A Multi-channel White Noise Signal Source Based on Microwave Photonics

Abstract

The invention provides a multi-channel white noise signal source based on microwave photonics, comprising a gain optical fiber, an optical wavelength division multiplexer, a pump source, an optical isolator, an optical filter, an optical fiber coupler, a photodetector, a current-to-voltage converter and an electrical amplifier; two ends of the gain optical fiber are respectively connected to one end of an optical wavelength division multiplexer, and the other end of each optical wavelength division multiplexer is sequentially connected to an optical isolator, an optical filter and an optical fiber coupler; each optical wavelength division multiplexer is connected to a pump source, and the pump source injects pump light into the gain optical fiber; spontaneous radiation light generated by the gain optical fiber is sequentially output to the optical filter through the optical isolator for filtering, and then enters the photodetector after being split by the optical fiber coupler; the current-to-voltage converter converts the output current of the photodetector into a voltage signal, and the electrical amplifier amplifies the output voltage signal to a predetermined voltage amplitude as a white noise signal output.

Description

Technical Field

[0001] The invention belongs to the field of optoelectronic technology, and in particular relates to a multi-channel white noise signal source based on microwave photonics. Background Art

[0002] As an ideal random signal, white noise has the characteristics of zero mean and non-zero power spectrum density. It plays an extremely important role in optical communication, signal processing, linear system analysis and design, etc. In scientific research and practical applications, white noise is generally obtained through any signal generator or commercial special instruments and equipment. Although these instruments and equipment are fully functional, they are expensive, large in size and weight, and not very practical for some special occasions. Summary of the invention

[0003] In order to solve the above technical problems, the present invention proposes a multi-channel white noise signal source based on microwave photonics, wherein the white noise signal source comprises 1 gain optical fiber, 2 optical wavelength division multiplexers, 2n pump sources, 2 optical isolators, 2 optical filters, 2 optical fiber couplers, 2m photodetectors, 2m current-to-voltage converters and 2m electrical amplifiers;

[0004] The two ends of the gain optical fiber are respectively connected to one end of the optical wavelength division multiplexer, and the other end of each optical wavelength division multiplexer is sequentially connected to one optical isolator, one optical filter and one optical fiber coupler;

[0005] Each of the optical wavelength division multiplexers is connected to n pump sources, and the pump sources inject pump light into the gain optical fiber;

[0006] The spontaneous radiation light generated by the gain optical fiber is output to the optical filter through the optical isolator in turn, filtered by the optical filter, split by the optical fiber coupler and enter the photodetector, the current-to-voltage converter converts the output current of the spontaneous radiation light responded by the photodetector into a voltage signal, and the electrical amplifier amplifies the output voltage signal of the current-to-voltage converter to a predetermined voltage amplitude and outputs it as a white noise signal.

[0007] Where n≥1, m≥1.

[0008] Further, the gain optical fiber includes: an active optical fiber with a core doped with rare earth activated ions in a single-cladding, double-cladding or triple-cladding structure;

[0009] The core diameter of the gain optical fiber is 3-200 μm, and the core numerical aperture of the gain optical fiber is 0.06-0.12 NA; the inner cladding diameter of the gain optical fiber is 125-1000 μm, and the inner cladding numerical aperture is 0.12-0.46 NA.

[0010] Furthermore, the rare earth activation ions include: ytterbium, erbium, thulium, and holmium.

[0011] Furthermore, the optical wavelength division multiplexer, the wavelength division multiplexer, the optical isolator, the optical filter, the fiber coupler and the photodetector are all devices with optical fiber pigtails, and the connection between the optical wavelength division multiplexer, the wavelength division multiplexer, the optical isolator, the optical filter, the fiber coupler and the photodetector is achieved through coupling between the optical fiber pigtails.

[0012] Furthermore, the coupling between the optical fiber pigtails includes: optical fiber welding or fixed connection with a fixed coupler; the geometric dimensions of the two interconnected optical fiber pigtails are matched.

[0013] Furthermore, the optical wavelength division multiplexer comprises: an optical fiber pigtail connected to the gain optical fiber and an optical fiber pigtail connected to the pump source, wherein the geometric dimensions of the optical fiber pigtail connected to the gain optical fiber by the optical wavelength division multiplexer match the geometric dimensions of the gain optical fiber (1), and the geometric dimensions of the optical fiber pigtail connected to the pump source by the optical wavelength division multiplexer match the geometric dimensions of the optical fiber pigtail of the pump source.

[0014] Furthermore, the pump source includes: a fiber-coupled semiconductor laser, a fiber laser or a solid laser; the output fiber pigtail of the pump source is fused with the pump light input fiber end of the four optical wavelength division multiplexers; the central wavelength of the pump source includes: 915nm, 940nm, 976nm, 1018nm.

[0015] Furthermore, the optical filter performs spectral filtering on the spontaneous radiation beam output by the gain optical fiber according to a preset filtering band.

[0016] Furthermore, the operating frequency bandwidths of the photodetector, the current-to-voltage converter, and the electrical amplifier are all greater than the filtering bandwidth of the optical filter.

[0017] Furthermore, when only two white noise signal outputs are needed, the optical fiber coupler is not used, and the optical filter is directly connected to the photodetector.

[0018] The microwave photonics multi-channel white noise signal source of the present invention can generate a random stable optical signal based on amplified spontaneous radiation, thereby obtaining a white noise source with large bandwidth, low cost, small volume and weight.

[0019] By using the microwave photonics-based multi-channel white noise signal source of the present invention, multi-channel white noise signals can be generated simultaneously. The multi-channel output characteristic can simplify the system structure, reduce the system volume and weight, and save the system cost.

[0020] By using the microwave photonics-based multi-channel white noise signal source of the present invention, the output of white noise sources with different characteristics can be achieved by selecting optical filters with different bandwidths or different central wavelengths to meet the needs of different application scenarios. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 Schematic diagram of a multi-channel white noise signal source based on microwave photonics according to an embodiment of the present invention.

[0022] Figure 2 It is a schematic diagram of an improved multi-channel white noise signal source according to an embodiment of the present invention. DETAILED DESCRIPTION

[0023] In view of the shortcomings of the prior art, the present invention provides a multi-channel white noise signal source based on microwave photonics. In a laser gain medium with high gain, superfluorescent photons generated from spontaneous radiation will be amplified in power, and this process is called amplified spontaneous emission (ASE). Unlike the stimulated emission process of lasers, since ASE originates from spontaneous radiation, there is no coherence between photons, so the ASE light source has an ultra-wide bandwidth and ultra-low time correlation, and the generated signal is a smooth and random optical signal in timing, which has the same characteristics as white noise. Therefore, the present invention utilizes these characteristics of the ASE light source, combines the corresponding photodetector and current-voltage converter, converts the ASE light source signal into an electrical signal, and obtains a white noise source with small size, light weight and simple structure, which can greatly reduce the cost of related equipment.

[0024] The specific implementation modes of the present invention are described in detail below with reference to the accompanying drawings.

[0025] Example 1

[0026] A multi-channel white noise signal source based on microwave photonics, the structural diagram is as follows Figure 1 As shown, it includes a gain fiber 1, an optical wavelength division multiplexer 2-1, 2-2, a pump source 3-1, 3-2, an optical isolator 4-1, 4-2, an optical filter 5-1, 5-2, a photodetector 6-1, 6-2, a current-to-voltage converter 7-1, 7-2, and an electrical amplifier 8-1, 8-2.

[0027] During the implementation process, the pump sources 3-1 and 3-2, the optical wavelength division multiplexers 2-1 and 2-2, the isolators 4-1 and 4-2, and the optical filters 5-1 and 5-2 are connected by optical fiber fusion technology. After the pump light is injected into the gain fiber 1 through the optical wavelength division multiplexers 2-1 and 2-2, the pumping causes the gain fiber 1 to generate spontaneous radiation of photons, and the spontaneously radiated light is output from both ends of the gain fiber 1 through the optical wavelength division multiplexer. The output spontaneous radiation light signal passes through the photodetectors 6-1 and 6-2 respectively, and the current-voltage converters 7-1 and 7-2 convert the current responded by the photodetectors into voltage, and the electrical amplifiers 8-1 and 8-2 amplify the electrical signals output by the current-voltage converters 7-1 and 7-2. The output electrical amplified signal is the signal output by the white noise signal source, which can be used for different loads.

[0028] Example 2

[0029] An improved multi-channel white noise signal source based on microwave photonics, the structure of which is as follows Figure 2 As shown. Compared with Example 1, the main feature is that optical fiber couplers 9-1 and 9-2 are added on the basis of double-ended output to achieve the output of more channel signals. During the implementation process, the generated spontaneous radiation light signal can be split by optical fiber couplers 9-1 and 9-2 to form a multi-channel light signal. These split spontaneous radiation light signals pass through their respective photodetectors 6-1, 6-2, 6-3, 6-4, 6-5, 6-6, current-to-voltage converters 7-1, 7-2, 7-3, 7-4, 7-5, 7-6 and electrical amplifiers 8-1, 8-2, 8-3, 8-4, 8-5, 8-6 to obtain a multi-channel white noise signal amplification output. Each output electrical amplification signal can be used for different loads.

[0030] Finally, it should be noted that the above implementation modes are only used to illustrate the technical solutions of the embodiments of the present invention and are not intended to limit them. Although the embodiments of the present invention have been described in detail with reference to the above preferred implementation modes, those skilled in the art should understand that the technical solutions of the embodiments of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A multi-channel white noise signal source based on microwave photonics, characterized in that: The white noise signal source includes 1 gain optical fiber, 2 optical wavelength division multiplexers, 2n pump sources, 2 optical isolators, 2 optical filters, 2 optical fiber couplers, 2m photodetectors, 2m current-to-voltage converters and 2m electrical amplifiers; The two ends of the gain optical fiber are respectively connected to one end of the optical wavelength division multiplexer, and the other end of each optical wavelength division multiplexer is sequentially connected to one optical isolator, one optical filter and one optical fiber coupler; Each of the optical wavelength division multiplexers is connected to n pump sources, and the pump sources inject pump light into the gain optical fiber; The spontaneous radiation light generated by the gain optical fiber is output to the optical filter through the optical wavelength division multiplexer and the optical isolator in sequence, and after being filtered by the optical filter, it enters the photodetector after being split by the optical fiber coupler, the current-to-voltage converter converts the output current of the spontaneous radiation light responded by the photodetector into a voltage signal, and the electrical amplifier amplifies the output voltage signal of the current-to-voltage converter to a predetermined voltage amplitude and outputs it as a white noise signal; Where n≥1, m≥1, and m and n are both integers.

2. The signal source according to claim 1, characterized in that The gain optical fiber comprises: an active optical fiber with a core doped with rare earth activated ions and a single-cladding, double-cladding or triple-cladding structure; The core diameter of the gain optical fiber is 3-200 μm, and the core numerical aperture of the gain optical fiber is 0.06-0.12 NA; the inner cladding diameter of the gain optical fiber is 125-1000 μm, and the inner cladding numerical aperture is 0.12-0.46 NA.

3. The signal source according to claim 2, characterized in that The rare earth activating ions include: ytterbium, erbium, thulium and / or holmium.

4. The signal source according to claim 1, characterized in that The optical wavelength division multiplexer, the wavelength division multiplexer, the optical isolator, the optical filter, the fiber coupler and the photodetector are all devices with optical fiber pigtails, and the connection between the optical wavelength division multiplexer, the wavelength division multiplexer, the optical isolator, the optical filter, the fiber coupler and the photodetector is completed through coupling between the optical fiber pigtails.

5. The signal source according to claim 4, characterized in that The coupling between the optical fiber pigtails includes: optical fiber welding or fixed connection with a fixed coupler; the geometric dimensions of the two interconnected optical fiber pigtails are matched.

6. The signal source according to claim 1, characterized in that The optical wavelength division multiplexer comprises: an optical fiber pigtail connected to the gain optical fiber and an optical fiber pigtail connected to the pump source, wherein the geometric dimensions of the optical fiber pigtail connected to the gain optical fiber by the optical wavelength division multiplexer match the geometric dimensions of the gain optical fiber (1), and the geometric dimensions of the optical fiber pigtail connected to the pump source by the optical wavelength division multiplexer match the geometric dimensions of the optical fiber pigtail of the pump source.

7. The signal source according to claim 1, characterized in that The pump source includes: a fiber-coupled semiconductor laser, a fiber laser or a solid laser; the output fiber pigtail of the pump source is fused with the pump light input fiber end of the optical wavelength division multiplexer; the central wavelength of the pump source includes: 915nm, 940nm, 976nm and / or 1018nm.

8. The signal source according to claim 1, characterized in that The optical filter performs spectral filtering on the spontaneous radiation beam output by the gain optical fiber according to a preset filtering band.

9. The signal source according to claim 1, characterized in that The operating frequency bandwidths of the photodetector, the current-to-voltage converter, and the electrical amplifier are all greater than the filtering bandwidth of the optical filter.

10. The signal source according to claim 1, characterized in that When only two paths of white noise signal output are needed, the optical fiber coupler is not used, and the optical filter is directly connected to the photodetector.

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