1 Discrete Mode Laser Diodes with Very Narrow Linewidth Emission

Ex-facet, free-running low linewidth (~100 kHz), single mode laser emission is demonstrated using low cost, regrowth-free ridge waveguide Discrete Mode Fabry Pérot laser diode chips. These narrow linewidths are obtained from sub mW emission powers and above. Introduction: Attainment of the minimum achievable laser diode linewidth with the least associated level of device complexity and lowest component cost are critical for realising many single wavelength laser applications in optical communications, sensors and clocks. The free-running line-width reported for ordinary DFB and DBR laser devices is typically in the 1-5 MHz range which restricts their applications in coherent optica