A wavelength converter for LiDAR systems, such as automotive LiDAR, is disclosed. Implementation of the wavelength converter in LiDAR systems makes possible generation and modulation of laser light in the silicon response region, conversion of the laser light to an eye-safe wavelength for emission and reflection from a target, and efficient conversion of the wavelength of the laser light to the silicon response region. The wavelength converter may implement a single-loop counter-propagating wavelength conversion scheme which provides both up-conversion and down-conversion of the signal within the same loop. The wavelength conversion design also has the potential for vehicle-to-vehicle (V2V) communication to enable a combined LiDAR and V2V communication system.

A method of producing periodic polarization inversion structures requires the provision of first electrode piece part-arrays, each having electrode piece parts on a first main face of a ferroelectric crystal substrate. A voltage is applied on the first electrode piece part-arrays to form first periodic polarization inversion structures. Second electrode piece part-arrays are provided, each having electrode piece parts between the adjacent plural first periodic polarization inversion structures. A voltage is applied on the second electrode piece part-arrays to form second polarization inversion structures.

An all-optical optical parametric oscillator includes a laser module, a temperature control module, a plurality of filters and a beam splitter arranged in sequence. A bulk material or waveguide material is arranged in the temperature control module. Both ends of the bulk material are provided with a first OPO cavity mirror M.sub.1′ and a second OPO cavity mirror M.sub.2′. Each of the first OPO cavity mirror M.sub.1′ and the second OPO cavity mirror M.sub.2′ is coated with a high-reflectivity film with respect to an OPO signal light and an OPO idler light, and coated with a high-transmittance film with respect to an OPO pump light, a poling fundamental frequency light and a poling frequency doubled light. The temperature of the material is changed by changing the temperature of the temperature control module to realize temperature tuning of wavelength λ.sub.s of the OPO signal light and wavelength λ.sub.i of the OPO idler light.

Systems and embodiments for an integrated photonics mode splitter and converter are provided herein. In certain embodiments, a system includes a substrate having a first index of refraction. Additionally, the system includes a waveguide layer on the substrate, wherein the waveguide has a second index of refraction different from the first index of refraction. Also, the waveguide layer includes one or more mode splitters that receive at least one of a first photon in a first mode and a second photon in a second mode through an input port and provide one of the first photon through a first output port and the second photon through a second output port. The waveguide layer also includes a mode converter coupled to the second output of a mode splitter, wherein the mode converter receives the second photon through a port and outputs the second photon in the first mode through the port.

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 miniaturized PPKTP crystal-based entanglement source system using multi-mode reception is provided, which includes a pump light source, a pump light transmission module, an entanglement device, a first collection device, and a second collection device. In the entanglement source system, entangled lights are received by using multi-mode optical fibers, and an entangled light processing scheme of combining a temporal filtering technology and a spatial filtering technology is applied into a collecting device at one side of the entanglement source system, to form asymmetric device structures in the entanglement source system, to enable multi-mode reception.

A wavelength conversion device includes a second-order nonlinear optical medium with a polarization inversion structure, wherein the wavelength conversion device performs wavelength conversion between three wavelengths according to a relationship of 1/λ.sub.1=1/λ.sub.2+1/λ.sub.3, a polarization inversion period Λ of the polarization inversion structure is divided into 2a regions, and when the 2a regions divided from the polarization inversion period Λ each has a width ratio of an inverted region and a non-inverted region of r to 1−r (where 0≤r≤1), a ratio value r is set such that, when one period in phase of a sine function from 0 to 2π is divided into 2a regions, a value of the sine function in a center of each divided region is (1−2r)±0.1.

According to the present invention, a pulsed laser output section outputs a laser beam having a predetermined wavelength as first pulses. An optical path determining section receives the first pulses and determines one or more among two or more optical paths for each of the first pulses for output. A wavelength changing section receives light beams travelling, respectively, through the two or more optical paths and, when the power of the traveling light beams exceeds a threshold value, changes the light beams to have their respective different wavelengths for output. A multiplexer multiplexes outputs from the wavelength changing section. The optical path determining section allows for change in the power ratio between a first power of the light beam traveling through one of two among the two or more optical paths and a second power of the light beam traveling through the other of the two optical paths.

A method of performing HVPE heteroepitaxy comprises exposing a substrate to a carrier gas, a first precursor gas, a Group II/III element, and ternary-forming gasses (V/VI group precursor), to form a heteroepitaxial growth of a binary, ternary, and/or quaternary compound on the substrate; wherein the carrier gas is H.sub.2, wherein the first precursor gas is HCl, the Group II/III element comprises at least one of Zn, Cd, Hg, Al, Ga, and In; and wherein the ternary-forming gasses comprise at least two or more of AsH.sub.3 (arsine), PH.sub.3 (phosphine), H.sub.2Se (hydrogen selenide), H.sub.2Te (hydrogen telluride), SbH.sub.3 (hydrogen antimonide, or antimony tri-hydride, or stibine), H.sub.2S (hydrogen sulfide), NH.sub.3 (ammonia), and HF (hydrogen fluoride); flowing the carrier gas over the Group II/III element; exposing the substrate to the ternary-forming gasses in a predetermined ratio of first ternary-forming gas to second ternary-forming gas (1tf:2tf ratio); and changing the 1tf:2tf ratio over time.

Disclosed is a device for interaction between a laser beam and a hyperfine energy transition of a chemical species. The device further includes an electro-optic modulator with a single sideband with an input optical waveguide suitable for receiving a source laser beam and an output optical waveguide suitable for generating an output laser beam and an electronic system suitable for generating and applying, simultaneously, a first modulated electrical signal, sin(Ω.sub.1t)) to a first hyperfrequency pulse on a first high-frequency electrode of the electro-optic modulator and, respectively, another modulated electrical signal, cos(Ω.sub.1t)) to the first pulse on another high-frequency electrode of the electro-optic modulator, in such a way as to frequency-switch the output laser beam to a first optical frequency offset from the first pulse with respect to the initial optical frequency.