A device and method for implementing a tunable dual-passband microwave photonic filter

Abstract

The invention belongs to the field of optoelectronic technology, and in particular relates to a device and method for realizing a tunable double-passband microwave photon filter based on stimulated Brillouin scattering. The present invention adopts a laser as a light source, and utilizes an optical coupler to generate signal light and pump light. The signal light branch loads microwave signals to be filtered through electro-optic phase modulation, and the pump light branch uses Bri Deep scattering effect and suppressed carrier double sideband modulation in dual parallel Mach-Zehnder modulators to generate tunable dual-wavelength pump light; use the absorption spectrum of dual-wavelength pump light in highly nonlinear optical fibers to realize the corresponding frequency components in signal light The conversion from phase modulation to intensity modulation realizes a microwave photonic filter with narrow linewidth, high out-of-band rejection ratio and high stability. The frequency of the RF signal on the Del modulator can be tuned continuously in the same direction. In addition, the passband interval can be changed by changing optical fibers with different Brillouin frequency shifts.

Description

technical field [0001] The invention belongs to the field of optoelectronic technology, and in particular relates to a device and method for realizing a tunable double-passband microwave photon filter. Background technique [0002] Microwave filters are usually implemented in the electrical domain by single or multiple coupled resonators, used to select microwave signals in the desired frequency band and suppress microwave signals in the remaining frequency bands, and are essential devices in radio frequency systems and links. The main disadvantage of electric domain microwave filters is poor tuning, which cannot meet the application requirements of some radio frequency systems that require wide-band tuning. The microwave photonic filter modulates the electrical signal onto the light wave, processes the signal in the optical domain, and then converts it back to the electrical domain to obtain the filtered electrical signal, which effectively overcomes the problem of poor tun...

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Problems solved by technology

In 2016, J.Q.Li and others proposed a dual-bandband microwave photonic filter based on two independent pump lasers (J.Q.Li, Y.C.Xiao, W.Dong, et al.Dual-bandbandpass tunable microwave photonic filter based on stimulated Brillouinscattering .Optoelectronics Letters, 2016,12(4):276-279), realizes the free tuning of the dual passband, but the center frequency of the passband depends on the frequency difference between the lasers, so the frequency drift of the laser seriously affects the entire The stability of the filtering system. At the same time, the scheme uses the Brillouin gain spectrum to realize the conversion from phase modulation to intensity modulation, so Brillouin spontaneous emission noise is inevitably introduced, which deteriorates the signal-to-noise ratio of the system.

In 2017, S.L.Hu et al. used a single laser combined with electro-optic modulation to generate dual pump light, and realized a tunable dual-passband microwave photonic filter (Hu S, Li L, Yi X, et al. Tunable Dual-Passband Microwave Photonic FilterBased on Stimulated Brillouin Scattering.IEEE Photonics Technology Letters,2017,29(3):330-333), although the influence of laser frequency drift on the stability of the filtering system has been solved, the two filter passbands can only be The Brillouin frequency shift (about 10 GHz) is center-symmetrically distributed, which severely limits the tuning flexibility of the filter system. In addition, this scheme also uses the Brillouin gain spectrum to realize the conversion from phase modulation to intensity modulation, and Brillouin spontaneous radiation Noise still degrades the signal-to-noise ratio of the system

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