The disclosure relates in some aspects to providing miniature power-efficient agile photonic generators of microwave waveforms. Illustrative examples use chip lasers integrated in close thermal proximity with one another to provide a miniature microwave arbitrary waveform generator (AWG). Due to the small size of the lasers and the close integration, common ambient fluctuations from the environment or other sources can be efficiently reduced, yielding improved spectral purity of generated radio-frequency (RF) signals. Tight physical integration also permits a small device footprint with minimal acceleration sensitivity. The lasers may be locked to cavities or other resonators to allow efficient decoupling of the frequency and amplitude modulation of the lasers to provide flexibility to the waveform generator. Exemplary devices described herein can produce frequency chirped signals for radar applications. The frequency chirp may be linear and/or nonlinear. Tuning methods are also described herein.

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 synthesizer includes a first resonator mirror, a second resonator mirror, and a gain medium disposed within a laser resonator cavity defined by the first resonator mirror and the second resonator mirror. The synthesizer includes a saturable absorber operationally coupled to the gain medium and having active control such that the saturable absorber is configured to generate a waveform via an injection locking signal to create a mode locking effect, the waveform having a frequency comb defined by dimensions of the gain medium. The synthesizer also includes a crystal electro-optical modulator disposed within the laser resonator cavity. The waveform passes through the modulator to impinge on a photodiode to output an emission RF waveform. Changing the voltage applied to the modulator changes the index of refraction of the modulator, altering an optical path length of the laser resonator cavity to adjust a frequency of the emission RF waveform.

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.

A beam combining device and method for a Bragg grating external-cavity laser module has a plurality of side by side light-emitting modules that use a Bragg grating to perform wavelength locking. Output light of the modules is incident to a beam combining element after passing through a focusing optical element for beam combining, and light subjected to beam combining is reflected partially and transmitted partially under the effect of a light splitting element. A part is incident into a dispersion element at a diffraction angle of the element. Parallel light is formed under the effect of a conversion optical element. Spots of the light beams of corresponding wavelengths of the light-emitting modules are formed on an image acquisition mechanism. Whether the wavelengths of the corresponding light-emitting modules are locked is determined by whether there is a deviation between preset spots and spots formed by the module on the acquisition mechanism.

A laser module includes a gain chip, temperature sensors, a case, and a thermoelectric cooler (TEC). The gain chip emits a laser beam. One of the temperature sensors measures a first temperature of the gain chip and is encompassed by the gain chip. The other temperature sensor is adhered to the case and measures a second temperature. The TEC tunes the laser beam emitted by the gain chip to a desired wavelength by varying the first temperature of the gain chip through a set of third temperatures for various values of the second temperature. The set of third temperatures is selected from various values of the first temperature such that the laser beam emitted at the set of third temperatures is mode-hop free.

Disclosed herein are aspects of an optical pulse stretcher for temporally stretching a short duration pulsed light signal to reduce its peak power, thus reducing the risk of causing damage to components that receives the pulsed light signal. Some embodiments are directed to a molecule sequencing system, in which photochemical damage caused by laser pulses having high peak power may be mitigated by the optical pulse stretcher. In one embodiment, the optical pulse stretcher comprises a polarizing beam splitter, a quarter-wave plate and a single etalon disposed in series. In another embodiments, an optical pulse stretcher splits a pulsed light signal along multiple delay lines before combining the split signals together to form a stretched light signal.

Disclosed are a design method, a product and an application of a high-repetition-frequency and multi-wavelength ultrashort pulse mode-locked photonic integrated chip. Components for designing the mode-locked photonic integrated chip include a semiconductor optical amplifier array providing gains for N wavelength channels; a phase delay line array which includes phase delay lines with different lengths and separately compensates for different effective optical path differences of gain light of the wavelength channels caused by a dispersion effect; a flattened arrayed waveguide grating multiplexing the gain light with the effective optical path differences compensated, and multiplexing N-channel optical pulse signals into one-channel optical pulse signal; a saturable absorber forming, with the arrayed waveguide grating, N individual and synchronized different wavelength mode-locked optical pulse channels; and a semiconductor optical amplifier used for gaining and outputting an output pulse of the saturable absorber.

A photonic integrated circuit-based dual frequency comb source, an integrated system for dual comb spectroscopy and corresponding method are disclosed. The dual comb source includes, on a same substrate of the photonic integrated circuit, a first and second semiconductor integrated mode-locked laser, a master laser, and connection arrangement between the master laser and each of the first and second mode-locked laser. The master laser is configured for generating a lasing line for simultaneous optical injection-locking of the first and second mode-locked laser, the first and second mode-locked laser are configured for generating a first and second frequency comb respectively, and the connection arrangement is suitable for coherently transferring lasing light from the master laser to each mode-locked laser. The mode-locked lasers include a gain section and a saturable absorber section to provide mode-locking, and an extended optical cavity formed in the substrate.

An apparatus for emitting pulsed electromagnetic laser radiation includes a laser gain element; an optical arrangement defining a laser resonator and arranged to re-direct radiation emitted by the gain element along a beam path back onto the gain element, the optical arrangement comprising an output coupler configured to couple a portion of the radiation in the laser resonator out of the laser resonator; and, a pump arrangement configured to pump the laser gain element. The optical arrangement includes a mode locker placed in the laser resonator in the beam path, and a birefringent element placed in the laser resonator in the beam path.