Detecting spurious reflections in integrated photonic devices

Spurious reflections can be a problematic issue in integrated optical devices, such as lasers, detectors, or multi-mode interference (MMI) couplers. Here we demonstrate a simple method to localize such faint reflections occurring inside the chip, using only wavelength-swept power transmission measurements. The method does not require a special measurement setup and is based on minimum phase techniques, which were recently proposed for integrated optical device characterization.