An infinite impulse response microwave photonic filter and filtering method

Abstract

The invention discloses an infinite impulse response microwave photon filter and a filtering method. The infinite impulse response microwave photon filter comprises a multi-longitudinal mode fiber laser used as a light source to provide a light carrier, a polarization controller, an intensity modulator, a fiber loop and a photoelectric detector. The polarization controller regulates the polarization state of the light carrier to enable the light carrier to enter the intensity modulator, the intensity modulator works on a linear region by regulating the polarization voltage of the intensity modulator, microwave signals are modulated to the light carrier, optical signals achieve light splitting at the fiber loop, multi times of delaying and sampling are achieved on the light carrier bearing the microwave signals, the microwave signals with specific frequency are filtered, and the photoelectric detector detects the microwave signals through photovoltaic conversion to filter the light carrier. According to the filter and the filtering method, a large Q value can be provided, and a large free spectrum range is achieved due to the fact that the fiber loop can be very short.

Description

technical field [0001] The invention relates to signal processing technology, in particular to an infinite impulse response microwave photon filter and a filtering method. Background technique [0002] Filters are often used in signal processing. Compared with traditional filters, microwave photonic filters have many advantages: small loss, large bandwidth, anti-electromagnetic interference, and can provide short delays to generate ultra-high-speed sampling frequencies, which are often greater than 100GHZ, while electronic The sampling frequency of the technology can only reach a few GHZ; at the same time, microwave photonic filters also have functions such as bandwidth tunable and reconfigurable, which are difficult to achieve in traditional filters. Therefore, microwave photonic filters are more widely used. [0003] Microwave photon filters can be divided into finite impulse response (FIR) microwave photon filters and infinite impulse response (IIR) microwave photon fil...

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Problems solved by technology

[0005] The first one: use a single-frequency laser as the light source. Take a microwave photon filter with a distributed feedback laser (DFB) as the light source as an example. The DFB light source is characterized by good monochromaticity and large coherence length. If the fiber ring length is less than the light source coherence length, the carrier will be coherent in the optical fiber ring, and filtering cannot be effectively realized. In order to avoid the carrier coherence provided by the light source, the length of the fiber ring must be greater than the coherent length of the light source, which limits the sampling interval of the IIR microwave photon filter, and cannot obtain a larger Free Spectral Range (FSR)

[0006] The second type: use a filter to filter out a part of spontaneous emission (ASE) as a microwave photon filter as a light source. The ASE light source itself is limited by the filter, and the side mode suppression ratio (SMSR) is small, resulting in the main side lobe suppression of the microwave photon filter. ratio (MSSR) is limited

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