A method and device for increasing extinction ratio

Abstract

The invention relates to the optical technical field, and discloses a method and a device of improving extinction ratio. The method comprises the following steps: linearly polarized light, which enters into a diffraction grating, is output by light though a beamsplitter; the linearly polarized light is reflected out from the diffraction grating, and reaches to a DLC chip through a quarter-wave plate; return light is reflected out by the DLP chip, and reaches to the diffraction grating through the quarter-wave plate; and the return light is emanated out through the beamsplitter after being reflected out from the diffraction grating. Based on the characteristics of total digitized programmable tuning central wavelength and bandwidth of the DLP chip, and through the mutual matching of the polarization beamsplitter, the light is allowed to pass through the quarter-wave plate twice to change the polarization state of the light; the return light reaches to the polarization beamsplitter and is output by reflection; therefore, the smoothing function is realized. Additionally, as the reflected light and stray light of optical elements of the light path dissatisfy the polarization relativity, so as to be transmitted directly by the polarization beamsplitter and not be able to be output by reflection with the return light; therefore, the extinction ratio is improved.

Description

technical field [0001] The invention relates to the field of optical technology, and is mainly applicable to a method and a device for improving the extinction ratio. Background technique [0002] The optical transmission of 100Gb / s has been commercialized now, and the modulation format of DP-QPSK is mostly used. This modulation format enables 100Gb / s signals to be transmitted under the single-channel 50GHz ITU (International Telecommunications Union, International Telecommunication Union) grid. Studies have shown that for optical transmission greater than 100Gb / s, a format with high spectral utilization must be selected, or the spectral width of the signal must be increased to support 400Gb / s or 1Tb / s transmission. The modulation format with higher spectral efficiency limits the distance of signal transmission due to the deterioration of OSNR (Optical Signal Noise Ratio), and increasing the spectral width means that the signal no longer matches the 50GHz ITU grid . [00...

AI Technical Summary

Problems solved by technology

However, due to the reflection of various optical devices in the optical path and the influence of stray light, the extinction ratio is very low, generally only up to 20dB

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