Multi‐Object Silicon Photonic Spectrometer

Abstract

A multi‐object silicon photonic spectrometer with N input ports is proposed and realized by integrating a multi‐channel passband optical filter (POF), a tunable narrow‐band optical filter as well as a calibration‐free N × 1 Mach–Zehnder switch (MZS) array. Here, the multi‐channel POF consisting of a multimode waveguide grating (MWG) and a mode (de)multiplexer is used to achieve a broadened working window and an enhanced dynamic range for the present spectrometer, while the narrow‐band optical filter is realized with a thermally‐tunable Euler micro‐ring resonator (EMR) for achieving a very high spectral resolution. The introduction of the N × 1 MZS enables the time‐division‐multiplexed (TDM) spectrum analysis for multiple objects. In this paper, a multi‐object silicon photonic spectrometer with 16 input ports is demonstrated with an on‐chip loss of less than 3 dB and inter‐channel crosstalk as low as −25 dB. This multi‐object spectrometer can be used to analyze the spectra of 16 objects one by one by setting the 16 × 1 MZS, the resolution is as high as 50 pm, and the working window is ≈84 nm.