A device includes a first cladding layer, a waveguide laser, an absorption layer, and a second cladding layer. The absorption layer is constituted by an oversaturation absorption body such as graphene. Also, the absorption layer is provided between the active layer and the distributed Bragg reflection portion. The absorption layer is formed below a core forming an optical waveguide between the active layer and a distributed Bragg reflection portion.

A semiconductor light source including a planar optical component that focuses long-wavelength (e.g., infrared) light emitted in a resonant cavity into a nonlinear crystal, which then converts the long-wavelength light into light having a shorter wavelength (e.g., visible light) by frequency doubling. A wavelength-selective reflection layer on the nonlinear crystal reflects the long-wavelength light back into the resonant cavity to form an external cavity and transmits the light having the shorter wavelength out of the external cavity. The resonant cavity includes an active region that emits the long-wavelength light at a high efficiency. The planar optical component includes a micro-lens formed in semiconductor layers or a gradient refractive index lens formed in the nonlinear crystal.

A photonic synthesizer includes a multifrequency optical source to produce a signal of interest from a pair of lasers, which may be self-injection locked chip lasers. The signal is referenced to a high frequency clock using a photonic mixer/divider based on an electro-optical modulator and a relatively slow photodiode. The electro-optical modulator produces optical harmonics from the beams from the pair of lasers, where one harmonic from the first laser beam and one harmonic from the second laser beam beat on the photodiode. A phase locked control signal is generated for controlling the output frequency of one or both of the two lasers. The output signal of the photonic synthesizer is generated using a relatively fast photodiode based on a difference in frequencies of the pair of lasers. The output signal may be a millimeter wave-band signal. The photonic synthesizer can be formed as a photonic integrated circuit (PIC).

A multi-wavelength laser and a wavelength control method are disclosed. The multi-wavelength laser includes a waveguide, a first electrode, and a second electrode. The first electrode and the second electrode are disposed on the waveguide. The first electrode is electrically isolated from the second electrode. The first electrode includes a plurality of sub-electrodes, and every two adjacent sub-electrodes are electrically isolated. The second electrode is configured to amplify an optical signal in the waveguide by loading a current. At least one sub-electrode is configured to adjust a wavelength of the optical signal in the waveguide by loading a current or a voltage.

A sensor system includes an optical aperture, a light source configured to generate a light pulse along a first optical path, a reflective surface configured to reflect the light pulse from the first optical path to a second optical path for passing through the optical aperture, a beam steering device positioned in the optical aperture and configured to steer the light pulse along different directions to one or more objects in an angle of view of the sensor system, a detector configured to receive a reflected light pulse and convert the reflected light pulse into an electrical signal, the reflected light pulse being reflected back from the one or more objects and passed through the beam steer device, and a spatial filtering device positioned between the beam steering device and the detector to block undesirable light in both the light pulse and the reflected light pulse.

A monolithic laser device assembly 10A in the present disclosure includes a first gain portion 20 having a first end portion 20A and a second end portion 20B, a second gain portion 30 having a third end portion 30A and a fourth end portion 30B, one or multiple ring resonators 40, a semiconductor optical amplifier 50 for amplifying a laser light emitted from the first gain portion 20, and a pulse selector 60 disposed between the first gain portion 20 and the semiconductor optical amplifier 50, in which the ring resonator 40 is optically coupled with the first gain portion 20 and with the second gain portion 30, and laser oscillation is performed on either the first gain portion 20 or the second gain portion 30.

There is disclosed in one example a fiberoptic communication device, including: a modulator to modulate data onto a laser pulse; and a semiconductor laser source including an active optical waveguide to provide optical gain and support an optical mode, the laser source further including a V-shaped current channel superimposed on the optical waveguide, and disposed to feed the active optical waveguide with electrical current along its length, the current channel having a proximate end to the optical mode, the proximate end having a width substantially matching a diameter of the optical mode, and a removed end from the optical mode, wherein the removed end is substantially wider than the proximate end.

Low phase noise signal generated in a small structure is required for communication and high-resolution imaging. A DBR based multi-mode laser is combined with mode-locking method to build frequency stabilized and tunable RF signal generator. The number of the output modes from each laser is adjusted using reflecting bandwidth of distributed Bragg reflector and electro-absorption (EA) modulator for amplitude control, while the phase section in integrated laser system provides frequency tuning. Mode-locking of 60 laser modes results in a highly frequency stable 10 GHz RF beat-notes with a calculated phase noise of −150 dBc/Hz at 10 kHz offset frequency.

A semiconductor light source including a planar optical component that focuses long-wavelength (e.g., infrared) light emitted in a resonant cavity into a nonlinear crystal, which then converts the long-wavelength light into light having a shorter wavelength (e.g., visible light) by frequency doubling. A wavelength-selective reflection layer on the nonlinear crystal reflects the long-wavelength light back into the resonant cavity to form an external cavity and transmits the light having the shorter wavelength out of the external cavity. The resonant cavity includes an active region that emits the long-wavelength light at a high efficiency. The planar optical component includes a micro-lens formed in semiconductor layers or a gradient refractive index lens formed in the nonlinear crystal.

Provided are a laser device and a method of transforming laser spectrum, which provide a laser frequency stabilization and significant narrowing a laser spectrum. A laser device includes at least one multiple longitudinal mode laser (L) for generating a laser light having a spectrum of multiple longitudinal modes; at least one high quality factor (high-Q) microresonator (M) optically feedback coupled to the at least one multiple longitudinal mode laser (L); and a tuner (TU) for tuning the spectrum of multiple longitudinal modes of the laser light. The laser device is configured to output an output laser light having an output spectrum with at least one dominant longitudinal laser mode each at a reduced linewidth of the dominant longitudinal laser mode. The laser device allows increasing an emission power of a narrow linewidth lasing without an additional amplification while keeping a compact size of a device with a limited number of optical elements.