A continuous chaotic few-mode laser based on a degenerate cavity

Abstract

The present application relates to the field of laser technology, and provides a continuous chaotic few-mode laser based on a degenerate cavity, comprising a reflector, a gain medium, a first lens, a pinhole aperture, a second lens, and an output coupling mirror coaxially arranged in sequence; the gain medium and the first lens form a combined lens, and the reflector is arranged on the focal plane of the combined lens, the output coupling mirror is arranged on the focal plane of the second lens, and the focal plane of the combined lens and the second lens on one side remain coincident. The present application can have high power and high control freedom to meet the needs of practical applications.

Description

Technical Field

[0001] The present application relates to the field of laser technology, and in particular to a continuous chaotic few-mode laser based on a degenerate cavity. Background Art

[0002] A degenerate cavity usually refers to an optical resonant cavity in which, under certain conditions, there are multiple optical modes with the same or similar resonant frequencies in the resonant cavity. These modes can be degenerate with each other, that is, they exhibit the same physical properties, such as wavelength, phase, etc., to some extent.

[0003] Due to its noise-like characteristics, chaotic lasers have important applications in secure communications, random number generation, laser radar, etc. Currently, the devices used to generate chaotic lasers are mainly semiconductor lasers with external cavity feedback structures.

[0004] Existing chaotic laser devices mainly use semiconductor lasers with external cavity feedback structures, which have problems such as insufficient power and low control freedom.

[0005] Therefore, in order to meet the practical application needs such as free-space chaotic optical communications, due to the inherent defects of traditional semiconductor lasers, it is urgent to develop new chaotic light sources with high power, low cost, high complexity and large control freedom.

[0006] Application Contents

[0007] The purpose of this application is to provide a continuous chaotic few-mode laser based on a degenerate cavity that has high power and high control freedom to meet practical application needs.

[0008] The embodiments of the present application are implemented through the following technical solutions: a continuous chaotic few-mode laser based on a degenerate cavity, comprising a reflector, a gain medium, a first lens, a pinhole aperture, a second lens and an output coupling mirror coaxially arranged in sequence; the gain medium and the first lens form a combined lens, and the reflector is arranged on the focal plane of the combined lens, the output coupling mirror is arranged on the focal plane of the second lens, and the focal plane of the combined lens and the second lens on one side remain overlapped.

[0009] Furthermore, a rotating shaft is provided at both ends of the output coupling mirror, and the rotating shaft is connected to a bracket, and a locking groove wheel is provided at one end of the rotating shaft; a mounting plate is provided on the bracket, and a plug-in piece for engaging with the locking groove wheel is passed through the mounting plate, and a base is provided at the tail end of the plug-in piece, and a reset spring is sleeved on the plug-in piece and clamped between the mounting plate and the base.

[0010] Furthermore, a support column is provided at the bottom of the bracket, a driven gear is installed on the support column, and the driven gear is meshedly connected with a driving gear.

[0011] Furthermore, the bracket is a semicircular ring structure.

[0012] Furthermore, it also includes a mounting base plate, on which an adjustment slot is provided, and the reflector, the first lens, the second lens and the output coupling mirror are slidably matched with the adjustment slot.

[0013] Furthermore, the pinhole aperture is arranged on a focal plane where the combined lens and the second lens overlap.

[0014] Furthermore, the gain medium is made of solid crystal.

[0015] The technical solutions of the embodiments of the present application have at least the following advantages and beneficial effects:

[0016] 1. This application generates high-power lasers through solid gain media, avoiding the limitation of device size and power due to chip overheating when using semiconductor lasers;

[0017] 2. The beat frequency principle is used to interact with the mode to generate spontaneous chaos. There is no external cavity feedback device, which reduces the overall volume. The position and angle of the optical element can be manually adjusted, which is more flexible.

[0018] 3. The degenerate resonant self-imaging and small aperture mode-limiting structure are adopted, so that the cavity can have a similar Q value in the transverse mode, and obtain better beam quality while reducing the threshold power;

[0019] 4. Due to the large output power, compared with semiconductor lasers, there is no need to use power amplifier devices such as EDFA. It uses spatial optical path output and can be directly connected to the free space optical communication system. It does not require collimation and beam expansion equipment, saving operating costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0021] Figure 1 A schematic diagram of the structure of a continuous chaotic few-mode laser based on a degenerate cavity provided in an embodiment of the present application;

[0022] Figure 2 This is a schematic diagram of the multi-angle adjustment structure of the output coupling mirror in this application;

[0023] Figure 3 A top view of the installation base plate in this application;

[0024] Figure 4 Schematic diagram of the output light intensity of the laser in this application;

[0025] Figure 5 is the power spectrum of the laser in this application.

[0026] Icons: 1-reflector, 2-gain medium, 3-first lens, 4-pinhole aperture, 5-second lens, 6-output coupling mirror, 61-rotating shaft, 62-locking groove wheel, 7-bracket, 8-insert, 81-base, 9-mounting plate, 10-reset spring, 11-support column, 12-driven gear, 13-driving gear, 14-mounting base plate, 141-adjusting slide groove. DETAILED DESCRIPTION

[0027] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. The components of the embodiments of the present application described and shown in the drawings here can be arranged and designed in various different configurations.

[0028] Therefore, the following detailed description of the embodiments of the present application provided in the accompanying drawings is not intended to limit the scope of the present application for which protection is sought, but merely represents selected embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without creative work are within the scope of protection of the present application.

[0029] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0030] Example

[0031] The following is further described in conjunction with specific embodiments. Figure 1-Figure 3As shown, this embodiment is a continuous chaotic few-mode laser based on a degenerate cavity, comprising a reflector 1, a gain medium 2, a first lens 3, a pinhole aperture 4, a second lens 5 and an output coupling mirror 6 which are coaxially arranged in sequence; the gain medium 2 and the first lens 3 form a combined lens, and the reflector 1 is arranged on the focal plane of the gain medium 2 and the first lens 3, the output coupling mirror 6 is arranged on the focal plane of the second lens 5, and the focal planes of the combined lens and the second lens 5 on one side are kept coincident; specifically, the mathematical model of the degenerate cavity is constructed using the ABCD transmission matrix, assuming that the focal length of the thermal lens generated by the gain medium 2 is f1, the focal lengths of the first lens 3 and the second lens 5 are f2 and f3 respectively, the distance between the reflector 1 and the gain medium 2 is l1, the distance between the gain medium 2 and the first lens 3 is l2, the distance between the first lens 3 and the pinhole aperture 4 is l3, the distance between the pinhole aperture 4 and the second lens 5 is l4, and the distance between the second lens 5 and the output coupling mirror 6 is l5, and the forward loop matrix of the whole system along the coaxial positive direction is:

[0032]

[0033] The backward loop matrix of the entire system along the negative coaxial direction is:

[0034]

[0035] The loop matrix of the system:

[0036] The distances between the optical components are adjusted so that A=D=1 of the ABCD matrix of the system, thereby satisfying the degeneracy condition. In order to obtain the highest mode degeneracy, B=C=0 of the system.

[0037] From the perspective of geometric optics, any light ray in the system returns to its original position after a single loop. From the perspective of physical optics, there are countless transverse modes degenerate under each longitudinal mode of the system, and all transverse modes have the same Q value.

[0038] The reflector 1 and the output coupling mirror 6 form a resonant cavity, which extends the length of the gain medium 2 by reflecting the light back and forth, increases the photon energy density in the cavity, and finally enables the photons to achieve stimulated radiation. The gain medium 2 has an energy level structure that produces stimulated radiation, which provides an amplification effect on the photons. The thermal lens equivalent to the gain medium 2 and the first lens 3 are combined as a lens to form a self-imaging system together with the second lens 5. The pinhole aperture 4 acts as a transverse mode selector, which increases the loss of high-order transverse modes. For transverse modes with the same Q value, the order of the mode will be reduced, so that the laser is in a few-mode state with a mode number of 2-4, reducing the beam divergence angle.

[0039] Reference Figure 2As shown, in this embodiment, both ends of the output coupling mirror 6 are provided with a rotating shaft 61, and the rotating shaft 61 is connected to a bracket 7, and one end of the rotating shaft 61 is provided with a locking groove wheel 62; a mounting plate 9 is provided on the bracket 7, and a plug-in piece 8 for engaging with the locking groove wheel 62 is passed through the mounting plate 9, and a base 81 is provided at the tail end of the plug-in piece 8, and a reset spring 10 is sleeved on the plug-in piece 8 and clamped between the mounting plate 9 and the base 81. A support column 11 is provided at the bottom of the bracket 7, and a driven gear 12 is installed on the support column 11, and the driven gear 12 is meshed and connected with a driving gear 13; specifically, by setting a rotating shaft 61 and a support column 11, the rotating shaft 61 is located in the horizontal direction, and the support column 11 is located in the vertical direction, and the output coupling mirror 6 is rotated around the rotating shaft 61, and the insert 8 is used in combination with the elastic force of the reset spring 10 to be clamped in the groove of the lock groove wheel 62 for locking, so as to adjust the inclination angle in this direction; then the driving gear 13 is manually turned to drive the driven gear 12 and the support column 11 to rotate and adjust the vertical angular position of the output coupling mirror 6, so that the cavity loses the rotational symmetry in the coaxial direction of multiple elements, generates transverse mode dedegeneracy in the spectral structure, and generates a transverse mode beat frequency ω b , so that ω b and the relaxation oscillation frequency ω of the laser r interact with each other and adjust the inclination angle so that ω r <ω b <2ω r , the laser output light intensity shows a noise-like phenomenon such as Figure 4 As shown in Figure 2, the system is in a chaotic state. Using a spectrum analyzer to observe the spectrum structure, the power spectrum has no obvious relaxation oscillation peak, and is shown as a flat power spectrum. Figure 5 shown.

[0040] In order to facilitate the contact and adjustment of the tilt angle of the output coupling mirror 6, the bracket 7 can be designed as a semicircular ring structure.

[0041] Reference Figure 1 and Figure 3 As shown, this embodiment also includes a mounting base plate 14, on which an adjustment slot 141 is provided, and the reflector 1, the first lens 3, the second lens 5 and the output coupling mirror 6 are slidably matched with the adjustment slot 141; in order to facilitate the adjustment of the straight-line distance between each component to achieve the correct working position, the bottom blocks of the reflector 1, the first lens 3, etc. are inserted into the adjustment slot 141 for movement.

[0042] The pinhole aperture 4 is arranged on the focal plane where the combined lens and the second lens 5 overlap. The pinhole aperture 4 can be a circular aperture, a square aperture or the like. The circular aperture is 0.5-1 mm, and the square aperture is 0.75 mm in length and 0.75 mm in width.

[0043] It is worth mentioning that the gain medium 2 adopts a solid structure and can be made of Nd:YAG, Nd:YO4, Nd:YLF and other Nd3+ The doped gain medium has a concentration of 0.8at%-1.2at%, a thickness of 1-3mm, and a cylindrical or square structure.

[0044] The above are only preferred embodiments of the present application and are not intended to limit the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A continuous chaotic few-mode laser based on a degenerate cavity, characterized in that: It comprises a reflector (1), a gain medium (2), a first lens (3), a pinhole aperture (4), a second lens (5) and an output coupling mirror (6) which are coaxially arranged in sequence; The gain medium (2) and the first lens (3) form a combined lens, and the reflector (1) is arranged on the focal plane of the combined lens of the gain medium (2) and the first lens (3), and the output coupling mirror (6) is arranged on the focal plane of the second lens (5), and the focal planes of the combined lens and the second lens (5) on one side are kept overlapping.

2. The continuous chaotic few-mode laser based on a degenerate cavity according to claim 1, characterized in that: The output coupling mirror (6) is provided with a rotating shaft (61) at both ends, and the rotating shaft (61) is connected to a bracket (7), and a locking groove wheel (62) is provided at one end of the rotating shaft (61); The bracket (7) is provided with a mounting plate (9), the mounting plate (9) is penetrated with an inserting piece (8) for engaging with the locking groove wheel (62), a base (81) is provided at the rear end of the inserting piece (8), and a return spring (10) is sleeved on the inserting piece (8) and is engaged between the mounting plate (9) and the base (81).

3. The continuous chaotic few-mode laser based on a degenerate cavity according to claim 2, characterized in that: A support column (11) is provided at the bottom of the bracket (7), a driven gear (12) is mounted on the support column (11), and the driven gear (12) is meshedly connected with a driving gear (13).

4. The continuous chaotic few-mode laser based on a degenerate cavity according to claim 2, characterized in that: The support (7) is a semicircular ring structure.

5. The continuous chaotic few-mode laser based on a degenerate cavity according to claim 1, characterized in that: It also comprises a mounting base plate (14), the mounting base plate (14) being provided with an adjustment slide groove (141), and the reflector (1), the first lens (3), the second lens (5) and the output coupling mirror (6) are slidably matched with the adjustment slide groove (141).

6. The continuous chaotic few-mode laser based on a degenerate cavity according to claim 1, characterized in that: The pinhole stop (4) is arranged on a focal plane where the combined lens and the second lens (5) overlap.

7. The continuous chaotic few-mode laser based on a degenerate cavity according to claim 1, characterized in that: The gain medium (2) is made of solid crystal.

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