A cascaded harmonic generator, for cascaded optical harmonic generation from an optical beam provided by a laser source, may include a second harmonic generator to generate a second harmonic optical beam based on a residual beam associated with the optical beam. The cascaded harmonic generator may include a third harmonic generator to generate a third harmonic optical beam based on the second harmonic optical beam and the optical beam. The third harmonic generator may be positioned in an optical path upstream from the second harmonic generator. A harmonic generator delay time, associated with the optical path, may be approximately equal to, or may be an approximate integer multiple of, a laser source round-trip time.

A system for conversion or amplification using quasi-phase matched nonlinear optical wave-mixing includes a first radiation source for providing a pump radiation beam, a second radiation source for providing a signal radiation beam, a bent structure for receiving the pump radiation beam and the signal radiation beam, and an outcoupling radiation propagation portion for coupling out an idler radiation beam generated in the bent structure. A radiation propagation portion of the bent structure is made of a uniform three-dimensional material at least partly covered by a two-dimensional or quasi-two-dimensional material layer and has a dimension taking into account the spatial variation of the nonlinear optical susceptibility along the radiation propagation portion as experienced by radiation traveling along the bent structure for obtaining quasi-phase matched nonlinear optical wave-mixing in the radiation propagation portion. The dimension thereby is substantially inverse proportional with the linear phase mismatch for the nonlinear optical process.

An optical output coupler includes an uncoated plano-concave lens having a planar side and a concave side. An optical axis of the plano-concave lens is tilted at or near a Brewster angle relative to a beam axis. A first optical element is configured to focus a beam of radiation emerging from the planar side of the plano-concave lens along a first axis that is perpendicular to the beam axis. The first optical element is disposed between the planar side of the plano-concave lens and a second optical element. The second optical element is configured to focus a beam of radiation emerging from the planar side of the plano-concave lens along a second axis that is perpendicular to the beam axis, wherein the second axis is different from the first axis.

A nonlinear optical device includes two coupling systems. A coupling coefficient between the two coupling systems is regulated and controlled. During operation, the pump light input from a straight waveguide is coupled into the second coupling system through the first coupling system and obtains great resonance enhancement in the second coupling system, so it is ensured that the second coupling system is in a high energy state. For signal light input from the same end of the straight waveguide, the signal light enters a resonator of the second coupling system through the coupling between the first and second coupling systems. A nonlinear effect of the system mainly occurs in the resonator of the second coupling system because in the resonator of the second coupling system, the pump light is in a great resonance enhancement. The entire resonator is in a high energy state.

An optical filter for attenuating higher-order modes in an optical waveguide includes a shoulder slab formed of a first material having a first index of refraction and disposed on a second material having a second index of refraction, the first index of refraction being higher than the second index of refraction. The shoulder slab defines a near end having a first width, an intermediate section, adjacent to the first end section, and a far end section, adjacent to the intermediate section and opposite the first end section along a direction of beam propagation. The optical filter also includes a waveguide ridge, formed of the first material and disposed atop the shoulder slab, that traverses the shoulder slab, and is configured to guide light of a fundamental mode along the direction of beam propagation from the near end section to the far end section.

An optical filter for attenuating higher-order modes in an optical waveguide includes a shoulder slab formed of a first material having a first index of refraction and disposed on a second material having a second index of refraction, the first index of refraction being higher than the second index of refraction. The shoulder slab defines a near end having a first width, an intermediate section, adjacent to the first end section, and a far end section, adjacent to the intermediate section and opposite the first end section along a direction of beam propagation. The optical filter also includes a waveguide ridge, formed of the first material and disposed atop the shoulder slab, that traverses the shoulder slab, and is configured to guide light of a fundamental mode along the direction of beam propagation from the near end section to the far end section.

A cascaded harmonic generator, for cascaded optical harmonic generation from an optical beam provided by a laser source, may include a second harmonic generator to generate a second harmonic optical beam based on a residual beam associated with the optical beam. The cascaded harmonic generator may include a third harmonic generator to generate a third harmonic optical beam based on the second harmonic optical beam and the optical beam. The third harmonic generator may be positioned in an optical path upstream from the second harmonic generator. A harmonic generator delay time, associated with the optical path, may be approximately equal to, or may be an approximate integer multiple of, a laser source round-trip time.

Apparatuses and methods are provided for an optical frequency converter configured to double or have a carrier frequency of an input optical signal. The input optical signal provided to the optical frequency converter is a higher order mode than a mode of the output optical signal. The optical frequency converter comprises a core, cladding material, and a substrate. The core includes a first core portion of non-linear crystalline material which is non-centrosymmetric, and a second core portion and a third core portion of the non-linear crystalline material each of which is centrosymmetric. The first, the second, and the third core portions are coplanar with and adjacent to the first core portion between the second and the third core portions.

An electro-optical modulator includes a hybrid waveguide with electrodes located on both sides of the hybrid waveguide. A method of making the electro-optical modulator includes providing a first component, which includes a silicon layer and conductive wiring structures located on both sides of the silicon layer; providing a second component, which includes a nonlinear optical material layer and conductive wiring structures located on both sides of the nonlinear optical material layer; and bonding the first component to the second component, wherein the silicon layer and the nonlinear optical material layer are stacked to form the hybrid waveguide, and the conductive wiring structures located on both sides of the silicon layer are electrically connected to those located on both sides of the nonlinear optical material layer to form the electrodes. By implementing embodiments of the present application, a compact, high-efficiency, low-power electro-optical modulator can be integrated into a silicon optical chip.

An optical circuit includes a resonator including a nonlinear optical material having intensity-dependent absorption, an input, and an output. The optical circuit includes an optical input path coupled to the input of the resonator and provides an optical logic input, an optical reference path coherently coupled to the resonator and configured to provide a first reference signal coupled to the optical input path and a second reference signal, and an optical output path coupled to the output of the resonator and configured to receive the second reference signal. The resonator receives a combined version of the optical logic input and the first reference signal, and provides an optical output signal based on the optical logic input, the first reference signal, and an intensity threshold of the nonlinear optical material. The optical output path provides an optical logic output corresponding to an output logic state based on the optical output signal and the second reference signal. The coherent coupling of the optical reference path to the resonator is configured to provide optical gain.