Method for improving wavelength resolution of spatial spectrum separated wave filter

Abstract

The invention relates to a method for improving wavelength resolution of a spatial spectrum separated wave filter. The wave filter comprises an input waveguide, a wave filter module functional block and an output waveguide. Under a precondition that the inner design of the spatial spectrum separated wave filter is unchanged, bandwidth of the wave filter is compressed through changing mode field coupling characteristics of an input collimator and an output collimator, thereby improving resolution of the wave filter. Input and output single-mode waveguides with different mode field diameters are utilized. Different collimator lens characteristics are utilized. The single-mode waveguides are commonly single-mode fibers. According to the method, under a precondition that the inner optical path design is unchanged, wavelength resolution capability of a fiber-and-grating type spectrum processing and analyzing product is remarkably improved through changing the characteristics of an input fiber, an output fiber and a collimating system, and FWHM of the product is compressed by about 20%.

Description

technical field [0001] The invention relates to a wavelength resolution technology for spectrum processing and analysis products, in particular to a method for improving the resolution of a spatial spectrum separation filter. Background technique [0002] Optical filters based on the idea of ​​spatial spectrum separation can be divided into adjustable filters and fixed filters. Common spatial dispersion methods include prism dispersion, various gratings, arrayed waveguide gratings, and acousto-optic optical filters. [0003] Such as Figure 6 As shown, in the traditional tunable filter, the signal light enters the function block ③ of the tunable filter module through the incident fiber ① of the tunable filter, and the filtered signal light passes through the output fiber ② of the tunable filter to output to For other functional modules such as photodiodes. [0004] Several common implementations of optical channel monitors are as follows: [0005] [0006] The flexibil...

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Problems solved by technology

[0013] The document of Chinese patent application number 201410362340 discloses a MEMS-based tunable flat-top narrow-band optical filter, which introduces an attempt to transform the input and output optical fibers to achieve the effect of spectral flattening, but its defects are also relatively obvious

However, the patent adopts the idea of ​​multiple passes, which will inevitably double the discount on the insertion loss of the tunable filter. For example, the original insertion loss of a tunable filter is 3dB, and the insertion loss will increase at least As large as 6dB, however the compressed spectral bandwidth is not obvious

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