polarization beam splitter; 18. Diffraction grating; 19. Photoelectric receiver; 20. Power divider; 21. Frequency counter; 22. Low-pass filter; 23. Bias-frequency locking system; 24. Chromium atomic beam; 25. Atomic lithography grating. DETAILED DESCRIPTION

[0044] The technical solution of the present invention is further described below by means of the accompanying drawings and embodiments. It should be noted that unless otherwise specifically stated, the relative arrangement of components and steps, numerical expressions and numerical values ​​described in these embodiments do not limit the scope of the present application.

[0045] The following description of at least one exemplary embodiment is merely illustrative in nature and is in no way intended to limit the present application, its application, or uses.

[0046] Technologies, methods, and equipment known to ordinary technicians in the relevant art may not be discussed in detail, but where appropriate, the technologies, methods, and equipment should be considered part of the specification.

[0047] In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not limiting. Therefore, other examples of the exemplary embodiments may have different values.

[0048] Unless otherwise defined, technical or scientific terms used in the present invention shall have the common meanings understood by one having ordinary skills in the field to which the present invention belongs.

[0049] like Figure 1 and Figure 2 As shown, the present invention provides a chromium atomic lithography grating 25 preparation device based on optical frequency comb bias frequency locking wavelength, including an optical frequency comb 1, a continuously tunable laser 8, a frequency doubling optical path, a polarization-maintaining fiber beam splitter 11, a polarization-maintaining fiber beam combiner 13, a beat frequency detection optical path, a power divider 20, a frequency counter 21, a bias frequency locking system 23 and an atomic lithography deposition system;

[0050] The output end of the optical frequency comb 1 is connected to the frequency doubling optical path. The output band of the optical frequency comb 1 covers 851±2nm, the output power is greater than 10mW, and the reference source is a high-stability time-frequency signal.

[0051] The output end of the continuously tunable laser 8 is connected to the input end of the polarization-maintaining fiber beam splitter 11 . The output band of the continuously tunable laser 8 covers 425.5±1.0 nm, and a frequency tuning module is provided at the input end.

[0052] A second half-wave plate 9 and a second coupler 10 are sequentially arranged on one side of the output end of the continuously tunable laser 8;

[0053] The frequency doubling optical path and the first output end of the polarization-maintaining optical fiber splitter 11 are respectively connected to the input end of the optical fiber combiner;

[0054] Further, the frequency doubling optical path includes a filter 2, a first half-wave plate 3, a first convex lens 4, a frequency doubling crystal PPLN5, a second convex lens 6 and a first coupler 7;

[0055] The output end of the optical frequency comb 1 is connected to the input end of the filter 2;

[0056] The output end of the filter plate 2 is connected to the input end of the first half-wave plate 3;

[0057] The output end of the first half-wave plate 3 is connected to the input end of the frequency doubling crystal PPLN5;

[0058] A first convex lens 4 and a second convex lens 6 are provided at both ends of the frequency doubling crystal PPLN5 so that the light beam is focused inside the frequency doubling crystal PPLN5.

[0059] The output end of the polarization-maintaining optical fiber combiner 13 is connected to the input end of the beat frequency detection optical path;

[0060] The output end of the beat frequency detection optical path is connected to the input end of the power divider 20 through the photoelectric receiver 19 , and a low-pass filter 22 is provided between the photoelectric receiver 19 and the offset frequency locking system 23 .

[0061] Further, the beat frequency detection optical path includes a third coupler 14, a reflector 15, a third half-wave plate 16, a polarization beam splitter prism 17 and a diffraction grating 18;

[0062] The optical path output end of the polarization-maintaining fiber combiner 13 passes through the third coupler 14 , the reflector 15 , the third half-wave plate 16 , the polarization beam splitter prism 17 and the diffraction grating 18 in sequence and is connected to the input end of the photoelectric receiver 19 .

[0063] The input end of the frequency counter 21 is connected to the first output end of the power divider 20;

[0064] The input end of the bias frequency locking system 23 is connected to the second output end of the power divider 20;

[0065] The output end of the bias frequency locking system 23 is connected to the control input end of the continuously tunable laser 8 .

[0066] Furthermore, the atomic lithography deposition system heats the metal powder to a sublimation state in a vacuum environment and draws out a chromium atomic beam 24 in a leakage manner, and collimates the chromium atomic beam 24. The collimated chromium atomic beam 24 is spatially periodically distributed and regulated by a laser converging standing wave field, and the atoms are periodically arranged and deposited on the substrate to form an atomic lithography grating 25 structure.

[0067] The atomic lithography deposition system achieves collimation of the chromium atom beam 24 through a slit or a transverse laser light field;

[0068] The atomic lithography deposition system has a light cutting ratio of 10% to 50% for the focusing light 12 and the substrate;

[0069] The substrates used in the atomic lithography deposition system include single crystal silicon, microcrystalline glass or indium phosphide materials.

[0070] The present application also provides a method for preparing a chromium atom lithography grating 25 based on an optical frequency comb bias frequency locking wavelength, comprising the following steps:

[0071] S1. Based on the bias frequency locking technology, a beat frequency optical path was built and a bias frequency locking system 23 was developed to strictly lock the 425.5nm continuous laser to an optical frequency comb 1 that can be traced back to a high-precision time and frequency reference;

[0072] S2, fixedly changing the bias frequency locking value to a specific value, based on the atomic lithography technology, using the interaction between the chromium atomic beam 24 and the laser convergence standing wave field, performing an atomic lithography on the substrate, and obtaining an atomic lithography grating 25 sample;

[0073] S3, loop and execute S2 several times;

[0074] S4. By characterizing the morphology of each sample, the optimal laser bias frequency locking value for the atomic lithography experiment is determined, and a large-area atomic lithography grating 25 with high diffraction efficiency is prepared by combining the method of splicing the atomic lithography grating 25.

[0075] The specific implementation process is as follows:

[0076] (1) Using the frequency doubling crystal PPLN5 to generate an optical frequency comb band covering 425.5±1nm;

[0077] (2) The 425.5 nm continuously tunable laser 8 is divided into two paths by a fiber beam splitter. One path is used for atomic lithography deposition experiments, and the other path and the frequency-doubled optical frequency comb 1 are combined with a fiber beam combiner to generate a beat signal with a signal-to-noise ratio greater than 30 dB. The beat signal is input into the bias frequency locking system 23 to generate a stable frequency laser near 425.5 nm.

[0078] (3) setting a series of equally spaced bias frequency locking values, and based on the atomic lithography technology, using the interaction between the chromium atomic beam 24 and the laser converging standing wave field, sequentially conducting preliminary experiments on the preparation of atomic lithography grating 25 samples on the substrate;

[0079] (4) Characterize the morphology of each sample to determine the optimal bias frequency locking value, and combine the splicing atomic lithography technology to prepare a 10mm×10mm large-area atomic lithography grating 25 with high diffraction efficiency.

[0080] like Figure 3 and Figure 4 As shown, the present application can ensure the high diffraction efficiency of the grating while achieving the size expansion of the atomic lithography grating 25. When the quality of the standing wave field allows, multiple splicing can be achieved based on long-term high-stability lasers, and the standing wave field direction of the self-traceable grating has a large expansion space.

[0081] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that they can still modify or replace the technical solution of the present invention with equivalents, and these modifications or equivalent replacements cannot cause the modified technical solution to deviate from the spirit and scope of the technical solution of the present invention.

Claims

1. A chromium atom lithography grating preparation device based on optical frequency comb offset frequency locking wavelength, characterized in that: Including, optical frequency comb, continuously tunable laser, frequency doubling optical path, polarization-maintaining fiber beam splitter, polarization-maintaining fiber beam combiner, beat frequency detection optical path, power divider, frequency counter, bias frequency locking system and atomic lithography deposition system; The output end of the optical frequency comb is connected to the frequency doubling optical path; The output end of the continuously tunable laser is connected to the input end of the polarization-maintaining optical fiber beam splitter; A second half-wave plate and a second coupler are sequentially arranged on one side of the output end of the continuously tunable laser; The frequency doubling optical path and the first output end of the polarization-maintaining optical fiber beam splitter are respectively connected to the input end of the optical fiber combiner; The output end of the polarization-maintaining optical fiber combiner is connected to the input end of the beat frequency detection optical path; The output end of the beat frequency detection optical path is connected to the input end of the power divider through a photoelectric receiver; The input end of the frequency counter is connected to the first output end of the power divider; The input end of the offset frequency locking system is connected to the second output end of the power divider; The output end of the bias frequency locking system is connected to the control input end of the continuously tunable laser; The atomic photolithography deposition system heats metal powder to a sublimation state in a vacuum environment and draws out a chromium atomic beam in a leakage manner, and collimates the chromium atomic beam. The collimated chromium atomic beam is spatially periodically distributed and regulated by a laser converging standing wave field, and atoms are periodically arranged and deposited on a substrate to form an atomic photolithography grating structure. The atomic lithography deposition system realizes the collimation of the chromium atomic beam through a slit or a transverse laser light field; The atomic lithography deposition system has a light-cutting ratio of 10% to 50% for the focused light and the substrate; The substrate used in the atomic lithography deposition system includes single crystal silicon, microcrystalline glass or indium phosphide material; The chromium atom lithography grating preparation device based on optical frequency comb bias frequency locking wavelength realizes the preparation process through a chromium atom lithography grating preparation method based on optical frequency comb bias frequency locking wavelength, including the following steps: S1. Based on the bias frequency locking technology, build a beat frequency optical path and develop a bias frequency locking system to strictly lock the 425.5nm continuous laser to an optical frequency comb that can be traced back to a high-precision time and frequency reference; S2, fixedly changing the bias frequency locking value, based on the atomic lithography technology, using the interaction between the chromium atomic beam and the laser convergence standing wave field, performing an atomic lithography on the substrate to obtain an atomic lithography grating template; S3, loop and execute S2 several times; S4. By characterizing the morphology of each sample, the optimal laser bias frequency locking value for the atomic lithography experiment is determined, and a large-area atomic lithography grating with high diffraction efficiency is prepared by combining the splicing atomic lithography grating method.

2. The device for preparing chromium atom lithography grating based on optical frequency comb bias frequency locking wavelength according to claim 1, characterized in that: The frequency doubling optical path includes a filter, a first half-wave plate, a first convex lens, a frequency doubling crystal PPLN, a second convex lens and a first coupler; The output end of the optical frequency comb is connected to the input end of the filter; The output end of the filter is connected to the input end of the first half-wave plate; The output end of the first half-wave plate is connected to the input end of the frequency doubling crystal PPLN; A first convex lens and a second convex lens are disposed at two ends of the frequency doubling crystal PPLN so that the light beam is focused inside the frequency doubling crystal PPLN.

3. The device for preparing chromium atom lithography grating based on optical frequency comb bias frequency locking wavelength according to claim 1, characterized in that: The beat frequency detection optical path includes a third coupler, a reflector, a third half-wave plate, a polarization beam splitter prism and a diffraction grating; The optical path output end of the polarization-maintaining fiber combiner is connected to the input end of the photoelectric receiver after passing through the third coupler, the reflector, the third half-wave plate, the polarization beam splitter prism and the diffraction grating in sequence.

4. The device for preparing chromium atom lithography grating based on optical frequency comb bias frequency locking wavelength according to claim 1, characterized in that: The optical frequency comb output band covers 851±2nm, the output power is greater than 10mW, and the reference source is a high-stability time-frequency signal.

5. The device for preparing chromium atom lithography grating based on optical frequency comb bias frequency locking wavelength according to claim 1, characterized in that: The continuously tunable laser has an output band covering 425.5±1.0 nm, and a frequency tuning module is provided at the input end.

6. The device for preparing chromium atom lithography grating based on optical frequency comb bias frequency locking wavelength according to claim 1, characterized in that: A low-pass filter is arranged between the photoelectric receiver and the offset frequency locking system.

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