Method for operating a frequency agile tunable self-injection locking laser system and self-injection locking laser system

A control unit for operating a frequency agile tunable self-injection locking laser system being formed by a laser device coupled to at least one optical resonator, wherein the control unit is configured:

• to control a diode current of a laser diode of the laser device, and
• to control an actuation voltage of a piezo or an electro-optical actuator configured to apply a variation of the refractive index of a resonator material through mechanical stress or an electric displacement field, respectively, at least partially onto the at least one optical resonator, inducing a change in the effective optical path length of the at least one optical resonator,
• wherein the control unit is further configured to operate the laser system with actuation voltages in a range depending on a determined maximum tuning range, wherein the maximum tuning range is determined by the steps of:
• selecting a self-injection locking range among a plurality of self-injection locking ranges by varying the diode current and monitoring self-injection locking ranges, wherein self-injection locking ranges corresponding to current ranges in which self-injection locking occurs, wherein the self-injection locking corresponds to an optical feedback phase for back-reflected light from the at least one optical resonator into the laser device,
• setting the diode current from the current range of the selected self-injection locking mode;
• and
• determining the maximum tuning range of the actuation voltage in which self-injection locking is maintained.