Potential of commercial SiN MPW platforms for developing mid/high-resolution integrated photonic spectrographs for astronomy

TL;DR

This study evaluates the potential of commercial SiN MPW platforms for developing miniaturized, high-resolution integrated photonic spectrographs for astronomy, demonstrating promising performance metrics through simulations and laboratory tests.

Contribution

It provides a detailed analysis of SiN waveguide geometries and phase error impacts, showing MPW platforms can produce high-resolution spectrographs with significant throughput.

Findings

Achievable resolution R ~ 10,000 with MPW runs

Potential throughput of approximately 60%

MPW platforms are promising for astronomical spectrograph development

Abstract

Integrated photonic spectrographs offer an avenue to extreme miniaturization of astronomical instruments, which would greatly benefit extremely large telescopes and future space missions. These devices first require optimization for astronomical applications, which includes design, fabrication and field-testing. Given the high costs of photonic fabrication, Multi-Project Wafer (MPW) SiN offerings, where a user purchases a portion of a wafer, provide a convenient and affordable avenue to develop this technology. In this work we study the potential of two commonly used SiN waveguide geometries by MPW foundries, i.e. square and rectangular profiles to determine how they affect the performance of mid-high resolution arrayed waveguide grating spectrometers around 1.5 $\mu$m. Specifically, we present results from detailed simulations on the mode sizes, shapes, and polarization properties, and on the impact of phase errors on the throughput and cross talk as well as some laboratory results of coupling and propagation losses. From the MPW-run tolerances and our phase-error study, we estimate that an AWG with R $\sim$ 10,000 can be developed with the MPW runs and even greater resolving power is achievable with more reliable, dedicated fabrication runs. Depending on the fabrication and design optimizations, it is possible to achieve throughputs $\sim 60\%$ using the SiN platform. Thus, we show that SiN MPW offerings are highly promising and will play a key role in integrated photonic spectrograph developments for astronomy.