A wavelength converter stabilizes output light intensity in which the light coupling efficiency to a light waveguide core is not easily varied. A mounting structure is adopted in which a substrate of a wavelength conversion element is a material with a lower refractive index for signal light than that of the core, and a support structure that suppresses elastic deformation by supporting the element through a contact at a tip end surface at a position corresponding to both end portions of the core at the occurrence of elastic deformation due to the thermal stress of the element is provided. The support structure is provided at a portion apart from a temperature control element at the top surface of a metal housing bottom surface member, and its top surface is disposed in the vicinity of a portion corresponding to both end portions of the core of the element in a support member.

The adaptive methodology of (purposefully, intentionally aperiodically) poling of an optical waveguide made in a nonlinear material substrate to achieve a continuous increase of overall nonlinear conversion efficiency with increase in the length of such waveguide. As a result of such poling, the variation of at least a waveguide thickness is compensated by adjusting the poling period along the waveguide to match the local momentum difference of the nonlinear process. For a second-harmonic generation, a near-ideal performance of the nonlinear energy conversion process was demonstrated even for a 21 mm long waveguide (with the SHG efficiency as high as 9415%/W and a 82.6% absolute power conversion efficiency). The adaptive poling methodology can also be applied to compensate other systematic inhomogeneity of a WG device in, for example, etching depth, diffusion depth, dose of lithographic exposure of the nonlinear material, and doping density across the nonlinear material substrate.

Tunable monolithic cavity-based frequency converter pumped by a single-frequency laser where cavity resonance(s) are achieved by independently changing the temperatures of different sections of the crystal, including the periodically poled section and one or more adjacent, non-poled regions. Having independent control of the phase matching temperature and the cavity resonance for a down-converted beam increases the efficiency.

A heterogeneous waveguide is configured to achieve a nonlinear optical interaction, the waveguide including at least two materials in cross-section. The first material may or may not be poled or patterned and generally has a nonlinear optical property for generating at least one new frequency by mixing two of a plurality of input optical waves, and at least one of the other (second) materials is patterned for defining a waveguide mode in the cross-section, and for achieving phase-matched interactions of the waves along the propagation direction. Alternatively, the second material may be employed in increasing the modal confinement and improving efficiency. The optical modes are distributed between the two or more materials (e.g., in a hybrid mode). Implementations described also include methods of fabricating the heterogeneous waveguide.

A periodic polarization reversal electrode, periodic polarization reversal structure forming method and periodic polarization reversal element. The element includes a plurality of stripe electrode sections with a stripe shape extending in parallel at a gap from each other, arranged in contact with the +Z surface of a ferroelectric crystal substrate; an insulation film arranged over the +Z surface so as to cover the plurality of stripe electrode sections; and an equipotential electrode section which has a portion that opposes at least a part of each of the plurality of stripe electrode sections across the insulation film and is arranged over the insulation film without contacting the ferroelectric crystal substrate or the plurality of stripe electrode sections, wherein an electric field is generated in the area of the ferroelectric crystal substrate directly below the plurality of stripe electrode sections by applying a voltage to the equipotential electrode section.

The present invention relates to a frequency comb article includes an oscillator; a fiber amplifier; a frequency doubler; a nonlinear fiber; and an interferometer, wherein the fiber amplifier and the nonlinear fiber include a polarization maintaining fiber, and the oscillator, frequency doubler, and interferometer are entirely polarization maintaining.

A nonlinear wave mixing system with grating assisted phase matching is provided. The system includes a pump laser and a nonlinear waveguide. The pump laser is used to generate pump light at a select wavelength. The nonlinear waveguide is configured to generate produced light from the pump light that is directed into the nonlinear waveguide. The nonlinear waveguide includes at least one backward grating that is configured to diffract the produced light in a backward direction relative to a direction the produced light travels in the nonlinear waveguide to reach the backward grating. The backward grating having a grating momentum that generates counter-propagating phase matching in the produced light.

Provided is a wavelength converter that receives signal light and generates difference frequency light having a wavelength different from the signal light, the wavelength converter including: an optical waveguide core; a substrate having a refractive index lower than the optical waveguide core with respect to the signal light; a wavelength conversion element that converts the wavelength of the signal light; an overcladding formed on at least a part of a surface of the optical waveguide core and having a refractive index lower than the optical waveguide core with respect to optical wavelengths of the signal light and control light multiplexed with the signal light; and a temperature control element that controls a temperature of the wavelength conversion element.

Embodiments described herein relate to an apparatus that includes a chamber, and a molecular radical detector coupled to the chamber. In an embodiment, the molecular radical detector includes a diode laser, and a periodically poled lithium niobate (PPLN) waveguide coupled to the diode laser by a first optical fiber. In an embodiment, a filter is optically coupled to the PPLN waveguide by a second optical fiber, and a detector is optically coupled to the filter. In an embodiment, the PPLN waveguide is configured to frequency double a beam originating from the diode laser before the beam passes through an optical port in the chamber. In an embodiment, the detector is configured to receive the beam after the beam passes through the chamber.

A manufacturing method for a wavelength conversion element, including: a first process of forming an optical waveguide core substrate having one or more periodic polarization inversion region with a second-order nonlinear effect; a second process of bonding the optical waveguide core substrate to a substrate having a refractive index lower than a refractive index of the optical waveguide core substrate in a range of used light wavelengths to form a bonded substrate, and thinning the optical waveguide core substrate to form a core layer; and a third process of processing the core layer of the bonded substrate to form an optical waveguide core, wherein, in the third process, a polarization inversion period of a periodic polarization inversion structure of the formed optical waveguide core is adjusted at least locally by selecting a formation position of the optical waveguide core with respect to the one or more periodic polarization inversion region.