Broadband tunable high-precision optical fractional Fourier converter and implementation method thereof

A fractional Fourier, high-precision technology, applied in optical fiber transmission, electromagnetic wave transmission systems, electrical components, etc., can solve the problem of low speed and bandwidth, low resolution, large storage space and Computational costs, etc.

Inactive Publication Date: 2019-07-16
GUANGDONG UNIV OF TECH
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0003] At present, there are two key bottlenecks in the implementation of fractional Fourier transforms in the digital domain: First, due to the physical limit of carrier mobility, electronic analog-to-digital converters have speed and bandwidth bottlenecks. The rate and bandwidth of the converter are limited to a low level; second, when processing complex signals, it will take up huge storage space and computing overhead, which is difficult to meet the needs of real-time signal processing
[0004] The fractional-order Fourier transform based on the space lens optical system is bulky, which is not conducive to system integration (P.Pellat-Finet, "Fresnel diffraction and the fractional-order Fouriertransform," Opt. Lett., 1994, 19(18): 1388-1390)
The optical fractional Fourier transformer based on the fiber group velocity dispersion effect has a compact structure (S. M. Brunel, D. Lebrun, and C. "Characterization of chirped pulses with the fractional-order Fouriertransformation," J.Opt.Soc.Am.A,2001,18(11):2754-2759), but poor order tunability and low resolution (best resolution only on the order of GHz)
If the resolution is increased by increasing the length of the optical fiber, the real-time performance of signal processing will be degraded; if the resolution is improved by using a time lens, the duration of the signal to be processed will be severely limited (limited to less than a few hundred ps)
Using chirped fiber gratings instead of optical fibers can obtain greater dispersion to improve resolution, while reducing system delay and ensuring real-time requirements, but the problem of poor tunability has not been solved (Cuadrado-Laborde, A.Carrascosa, A .Díez, J.L.Cruz, and M.V.Andres, “Photonics fractional Fourier transformer with a single dispersive device,” Opt.Express, 2013, 21(7):8558-63)
To sum up, the existing optical fractional Fourier transform scheme cannot simultaneously realize high-precision, broadband and order-tunable real-time fractional Fourier transform, which is also the key problem to be solved by the present invention

Method used

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  • Broadband tunable high-precision optical fractional Fourier converter and implementation method thereof
  • Broadband tunable high-precision optical fractional Fourier converter and implementation method thereof
  • Broadband tunable high-precision optical fractional Fourier converter and implementation method thereof

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Embodiment 1

[0035] Such as figure 2 As shown, a broadband tunable high-precision optical fractional Fourier transformer includes a DC light source 1, an electro-optical modulator 2, a 1×3 fiber coupler 3, a first 2×2 fiber coupler 4, a first shift Frequency optical loop, first photodetector 8, second 2×2 optical fiber coupler 9, second frequency shift optical loop, second photodetector 13, third 2×2 optical fiber coupler 14, third frequency shift optical ring Road, the third photodetector 18, real-time oscilloscope 19. The DC light source 1 generates a DC optical carrier, and the microwave signal to be processed is modulated on the envelope of the optical carrier by the electro-optic modulator 2; the electro-optic modulator 2 is biased at a linear bias point, and its output is connected to the 1 The input of ×3 fiber coupler 3; the a port of the 1×3 fiber coupler 3 is connected to the a port of the first 2×2 fiber coupler 4, for inputting the first channel modulation signal into the fir...

Embodiment 2

[0037] Such as figure 2 As shown, the DC light source 1 outputs a DC optical carrier, and the linearly biased electro-optic intensity modulator 2 modulates the microwave signal on the envelope of the DC optical carrier. The modulated signal is divided into three channels with equal power through a 1×3 fiber coupler. The modulated signals of the three channels are respectively input from the a input ports of the three 2×2 fiber couplers 4, 9, and 14, and then simultaneously from the c port and d port output. The c-port output signals of the three 2×2 optical fiber couplers 4, 9, and 14 are respectively used as the input signals of the first, second, and third frequency-shifting optical rings, and are sequentially passed through the three optical fiber frequency shifters 5, 10, and 15 respectively. Realize the frequency shift amount is f s1 , f s2 , f s3 The frequency shift copy of the three optical amplifiers 6, 11, 16 is used to compensate the power loss in the three loop...

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Abstract

The invention belongs to the technical field of photoelectricity, and relates to a broadband tunable high-precision optical fractional Fourier converter and an implementation method thereof. Accordingto the invention, an optical fractional order Fourier converter is constructed by using three paths of frequency shift optical loops with coprime free spectral ranges; based on the principle of frequency shift replication and delay interference of signals, continuous tunable equivalent large-group velocity dispersion is obtained, high-precision fractional Fourier transform of the signals is achieved in an analog domain, orders can be freely tuned, and frequency measurement and chirp rate measurement of broadband microwave signals can be achieved by combining a reconstruction algorithm.

Description

technical field [0001] The field of optoelectronic technology of the present invention specifically relates to a broadband tunable high-precision optical fractional Fourier transformer and a realization method thereof. Background technique [0002] Fractional Fourier transform is a general form of Fourier transform. Compared with Fourier transform, fractional Fourier transform realizes signal analysis in the intermediate domain between time domain and frequency domain, and has a larger order Degree of freedom and flexibility, because its basis function has linear chirp characteristics, it is especially suitable for the analysis and processing of non-stationary signals such as linear chirp signals. Therefore, the fractional Fourier transform has been widely used in radar signal processing, image encryption, image digital watermarking, holographic computing and other fields. [0003] At present, there are two key bottlenecks in the implementation of fractional Fourier transfo...

Claims

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Application Information

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IPC IPC(8): H04B10/079H04B10/25
CPCH04B10/07951H04B10/25891
Inventor 彭迪谢康姜海明申方成夏宏燕
Owner GUANGDONG UNIV OF TECH
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