Measurement of Facet Reflectivity Through Reflection Gain in Fabry–PÉrot Laser Diode

We propose a simple and useful method to measure the facet reflectivity in a Fabry-Perot laser diode (LD). The new measurement method does not require information on LD parameters such as threshold current or optical spectrum. The measurement is based on a simple formula that describes the relationship of facet reflectivity and reflection gain with launching the probe beam of a narrow spectral width.