The Design of On-chip Digital Fourier Transform Spectrometer

The optical on-chip integration technology can be used to realize spectrum analysis. Compared with the traditional bulky high performance optical spectrum analyzer which is always used in laboratory, on-chip spectrometer has the advantages of chip-scaled, low-cost and suitable for detection in complicated environment. For example, it can be utilized for detection of toxic gases such as carbon monoxide and hydrogen fluoride. In the past decade, several kinds of on-chip spectrometer, dispersive spectrometer and Fourier transform spectrometers, have been demonstrated as promising candidates for wide range of spectral application. In this paper, a digital Fourier transform spectrometer based on an interferometer whose arms consist of several optical switches which are connected by Mach-Zechnder Interferomter (MZI) with different arm lengths is demonstrated. The optical switch based on thermo-optic effect is used to select the different arms of an MZI, so the combination of optical switches and MZIs can lead to a series of different optical path difference. The proposed on-chip spectrometer is designed for Original-band (O-band) and the prospective spectral resolution is 0.3 nm. The future effort will focus on the test of the proposed spectrometer and the followed data processing including dispersive compensation and spectral reconstruction.