System and method for manufacturing complex period photonic crystal through multi-beam laser holography

Abstract

The invention relates to the field of photonic crystal manufacturing, in particular to a multi-beam laser holography complex period photonic crystal manufacturing system and method, and the system is provided with a laser, a multi-beam generation element, a beam collimation element, a displacement table, a spatial light modulator, a focusing lens, a photoresist plate, a multi-axis displacement table and an upper computer. The upper computer is used for controlling the displacement table, the spatial light modulator and the multi-axis displacement table, laser is emitted from the laser device and passes through the multi-beam generation element in the normal direction to generate multiple beams of coherent light, the multiple beams of coherent light are collimated into parallel light through the beam collimation element, and the parallel light is transmitted to the spatial light modulator through the multi-axis displacement table. A spatial light modulator is controlled by an upper computer to change the phase and polarization state of each parallel light beam, and then each parallel light beam is converged to a photoresist plate through a focusing lens. The large-area complex period photonic crystal can be repeatedly prepared on a large scale under modularization, high integration and fine control, and the method plays an important role in the optical fields of optical integration, optical communication and the like.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of photonic crystal manufacturing, in particular to a system and method for manufacturing a multi-period photonic crystal by multi-beam laser holography. BACKGROUND

[0002] Laser holography (laser interference lithography) uses multiple coherent light beams to overlap and interfere to form a holographic pattern, and through the interaction between light and photosensitive substances, an ordered structure with spatial periodic variation of medium refractive index is formed. The structure period produced by this method is in the wavelength range of optics, and the design of the lattice structure is diverse and flexible. Not only can it be used to produce periodic structures with translational symmetry, but also can be used to produce large-area quasi-structures with rotational symmetry.

[0003] A photonic crystal is a microstructure of artificial design and manufacture of dielectric with different dielectric constants arranged periodically or quasi-periodically in the optical scale, which is a product of the combination of solid theory and electromagnetic theory. Unlike single-period photonic crystals, multi-period photonic crystals can be considered as a combination of another single-period photonic crystal structure in a single-period photonic crystal. Photonic crystals are microstructure materials of dielectric with spatial periodic distribution of dielectric constant. Just like the band gap (forbidden band) of electrons in a semiconductor caused by the action of atomic potential field, there is also a band gap in the photonic crystal microstructure. According to the properties of the photonic crystal band gap, it can be divided into incomplete band gap and complete band gap. The complete band gap is characterized by the prohibition of light wave propagation in any direction within the forbidden frequency interval; the incomplete band gap is characterized by the prohibition of light wave propagation in a specific direction, while there are still photons in other directions in the whole space. Therefore, photonic crystals can effectively control electromagnetic waves and filter out unwanted light waves in a specific frequency interval. The study of photonic crystals has shown that it has many important applications, such as the formation of optical microcavities by introducing point defects into photonic crystals, the formation of optical waveguides and high-performance wavelength filters by introducing line defects into photonic crystals, etc. These applications are based on the band gap properties of photonic crystals. Generally, the wider the band gap of the photonic crystal, the better the stability of the photonic crystal obtained.

[0004] Multi-period structures have better band gap properties than single-period structures. The introduction of multi-period structures is mainly to regulate the position, width and number of photonic band gaps, greatly enriching the application range of photonic crystals. Multi-period photonic crystals mainly add another structure with different shapes, sizes and refractive indices to the single-period photonic crystal structure. Due to the addition of a new structure, the symmetry of the original structure is destroyed, and the width of the photonic band gap will also change. Generally, the band gap width of a multi-period photonic crystal structure is wider than that of a single-period photonic crystal. However, the existing technology cannot realize the preparation of large-area multi-period photonic crystals.

[0005] Therefore, the present application proposes a multi-beam laser holographic manufacturing complex periodic photonic crystal system and method to solve the above problems. SUMMARY

[0006] (I) Technical problems solved

[0007] The present application provides a multi-beam laser holographic manufacturing complex periodic photonic crystal system and method, which can simultaneously prepare photonic crystals and complex periodic photonic crystal structures through innovative design, and combines precise modulation of laser phase and polarization state, thereby breaking through the technical bottlenecks of traditional small area, large scale, low efficiency, single function and complex system structure, and providing a large area, small scale, high efficiency and high solution for photonic crystal preparation.

[0008] (II) Technical solutions

[0009] In order to achieve the above purpose, the present application specifically adopts the following technical solutions:

[0010] A multi-beam laser holographic manufacturing complex periodic photonic crystal system, which is sequentially provided with a laser, a multi-beam generating element, a beam collimating element, a displacement table, a spatial light modulator, a focusing lens, a photoresist plate, a multi-axis displacement table and an upper computer:

[0011] The laser is used for emitting 532nm waveband laser;

[0012] The multi-beam generating element is used for generating multiple laser beams after transmitting single laser beam;

[0013] The beam collimating element is installed on the displacement table and is controlled in left and right positions by the displacement table to change the interval of each parallel light;

[0014] The spatial light modulator is used for modulating the phase and polarization state of each parallel light beam, which is controlled by the upper computer;

[0015] The focusing lens is used for focusing each parallel light beam;

[0016] The photoresist plate is used for receiving interference exposure to form a photonic crystal;

[0017] The photoresist plate is installed on the multi-axis displacement table and is controlled in multi-axis displacement by the multi-axis displacement table so that the photoresist plate is in an interference position;

[0018] The laser is taken as the origin, the laser is emitted from the laser, the multi-beam coherent light is generated after the laser passes through the multi-beam generating element along the normal direction, the multi-beam coherent light is collimated into parallel light by the beam collimating element, the phase and the polarization state of each parallel light beam are changed by the host computer control spatial light modulator, then each parallel light beam is converged to the photoresist plate by the focusing lens, finally the movement of the beam collimating element is controlled by the host computer linkage displacement table, the phase and the polarization state of the light beam are controlled by the spatial light modulator, and the movement of the photoresist plate is controlled by the multi-axis displacement table, the period of the photonic crystal and the interference exposure position are changed, the complex period photonic crystal is formed, and the preparation of the complex period photonic device is completed after development.

[0019] Further, the spatial light modulator is a liquid crystal spatial light modulator or a digital micromirror device, which can dynamically adjust the phase or polarization state of the light beam.

[0020] Further, the complex period photonic crystal structure dimension includes one-dimensional, two-dimensional or three-dimensional, and the complex period photonic crystal structure distribution includes a triangular complex period structure or a square complex period structure.

[0021] Further, the size of the complex period photonic crystal structure unit in any direction ranges from 0.5 μm to 100 μm.

[0022] Further, the photoresist plate adopts positive photoresist or negative photoresist, and the exposed area forms a periodic structure after development.

[0023] A system application method for manufacturing a complex period photonic crystal by multi-beam laser holography includes the following steps:

[0024] Step 1: Prepare a positive photoresist or negative photoresist plate meeting the requirements of the laser wavelength;

[0025] Step 2: Emit a laser beam from the laser, generate multi-beam coherent light after passing through the multi-beam generating element, collimate the multi-beam coherent light into parallel light by the beam collimating element, and convert the parallel light beam into a modulated parallel light beam by the host computer control spatial light modulator, the modulated parallel light beam being light with arbitrary phase and arbitrary polarization state;

[0026] Step 3: Fix the positive photoresist or negative photoresist plate on the multi-axis displacement table, and converge each parallel light beam to the photoresist plate by the focusing lens;

[0027] Step 4: The host computer linkage displacement table controls the movement of the beam collimating element, the spatial light modulator controls the phase and polarization state of the light beam, and the multi-axis displacement table controls the movement of the positive photoresist or negative photoresist plate, so as to change the period of the photonic crystal and the exposure position;

[0028] Step 5: Develop the exposed positive photoresist or negative photoresist plate to complete the complex period photonic crystal.

[0029] Further, step 4 is specifically as follows:

[0030] The displacement table makes the light beam collimation element close to or away from the multi-beam generation element, the photonic crystal period becomes large or small, the multi-axis displacement table multi-axis movement makes the spatial light modulator dynamically change the phase or polarization state of each parallel light beam, and the positive photoresist or negative photoresist plate is exposed in a large area.

[0031] (Three) beneficial effects

[0032] Compared with the prior art, the present application provides a multi-beam laser holographic method for manufacturing a complex periodic photonic crystal, which has the following beneficial effects

[0033] The photonic crystal structure prepared by the present application is based on the multi-beam laser interference theory, and is prepared by laser processing, spatial light modulation, and photoetching and development methods in a large area; the present application provides a high-efficiency, large-area, and integrated photonic crystal preparation method and system based on multi-beam laser holography, which plays an important role in optical control, optical communication, and integrated optical systems. BRIEF DESCRIPTION OF DRAWINGS

[0034] The accompanying drawings are included to provide a further understanding of the present application, and constitute a part of the specification, which together with the embodiments of the present application, serve to explain the present application, and do not constitute a limitation of the present application.

[0035] Figure 1 A schematic diagram of a three-dimensional photonic crystal structure obtained by the system and method of the present application;

[0036] Figure 2 A schematic diagram of an experimental system for preparing a three-dimensional photonic crystal structure based on a multi-beam laser holographic method;

[0037] Figure 3 A schematic diagram of a complex periodic photonic crystal structure obtained by the system and method of the present application;

[0038] Figure 4 A schematic diagram of an experimental system for preparing a complex periodic photonic crystal structure based on a multi-beam laser holographic method;

[0039] Figure 5 A diagram of fixing the light beam collimator in the system of the present application in the displacement table;

[0040] Figure 6 A diagram of fixing the photoresist plate in the system of the present application in the multi-axis displacement table;

[0041] Figure 7 A diagram of the photonic crystal structure obtained by the system and method of the present application;

[0042] Figure 8A schematic diagram of a complex-period photonic crystal structure obtained by the system and method of the present application. DETAILED DESCRIPTION

[0043] The technical solutions in the embodiments of the present application will be clearly and completely described below with specific embodiments and drawings. Obviously, the described embodiments are only some of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of protection of the present application.

[0044] Embodiment one:

[0045] A system for manufacturing complex-period photonic crystals by multi-beam laser holography, the system comprising a laser, a multi-beam generating element, a beam collimating element, a displacement table, a spatial light modulator, a focusing lens, a photoresist plate, a multi-axis displacement table, and an upper computer.

[0046] After the laser is emitted from the laser, the multi-beam generating element generates multiple coherent beams in the normal direction, and then the beam collimating element collimates the multiple coherent beams into parallel light. The upper computer controls the spatial light modulator to change the phase and polarization state of each parallel light beam. Then, the focusing lens converges each parallel light beam to the photoresist plate. Finally, the upper computer controls the displacement table to move the beam collimating element, the spatial light modulator to control the phase and polarization state of the light beam, and the multi-axis displacement table to move the photoresist plate, so as to change the period of the photonic crystal and the interference exposure position, form a complex-period photonic crystal, and complete the preparation of the complex-period photonic device after development.

[0047] The spatial light modulator is suitable for all reflective or transmissive spatial light modulators.

[0048] The displacement table or the multi-axis displacement table has a sub-micron level of movement precision.

[0049] The complex-period photonic crystal structure has one-dimensional, two-dimensional or three-dimensional dimensions, and the complex-period photonic crystal structure has a triangular complex-period structure or a square complex-period structure.

[0050] The period of the photonic crystal is changed by the upper computer controlling the displacement table, and the size of the structure unit of the photonic crystal in any direction ranges from 0.5 microns to 100 microns.

[0051] Embodiment two:

[0052] A system application method for manufacturing complex-period photonic crystals by multi-beam laser holography, comprising the following steps:

[0053] Step 1: Prepare a positive photoresist or negative photoresist plate that meets the requirements of the laser wavelength band.

[0054] Step 2: the laser emits a laser beam, generates a plurality of coherent light beams after passing through the multi-beam generating element, collimates the plurality of coherent light beams into parallel light beams by the beam collimating element, and converts the modulated parallel light beams into modulated parallel light beams with arbitrary phase and arbitrary polarization state by the host computer controlling the spatial light modulator.

[0055] Step 3: fix the positive photoresist or negative photoresist plate on the multi-axis displacement table, and converge each parallel light beam to the photoresist plate through the focusing lens.

[0056] Step 4: the host computer controls the movement of the beam collimating element, the spatial light modulator controls the phase and polarization state of the light beam, and the multi-axis displacement table controls the movement of the positive photoresist or negative photoresist plate to change the period of the photonic crystal and the exposure position.

[0057] Step 5: develop the exposed positive photoresist or negative photoresist plate to complete the complex period photonic crystal.

[0058] Step 4 is as follows:

[0059] The displacement table moves the beam collimating element closer to or farther away from the multi-beam generating element, the period of the photonic crystal becomes larger or smaller, the multi-axis displacement table moves in multiple axes to dynamically change the phase or polarization state of each parallel light beam by the spatial light modulator, and the positive photoresist or negative photoresist plate is exposed in a large area.

[0060] Example Three:

[0061] As shown in Figure 1 and Figure 3 , to verify that the method of the application can prepare a three-dimensional photonic crystal, the following experiment is performed.

[0062] The selected photoresist plate is SU8 photoresist;

[0063] First, the host computer controls the displacement table to make the beam collimating element distance the multi-beam generating element meet the 1um period requirement of the three-dimensional photonic crystal in the X-axis; then, the host computer controls the spatial light modulator according to the required phase and polarization state matching conditions.

[0064] The selected laser is GLM-100, the wavelength is 532nm, and the maximum power is 200MW;

[0065] The photoresist plate used is placed on a three-dimensional moving machining platform with machining precision in the sub-micron level controlled by the host computer, the photoresist plate can translate along the x-axis perpendicular to the laser beam of the machining platform, and the sample can move up and down along the z-axis, the computer is used to set the required result size, and the laser can be used for exposure.

[0066] Developing using PGMEA solution can prepare a three-dimensional photonic crystal with a period of 1um in the X-axis.

[0067] Example Four:

[0068] As shown in Figure 1 and Figure 3 To verify the method of the present application can be prepared complex period photonic crystals, the following experiments.

[0069] The selected photoresist plate is SU8 photoresist;

[0070] First, by host computer control displacement table so that the collimating element distance multi-beam generating element to meet the photonic crystal period of 1 um requirements; then according to the required to meet the phase, polarization matching conditions by host computer control spatial light modulator to achieve.

[0071] The selected laser GLM-100, wavelength of 532 nm, the maximum power of 200 MW;

[0072] The photoresist plate used by the host computer control processing precision in the sub-micron order of three-dimensional moving processing platform, photoresist plate can be along the processing platform perpendicular to the laser beam x-axis translation, while the sample can be moved up and down along the z-axis, using a computer to set the desired result size, can be used laser exposure.

[0073] Using the host computer control spatial light modulator, change the phase of the light beam, polarization to meet the needs; two exposure.

[0074] Using PGMEA solution development, can be prepared complex period photonic crystals.

[0075] Finally, it should be noted that: the above only for the preferred embodiments of the present application, and not for limiting the present application, although the present application has been described in detail with reference to the foregoing examples, for the skilled in the art, it still can be modified, or the equivalent replacement of the technical solutions recorded in the foregoing embodiments. Any modification, equivalent replacement, improvement, etc. within the spirit and principles of the present application, shall be included in the scope of protection of the present application.

Claims

1. A system for the fabrication of a multi-beam laser holographic photonic crystal with a complex period, characterized in that, The laser, the multi-beam generating element, the beam collimating element, the displacement table, the spatial light modulator, the focusing lens, the photoresist plate and the multi-axis displacement table are sequentially arranged; The laser is used for emitting 532nm waveband laser; The multi-beam generating element is used for generating multiple laser beams after single laser beam passes through; The beam collimating element is installed on the displacement table and the left and right positions are controlled through the displacement table to change the interval of the parallel light; The spatial light modulator is used for modulating the phase and polarization state of each parallel light beam and is controlled by the host computer; The focusing lens is used for focusing each parallel light beam; The photoresist plate is used for receiving interference exposure to form a photonic crystal; The photoresist plate is installed on the multi-axis displacement table and is controlled by the multi-axis displacement table to make the photoresist plate in the interference position; The laser is taken as the origin, the laser is emitted from the laser, multiple coherent beams are generated along the normal direction after the laser passes through the multi-beam generating element, the multiple coherent beams are collimated into parallel light by the beam collimating element, the phase and polarization state of each parallel light beam are changed by the spatial light modulator controlled by the host computer, each parallel light beam is converged to the photoresist plate by the focusing lens, and finally the beam collimating element is moved by the displacement table controlled by the host computer, the phase and polarization state of the light beam are controlled by the spatial light modulator, and the photoresist plate is moved by the multi-axis displacement table, so that the period of the photonic crystal and the interference exposure position are changed, the complex period photonic crystal is formed, and the complex period photonic device preparation is completed after development.

2. The system for fabricating a multi-period photonic crystal according to claim 1, wherein: The spatial light modulator is a liquid crystal spatial light modulator or a digital micromirror device, which can dynamically adjust the phase or polarization state of the light beam.

3. The system for fabricating a multi-period photonic crystal according to claim 1, wherein: The complex period photonic crystal structure dimension includes one-dimensional, two-dimensional or three-dimensional, and the complex period photonic crystal structure distribution includes a triangular complex period structure or a square complex period structure.

4. The system for fabricating a multi-period photonic crystal according to claim 1, wherein: The size of the complex period photonic crystal structure unit in any direction ranges from 0.5μm to 100μm.

5. The system for fabricating a multi-period photonic crystal according to claim 1, wherein: The photoresist plate adopts positive photoresist or negative photoresist, and the exposed area forms a periodic structure after development.

6. The application method of a system for fabricating a multi-period photonic crystal by multi-beam laser holography, applied to the system for fabricating a multi-period photonic crystal by multi-beam laser holography according to any one of claims 1-5, characterized in that, The method comprises the following steps: Step 1: preparing a positive photoresist or negative photoresist plate meeting the requirements of the laser waveband; Step 2: emitting a laser beam from the laser, generating multiple coherent beams after the laser passes through the multi-beam generating element, collimating the multiple coherent beams into parallel light by the beam collimating element, converting the parallel light beam into a modulated parallel light beam by the spatial light modulator controlled by the host computer, and the modulated parallel light beam is light with arbitrary phase and arbitrary polarization state; Step 3: fixing the positive photoresist or negative photoresist plate on the multi-axis displacement table, and converging each parallel light beam to the photoresist plate by the focusing lens; Step 4: the host computer controls the movement of the beam collimating element, the phase and polarization state of the light beam are controlled by the spatial light modulator, and the positive photoresist or negative photoresist plate is moved by the multi-axis displacement table, so that the period of the photonic crystal and the exposure position are changed; Step 5: developing the exposed positive photoresist or negative photoresist plate to complete the complex period photonic crystal.

7. The method according to claim 6, wherein the system is used for fabricating a multi-period photonic crystal by multiple-beam laser holography. Step 4 is specifically as follows: The displacement table makes the light beam collimation element close to or away from the multi-beam generation element, the photonic crystal period becomes larger or smaller, the multi-axis displacement table multi-axis movement makes the spatial light modulator dynamically change the phase or polarization state of each parallel light beam, and the positive photoresist or negative photoresist plate is exposed in a large area.

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