A supercontinuum light source can include a seed laser arranged to provide seed pulses with a pulse frequency F.sub.seed; a pulse frequency multiplier (PFM) arranged to multiply the seed pulses by converting pulses having the pulse frequency F.sub.seed to pump pulses with a pulse frequency F.sub.pump, where F.sub.pump is larger than F.sub.seed; and a non-linear element arranged to receive said pump pulses and convert said pump pulses to pulses of supercontinuum light. The PFM can further include a splitter for splitting pulses into first and second sub beams each having the same pulse frequency, where the PFM is configured such that the sub beams experience different delays; and a combiner for combining said first and second sub beams into a beam having the pulse frequency that is greater than said same pulse frequency. The splitter can have an uneven splitter ratio.

A fully integrated photonic coherent microwave generator includes an external laser cavity on a suitable material waveguide platform (e.g., LiNbO3) operationally integrated with a III-V gain element. Operational components include a tunable high-Q resonator (e.g., LiNbO3 microresonator) and one or more end mirrors to form an integrated semiconductor external-cavity laser. Operationally coupled electrical components enable coherent microwave and phase-locked laser comb outputs as follows. An optical detector converts the beating of generated laser-comb modes into microwaves with a fundamental frequency equal to the free-spectral range f.sub.R of the microresonator. The external laser cavity enables high-speed electro-optic modulation of laser modes directly inside the laser cavity. Phase locking of the lasing modes is accomplished via electro-optic modulation and electro-optic comb generation directly inside the laser cavity. Highly coherent microwaves are generated via phase-locked comb-like lasing modes.

A laser apparatus includes a light source unit and a light combining unit. The light source unit outputs first laser light and second laser light having a wavelength different from that of the first laser light to different optical paths. The light combining unit is optically coupled to the light source unit, and combines the first laser light and the second laser light to generate a burst pulse with a frequency according to a difference between the wavelength of the first laser light and the wavelength of the second laser light. In the light source unit, the wavelengths of the first laser light and the second laser light are set in advance or settable such that the frequency of the burst pulse is 1 GHz or more.

The present application provides a radiation output device and a method. The radiation output device includes a radiation generating module configured to generate initial radiation; a filter module configured to reflect a portion of a first preset wavelength of the initial radiation to the radiation generating module and transmit a portion of a second preset wavelength of the initial radiation, the transmitted radiation is therefore used as an output radiation of the radiation output device; a detection feedback module, using a portion of or all of the output radiation as a feedback radiation, configured to instruct a modulating module to modulate the filter module according to the feedback radiation. The modulating module is connected to the filter module and configured to modulate a position and/or an angle of the filter module according to the instruction of the detection feedback module.

A unipolar-doped light emitting diode or laser diode is described. The diode includes a bottom region having an n-type layer, a top region having an n-type layer, and a middle region between the top and bottom regions having at least one material different from the top or bottom region forming two or more heterojunctions. The top and bottom regions create light emission by interband tunneling-induced photon emission. Systems including the unipolar-doped diode including LIDAR are also taught.

A supercontinuum light source can include a seed laser arranged to provide seed pulses with a pulse frequency F.sub.seed; a pulse frequency multiplier (PFM) arranged to multiply the seed pulses by converting pulses having the pulse frequency F.sub.seed to pump pulses with a pulse frequency F.sub.pump, where F.sub.pump is larger than F.sub.seed; and a non-linear element arranged to receive said pump pulses and convert said pump pulses to pulses of supercontinuum light. The PFM can further include a splitter for splitting pulses into first and second sub beams each having the same pulse frequency, where the PFM is configured such that the sub beams experience different delays; and a combiner for combining said first and second sub beams into a beam having the pulse frequency that is greater than said same pulse frequency. The splitter can have an uneven splitter ratio.

A laser assembly (1) comprising: a semiconductor laser (2) with a fast gain medium, wherein the gain relaxation time of the gain medium is smaller than the round-trip time in the standing wave cavity, in particular a quantum cascade laser or an interband cascade laser, and a standing wave cavity (3); a DC source (9) coupled to the standing wave cavity (3) for pumping the laser (2); and an AC injection device (10) for injecting an electrical AC signal into the standing wave cavity (3) to stabilize an optical frequency comb, the AC injection device being suitable for producing an electrical AC signal within a range and/or within an integer multiple of the range, wherein the range is within ±1% of the natural round-trip frequency in the standing wave cavity, comprising at least a first and a second electric contact section (5, 6) extending along a first longitudinal side of the longitudinal extension of the standing wave cavity (3), wherein the AC injection device (10) is coupled to the first and/or to the second electric contact section (5, 6) such that the complex amplitude of the injected electrical AC signal differs for the first and the second longitudinal electric contact section (5, 6).

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 laser master-oscillator power-amplifier (MOPA) is operated to provide successive bursts of ultrashort pulses. The pulse-bursts are selected by an optical modulator from a pulse train delivered by the master oscillator prior to amplification in the power amplifier. The optical modulator has a selectively variable transmission specified by an analog voltage signal having a stepped waveform. The voltage signal is delivered by a sequentially-switched parallel switch-array connected in parallel with a parallel DAC having multiple parallel DC voltage outputs corresponding to steps of the stepped waveform.

A Dense Wavelength Division Multiplexing (DWDM) photonic integration circuit (PIC) that implements a DWDM system, such as a transceiver, is described. The DWDM PIC architecture includes photonic devices fully integrating on a single manufacturing platform. The DWDM PIC has a multi-wavelength optical laser, a quantum dot (QD) laser with integrated heterogeneous metal oxide semiconductor (H-MOS) capacitor, integrated on-chip. The multi-wavelength optical laser can be a symmetric comb laser that generates two equal outputs of multi-wavelength light. Alternatively, the DWDM PIC can be designed to interface with a stand-alone multi-wavelength optical laser that is off-chip. In some implementations, the DWDM PIC integrates multiple optimally designed photonic devices, such as a silicon geranium (SiGe) avalanche photodetector (APD), an athermal H-MOS wavelength splitter, a QD photodetector, and a heterogenous grating coupler. Accordingly, fabricating the DWDM PIC includes a unique III-V to silicon bonding process, which is adapted for its use of SiGe APDs.