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.

A wavelength conversion device that restrains output power of light when a temperature of a wavelength conversion element, including a ferroelectric substrate, is changed. The wavelength conversion device includes, in a casing, the wavelength conversion element, a temperature control element that controls a temperature of the wavelength conversion element, a static elimination mechanism, and a surface potential measurement mechanism, and eliminates static electricity by driving the static elimination mechanism when the surface potential measurement mechanism detects a change in surface potential of the wavelength conversion element.

An integrated electro-optic frequency comb generator based on ultralow loss integrated, e.g. thin-film lithium niobate, platform, which enables low power consumption comb generation spanning over a wider range of optical frequencies. The comb generator includes an intensity modulator, and at least one phase modulator, which provides a powerful technique to generate a broad high power comb, without using an optical resonator. A compact integrated electro-optic modulator based frequency comb generator, provides the benefits of integrated, e.g. lithium niobate, platform including low waveguide loss, high electro-optic modulation efficiency, small bending radius and flexible microwave design.

An ultrahigh-resolution mid-infrared (MIR) dual-comb spectroscopy (DCS) measurement device includes a pump unit, a microring resonator (MRR) unit, a modulation unit, a splitting unit, a testing unit, a signal detection unit, a power balance unit, a reference detection unit and a spectral analysis unit. The measurement method includes: adjusting the laser emitted by the pump unit to the MRR unit; adjusting the modulation unit and performing dual-frequency modulation; generating two sets of MIR optical frequency combs (OFCs) with different repetition rates and splitting the MIR OFCs into the test light and the reference light; performing photoelectric conversion on the test light and injecting the test light to the spectral analysis unit; performing photoelectric conversion on the reference light and injecting the reference light to the spectral analysis unit; and performing Fourier transformation and data processing on test results to obtain absorption spectrum of the to-be-tested sample.

According to one embodiment, a nitride crystal includes first, second, and third nitride crystal regions. The third nitride crystal region includes Al, and is provided between the first and second nitride crystal regions. A third oxygen concentration in the third nitride crystal region is greater than a first oxygen concentration in the first nitride crystal region and greater than a second oxygen concentration in the second nitride crystal region. A third carbon concentration in the third nitride crystal region is greater than a first carbon concentration in the first nitride crystal region and greater than a second carbon concentration in the second nitride crystal region. A <0001> direction of the first nitride crystal region is one of a first orientation from the second nitride crystal region toward the first nitride crystal region or a second orientation from the first nitride crystal region toward the second nitride crystal region.

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.

Radiation source assemblies and methods for generating broadened radiation by spectral broadening. A radiation source assembly includes a pump source configured to emit modulated pump radiation at one or more wavelengths. The assembly further has an optical fiber configured to receive the modulated pump radiation emitted by the pump source, the optical fiber including a hollow core extending along at least part of a length of the fiber. The hollow core is configured to guide the received radiation during propagation through the fiber. The radiation emitted by the pump source includes first radiation at a pump wavelength, and the pump source is configured to modulate the first radiation for stimulating spectral broadening in the optical fiber.

An emission enhancement structure having at least one energy augmentation structure; and an energy converter capable of receiving energy from an energy source, converting the energy and emitting therefrom a light of a different energy than the received energy. The energy converter is disposed in a vicinity of the at least one energy augmentation structure such that the emitted light is emitted with an intensity larger than if the converter were remote from the at least one energy augmentation structure. Also described are various uses for the energy emitters, energy augmentation structures and energy collectors in a wide array of fields.

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.

A graphene structure includes one or more graphene layers. The graphene layers allow for microwave squeezing with gains up to 24 dB over a wide bandwidth.