Polarization of the output of InGaAsP semiconductor diode lasers

Measurements of the degree of polarization (ρ) of the output of 1.3-μm InGaAsP semiconductor diode lasers as a function of current are discussed. It is found that ρ measured for well below threshold (ρ_b) is a better indicator of mechanical strain in the active region than ρ measured near or above threshold. ρ_b exhibits little dependence on drive level, mode reflectivity, threshold, or saturation of the gain. A possible correlation between the magnitude of ρ_b and device operating characteristics was found. More work is required to confirm this possibility. Data which provide experimental evidence for the magnitude of the difference between the reflectivities of the TE and TM modes are presented