Methods and systems concerning non-reciprocal sensing paths for a self-mixing interferometry operation are disclosed herein. Optical components may be used to direct light transmit from a light source along an illumination path. The optical components may additionally return light to the light source after being reflected from a target and may direct the returned light along a collection path. The illumination path and the collection path may be at least partially non-reciprocal so that the transmitted light and the returned light follow along partially different paths. Once the received light is received within a cavity of the light source, a self-mixing interferometry operation may be performed and may be used to detect a property of the target in relation to the light source.