Tunable Oscillations in Optically Injected Semiconductor Lasers With Reduced Sensitivity to Perturbations

Narrow linewidth optical injection into a semiconductor laser can induce periodic oscillations in the injected laser's output power with a frequency that is widely tunable by simply varying the steady-state bias current and operating temperature. Recently, it has been demonstrated that this oscillation frequency can be made nearly insensitive to small-signal fluctuations of these two parameters at certain operating points [1]. Here, we demonstrate that this insensitivity arises from multiwave mixing and interference that minimizes the response of both the gain medium and the circulating optical power at the oscillation frequency. Both experimental measurements and model calculations of optical spectra show that at the operating points of reduced oscillation frequency sensitivity, all strong components of the optical spectrum still exhibit a response to the perturbations. However, in the power spectra and the (calculated) carrier-density spectra, the response is strongly attenuated. Novel operating points that limit the sensitivity of the laser power oscillation frequency to perturbations offer the promise for improved operation of tunable photonic oscillators for radio-and microwave-frequency applications.