Method for Improving Wavelength Resolution of Spatial Spectral Separation Filter

Abstract

The invention relates to a method for improving the resolution of a spatial spectrum separation filter. The filter includes an input waveguide, a filter module functional block, and an output waveguide. Under the premise of not changing the internal design of the spatial spectrum separation filter, the mode field coupling characteristics of the input collimator and the output collimator are changed to achieve Compress the bandwidth of the filter and improve the resolution of the filter; including input and output single-mode waveguides with different mode field diameters, different collimator lens characteristics, and the single-mode waveguide is usually a single-mode fiber. Under the premise of not changing the design of the internal optical path, this method significantly improves the wavelength resolution capability of the fiber + grating type spectrum processing and analysis product by changing the characteristics of the input and output optical fibers and the collimation system, and the 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 Image 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 flexibili...

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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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