Accurate measurement of scattering and absorption loss in microphotonic devices

TL;DR

This paper introduces a straightforward method to accurately measure and analyze the scattering and absorption losses in microphotonic devices, particularly high-Q silicon microresonators, revealing that absorption can dominate total loss.

Contribution

A new measurement technique applicable to microphotonic components that isolates scattering and absorption losses using minimal prior knowledge.

Findings

Linear absorption accounts for over half of the total loss in high-Q silicon microdisk resonators.

The method effectively distinguishes between radiation and absorption losses.

High-quality silicon microresonators exhibit significant linear absorption contributions.

Abstract

We present a simple measurement and analysis technique to determine the fraction of optical loss due to both radiation (scattering) and linear absorption in microphotonic components. The method is generally applicable to optical materials in which both nonlinear and linear absorption are present, and requires only limited knowledge of absolute optical power levels, material parameters, and the structure geometry. The technique is applied to high quality factor (Q=1-5 X 10^6) silicon-on-insulator microdisk resonators. It is determined that linear absorption can account for more than half the total optical loss in the high-Q regime of these devices.