Modulation of the emission frequency of a single-mode homojunction laser by an injection current

A study was made of the emission spectra of a cooled single-mode homojunction laser used in scanning interferometers under conditions when a sinusoidal component of frequency $f_m$ up to 1.2GHz was superimposed on a constant injection current. It was found that a strong frequency modulation could be achieved for a fairly small depth of amplitude modulation amounting to $M\lesssim10\%$. The frequency modulation coefficient $K_{fm}$ was within the range 0.1–0.8GHz/mA, depending on the degree of excess above the threshold and on the frequency $f_m$. The physical mechanisms governing the dependence $K_{fm}(f_m)$ were analyzed.