A cylindrical electrode module of a fiber optic laser system includes an inner cylinder having an inner repeating pattern of longitudinally-aligned positive and negative electrodes on an outer surface of the inner cylinder. The cylindrical electrode mode includes an outer cylinder that encloses the inner cylinder. The outer cylinder that has an outer repeating pattern of longitudinally-aligned negative and positive electrodes on an inner surface of the inner cylinder that are in corresponding and complementary, parallel alignment with the positive and negative electrodes of the inner repeating pattern on the outer surface of the inner cylinder. The cylindrical electrode module includes an optical fiber having an input end configured to align with and be optically coupled to a high power pump laser. The optical fiber is wrapped around the inner cylinder within the outer cylinder to form a cylindrical fiber assembly. The electrodes are activated to achieve quasi-phase matching.

A method of practicing the invention includes at least the following steps of generating pump laser radiation having a spectrum containing a plurality of equidistant spectral lines; passing the pump laser radiation through a non-linear medium of a singly resonant, single-frequency optical parametric oscillator, wherein the pump laser radiation is continuously a wave or is pulsed, wherein the pulse duration in the latter case is longer than the time the optical parametric oscillation requires to reach its steady state; and coupling out the non-resonant idler or signal laser radiation from the optical parametric oscillator as usable frequency converted laser radiation. Further provided is a laser device used to carry out the method of the invention.

An optical frequency mixing module is described that comprises a nonlinear medium for frequency mixing the photons of one or more input optical fields to generate an output optical field; a nonlinear medium tuner for automatically phase matching the nonlinear medium to the one or more input optical fields to select the wavelength of the output optical field generated by the nonlinear medium; and a first direction correcting optic. The position of the first direction correcting optic relative to the nonlinear medium is dependent upon the selected wavelength of the output optical field and therefore ensures that the position and angle of propagation of this field remains constant and independent of its wavelength of. The optical frequency mixing modules therefore provides a means for automatically selecting the wavelength of the output field with no deviation being imparted onto the position or angle of propagation of the output field.

Some embodiments are directed to a generating device, including a pulse laser source providing primary photons having at least one wavelength, shaping device(s) acting on the primary photons to provide an input beam, a nonlinear crystal, and controller(s) generating, in the nonlinear crystal, at least one electric field that is synchronous with the input beam and suitable for inducing a phase mismatching in the nonlinear crystal through an electro-optical effect, in order to convert the primary photons of the input beam into secondary photons having wavelengths belonging to a supercontinuum.

An apparatus for generating electromagnetic radiation includes a pump laser so adapted that in operation of the apparatus it generates electromagnetic continuous-wave pump radiation; an optical parametric oscillator which is arranged in the beam path of the pump radiation and has a non-linear optical crystal, and is so adapted that in operation of the apparatus it generates signal and idler radiation from the pump radiation, and a non-linear optical device having a non-linear optical crystal, being arranged at least in a beam path of the signal radiation or idler radiation, and being so adapted that in operation of the apparatus it generates from the signal or idler radiation electromagnetic radiation at a frequency greater than a frequency of the signal or idler radiation. The non-linear optical crystal being heated in a furnace so that the crystal has a temperature gradient in the beam direction of the signal or idler radiation.

Reduction of output power of light with a wavelength converted is suppressed, which is caused by a pyroelectric effect that occurs when a temperature of a wavelength conversion element including a ferroelectric substrate is changed. Provided is a wavelength conversion device that generates light different from a wavelength of a signal light when the signal light is inputted, and includes a wavelength conversion element that converts a wavelength of the signal light, and a temperature control element for controlling a temperature of the wavelength conversion element, wherein the wavelength conversion element and the temperature control element are sealed in an inside of a metal casing, the inside of the metal casing is filled with dry gas including one kind or more selected from nitrogen, oxygen, argon or helium, the wavelength conversion element includes an optical waveguide core and a substrate having a lower refractive index to the signal light than the optical waveguide core, and the substrate is a ferroelectric substance in which directions of spontaneous polarization are random.

A radiation source includes an initial source, a non-linear optical frequency converter, a conversion detector and a controller. The controller is arranged such that in a first mode of operation, the controller generates the conversion control signal in dependence on the conversion measurement signal such that the resonance frequency is controlled to follow the initial centre frequency. The controller is selectably switchable between the first mode of operation and a second mode of operation. In the second operating mode the power of the converted radiation is controlled such that either the power of the converted radiation has a smaller relative variation over time than the power of the initial radiation in the beam direction in front of the coupling mirror or the power of the initial radiation in the beam direction behind the coupling mirror has a smaller relative variation over time than the power of the initial radiation in the beam direction in front of the coupling mirror.

A terahertz-wave generating element includes a waveguide including an electro-optic crystal; an optical coupling member that extracts a terahertz wave, which is generated from the electro-optic crystal as a result of light propagating through the waveguide, to a space; and at least two electrodes that cause a first-order electro-optic effect in the electro-optic crystal by applying an electric field to the waveguide so as to change a propagation state of the light propagating through the waveguide. A crystal axis of the electro-optic crystal of the waveguide is set such that the terahertz wave generated by a second-order nonlinear optical process and the light propagating through the waveguide are phase-matched.

Stress applied to a wavelength conversion element is relaxed at the time of temperature control of the wavelength conversion element, and stable operation and improvement of long-term reliability of a wavelength conversion device are realized. A wavelength conversion device includes: a wavelength conversion element that receives excitation light and signal light and outputs wavelength-converted output signal light; a temperature control element that controls a temperature of the wavelength conversion element; an upper member that is provided between the wavelength conversion element and the temperature control element and transfers heat between the temperature control element and the wavelength conversion element; and a sheet-like adhesive sheet provided between the wavelength conversion element (and the upper member. At least a part of the adhesive sheet has a surface facing the wavelength conversion element adhered to the wavelength conversion element, and a surface facing the upper member adhere to the upper member.

In semiconductor inspection using second-harmonic generation within an object, a weak second-harmonic is detected at high sensitivity. In a semiconductor inspecting apparatus which irradiates a pulsed laser with a very short pulse width to a surface of a semiconductor device as the object, and measures the second-harmonic generated within the semiconductor device, a second-harmonic generation element is disposed between a light source and the object to generate a first second-harmonic. Further, the apparatus modulates a phase of only the first second-harmonic using an electric optical crystal, and then, a fundamental wave is irradiated onto the object. When the fundamental wave is irradiated onto the semiconductor device, the second-harmonic is generated therefrom. The first second-harmonic interferes with the second second-harmonic on a detector, and an intensity of the light obtained by the interfering is modulated at the same period as that of the phase modulation of the first second-harmonic. An amplitude of the second second-harmonic may be obtained from a modulated amplitude thereof, and a phase of the second second-harmonic may be measured from a modulated phase thereof.