Chaotic optical signal output device taking volute-shaped microcavity semiconductor laser as light source

Abstract

The invention discloses a chaotic optical signal output device taking a volute-shaped microcavity semiconductor laser as a light source, and belongs to the technical field of semiconductor photoelectronics. The prior art is complex in structure and poor in light emitting stability. According to the invention, the 0-degree angle end of a volute-shaped microcavity of the volute-shaped microcavity semiconductor laser is a light output end, the curvature mutation position of the + / -130-degree rear end surface of the volute-shaped microcavity is a light overflow position, and the normal lines of the reflecting mirror surfaces of two optical total reflection mirrors intersect with the two light overflow positions respectively. The included angles theta between the two normal lines and the 0-degree angle end direction are + 130 degrees and-130 degrees respectively, and the space between the optical total reflection mirror and the worm-line-shaped microcavity forms an outer cavity of the worm-line-shaped microcavity semiconductor laser. The distances from the respective reflection mirror surfaces to the two light overflow positions along the respective normal lines of the two optical total reflection mirrors are the feedback cavity lengths a1 and a2 of the two outer cavities; the light amplification device is located on the 0-degree-angle end light output path, and the light amplification device outputs a chaotic light signal. The method is applied to the field of chaotic secret communication.

Description

Technical Field

[0001] The invention discloses a chaotic optical signal output device using a spiral microcavity semiconductor laser as a light source, and belongs to the technical field of semiconductor optoelectronics. Background Art

[0002] Disturbing the optical mode causes chaos of light and generates chaotic optical signals. Chaotic optical signals have the characteristics of concealment, unpredictability and high complexity. They are widely used in chaotic secure communication, chaotic radar, high-speed random key generation and physical random number generation, and play a vital role in scientific computing and communication security. In order to meet the practical application needs of chaotic optical signals in the above-mentioned related fields, how to obtain chaotic optical signals has become a hot research topic in this field. Chaotic optical signals are divided into nonlinear chaotic optical signals inside the laser and nonlinear chaotic optical signals outside the laser according to the generation principle. The former refers to the chaotic optical signal obtained by the interaction between the optical modes in the cavity, and the latter refers to the chaotic optical signal obtained by introducing additional perturbation light. The specific methods include external light injection method, photoelectric feedback method and external cavity optical feedback method. The external cavity optical feedback method has the characteristics of all-optical structure, simple operation and easy integration. Therefore, the external cavity feedback method has become the mainstream method for generating chaotic oscillations and obtaining chaotic light.

[0003] Semiconductor lasers are sensitive to external disturbance light, that is, light from the external cavity can significantly disturb the oscillation in the semiconductor laser cavity. In addition, semiconductor laser technology is mature, small in size and low in cost. Therefore, semiconductor lasers have become the main light source for chaotic optical signal generation devices.

[0004] Compared with FP cavity and DFB cavity semiconductor lasers, microcavity semiconductor lasers with whispering gallery mode have higher quality factors and smaller mode volumes, which can significantly enhance the interaction between light and matter. The advantage of the non-cleaved cavity surface of this microcavity semiconductor laser is that the output chaotic optical signal can be regulated on-chip, which can significantly improve the complexity of chaotic optical signals and directly obtain high-quality chaotic optical signal outputs in different optical modes. The existing typical chaotic optical signal generating device with whispering gallery mode microcavity semiconductor laser as the light source includes a microcavity semiconductor laser, an optical recycling device, an optical amplification device, a spectrometer, and an external cavity optical feedback device, such as Figure 1 As shown, the microcavity of the microcavity semiconductor laser is circular or square, and its structure is clear, and it can effectively generate chaotic light signal output. However, in the chaotic light signal generating device, the chaotic light signal output end and the external cavity light feedback input and output end are both in the same light beam loop, and there are many device accessories in the entire light beam loop, which makes the chaotic light signal generating device complex in structure, low in integration, low in adjustability, and poor in light output stability, and the quality of the output chaotic light is easily affected by the external environment. Summary of the invention

[0005] In order to simplify the structure of the chaotic optical signal generating device, improve the integration of the device, improve the adjustability of the chaotic optical signal intensity, improve the light output stability, and reduce the impact of the external environment on the chaotic optical signal quality, we proposed an invention named "chaotic optical signal output device using a snail-shaped microcavity semiconductor laser as a light source".

[0006] The chaotic optical signal output device of the present invention using a spiral microcavity semiconductor laser as a light source is characterized by: Figure 2 As shown, the 0° angle end of the snail-shaped microcavity 1 of the snail-shaped microcavity semiconductor laser is the light output end, the ±130° rear end face curvature mutation point of the snail-shaped microcavity 1 is the light overflow point, the normal lines of the reflection mirror surfaces of the two optical total reflection mirrors 2 intersect with the two light overflow points respectively, and the angles θ between the two normal lines and the 0° angle end direction are +130° and -130° respectively, the space between the optical total reflection mirror 2 and the snail-shaped microcavity 1 becomes the external cavity of the snail-shaped microcavity semiconductor laser, and the distances from the respective reflection mirror surfaces to the two light overflow points along the respective normal lines of the two optical total reflection mirrors 2 are the feedback cavity lengths a1 and a2 of the two external cavities; the optical amplification device is located on the light output optical path of the 0° angle end, and the chaotic optical signal is output by the optical amplification device.

[0007] When the chaotic optical signal output device of the present invention using the spiral microcavity semiconductor laser as the light source is working, Figure 3 As shown in FIG. 1 , current is injected between the annular upper electrode 3 and the lower electrode 9 of the spiral microcavity semiconductor laser to pump the carriers in the active gain region 6 to form photon radiation, as shown in FIG. Figure 4 As shown in FIG. 1 , the radiated photons oscillate and amplify in the snail-shaped microcavity 1. In addition to forming laser output in the 0° direction, there is light overflow in the directions of +130° and -130° where the curvature of the rear end face of the snail-shaped microcavity 1 suddenly changes. The overflowing light forms an external cavity oscillation in the external cavity of the snail-shaped microcavity semiconductor laser, as shown in FIG. Figure 2 As shown, interference lasers are formed and return to the snail-shaped microcavity 1 to form external cavity light feedback; the two interference lasers disturb the intracavity optical mode of the snail-shaped microcavity 1, causing the optical mode to enter a chaotic state and generate a chaotic optical signal; finally, the chaotic optical signal is output from the 0° angle end of the snail-shaped microcavity 1, and then amplified by the optical amplifier device and output.

[0008] The technical effect of the present invention is to utilize the overflow light feedback disturbance. Combined with the radiation light field distribution characteristics of the whispering gallery mode of the snail-shaped microcavity semiconductor laser, the interaction between the overflow light radiation light field energy in two directions and the optical total reflection mirror 2 is utilized to form a convenient and efficient external cavity light feedback disturbance, and the external cavity light feedback and the chaotic light signal output occur in different directions of the snail-shaped microcavity 1, respectively, and do not affect each other. It can be seen that the chaotic light signal output device of the present invention no longer requires a spectroscopic device, an optical circulation device, etc., the structure is simplified, and the integration is improved. Therefore, the stability of the chaotic light signal output is greatly improved, and the influence of the external environment on the quality of the chaotic light signal is reduced.

[0009] The technical effect of the present invention is that the feedback cavity lengths of the two external cavities are a1 and a2 respectively, that is, the feedback cavity lengths of the two external cavities are different, and the disturbance light collection optical modes (wavelength, phase, etc.) that meet the external cavity oscillation conditions and feedback-couple into the snail-shaped microcavity 1 are different, which can form efficient disturbances, increase the dimension of the light oscillation disturbance of the snail-shaped microcavity 1, and facilitate the generation of high-quality chaotic optical signals. The intensity of the interference laser feedback-coupled into the snail-shaped microcavity 1 can also be finely adjusted by adjusting the feedback cavity length a of the two external cavities within the range of 200μm to 2000μm, and the intensity of the output chaotic optical signal can be adjusted without changing the external current injection.

[0010] The technical effect of the present invention is that, by adjusting the annular width b of the annular upper electrode 3 of the snail-shaped microcavity semiconductor laser within the range of 2 μm to 100 μm, the generation of high-order modes in the inner cavity of the snail-shaped microcavity semiconductor laser (the microcavity is from the center to the edge, and the optical mode is from high order to low order) can be effectively suppressed, and the regulation of the optical mode in the inner cavity of the snail-shaped microcavity semiconductor laser can be achieved, and the problem of the deterioration of the chaotic optical signal quality caused by the increase in the number of modes (not high order, but many orders) of the large radial size snail-shaped microcavity semiconductor laser (large radial size, high output optical power) can be solved, and the design of the snail-shaped microcavity semiconductor laser is facilitated. For example, while increasing the radial size of the snail-shaped microcavity semiconductor laser to improve the output intensity of the chaotic optical signal, the annular width b of the annular upper electrode 3 is appropriately widened to reduce the high-order mode and improve the quality of the chaotic optical signal. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 The present invention is a schematic block diagram of the overall structure of a chaotic optical signal generating device using a whispering gallery mode microcavity semiconductor laser as a light source.

[0012] Figure 2 It is a schematic top view of the overall structure of the present invention, which is also used as an abstract drawing; the optical total reflection mirror 2 in the figure is a plane mirror.

[0013] Figure 3The structure of the vortex line-shaped microcavity semiconductor laser in the present invention is Figure 2 Schematic diagram of the sectional main view in the AA direction.

[0014] Figure 4 This is a schematic diagram of the radiation light field distribution of the vortex line-shaped microcavity when the deformation factor ε=0.4. DETAILED DESCRIPTION

[0015] The present invention needs to be further defined as follows.

[0016] The snail shape is determined by the polar coordinate equation R(θ)=R0[1+εcos(θ)], where: characteristic radius R0=10μm~800μm, deformation factor ε=0.4~1.

[0017] The reflective mirror surface of the optical total reflector 2 is a plane, a concave spherical surface or a concave cylindrical surface, and the reflective mirror surface posture of the concave cylindrical surface is that the generatrix direction is parallel to the axis direction of the snail-shaped microcavity semiconductor laser.

[0018] The feedback cavity lengths a1 and a2 of the two external cavities are determined in the range of 200 μm to 2000 μm, and a1≠a2, such as a1=300 μm, a2=500 μm.

[0019] The annular width b of the annular upper electrode 3 of the vortex line microcavity semiconductor laser is 2 μm to 100 μm.

[0020] The structure of the snail-shaped microcavity semiconductor laser is as follows: Figure 3 As shown, from top to bottom, there are an annular upper electrode 3, an ohmic contact layer 4, an upper waveguide layer 5, an active gain region 6, a lower waveguide layer 7, a substrate 8, and a lower electrode 9. The annular upper electrode 3 is made of Ti / Pt / Au with a thickness of 200nm to 300nm; the ohmic contact layer 4 is made of InP; the upper waveguide layer 5 is made of P-type AlGaInAs with a thickness of 120nm to 150nm; the active gain region 6 is made of AlGaInAs multi-quantum well structure with a thickness of 5nm to 20nm; the lower waveguide layer 7 is made of N-type AlGaInAs with a thickness of 120nm to 150nm; the substrate 8 is made of InP with a layer thickness of 120μm to 180μm; and the lower electrode 9 is made of Au / Ge / Ni with a thickness of 200nm to 300nm.

Claims

1. A chaotic optical signal output device using a spiral microcavity semiconductor laser as a light source, characterized in that: The 0° angle end of a snail-shaped microcavity (1) of a snail-shaped microcavity semiconductor laser is a light output end, the ±130° rear end face curvature mutation point of the snail-shaped microcavity (1) is a light overflow point, the normal lines of the respective reflection mirror surfaces of two optical total reflection mirrors (2) intersect with the two light overflow points respectively, the angles θ between the two normal lines and the 0° angle end direction are +130° and -130° respectively, the space between the optical total reflection mirror (2) and the snail-shaped microcavity (1) becomes the external cavity of the snail-shaped microcavity semiconductor laser, and the distances from the respective reflection mirror surfaces to the two light overflow points along the respective normal lines of the two optical total reflection mirrors (2) are the feedback cavity lengths a1 and a2 of the two external cavities; the optical amplification device is located on the light output optical path of the 0° angle end, and the chaotic optical signal is output by the optical amplification device.

2. The chaotic optical signal output device using a spiral microcavity semiconductor laser as a light source according to claim 1, characterized in that: The snail shape is determined by the polar coordinate equation R(θ)=R0[1+εcos(θ)], where: characteristic radius R0=10μm~800μm, deformation factor ε=0.4~1.

3. The chaotic optical signal output device using a spiral microcavity semiconductor laser as a light source according to claim 1, characterized in that: The reflective mirror surface of the optical total reflector (2) is a plane, a concave spherical surface or a concave cylindrical surface, and the reflective mirror surface posture of the concave cylindrical surface is such that the generatrix direction is parallel to the axial direction of the snail-shaped microcavity semiconductor laser.

4. The chaotic optical signal output device using a spiral microcavity semiconductor laser as a light source according to claim 1, characterized in that: The feedback cavity lengths a1 and a2 of the two external cavities are determined within a range of 200 μm to 2000 μm, and a1≠a2.

5. The chaotic optical signal output device using a spiral microcavity semiconductor laser as a light source according to claim 1, characterized in that: The annular width b of the annular upper electrode (3) of the vortex line microcavity semiconductor laser is 2 μm to 100 μm.

Images