A method and a system for controlling an optical frequency comb, where the working power of the pump source is dynamically adjusted and controlled, which not only greatly shortens a control time of a stable mode-locking and realizes a fast mode-locking control, but also quickly stabilizes the power control of stable working condition, thereby reducing unnecessary power consumption caused by power reciprocating oscillation tracking controls and better achieving the energy-saving effect of the power adjustment control process. The temperature of the working environment of the pump source is dynamically adjusted and controlled, so that the environment temperature can quickly reach the reference environment temperature required for mode-locking, which not only creates a good temperature condition for the mode-locking of the optical comb system, but also improves the efficiency of environment temperature stability control in the stable working conditions.

A system and a method for generating tunable ultrafast optical pulses, the method comprising spectral broadening of a laser input beam by propagating the laser input beam in a nonlinear medium of a third-order nonlinear susceptibility χ.sup.(3), yielding an output laser spectrum; and one of: i) selecting at least one portion of the output laser spectrum, yielding an output pulse different than the input pulse and centered at a different frequency; ii) temporal compensation and spatial spreading of spectral components of the output laser spectrum; selecting two pulses at two different frequencies; and nonlinearly mixing the two pulses together in a first second-order nonlinear susceptibility χ.sup.(2) nonlinear crystal into a third pulse centered at a frequency which is a difference between the frequencies of the first two pulses; and iii) dividing output laser spectrum into a pump beam and a probe beam, directing a pump pulse to a third second-order nonlinear crystal for THz radiation generation; and directing a probe pulse to a third second-order nonlinear crystal for THz radiation reconstruction.

A electronic method, includes receiving, by a graphene structure, a microwave signal. The microwave signal has a driving voltage level. The electronic method includes generating, by the graphene structure, optical photons based on the microvolts. The electronic method includes outputting, by the graphene structure, the optical photons.

Microwave-to-optical transducers in an optical ring resonator having intracavity grating to split a single resonance order are provided. In one aspect, a microwave-to-optical transducer includes: an optical ring resonator with intracavity grating; and a microwave signal waveguide optically coupled to the optical ring resonator with the intracavity grating. Microwave-to-optical transducers having multiple pump photon optical ring resonators and multiple signal photon optical ring resonators optically coupled to the optical ring resonator with the intracavity grating are also provided, as is a method of forming a microwave-to-optical transducer, and a method for microwave-optical transduction.

Apparatus and methods for improved HHG of ultrashort pulse laser beams. A HHG assembly includes a gas distribution block and a waveguide cartridge having a HHG hollow core waveguide. The waveguide cartridge is attached to the gas distribution block and may be removed and replaced, while the gas distribution block remains affixed within the apparatus. The gas distribution block is configured to maintain a pressure profile within the hollow core fiber. The system also includes two operating beam sensors and two actuatable mirrors. The operating beam sensors are fixed with respect to the HHG assembly. The system is aligned before operation by adjusting the actuatable mirrors to optimize a sample beam through the waveguide and recording the position of the beam on the operating beam sensors. In operation, the mirrors are actuated to maintain the same positions of the input beam on the operating beam sensors.

The present disclosure describes systems and methods for novel phononic frequency combs and related sensing techniques realized by a piezoelectric multimode or single-mode mechanical resonator based on parametric pumping. In one embodiment of such a system, a single frequency electrical input provides an electrical signal comprising an amplitude and a single input frequency to a multimode mechanical resonator, in which a value of the single input frequency equals a sum of the resonance frequencies of the two resonance modes of the mechanical resonator. Accordingly, the mechanical resonator is configured to produce at least one phononic frequency comb in response to a motion of the mechanical resonator caused by the electrical signal.

The disclosed laser system is configured with a laser source outputting light at a fundamental frequency. The output light is incident on a frequency converter operative to convert the fundamental frequency to a higher harmonic including at least one frequency converting stage. The frequency converter is based on a SrB.sub.4O.sub.7 (SBO) or PbB.sub.4O.sub.7 (PBO) nonlinear crystal configured with a plurality of domains. The domains have periodically alternating polarity of the crystal axis enabling a QPM use and formed with each with highly parallel walls which deviate from one another less than 1 micron over a 10 mm distance.

A wavelength converter including: A. a crystal holder configured to hold a nonlinear crystal configured to convert a wavelength of a laser beam incident thereon and output the wavelength-converted laser beam; B. a first container configured to accommodate the crystal holder and include a light incident window so provided as to intersect an optical path of the laser beam incident on the nonlinear crystal and a light exiting window so provided as to intersect the optical path of the laser beam having exited out of the nonlinear crystal; C. a second container configured to accommodate the first container; D. a position adjusting mechanism configured to adjust at least a position of the first container; and E. an isolation mechanism configured to spatially isolate the light incident window and the light exiting window from the position adjusting mechanism.

A periodically poled microring resonator structure, a method for fabrication of the periodically poled microring resonator structure, and a method to achieve giant single-photon nonlinearity are disclosed. The strong single-photon nonlinearity in the microring resonator structure is achieved through its optimized design and fabrication procedures.

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.