Ratiometric wavelength monitor based on Mach-Zehnder interferometer over a 80nm wavelength range

Abstract

In this paper, a ratiometric wavelength monitor at around 1550 nm based on the passive Silicon-on-Insulator (SOI) integrated device is proposed, theoretically investigated and fabricated. This monitor is made of a single Mach-Zehnder Interferometer (MZI) with direction coupler acting as edge filter. The ouput spectral response is designed to be ‘X-type’. The device shows a resolution of better than 0.4 nm over the wavelength range from 1505 nm to 1585 nm with a discrimination range of 30.5 dB from 15.5 dB to -15dB, which is suitable for wavelength measurement. Based on the single mode principle, the waveguide has a 220 nm×500 nm cross section for TM-polarized mode, and the total chip size is only 18 um×20 um. In conclusion, this proposed ratiometric wavelength monitor based on a single Mach-Zehnder Interferometer on SOI platform can realize the excellent resolution over large wavelength range.