Chaotic optical signal output device taking microcavity semiconductor laser array as light source

Abstract

A chaotic optical signal output device taking a microcavity semiconductor laser array as a light source belongs to the technical field of semiconductor photoelectronics. In the prior art, the structure is complex, and the quality and output power of chaotic optical signals are low. According to the invention, 2-5 micro-cavity semiconductor lasers are arranged in a micro-cavity semiconductor laser array in a line, the micro-cavities of the micro-cavity semiconductor lasers have the same shape, and the micro-cavities are in a spiral shape, a spiral shape, an oval shape with a notch at the rear end or a quadrupole shape; light overflows from the rear end of the micro-cavity in the shape; the rear end of the microcavity faces a concave reflector, and an outer cavity of the microcavity semiconductor laser is formed between the rear end of the microcavity and the concave reflector; the front end of the microcavity of each microcavity semiconductor laser outputs a beam of chaotic optical signals, or the front end of each microcavity is in butt joint with the input coupling end of an optical waveguide, the output coupling end of each optical waveguide is in butt joint with a beam combining device, and the beam combining device outputs a beam of chaotic optical signals.

Description

Technical Field

[0001] The invention discloses a chaotic optical signal output device using a microcavity semiconductor laser array 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 communications, chaotic radars, high-speed random key generation and physical random number generation. They play a vital role in scientific computing, communication security and other military aspects. 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 1As shown, the microcavity of the microcavity semiconductor laser is circular or square, and its structure is clear, which can effectively generate chaotic optical signal output. However, the chaotic optical signal generating device has its shortcomings. First, since the chaotic optical signal output end of the microcavity semiconductor laser and the external cavity feedback light input end share the same waveguide, the light source in the chaotic optical signal generating device is a single tube of the microcavity semiconductor laser, and the final chaotic optical signal output power is difficult to improve. At the same time, since a part of the chaotic optical signal is separated by the optical splitting device and fed back to the inner cavity of the microcavity semiconductor laser via the external cavity light feedback device as a disturbance light, the final chaotic optical signal is further weakened. Although an optical amplifier is provided in the chaotic optical signal generating device, it is difficult to obtain a chaotic optical signal output of the required power. Second, the disturbance light comes from the inner cavity of a microcavity semiconductor laser, and the mode and phase are single, the disturbance to the optical mode in the cavity is slight, the chaotic state of the optical mode in the cavity is low, and the quality of the emitted chaotic optical signal is low. Third, the structure of the chaotic optical signal generating device is relatively complex, and each part thereof has many other accessories. Therefore, the structure is very complex and the integration is low. Affected by factors outside the cavity, the stability of the chaotic light output is poor. These are also the shortcomings of the chaotic optical signal generating device. Summary of the invention

[0005] In order to simplify the structure of the chaotic optical signal generating device and improve the quality and output power of the chaotic optical signal, we proposed a technical solution named "chaotic optical signal output device using microcavity semiconductor laser array as light source".

[0006] The chaotic optical signal output device of the present invention using a microcavity semiconductor laser array as a light source is characterized by: Figure 2 , Figure 3 As shown, 2 to 5 microcavity semiconductor lasers 2 are arranged in a line in the microcavity semiconductor laser array 1, and the microcavity shapes of the microcavity semiconductor lasers 2 are the same, and the microcavity shape is a spiral line shape, such as Figure 3 As shown; spiral, such as Figure 6 As shown; oval with a notch at the rear end, such as Figure 7 As shown; or quadrupole-shaped; light overflows from the rear end of the microcavity of the shape; the rear end of the microcavity faces a concave reflector 3, and an external cavity of the microcavity semiconductor laser 2 is formed between the rear end of the microcavity and the concave reflector 3; the front end of each microcavity of the microcavity semiconductor laser 2 outputs a chaotic light signal, such as Figure 2 As shown, or the front end of each microcavity is connected to the input coupling end of an optical waveguide 4, and the output coupling end of each optical waveguide 4 is connected to a beam combining device, as shown in FIG. Figure 3 As shown, a chaotic optical signal is output by the beam combining device.

[0007] When the chaotic optical signal output device of the present invention using the microcavity semiconductor laser array as the light source is working, a current is injected between the annular upper electrode 5 and the lower electrode 11 of the microcavity semiconductor laser 2, such as Figure 4 As shown, the carriers in the pump active layer 8 form photon radiation, the radiated photons oscillate and amplify in the microcavity, and form a strong directional light output at the front end of the microcavity, and form a small amount of light overflow at the rear end of the microcavity; Figure 2 , Figure 3 As shown, the overflow light interacts with the concave reflector 3 to form an external cavity oscillation. The light that meets the external cavity oscillation conditions is reflected and coupled back into the microcavity, forming an external cavity light feedback, which becomes a disturbance light to disturb the optical mode in the microcavity, causing the optical mode in the microcavity to enter a chaotic state and generate a chaotic light signal, which is output from the front end of the microcavity and collected and utilized by a beam combining device. In the above working process, the microcavity semiconductor laser 2 is both a disturbance light source and a chaotic light signal source. It can be seen that the technical effect of the present invention is that the distribution characteristics of the radiation light field of the non-circular microcavity semiconductor laser 2 with a whispering gallery mode can be effectively utilized, such as Figure 5 As shown, most of the radiation light field is distributed in the 0° direction, which is the front end of the microcavity, and the 180° direction is the rear end of the microcavity. In the range of 120° to 240°, which is symmetrical with respect to 180°, the radiation light field is also strongly distributed. This part of the radiation overflow is almost completely reflected by the concave reflector 3, forming an external cavity light feedback disturbance. The theoretical utilization rate of the radiation light field can be increased by about 10%. The radiation light field in the 0° direction becomes a chaotic light signal after being emitted. The generation of the disturbance light and the output of the chaotic light signal occur at both ends of the microcavity, which not only do not affect each other, A concave reflector 3 and a microcavity semiconductor laser 2 can cooperate to efficiently generate chaotic optical signals, and no longer need an optical circulation device and a spectrometer as in the prior art. Since the disturbance light is not emitted from the 0° direction radiation light field light output spectrometer, even a single microcavity semiconductor laser 2 can meet the usual needs, and the optical amplification device is no longer a necessary component. This is also the reason why the present invention includes an output mode in which the front end of the microcavity of each microcavity semiconductor laser 2 outputs a chaotic optical signal. Figure 2 As shown, moreover, it also includes an output mode in which 2 to 5 microcavity semiconductor lasers 2 output a chaotic light signal through a beam combining device, such as Figure 3 As shown, it can better meet special needs. Therefore, under the premise of meeting various requirements on the output power of chaotic optical signals, the structure of the chaotic optical signal output device is greatly simplified, and the reduction of links also improves the stability of chaotic optical signal output.

[0008] The technical effect of the present invention is that there are differences in the light emission modes between the 2 to 5 microcavity semiconductor lasers 2 arranged in a line in the microcavity semiconductor laser array 1, and the external cavity length c of each microcavity semiconductor laser 2 is set by artificially adjusting the position of each concave reflector 3, such as Figure 3 As shown, they are different from each other, and the radial dimensions of the microcavities of the microcavity semiconductor lasers 2 are artificially set to be different from each other, such as Figure 7 As shown, the optical modes of the chaotic optical signals output by each microcavity semiconductor laser 2 will therefore be very different from each other, and the complexity of the chaotic optical signal after beam combining will be significantly improved. This composite chaotic optical signal with more than two optical modes is a high-quality chaotic optical signal, which improves the information confidentiality in practical applications such as secure communications and wavelength division multiplexing, and expands the theoretical depth of chaotic optical signals in subjects such as random number generation. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] 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.

[0010] Figure 2 It is a schematic diagram of the overall structure of the present invention; the figure also shows that the front end of the microcavity of each microcavity semiconductor laser 2 outputs a chaotic light signal; in this figure, the microcavity shape of the microcavity semiconductor laser 2 is a vortex line shape, and the concave surface of the concave reflector 3 is a concave cylindrical surface.

[0011] Figure 3 It is a schematic diagram of the overall structure of the present invention, which also shows that a beam of chaotic light signals is output by the beam combining device, and the figure also serves as an abstract figure; in this figure, the microcavity shape of the microcavity semiconductor laser 2 is a vortex line shape, and the concave surface of the concave reflector 3 is a concave cylindrical surface.

[0012] Figure 4 The structure of the microcavity semiconductor laser array in the present invention is Figure 3 Schematic cross-sectional view in the AA direction.

[0013] Figure 5 This is a schematic diagram of the radiation light field distribution of the vortex line-shaped microcavity semiconductor laser when the deformation factor ε=0.4.

[0014] Figure 6 It is a schematic diagram of the overall structure of the present invention, which also shows that a chaotic light signal is output by the beam combining device; in this figure, the microcavity shape of the microcavity semiconductor laser 2 is spiral, and the concave surface of the concave reflector 3 is a concave cylindrical surface.

[0015] Figure 7It is a schematic diagram of the overall structure of the present invention, which also shows that a chaotic light signal is output by the beam combining device; in this figure, the microcavity shape of the microcavity semiconductor laser 2 is an ellipse with a notch at the rear end, and the concave surface of the concave reflector 3 is a concave cylindrical surface.

[0016] Figure 8 It is a schematic diagram of the overall structure of the present invention, which also shows that a chaotic light signal is output by the beam combining device; in this figure, the microcavity shape of the microcavity semiconductor laser 2 is a vortex line shape, and the concave surface of the concave reflector 3 is a concave spherical surface. DETAILED DESCRIPTION

[0017] The present invention needs to be further defined as follows.

[0018] Each microcavity semiconductor laser 2 is fabricated on a silicon wafer, sharing a substrate 10 and a lower electrode 11. Figure 4 As shown, the annular width a of the annular upper electrode 5 of the microcavity semiconductor laser 2 is 2 μm to 300 μm; the radial dimensions of the microcavities of the various microcavity semiconductor lasers 2 are the same or different.

[0019] like Figure 4 As shown, the thickness of the annular upper electrode 5 and the lower electrode 11 of the microcavity semiconductor laser 2 is 200nm-300nm, the thickness of the upper waveguide layer 7 and the lower waveguide layer 9 is 120nm-150nm, the thickness of the active layer 8 is 5nm-20nm, and the thickness of the substrate 10 is 120μm-180μm.

[0020] The concave surface of the concave reflector 3 is a concave cylindrical surface, such as Figure 2 , Figure 3 , Figure 6 , Figure 7 As shown, or a concave sphere, as Figure 8 As shown; the axis of the concave cylindrical surface is parallel to the axis of the microcavity, and the center of the concave spherical surface is aligned with the center of the rear end of the microcavity; the radial dimension of the concave reflector 3 is 1 to 3 times the radial dimension of the microcavity of the microcavity semiconductor laser 2; the concave depth b of the concave reflector 3 is 50μm to 300μm, as shown Figure 3 shown.

[0021] like Figure 3 As shown, the external cavity lengths c of the microcavity semiconductor lasers 2 are equal or unequal, and the external cavity lengths c are 200 μm to 2000 μm.

[0022] The present invention is further described by taking the snail-shaped microcavity semiconductor laser 2 as an example. The snail-shaped snail polar coordinate equation is ρ(θ)=ρ0[1+εcos(θ)], where: characteristic radius ρ0=200μm, deformation factor ε=0.4. The radial dimension of the concave reflector 3 is 1.25 times the radial dimension of the microcavity of the microcavity semiconductor laser 2; the concave depth b of the concave reflector 3 is 100μm; and the length c of the external cavity is 800μm.

[0023] The present invention is further described by taking an elliptical microcavity semiconductor laser 2 with a notch at the rear end as an example. Figure 7 As shown, three microcavity semiconductor lasers 2 are arranged in a line in a microcavity semiconductor laser array 1. The microcavity ellipse of the microcavity semiconductor laser 2 in the middle has a long axis of 400 μm and a short axis of 300 μm, and the microcavity ellipse of the microcavity semiconductor lasers 2 at both ends has a long axis of 200 μm and a short axis of 100 μm. Therefore, the external cavity length c of the microcavity semiconductor laser 2 in the middle and the microcavity semiconductor lasers 2 at both ends is also different; the annular widths a of the annular upper electrodes 5 of the three microcavity semiconductor lasers 2 are 30 μm, 50 μm, and 20 μm, respectively. The radial dimensions of the three microcavity semiconductor lasers 2 and the annular width a of the annular upper electrode 5 are different, and the chaos degree of the chaotic optical signal can be adjusted.

Claims

1. A chaotic optical signal output device using a microcavity semiconductor laser array as a light source, characterized in that: Two to five microcavity semiconductor lasers (2) are arranged in a line in a microcavity semiconductor laser array (1); the microcavities of the microcavity semiconductor lasers (2) have the same shape, and the microcavity shape is a snail shape, a spiral shape, an ellipse with a notch at the rear end, or a quadrupole shape; the rear end of the microcavity of the shape has light overflow; the rear end of the microcavity faces a concave reflector (3), and an external cavity of the microcavity semiconductor laser (2) is formed between the rear end of the microcavity and the concave reflector (3); the front end of the microcavity of each microcavity semiconductor laser (2) outputs a chaotic light signal, or the front end of each microcavity is connected to the input coupling end of an optical waveguide (4), and the output coupling end of each optical waveguide (4) is connected to a beam combining device, and the beam combining device outputs a chaotic light signal.

2. The chaotic optical signal output device using a microcavity semiconductor laser array as a light source according to claim 1, characterized in that: Each microcavity semiconductor laser (2) is manufactured on a silicon wafer, and shares a substrate (10) and a lower electrode (11); the annular width a of the annular upper electrode (5) of the microcavity semiconductor laser (2) is 2 μm to 300 μm; and the radial dimensions of the microcavities of each microcavity semiconductor laser (2) are the same or different.

3. The chaotic optical signal output device using a microcavity semiconductor laser array as a light source according to claim 1, characterized in that: The concave surface of the concave reflecting mirror (3) is a concave cylindrical surface or a concave spherical surface; the axis of the concave cylindrical surface is parallel to the axis of the microcavity, and the center of the concave spherical surface is aligned with the center of the rear end of the microcavity; the radial dimension of the concave reflecting mirror (3) is 1 to 3 times the radial dimension of the microcavity of the microcavity semiconductor laser (2); and the concave depth b of the concave reflecting mirror (3) is 50 μm to 300 μm.

4. The chaotic optical signal output device using a microcavity semiconductor laser array as a light source according to claim 1, characterized in that: The external cavity lengths c of the various microcavity semiconductor lasers (2) are equal or unequal, and the external cavity lengths c are 200 μm to 2000 μm.

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