High Resolution and Ultra-Compact On-Chip Spectrometer Using Bidirectional Edge-Input Arrayed Waveguide Grating

Two Edge-input arrayed waveguide gratings (AWGs) with star couplers of Confocal and Rowland configurations, respectively, are experimentally investigated and the one with the Rowland configuration shows better performance in terms of insertion loss and crosstalk. Based on the optimized Rowland configuration, two 64 × 0.4 nm ultra-compact on-chip spectrometers using bidirectional AWGs with two side inputs and different lengths of free propagation region (FPR) are designed and fabricated. Due to the utilization of two side inputs, the footprint of AWG spectrometer is significantly reduced compared to the conventional one center-input AWG spectrometer with the same resolution. The reduced footprint contributes to the performance improvement for an AWG spectrometer on high index contrast platforms, which is verified in our fabricated spectrometers on the silicon-on-insulator platform. The demonstrated ultra-compact on-chip spectrometer has large potential applications in miniaturized spectral analysis systems on a chip.