Single longitudinal mode operation of long, integrated passive cavity InGaAsP lasers

We propose a new 1.3‐μm wavelength InGaAsP laser—the integrated passive cavity (IPC) laser—and demonstrate its device performances compared with conventional lasers fabricated under similar procedures. The long IPC laser (3.55‐mm‐long passive cavity), as well as the short IPC laser, exhibited single frequency oscillation even just above the threshold, and the maximum ratio of longitudinal main to submode exceeded 30 dB. They also showed favorable effects in the oscillation frequency stabilization.