An illumination system (200) includes an illumination device (202); an optical element (206) positioned to receive light (208) from the illumination device (202); a layer (210) of a transparent material disposed on the optical element (206) and positioned to receive light (208) from the illumination device (202); and an interlock circuit (220) configured to measure a resistivity of the layer (210) of transparent material and to control operation of the illumination device (202) based on the measured resistivity.

There is provided a method of operating a laser. The method comprises receiving a target power and calculating an operating power of a lasing module of the laser. The operating power may be calculated based on the target power and a minimum lasing power of the lasing module. The method also comprises determining an operating current for the lasing module based on the operating power, and driving the lasing module at the operating current to produce an output light having the operating power. In addition, the method comprises providing the output light to an optical modulator of the laser, and operating the optical modulator to modulate the output light to have an output power corresponding to the target power.

Exemplary embodiments of the present disclosure include chip-scale laser sources, such as semiconductor laser sources, that produce directional beams with low spatial coherence. The lasing modes are based on the axial orbit in a stable cavity and have good directionality. To reduce the spatial coherence of emission, the number of transverse lasing modes can be increased by fine-tuning the cavity geometry. Decoherence is reached in as little as several nanoseconds. Such rapid decoherence facilitates applications in ultrafast speckle-free full-field imaging.

A driver circuit includes a fly capacitor with a first end and a second end. The driver circuit includes a laser diode having an anode and a cathode. The driver circuit is configured to operate in first and second operating states. The anode is coupled to the first end of the fly capacitor. In the first operating state, the cathode is coupled to a first voltage supply node, the first end of the fly capacitor is coupled to a second voltage supply node, and the second end of the fly capacitor is coupled to a first reference terminal. In the second operating state, the cathode is coupled to a second reference terminal and decoupled from the first voltage supply node, the first end of the fly capacitor is decoupled from the second voltage supply node, and the second end of the fly capacitor is coupled to a third reference terminal.

A laser diode drive system for generating a drive current for a laser diode is described. The laser diode drive system comprises a first laser diode driver connected to the laser diode by a first cable to provide a drive current source for the laser diode. A second laser diode driver is then connected to the laser diode by a second cable to provide a low current sink for the laser diode. A feedback control loop is employed to provide a feedback signal for the second laser diode driver from to sample of an output field of the laser diode. The laser diode drive system exhibits low power consumption while being capable of creating sufficient feedback bandwidth to reduce the excess optical noise by at least an order of magnitude at 1 MHz compared with laser diode drive systems comprising just a first laser diode driver.

In some implementations, a thermally-controlled photonic structure may include a suspended region that is suspended over a substrate; a plurality of bridge elements connected to the suspended region and configured to suspend the suspended region over the substrate, where a plurality of openings are defined between the plurality of bridge elements; and at least one heater element having a modulated width disposed on the suspended region. The at least one heater element having the modulated width may include at least one section of a greater width and at least one section of a lesser width. The at least one section of the greater width may be in alignment with an opening of the plurality of openings and the at least one section of the lesser width may be in alignment with a bridge element of the plurality of bridge elements.

In some implementations, a thermally-controlled photonic structure may include a suspended region that is suspended over a substrate; a plurality of bridge elements connected to the suspended region and configured to suspend the suspended region over the substrate, where a plurality of openings are defined between the plurality of bridge elements; and at least one heater element having a modulated width disposed on the suspended region. The at least one heater element having the modulated width may include at least one section of a greater width and at least one section of a lesser width. The at least one section of the greater width may be in alignment with an opening of the plurality of openings and the at least one section of the lesser width may be in alignment with a bridge element of the plurality of bridge elements.

Described are various configurations of integrated wavelength lockers including asymmetric Mach-Zehnder interferometers (AMZIs) and associated detectors. Various embodiments provide improved wavelength-locking accuracy by using an active tuning element in the AMZI to achieve an operational position with high locking sensitivity, a coherent receiver to reduce the frequency-dependence of the locking sensitivity, and/or a temperature sensor and/or strain gauge to computationally correct for the effect of temperature or strain changes.

A method (900) includes a gain current (I.sub.GAIN) to an anode of a gain-section diode (D.sub.0) disposed on a shared substrate of a tunable laser (310), delivering a modulation signal to an anode of an Electro-absorption section diode (D.sub.2) disposed on the shared substrate of the tunable laser, and receiving a burst mode signal (330) indicative of a burst-on state or a burst-off state. When the burst mode signal is indicative of the burst-off state, the method includes sinking a sink current (I.sub.SINK) away from the gain current at the anode of the gain-section diode. When the burst mode signal transitions to be indicative of the burst-on state from the burst-off state, the method includes ceasing the sinking of the sink current away from the gain current and delivering an overshoot current (I.sub.OVER) to the anode of the gain-section diode.

A method (900) includes a gain current (I.sub.GAIN) to an anode of a gain-section diode (D.sub.0) disposed on a shared substrate of a tunable laser (310), delivering a modulation signal to an anode of an Electro-absorption section diode (D.sub.2) disposed on the shared substrate of the tunable laser, and receiving a burst mode signal (330) indicative of a burst-on state or a burst-off state. When the burst mode signal is indicative of the burst-off state, the method includes sinking a sink current (I.sub.SINK) away from the gain current at the anode of the gain-section diode. When the burst mode signal transitions to be indicative of the burst-on state from the burst-off state, the method includes ceasing the sinking of the sink current away from the gain current and delivering an overshoot current (I.sub.OVER) to the anode of the gain-section diode.