1.55 MU-M GAIN-COUPLED QUANTUM-WELL DISTRIBUTED FEEDBACK LASERS WITH HIGH SINGLE-MODE YIELD AND NARROW LINEWIDTH

The first successful fabrication and characteristics of gain-coupled 1.55-mu-m GaInAlAs quantum-well metal-clad ridge-waveguide distributed feedback lasers are presented. The gain-coupling mechanism was provided by a thin ternary loss grating layer with an estimated gain-coupling strength about 30/cm. For as-cleaved devices, the single-mode yield was as high as 70 and 95% for 600 and 800-mu-m long devices, respectively. Typical threshold currents were 40 and 55 mA, respectively. Both the high single-mode yield and the pronounced asymmetric spectra have been calculated theoretically and give a strong indication that a significant amount of gain-coupling was realized in the present laser structure. For a 600-mu-m long device, a CW output power of 10 mW and a minimum linewidth of 1.6 MHz were measured.