A controller stabilizes a distributed feedback plus reflection (DFB+R) laser, which has a back facet, a DFB section, a passive section, and a front facet with a low reflective element. An etalon filter is formed by a portion of the DFB section, the passive section, and the low reflective element. Control circuitry directly modulates the DFB section with a modulation signal and biases the passive section with a bias signal. In operation, a lasing mode of the DFB section is aligned to a long wavelength edge of one of the periodic peaks of a reflection profile of the etalon filter. Meanwhile, photodiodes are arranged to monitor the output power emitted from the laser's front and back facets. The control circuitry monitors a ratio of the detected output power and adjusts the bias based on the monitored ratio.

An inspection method for inspecting a semiconductor laser device integrated with a semiconductor laser, an electroabsorption modulator for input the output of the semiconductor laser, and a photodetector for detecting intensity of part of the laser light output from the semiconductor laser includes a step of acquiring a transverse-mode light output characteristic that is a relationship between an injection current to the semiconductor laser and the output of the photodetector; a step of applying a reverse bias voltage to the electroabsorption modulator and acquiring a total light output characteristic that is a relationship between the injection current to the semiconductor laser and a photocurrent output from the electroabsorption modulator; and a step of comparing the total light output characteristic with the transverse-mode light output characteristic, thereby to determine whether or not the semiconductor laser device under inspection is abnormal in the transverse mode.

A first current injection unit that injects a DBR current into a rear DBR region and a front DBR region and a second current injection unit that injects a phase adjustment current into a phase adjustment region are included. The second current injection unit injects the phase adjustment current that changes at a frequency that is twice as much as that of the DBR current into the phase adjustment region in synchronization with the DBR current. The first current injection unit inverts the DBR current to a positive value in a region in which the DBR current is a negative value.

A method and apparatus provide for determining a temperature at a junction of a laser diode when the laser diode is operated in a lasing state that facilitates heat-assisted magnetic recording, comparing the junction temperature and an injection current supplied during the lasing state to stored combinations of junction temperature and injection current, and determining a likelihood of mode hopping occurring for the laser diode during the lasing state based on the comparison to stored combinations of junction temperature and injection current.

A synthesizer including a controller configured to receive a first signal. A digital-to-analog converter (DAC) is coupled to the controller and is configured to generate a voltage bias based on the first signal. The voltage bias corresponds to a target resonant frequency. A semiconductor laser is coupled to the DAC and is configured to receive a second signal tone. The semiconductor laser generates a plurality of tone signals having octave multiples of a base sub-harmonic tone of the second signal tone.

The present disclosure relates generally to a device, such as a wearable display device configured with a laser diode driver implementing dynamic voltage control for laser diodes. The laser diodes may include one or more of a red laser diode, a blue laser diode, and a green laser diode. The device may determine a load condition based on a frame to be displayed at the device, and determine a target voltage level for a laser diode operably coupled to the laser diode driver of the device based on the load condition (e.g., an image signal processor (ISP) frame buffer load). The device may generate the target voltage level for the laser diode based on a base voltage level. For example, the device may be configured with a voltage booster operably coupled to the laser diode driver to provide the target voltage level in addition to the base voltage level.

A method for a calibration of at least one laser diode, in particular at least one laser diode of a laser projection device. The at least one laser diode is calibrated on the basis of a comparison of at least one currently acquired characteristic value of the at least one laser diode with at least one characteristic value, stored in at least one database, of a model laser diode that is at least substantially identical in construction to the at least one laser diode.

A tuning arrangement for a vertical-cavity surface-emitting laser (VCSEL) may include a delta sigma modulator and a current source. The delta sigma modulator may be configured to generate a bitstream comprising bit signals, and the current source may be configured to provide a current to the VCSEL in a switchable manner depending on a control signal. The bitstream is generated based on a target state signal and the control signal corresponds to or is derived from the bit signals of the bitstream.

A device comprises three elements, realized as photonic integrated circuits. The first element comprises a tunable semiconductor laser emitting light at a laser output wavelength. The second element comprises a wavelength selective element, coupled to the first element. The third element comprises N photodetectors where N>=2, coupled to the second element. Light coupled into the second element from the first element is de-multiplexed by the wavelength selective element such that a ratio of light power coupled from the second element into one of the N photodetectors to light power coupled from the second element into another one of the N photodetectors is a function of the laser output wavelength. The responses of the N photodetectors facilitate at least one of measurement and control of the laser output wavelength.

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.