Packaged frequency-stable tunable 20 kHz linewidth 1.5 μm InGaAsP external cavity laser

Abstract
Packaged grating-tuned external cavity InGaAsP/InP lasers have been developed for use in coherent transmission systems that operate at a wavelength of 1.5 μm. The emission wavelength can be selected within a 60 nm range during manufacture, and can subsequently be tuned over 0.5 nm (63 GHz). The lasers have linewidths better than 20 kHz and show long-term relative frequency stability of better than 150 MHz.