CN105607276A - Novel ideal aspheric collimation system of semiconductor laser - Google Patents

Abstract

The invention belongs to the technical field of optical communication, in particular to a novel ideal aspheric collimation system of a semiconductor laser. The optical system is composed of ideal aspheric collimating plano-convex lens and triangular prism group, and the design method is based on three-dimensional vector refraction theory. The ideal aspheric collimating plano-convex lens collimates the laser beam with asymmetric divergence angle characteristics emitted by the semiconductor laser into a high-precision collimated laser beam, which can theoretically break through the diffraction limit. Applied to the situation where the semiconductor laser emission source has astigmatism, the divergence angle produced is obviously better than the collimation effect of the traditional rotating hyperboloid collimating plano-convex lens. Then the triangular prism group is used to shape the high-precision collimated light beam with an elliptical cross-section into a high-precision collimated light beam with a circular cross-section. The invention helps to improve the emission accuracy in the optical communication system under the condition that the semiconductor laser emission source has astigmatism.

Description

A New Ideal Aspheric Collimation System for Semiconductor Laser

technical field

The invention belongs to the technical field of optical communication, in particular to a novel ideal aspheric collimating optical system for emitting light beams from semiconductor lasers, which can generate high-precision collimating laser beams.

Background technique

With the development of science and technology, people's demand for communication capacity is getting higher and higher. Optical communication has the advantages of small beam divergence angle and high directivity (thus having high military confidentiality), high speed, large transmission capacity (3 to 5 orders of magnitude higher than microwave communication), light weight, etc., and has gradually become a International research hotspots. As a key transmitting component in the field of optical communication technology, the optical antenna has two key technical problems of high-precision collimation and shaping. Therefore, high-precision pre-collimation and shaping technology is the key technology to ensure the realization of long-distance space laser communication, and it is also an important guarantee to improve the accuracy of acquisition, alignment and tracking (APT).

Semiconductor laser is a laser source commonly used in optical communication systems. Its active region is similar to a rectangular planar dielectric waveguide, and it is easy to diverge during propagation. The cross-section of its outgoing beam has an elliptical shape, as shown in Figure 1(a). The typical divergence angle (half angle) of semiconductor lasers perpendicular to the junction plane (ie, the meridian plane) generally varies in the range of 0 to 30 degrees, and the divergence angle in the direction parallel to the junction plane (sagittal plane) is in the range of 0 to 10 degrees. Variety. The smaller the divergence angle, the better the directionality. In addition, the light source of the semiconductor laser in the meridian plane does not coincide with the light source in the sagittal plane, and there is a certain distance (Δl) in the direction of the optical axis, which is called astigmatism. The existence of asymmetrical divergence angle characteristics and astigmatism will inevitably affect the quality of the outgoing beam of the semiconductor laser and the transmission efficiency of the optical system. In order to transmit the Gaussian beam output by the semiconductor laser into the optical antenna with high quality and high efficiency, it is necessary to collimate and shape the output beam of the semiconductor laser, compress the beam divergence angle to improve the far-field symmetry and spot shape, and reduce image distortion. The effect of dispersion on the beam quality can be improved, and the transmission accuracy of the transmitting antenna in the optical communication system can be improved. Therefore, high-precision collimation and shaping of the beam emitted by the semiconductor laser is of great significance for long-distance laser communication systems.

In 2000, Oxford University reported in the "Nature" magazine that it used three-dimensional holography to make visible light photonic crystals, and its self-collimation characteristics can break through the diffraction limit of light. In 2012, Zheng Wanhua's research group at the Institute of Semiconductors, Chinese Academy of Sciences introduced photonic crystals into the traditional semiconductor laser resonator structure to regulate the laser oscillation mode and improve the output beam quality of the laser from the chip level. For the first time, a photonic crystal with high beam quality in the 905nm band was developed internationally. Laser, the laser output far field is distributed in a near circular spot, the vertical (fast axis) divergence angle is 6.5°, and the horizontal (slow axis) divergence angle is 7.1°. In 2013, the teachers and students of Jinan University published on "Optics Letter" that a biaxial hyperboloid microlens was fabricated on the fiber end face to compress the fast and slow axis divergence angles of the semiconductor laser to 6.9° and 32.3 mrad respectively, and couple them into the fiber. Efficiency increased to 80%. The optical system used in the above semiconductor laser pre-collimation method cannot fundamentally change the influence of semiconductor laser asymmetric divergence angle characteristics and astigmatism on optical transmission, thus limiting the emission accuracy and transmission efficiency of the optical antenna to a certain extent.

Contents of the invention

Aiming at the deficiencies in the prior art, the present invention proposes a new method for producing high-precision collimated laser beams, using an ideal aspheric collimator plano-convex lens to collimate the asymmetric divergence angle laser beams emitted by the semiconductor into high-precision collimation The laser beam is then shaped by a triangular prism group to shape the collimated beam with an elliptical cross-section to realize efficient coupling of the semiconductor laser beam to the optical antenna. The transmission of laser beams with collimated divergence angles close to the diffraction limit effectively ensures the realization of long-distance space optical communication.

The technical scheme adopted by the present invention can be summarized in the following two aspects: on the one hand, the ideal aspheric collimating plano-convex lens can collimate the asymmetric divergence angle Gaussian beam emitted by the semiconductor laser with high precision; on the other hand, the triangular prism group can further shape the beam is a Gaussian beam of circular cross-section. The system is applied to the Cassegrain antenna in the optical communication system, which can effectively improve the emission accuracy and transmission efficiency of the transmitting antenna in the optical communication system.

In the ideal aspheric collimating plano-convex lens in the present invention, after the light emitted by the point light source at its left focal point passes through the lens, the divergence angle between the outgoing beam and the optical axis is close to zero, which is a high-precision collimation Parallel beams, which can theoretically break through the diffraction limit.

In the ideal aspheric collimating plano-convex lens in the present invention, after the light emitted by the point light source (astigmatic light source) at a certain distance away from its left focus passes through the lens, the divergence angle between the outgoing light beam and the optical axis is better than the same The collimating divergence angle of a hyperbolic plano-convex lens of revolution for the parameters (focal length, central thickness, refractive index). Therefore, the ideal aspheric collimating plano-convex lens in the present invention has a better collimating effect on the outgoing beam of the semiconductor laser with certain astigmatism.

The triangular prism group in the present invention expands the short axis of the parallel light beam of the elliptical cross-section after the ideal aspherical collimating plano-convex lens collimates or compresses the long axis, and compresses (or enlarges) the light beam by changing the apex angle of the triangular prism ) multiples can be controlled to achieve various required compression multiples, so that the collimated beam with an elliptical cross-section can be shaped into a collimated beam with a circular cross-section.

The design of optical collimation and shaping optical system in the present invention is based on vector refraction theorem, establishes three-dimensional refraction surface and vector light model, utilizes MATLAB program to carry out optimal design to optical system structure, carries out three-dimensional to the space transmission of light in antenna Tracing to obtain image quality evaluation parameters. It specifically includes: 1) the divergence angle of the outgoing beam, that is, the three-dimensional distribution of the beam divergence angle and the spatial position of the beam; 2) the spot diagram, that is, the spot distribution on the receiving plane; 3) the energy uniformity, that is, the three-dimensional energy distribution surface on the receiving plane, etc. .

Description of drawings

FIG. 1 is a schematic diagram of the divergence and astigmatism characteristics of an outgoing beam of a semiconductor laser.

Fig. 2 is a structural block diagram of an ideal aspheric collimating plano-convex lens and a triangular prism group of a semiconductor laser according to an embodiment of the present invention.

Fig. 3 is an assembly diagram of an ideal aspheric collimating plano-convex lens and a triangular prism group of a semiconductor laser according to an embodiment of the present invention.

Fig. 4 is an optical path diagram of an ideal aspheric collimating plano-convex lens for a point source outgoing light beam according to an embodiment of the present invention.

Fig. 5 is an optical path diagram of an ideal aspheric collimating plano-convex lens for the output beam of an astigmatic light source according to an embodiment of the present invention.

Fig. 6 is an optical path diagram of astigmatism collimation of a rotating hyperboloid collimating plano-convex lens object as a comparison in an embodiment of the present invention.

Fig. 7 is a simulation diagram comparing the divergence angle of the ideal aspheric collimating plano-convex lens and the divergence angle of the rotating hyperboloid collimating plano-convex lens under the condition of an astigmatic light source in an embodiment of the present invention.

Fig. 8 is an optical path diagram of a triangular prism group shaping according to an embodiment of the present invention.

detailed description

The present invention will be further elaborated and illustrated below in conjunction with the accompanying drawings and embodiments.

FIG. 1 is a schematic diagram of the divergence characteristics and astigmatism characteristics of an outgoing beam of a semiconductor laser. The output beam of a semiconductor laser has an asymmetric divergence angle characteristic. The divergence angle (half angle) in the meridian plane generally changes in the range of 0° to 30°, and the divergence angle in the sagittal plane changes in the range of 0° to 10°. Moreover, the light source in the meridian plane and the light source in the sagittal plane do not intersect at the same point, and there is a certain astigmatism Δl) in the direction of the optical axis, which will inevitably affect the transmission efficiency of the semiconductor laser beam in the optical system. It performs high-precision collimation and shaping.

FIG. 2 is a structural block diagram of an ideal aspheric collimating plano-convex lens and a triangular prism group of a semiconductor laser according to an embodiment of the present invention. It is mainly composed of an ideal aspheric collimating plano-convex lens and a triangular prism group. The ideal aspheric collimating plano-convex lens can collimate the asymmetric divergence angle Gaussian beam emitted by the semiconductor laser with high precision; the triangular prism group further shapes the collimated beam with an elliptical cross-section into a collimated beam with a circular cross-section. Among them, the ideal aspheric collimating plano-convex lens and the triangular prism group are the content of the specific design of the present invention.

FIG. 3 is a schematic diagram of the assembly of an ideal aspheric collimating plano-convex lens and a triangular prism group of a semiconductor laser according to an embodiment of the present invention. The ideal aspheric collimating plano-convex lens is integrated with the exit end face of the semiconductor laser to collimate the Gaussian beam with asymmetric divergence angle emitted by the semiconductor laser into a collimated Gaussian beam with an elliptical cross-section. A triangular prism group is added to the optical path to compress the long axis of the parallel beam with elliptical cross section, so that the outgoing beam is a high-precision collimated Gaussian beam with circular cross section.

FIG. 4 is an optical path diagram of an ideal aspheric collimating plano-convex lens for a point source outgoing beam according to an embodiment of the present invention. Where n is the refractive index of the material, the focal length is l, and the central thickness of the plano-convex lens is d. α is the angle between any light emitted from the point source and the principal optical axis, β is the refraction angle of the light passing through the first refraction plane, and θ is the angle between the light emitted by the second refraction surface and the normal line of the refraction point. γ is the angle between the outgoing beam of the second refraction curved surface and the optical axis, that is, the collimation and divergence angle of the outgoing beam. The second refraction surface needs to be designed so that the outgoing rays corresponding to any refraction angle β are parallel to the optical axis, and the beam divergence angle γ=0 corresponding to any incident light. From the derivation, it can be obtained that as the point N changes, the change function x(β) of the coordinate x of the second refraction surface with the refraction angle β, and the change function y(β) of y with the refraction angle β are expressed as:

$<span\; class="notranslate">\; \{</span>\begin{array}{c}\mathrm{<span\; class="notranslate">\; x</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; \&beta;</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; l</span>}\mathrm{<span\; class="notranslate">\; cos</span>}\mathrm{<span\; class="notranslate">\; \&beta;</span>}}{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; cos</span>}\mathrm{<span\; class="notranslate">\; \&beta;</span>}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; \&lsqb;</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; -</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\sqrt{\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; no</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}{\mathrm{<span\; class="notranslate">\; sin</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}\mathrm{<span\; class="notranslate">\; \&beta;</span>}}}<span\; class="notranslate">\; +</span>\frac{\mathrm{<span\; class="notranslate">\; d</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>}{\mathrm{<span\; class="notranslate">\; l</span>}}<span\; class="notranslate">\; \&rsqb;</span>\\ \mathrm{<span\; class="notranslate">\; the\; y</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; \&beta;</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; l</span>}\mathrm{<span\; class="notranslate">\; sin</span>}\mathrm{<span\; class="notranslate">\; \&beta;</span>}}{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; cos</span>}\mathrm{<span\; class="notranslate">\; \&beta;</span>}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; \&lsqb;</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; -</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\sqrt{\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; no</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}{\mathrm{<span\; class="notranslate">\; sin</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}\mathrm{<span\; class="notranslate">\; \&beta;</span>}}}<span\; class="notranslate">\; +</span>\frac{\mathrm{<span\; class="notranslate">\; d</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>}{\mathrm{<span\; class="notranslate">\; l</span>}}<span\; class="notranslate">\; \&rsqb;</span><span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; l</span>}\frac{\mathrm{<span\; class="notranslate">\; no</span>}\mathrm{<span\; class="notranslate">\; sin</span>}\mathrm{<span\; class="notranslate">\; \&beta;</span>}}{\sqrt{\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; no</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}{\mathrm{<span\; class="notranslate">\; sin</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}\mathrm{<span\; class="notranslate">\; \&beta;</span>}}}\end{array}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>$

Using the above parametric equations, an ideal aspheric collimating plano-convex lens with rotational symmetry around the optical axis can be fabricated to achieve high-precision collimation of the beam emitted by the point light source at the left focal point.

FIG. 5 is an optical path diagram of an ideal aspheric collimating plano-convex lens for the output beam of an astigmatic light source according to an embodiment of the present invention. In the case of a given lens refractive index n, focal length l, and center thickness d, the position of the point light source moving along the negative direction of the optical axis by a distance Δl will have a certain influence on the divergence angle of the outgoing beam of the ideal aspheric collimated plano-convex lens.

FIG. 6 is an optical path diagram of astigmatism collimation of a rotating hyperboloid collimating plano-convex lens object as a comparison in an embodiment of the present invention. The rotating hyperboloid collimating plano-convex lens has a good collimating effect on point light sources. The distance Δl of the point light source away from the focal point (ie, the astigmatism of the light source) will have a certain influence on the divergence angle of the outgoing beam of the rotating hyperboloid collimating plano-convex lens.

As shown in FIG. 7 , it is a simulated diagram comparing the divergence angle of the ideal aspheric collimating plano-convex lens and the divergence angle of the rotating hyperboloid collimating plano-convex lens in the case of an astigmatic light source in an embodiment of the present invention. In the case of a given lens refractive index n, focal length l, and center thickness d, for different astigmatism distances Δl, the collimation divergence angle of an ideal aspheric collimating plano-convex lens is significantly better than that of a rotating hyperboloid collimating plano-convex lens Collimation effect. It shows that the ideal aspherical collimating plano-convex lens is more suitable for the semiconductor laser source with certain astigmatism than the rotating hyperboloid collimating plano-convex lens.

FIG. 8 is a schematic diagram of the shaping optical path of the triangular prism group according to an embodiment of the present invention. A triangular prism group is used to expand the short axis of the elliptical truncated parallel beam or to compress the long axis, so that the elliptical cross-section beam is shaped into a circular cross-section collimated beam. Two right-angle prisms have the same shape, and their apex angles are both δ. The magnification of the first prism is:

${\mathrm{<span\; class="notranslate">\; m</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; d</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}}{{\mathrm{<span\; class="notranslate">\; d</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; cos\&phi;</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}}{{\mathrm{<span\; class="notranslate">\; cos\&phi;</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}}<span\; class="notranslate">\; =</span>\frac{\sqrt{\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; no</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}{\mathrm{<span\; class="notranslate">\; sin</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}{\mathrm{<span\; class="notranslate">\; \&phi;</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}}}{{\mathrm{<span\; class="notranslate">\; cos\&phi;</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}}<span\; class="notranslate">\; =</span>\frac{\sqrt{\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; no</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}{\mathrm{<span\; class="notranslate">\; sin</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}\mathrm{<span\; class="notranslate">\; \&delta;</span>}}}{\mathrm{<span\; class="notranslate">\; c</span>}\mathrm{<span\; class="notranslate">\; o</span>}\mathrm{<span\; class="notranslate">\; the\; s</span>}\mathrm{<span\; class="notranslate">\; \&delta;</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; )</span>$

Since the two triangular prisms are the same, and the light beam is also vertically incident on the first surface of the second lens, then also:

${\mathrm{<span\; class="notranslate">\; m</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; d</span>}}_{\mathrm{<span\; class="notranslate">\; 3</span>}}}{{\mathrm{<span\; class="notranslate">\; d</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}}<span\; class="notranslate">\; =</span>\frac{\sqrt{\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; no</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}{\mathrm{<span\; class="notranslate">\; sin</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}\mathrm{<span\; class="notranslate">\; \&delta;</span>}}}{\mathrm{<span\; class="notranslate">\; c</span>}\mathrm{<span\; class="notranslate">\; o</span>}\mathrm{<span\; class="notranslate">\; the\; s</span>}\mathrm{<span\; class="notranslate">\; \&delta;</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 3</span>}<span\; class="notranslate">\; )</span>$

So get the total magnification (or compression) factor:

$\mathrm{<span\; class="notranslate">\; m</span>}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; m</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; \&times;</span>{\mathrm{<span\; class="notranslate">\; m</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; d</span>}}_{\mathrm{<span\; class="notranslate">\; 3</span>}}}{{\mathrm{<span\; class="notranslate">\; d</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; no</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}{\mathrm{<span\; class="notranslate">\; sin</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}\mathrm{<span\; class="notranslate">\; \&delta;</span>}}{{\mathrm{<span\; class="notranslate">\; cos</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}\mathrm{<span\; class="notranslate">\; \&delta;</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 4</span>}<span\; class="notranslate">\; )</span>$

By simulating the effect of the vertex angle of the prism on the compression (or amplification) multiple M of the beam, various required compression multiples can be achieved, thereby realizing the shaping of the collimated beam with an elliptical cross-section into a collimated beam with a circular cross-section.

The design of ideal aspheric collimating plano-convex lens and triangular prism group in the present invention is based on vector refraction theorem, establishes each refraction surface of three-dimensional optical system and vector light model, utilizes MATLAB program to carry out three-dimensional tracing to the space transmission of light in optical system, Obtain the relationship between the exit divergence angle and the spatial position of the beam, as well as the beam cross-sectional energy distribution. The specific steps are: 1) establishing three-dimensional parameter equations of each refraction surface, and determining the size and display area of each refraction surface according to actual needs. Use the MATLAB program to draw the three-dimensional surface corresponding to the parameter equation of each surface; 2) draw the incident light according to the direction cosine of the incident light, and establish the vector equation of the incident light, and solve it jointly with the equation of the first refraction surface to obtain each surface on the refraction surface The coordinates of the refraction point, plotting the incident ray in 3D. Then find the cosine of the normal direction of the refraction surface at the refraction point, and obtain the direction cosine of the refracted light based on the vector refraction theorem; then take the refracted light as the incident light of the second refraction surface, and obtain the refracted light of the second refraction surface , and draw the refracted ray, and so on; 3) Calculate the angle between the outgoing ray and the main axis according to the direction cosine of the refracted ray on the last refracting surface, and draw the relationship between the spatial divergence angle and the position of the light; 4) Use the coordinates of the intersection of the outgoing light and the observation plane to draw the spot diagram, and obtain the energy distribution in the observation plane according to the Gaussian beam energy calculation formula; 5) Draw the beam aberration curve in the observation plane according to the definition of each aberration.

Claims (5)

1. A novel ideal aspheric collimation system of a semiconductor laser, characterized in that it utilizes an ideal aspheric collimating plano-convex lens to the high-precision collimation of the asymmetrical divergence angle Gaussian beam emitted by the semiconductor laser; The collimated beam is further shaped into a circular cross-section collimated beam. The system is applied in the optical communication system, and can effectively improve the emission accuracy and transmission efficiency of the transmitting antenna in the optical communication system. 2. the novel ideal aspheric collimation system of a kind of semiconductor laser according to claim 1, it is characterized in that described ideal aspheric collimation plano-convex lens, the light that is positioned at the point light source that its left focus place sends passes through this After the lens, the divergence angle between the outgoing beam and the optical axis is close to zero, which is a highly collimated parallel beam, which can theoretically break through the diffraction limit. 3. the novel ideal aspheric collimation system of a kind of semiconductor laser according to claim 1 is characterized in that described ideal aspheric collimation plano-convex lens deviates from the point light source (astigmatism) at its left focal point certain distance place After the light emitted by the light source passes through the lens, the divergence angle between the outgoing beam and the optical axis is better than the collimation divergence angle of the rotating hyperboloid plano-convex lens under the same parameters (focal length, central thickness, refractive index). Therefore, the ideal aspheric collimating plano-convex lens in the present invention has a better collimating effect on the outgoing beam of the semiconductor laser with certain astigmatism. 4. the novel ideal aspheric collimation system of a kind of semiconductor laser according to claim 1, it is characterized in that described triangular prism group is to the ellipse after collimating through ideal aspheric collimating plano-convex lens described in claim 2 The short axis of the parallel beam of cross-section is expanded or the long axis is compressed. By changing the vertex angle of the prism to control the compression (or magnification) multiple of the beam, various required compression multiples can be achieved, thereby realizing the elliptical cross-section. The collimated beam is shaped into a collimated beam of circular cross-section. 5. the novel ideal aspheric collimation system of a kind of semiconductor laser according to claim 1, it is characterized in that the design of described ideal aspheric collimating plano-convex lens and triangular prism group is based on vector reflection theorem, establishes three-dimensional reflecting surface and The vector ray model uses the MATLAB program to optimally design the structure of the optical system, and simulates and analyzes the spatial transmission of light in the optical system.