A parallel time-delay-free chaotic light source based on degenerate cavity

Abstract

The utility model discloses a kind of parallel no time-delay chaotic light source based on degenerate cavity, including plane mirror and coupling output mirror, coaxial first lens, second lens are provided between the plane mirror and coupling output mirror, solid gain medium is provided between the plane mirror and first lens, or between first lens and second lens, or between second lens and coupling output mirror;The plane mirror is set on the front focal plane of first lens, and coupling output mirror is set on the back focal plane of solid gain medium;The utility model is based on the multiple transverse mode characteristics of degenerate cavity, constructs parallel chaotic laser from spatial dimension, realizes the parallel output of chaotic light signal, and the device can increase data transmission capacity, improve the generation rate of random number.

Description

Technical Field

[0001] This invention belongs to the technical field of chaotic light sources, specifically relating to a parallel, time-delay-free chaotic light source based on a degenerate cavity. Background Technology

[0002] Chaos, as a nonlinear dynamic process, is sensitive to initial conditions. In the field of optics, the fusion of chaotic lasers with multi-scale information scenes is creating a new paradigm for intelligent sensing. Due to the noise-like characteristics of chaotic systems, chaotic signals can be used as physical entropy sources to extract random signals, and this has already been applied in fields such as secure communication, random number generation, lidar, and optical computing. Currently, traditional solutions use external cavity feedback to generate optical chaos. The resulting chaotic signals are difficult to output in parallel and contain significant time delays, failing to meet the high throughput and security requirements of future systems. Therefore, there is an urgent need to develop parallel, time-delay-free chaotic light sources to meet the practical application needs of MIMO secure communication systems and parallel random number generation.

[0003] To address the deficiency in existing technologies regarding the lack of parallel, time-delay-free chaotic light sources, this invention discloses a parallel, time-delay-free chaotic light source based on a degenerate cavity. Utility Model Content

[0004] This invention discloses a parallel, time-delay-free chaotic light source based on a degenerate cavity. Based on the multi-transverse mode degeneracy characteristics of the degenerate cavity, a parallel chaotic laser is constructed from the spatial dimension, realizing the parallel output of chaotic optical signals. This device can increase the data transmission capacity and improve the random number generation rate.

[0005] This utility model is achieved through the following technical solution: A parallel, time-delay-free chaotic light source based on a degenerate cavity includes a plane mirror and a coupling output mirror, which form a laser resonant cavity. A first lens and a second lens are coaxially disposed between the plane mirror and the coupling output mirror. A solid-state gain medium is disposed between the plane mirror and the first lens, or between the first lens and the second lens, or between the second lens and the coupling output mirror. The plane mirror is disposed on the front focal plane of the first lens, and the coupling output mirror is disposed on the back focal plane of the solid-state gain medium.

[0006] To better realize this utility model, the solid gain medium is further defined as a column structure, the end face radius of the column structure is equal to 1.5 mm, and the axial length of the column structure is equal to 6.7 cm.

[0007] To better realize this utility model, the column structure further includes a cylindrical structure and a square column structure.

[0008] To better realize this utility model, further, the axial distance between the plane mirror and the solid gain medium is equal to 3mm, the axial distance between the solid gain medium and the first lens is equal to 30mm, the axial distance between the first lens and the second lens is equal to 17cm, and the axial distance between the second lens and the output coupling mirror 5 is equal to 10cm.

[0009] To better realize this utility model, the planar reflector is further coated with a first reflective film layer, and the reflectivity of the reflective film layer is greater than or equal to 99.9%.

[0010] To better realize this utility model, the coupling output mirror is further coated with a second transmission film layer and a second reflection film layer, and the reflection to transmission beam splitting ratio of the coupling output mirror is 7:3-9:1.

[0011] To better realize this utility model, the first lens and the second lens are further configured as plano-convex lenses or biconvex lenses, and the first lens and the second lens are coated with a first transmission film layer.

[0012] To better realize this utility model, a semiconductor laser is further provided on one side of the solid gain medium, and the semiconductor laser is pumped on the side of the solid gain medium.

[0013] To better realize this utility model, a mask is further provided at the optical path output end of the coupling output mirror.

[0014] To better realize this utility model, the optical path output end of the mask is further provided with a photodetector, which is connected to the oscilloscope via a cable.

[0015] Compared with the prior art, this utility model has the following advantages and beneficial effects: This invention develops a spatially integrated parallel chaotic light source by adopting a degenerate cavity structure, realizing independent output of multiple transverse mode beams and improving channel capacity from a spatial dimension. By abandoning the traditional external cavity structure and using mode interaction to generate spontaneous chaos, there is no external cavity delay label, which increases the key space from the physical layer and results in high complexity of chaotic signals. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the structure of this utility model; Figure 2 A schematic diagram of a parallel, time-delay-free chaotic light source detection system; Figure 3 A schematic diagram of an array formed by sixteen chaotic light sources; Figure 4 A schematic diagram of a noise-like phenomenon formed by sixteen chaotic light sources; Figure 5 This is a schematic diagram of the spectral structure of a time signal; Figure 6 This is a thermodynamic diagram illustrating the correlation. Figure 7 A schematic diagram of a normalized time series; Figure 8 This is a schematic diagram illustrating the cross-correlation between two time series.

[0017] Wherein: 1-plane mirror; 2-first lens; 3-second lens; 4-solid gain medium; 5-coupled output mirror; 6-semiconductor laser; 7-mask; 8-photodetector; 9-cable wire; 10-oscilloscope. Detailed Implementation

[0018] Example 1: This embodiment presents a parallel, time-delay-free chaotic light source based on a degenerate cavity, such as... Figure 1 As shown, it includes a plane mirror 1 and a coupling output mirror 5. A first lens 2 and a second lens 3 are coaxially arranged between the plane mirror 1 and the coupling output mirror 5. A solid gain medium 4 is arranged between the plane mirror 1 and the first lens 2, or between the first lens 2 and the second lens 3, or between the second lens 3 and the coupling output mirror 5. The plane mirror 1 is arranged on the front focal plane of the first lens 2, and the coupling output mirror 5 is arranged on the rear focal plane of the solid gain medium 4.

[0019] The plane mirror 1 and the output coupling mirror 5 form a laser resonant cavity. By reflecting light back and forth within the cavity, the working length of the solid gain medium 4 is extended, suppressing spontaneous emission of photons and increasing the photon number density within the cavity. The solid gain medium 4 has an energy level structure that forms population inversion, providing optical gain. A combined lens, consisting of the equivalent thermal lens of the solid gain medium 4 and the second lens 3, together with the first lens 2, forms a self-imaging system. This changes the wavefront distribution of the incident light, allowing any paraxial light ray to reflect back and forth within the cavity without overflowing, increasing the working area of ​​the gain medium, and achieving a large-area array mode field output. The principle of the device is explained below: Within a degenerate cavity, the resonant frequency of the cavity's intrinsic modes. for subscript The subscript represents the ordinal number of the longitudinal modulus of the intrinsic mode. , The two transverse modulus ordinal numbers representing the intrinsic modes, The speed of light in a vacuum For the optical length of the degenerate cavity, and These are the values ​​of the ABCD matrix of the resonant cavity. For a degenerate cavity, ,at this time That is, the resonant frequency of the cavity is independent of the transverse mode number. Under the same longitudinal mode, countless transverse modes oscillate simultaneously, and each mode is an independent laser mode.

[0020] Due to the limitations of the cavity's geometric dimensions and diffraction losses, the specific number of transverse modes is determined by... Given, where Fresnel numbers , The system aperture radius refers to the radius of the end faces on both sides of the solid gain medium 4 within the degenerate cavity. It is the distance between the two system apertures, and in a degenerate cavity, it refers to the length of the solid-state gain medium 4. It is the laser wavelength.

[0021] In this embodiment, the distance between the plane mirror 1 and the solid gain medium 4 is 3 mm, the distance between the solid gain medium 4 and the first lens 2 is 30 mm, the focal length of the first lens 2 is 75 mm, the distance between the first lens 2 and the second lens 3 is 17 cm, the focal length of the second lens 3 is 10 cm, and the distance between the second lens 3 and the output coupling mirror 5 is 10 cm. The solid gain medium 4 is a cylindrical structure with an end face radius of 1.5 mm, a length L = 6.7 cm, and a concentration of 0.6 at%. A semiconductor laser (6) is used to pump the solid gain medium 4 from the side. Theoretically, it can support up to 10466 transverse modes under the same longitudinal mode. However, due to the pumping method, mode distortion, and mode gain competition within the cavity, the number of modes generated by the degenerate cavity laser will be greatly reduced.

[0022] Example 2: This embodiment discloses a parallel, time-delay-free chaotic light source based on a degenerate cavity, which is an optimization based on Embodiment 1. The solid gain medium 4 is a cylindrical structure with an end face radius of 1.5 mm and an axial length of less than or equal to 6.7 cm.

[0023] Solid gain medium 4 can be Nd:YAG, Nd:YLF, Nd:YO4, etc. 3+ The doped gain medium has a concentration of 0.8at%-1.2at% and a length of 1-3mm.

[0024] Furthermore, the column structure includes a cylindrical structure and a square column structure.

[0025] The rest of this embodiment is the same as that of Embodiment 1, so it will not be described again.

[0026] Example 3: This embodiment discloses a parallel, time-delay-free chaotic light source based on a degenerate cavity, which is optimized based on embodiment 1 or 2. The axial distance between the plane mirror 1 and the first lens 2 is 10cm, the axial distance between the first lens 2 and the second lens 3 is 17cm, the axial distance between the second lens 3 and the solid gain medium 4 is 7cm, and the axial distance between the solid gain medium 4 and the output coupling mirror 5 is 3mm.

[0027] The rest of this embodiment is the same as that of embodiment 1 or 2, so it will not be described again.

[0028] Example 4: This embodiment discloses a parallel, time-delay-free chaotic light source based on a degenerate cavity, which is optimized based on any one of embodiments 1-3. The planar mirror 1 is coated with a first reflective film layer for a wavelength of 1064nm, the reflectivity of the reflective film layer is greater than or equal to 99.9%, and the diameter of the planar mirror 1 is 25.4mm-50.8mm.

[0029] The coupling output mirror 5 is coated with a second transmission film and a second reflection film for a wavelength of 1064nm. The reflection to transmission beam splitting ratio of the coupling output mirror 5 is 7:3-9:1, preferably 7:3, 8:2, or 9:1. The diameter of the coupling output mirror 5 is 25.4mm-50.8mm.

[0030] The first lens 2 and the second lens 3 are plano-convex lenses or biconvex lenses, and the first lens 2 and the second lens 3 are coated with a first transmission film layer for a wavelength of 1064nm. The focal length of the first lens 2 and the second lens 3 is 5cm-10cm, and the diameter is 25.4mm-50.8mm. The specific focal length and mounting structure of the first lens 2 and the second lens 3 are matched according to the focal length of the thermal lens of the solid gain medium 4, so that the laser can form a self-imaging structure.

[0031] The rest of this embodiment is the same as any one of embodiments 1-3, so it will not be described again.

[0032] Example 5: This embodiment discloses a parallel, time-delay-free chaotic light source based on a degenerate cavity, which is an optimization based on any one of embodiments 1-4, and also includes a semiconductor laser 6, wherein the semiconductor laser 6 is side-pumped corresponding to the solid gain medium 4.

[0033] A semiconductor laser 6 is placed at the same height as the side of a solid-state gain medium 4, such as a crystal rod or crystal block. The laser beam output from the semiconductor laser 6 irradiates the sidewall of the solid-state gain medium 4 in a horizontal direction, achieving side pumping. The pump light is effectively coupled into the solid-state gain medium 4 through optical coupling, thereby exciting the stimulated emission process of the solid-state gain medium 4.

[0034] Furthermore, a mask 7 is provided at the optical path output end of the coupling output mirror 5, and a photodetector 8 is provided at the optical path output end of the mask 7. The photodetector 8 is connected to the oscilloscope 10 through a cable 9.

[0035] A mask 7 is disposed outside the output coupling mirror 5 and is used to spatially modulate the output chaotic light. The mask 7 has a 4×4 array structure, which can split the chaotic light into parallel output channels to generate parallel chaotic light signals. After passing through the mask 7, the light forms a shape like... Figure 3 The array shown consists of 16 chaotic light sources. The photodetector 8 is disposed in the optical path of the laser output end to receive the chaotic light signal and convert it into an electrical signal; the electrical output end of the photodetector 8 is connected to the input end of the oscilloscope 10 through a cable 9 so that the time-domain waveform of the chaotic light signal can be displayed on the oscilloscope 10 in real time.

[0036] Using an oscilloscope 10 and a photodetector 8, the output light intensity variation curves of 16 laser array units were acquired in separate regions, exhibiting noise-like phenomena. Figure 4 As shown, the mode intensity change is in a chaotic state at this time, and the maximum Lyapunov exponent is quantitatively calculated. Approximately 75 ms -1 This indicates that the time series is a chaotic sequence. Using digital signal processing techniques, the spectral structure of the time signal is obtained through Fast Fourier Transform, as shown below. Figure 5 As shown, the power spectrum does not have obvious relaxation oscillation peaks and exhibits a flat power spectrum. With a starting frequency of 1 kHz, the effective bandwidth of 80% of the power spectrum is approximately 62 kHz.

[0037] Furthermore, we measured 16 arrays: A1~A16 within the same time period, i.e., 500 ms, and calculated the correlation thermodynamic plot as follows. Figure 6 As shown, excluding the perfectly correlated elements on the diagonal, the cross-correlation of the array elements is all below 5%, proving that the array elements are independent of each other. Taking A6 and A7 as examples... Figure 7 As shown, although the normalized time series all exhibit chaotic emission, there is no synchronous emission phenomenon. Figure 8As shown, the cross-correlation function of the two time series was calculated, and the maximum value of the cross-correlation function was less than 0.04. It should be noted that the periodic fluctuations in the cross-correlation curve originate from the residual 50 Hz AC signal in the industrial drive power supply.

[0038] The rest of this embodiment is the same as any one of embodiments 1-4, so it will not be described again.

[0039] The above description is merely a preferred embodiment of the present utility model and is not intended to limit the present utility model in any way. Any simple modifications or equivalent changes made to the above embodiments based on the technical essence of the present utility model shall fall within the protection scope of the present utility model.

Claims

1. A parallel, time-delay-free chaotic light source based on a degenerate cavity, comprising a plane mirror (1) and a coupling output mirror (5), characterized in that, A first lens (2) and a second lens (3) are coaxially arranged between the plane mirror (1) and the coupling output mirror (5). A solid gain medium (4) is arranged between the plane mirror (1) and the first lens (2), or between the first lens (2) and the second lens (3), or between the second lens (3) and the coupling output mirror (5). The plane mirror (1) is arranged on the front focal plane of the combined lens of the first lens (2) and the solid gain medium (4), and the coupling output mirror (5) is arranged on the rear focal plane of the second lens (3).

2. The parallel, time-delay-free chaotic light source based on a degenerate cavity according to claim 1, characterized in that, The solid gain medium (4) is a column structure with an end face radius of 1.5 mm and an axial length of 6.7 cm.

3. The parallel, time-delay-free chaotic light source based on a degenerate cavity according to claim 2, characterized in that, The column structure includes cylindrical structure and square column structure.

4. A parallel, time-delay-free chaotic light source based on a degenerate cavity according to claim 3, characterized in that, The axial distance between the plane mirror (1) and the gain medium (4) is 3 mm, the axial distance between the gain medium (4) and the first lens (2) is 30 mm, the axial distance between the first lens (2) and the second lens (3) is 17 cm, and the axial distance between the second lens (3) and the coupling output mirror (5) is 10 cm.

5. A parallel, time-delay-free chaotic light source based on a degenerate cavity according to any one of claims 1-4, characterized in that, The planar mirror (1) is coated with a first reflective film layer, the reflectivity of which is greater than or equal to 99.9%.

6. A parallel, time-delay-free chaotic light source based on a degenerate cavity according to any one of claims 1-4, characterized in that, The coupling output mirror (5) is coated with a second transmission film and a second reflection film, and the reflection to transmission beam splitting ratio of the coupling output mirror (5) is 7:3-9:

1.

7. A parallel, time-delay-free chaotic light source based on a degenerate cavity according to any one of claims 1-4, characterized in that, The first lens (2) and the second lens (3) are plano-convex lenses or biconvex lenses, and the first lens (2) and the second lens (3) are coated with a first transmission film layer.

8. A parallel, time-delay-free chaotic light source based on a degenerate cavity according to any one of claims 1-4, characterized in that, A semiconductor laser (6) is disposed on one side of the solid gain medium (4), and the semiconductor laser (6) is pumped on the side of the solid gain medium (4).

9. A parallel, time-delay-free chaotic light source based on a degenerate cavity according to claim 8, characterized in that, The optical path output end of the coupling output mirror (5) is provided with a mask (7).

10. A parallel, time-delay-free chaotic light source based on a degenerate cavity according to claim 9, characterized in that, The optical path output end of the mask plate (7) is provided with a photodetector (8), and the photodetector (8) is connected to the oscilloscope (10) through a cable (9).

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