Variation of intensity noise and frequency noise with the spontaneous emission factor in semiconductor lasers

The intensity noise level and the spectral line-width of semiconductor injection lasers are theoretically analyzed. Approximated but simple forms representing these characteristics are found to give criteria for various types and sizes of cavity, including microcavity lasers. The noise and the line-width are reduced by operation with high injection current or high optical power in general. For operation at a low-power level in the microcavity laser, increase of the spontaneous emission factor as well as reduction of the threshold current level and the threshold gain level are important to get a low noise level and narrow line-width