The potential application of using the measurement of FM noise to probe very high levels of optical feedback to a semiconductor laser is demonstrated from calculations. Frequency noise spectroscopy (FNS) (using absorption on an atomic resonance) has been used as the method of simulating the FM noise measurement. The quantities of the maximum FNS signal level observed, the detection frequency at which the maximum FNS signal level will be observed (this is also the frequency at which the maximum FM noise level occurs), and the full width at half maximum (FWHM) for the FNS signal with detection frequency, all as functions of feedback factor, are shown to be usable probes of the optical feedback. In the theoretical framework used (describing a 0.5m external cavity) feedback factors in the range 2 × 108-1 × 1010 can be probed sensitively by measuring the detection frequency that gives the greatest value of the maximum FNS signal. Feedback factors of greater than 6 × 109 can be probed sensitively by measuring the maximum of the FNS signal, or equivalently the full width at half maximum (FWHM) of the maximum of the FNS signal, as a function of detection frequency. The latter requires that the natural line width of the atomic resonance is narrower than the FM noise bandwidths to be measured.
|Number of pages||6|
|Journal||International Journal of Optoelectronics|
|Publication status||Published - Jan 1998|