A self-seeded optical parametric amplifier (OPA) system includes a cavity mirror, a wavelength conversion unit, and a dichroic filter. The cavity mirror is configured to allow high transmission for an input laser beam and high reflection for a feedback beam. The wavelength conversion unit is configured to convert the input laser beam into a signal laser beam and an idler laser beam. The dichroic filter is configured to allow one of the signal laser beam and the idler laser beam to pass through the dichroic filter and reflect the other one onto a feedback path.

A display apparatus includes a display, a plate-like body, and a gap portion. The display is configured to display an image and having a front surface. The plate-like body is provided along the front surface of the display and configured to transmit image light emitted from the front surface of the display. The gap portion is formed between the front surface of the display and the plate-like body and configured to switch between a state filled with a fluid and a state where the fluid is discharged.

The present application relates to a mid-infrared (MIR) optical frequency comb (OFC) generation system and method based on manipulation of the multi-photon absorption (MPA) effect, which can break through the repetition-rate limitation for traditional systems and restricted bandwidth as well as high dependence on high-performance pump sources for microcavity-based frequency combs. The system includes a pump light source unit for providing a pump laser, a microring resonator (MRR) unit for broadband comb generation through nonlinear four-wave-mixing process, and an MPA effect control unit for realizing the MIR soliton-state OFC by controlling the loaded voltage or current on the MRR unit. The proposed system and operation method have advantages of being simple in structure, economic for use, and easy to implement for broadband low-noise frequency comb generation.

A nonlinear crystal comprising a first end face and an opposing second end face is described. The first and second end faces are separated along an optical axis of the nonlinear crystal by a length in the range of 0.25 mm and 2 mm. Although the length of the nonlinear crystal results in a reduction in the nonlinear effects induced on an optical field propagating through the crystal it also provides for reduced deviation experienced by the generated optical field when the nonlinear crystal is rotated. Therefore, when the nonlinear crystals are incorporated within an enhancement cavity their reduced length allows for the deviation of the output field to be minimised by servo control electronics arranged to adjust a single cavity mirror. This significantly reduces the complexity, and thus expensive of the servo control electronics when compared to those employed with the prior art enhancement cavities.

A doubly resonant optical parametric oscillator (1) includes a fan-out crystal (5, 55, 105) having an optical non-linearity of order 2 and placed in an optical cavity (6) able to reflect a pump (2). The crystal (5, 55, 105) has an entrance face (59) and an exit face (60), through which faces the optical axis passes, an upper face (57) and a lower face (58). The optical parametric oscillator (1) has a crystal (105) includes a grating of polarity-inverted lines (106) originating separately and in a narrowly spaced manner at a fictional upper line (61) that is parallel to the upper face (57) of the crystal (105), and ending separately and in a widely spaced manner either at a fictional lower line (63) that is parallel to the lower face (58) of the crystal (105), or at the entrance face (59) of the crystal, two successive lines (106) making between each other a constant angle, the grating starting with a first line (108) originating at the exit face (60) of the crystal (105) and extending towards the lower fictional straight line (63) while diverging from said exit face (60). All the other lines gradually and monotonically inclining from the first straight line (108) towards the entrance face (59) of the crystal (105).

An optical modulator is disclosed that includes an optical resonator structure. The optical resonator structure includes at least one non-linear portion, the at least one non-linear portion comprising at least one radial junction region. The at least one radial junction region is formed between at least first and second materials, respectively, having different electronic conductivity characteristics. A principal axis of the at least one radial junction region is oriented along a radius of curvature of the at least one non-linear portion. The optical modulator includes an optical waveguide that is coupled to the at least one non-linear portion of the optical resonator structure.

The technology disclosed in this patent document can be used to implement an optical device for generating broadband optical pulses, including an optical waveguide having different waveguide structures at different locations along the optical waveguide and with varying dimensions or pressure gradient that change adiabatically along the different locations to enable non-linear four wave mixing over a broad spectral range.

There is provided an optical module comprising a semiconductor laser element; and a planar lightwave circuit (PLC) in which a waveguide is formed on a substrate. A position of a light-emitting point of the semiconductor laser element is approximately aligned with a position of a core of the waveguide. In a plan view, a first line segment representing an emission surface of the semiconductor laser element and a second line segment corresponding to the first line segment and representing an incident surface of the waveguide are arranged oblique to each other, and the light-emitting point of the semiconductor laser element is disposed closer to an intersection point of an extension line of the first line segment and the second line segment or an extension line of the second line segment than a center of the first line segment.

A display apparatus includes a display, a plate-like body, and a gap portion. The display is configured to display an image and having a front surface. The plate-like body is provided along the front surface of the display and configured to transmit image light emitted from the front surface of the display. The gap portion is formed between the front surface of the display and the plate-like body and configured to switch between a state filled with a fluid and a state where the fluid is discharged.

An optical parametric oscillator for producing idler coherent light and signal coherent light from pump coherent light by balanced parametric dispersion includes: substrate cladding; a microring resonator disposed on the substrate cladding and including: a broadly transparent Kerr nonlinear medium including a annulus with a radius R, a height H, and a width W that provides a balanced parametric dispersion; and that: receives pump coherent light from a waveguide; and produces idler coherent light and signal coherent light from the pump coherent light, the idler coherent light and signal coherent light produced according to the balanced parametric dispersion of the microring resonator; and the waveguide disposed on the substrate cladding in optical communication with the microring resonator and comprising a broadly transparent medium such as silicon nitride and that: receives pump coherent light; and communicates the pump coherent light to the microring resonator for production of the idler coherent light and the signal coherent light from the pump coherent light.