Properties of an external-cavity traveling-wave semiconductor ring laser

We describe the lasing characteristics of an external-cavity 1.3-microm-wavelength traveling-wave semiconductor laser that uses a tilted-stripe optical amplifier. It was found that within a 45-nm-wavelength tuning range the power level does not suffer any discontinuous change. The lasing spectrum remains single mode within a 35-nm range, and the linewidth is less than 50 kHz. The lasing frequency is stable and changes by only 25 MHz/ degrees C and by approximately 1.6 MHz/mA. For cw operation the intracavity power reaches 24 mW, and for long-pulse operation the power level is as high as 175 mW. The lasing power level exhibits long-term stability. Moreover the intracavity power level is found to be insensitive to the coupled output power.