A method for fabricating an optical waveguide comprises: providing a sample of lithium niobate doped with magnesium oxide and having at least one grating of periodic domain inversion defined therein; applying a layer of metallic zinc to a surface of the sample over the at least one grating using sputter deposition; heating the sample in an atmosphere of pure oxygen to cause the zinc to indiffuse into the lithium niobate to form a waveguiding layer of increased refractive index under the surface of the sample; and using a dicing blade to cut two substantially parallel channels along a length direction of the at least one grating, to define a ridge waveguide between the two channels.

A wavelength conversion element manufacturing method capable of realizing, in a wavelength conversion element having a structure in which a thin film substrate having a periodic polarization inversion structure and a support substrate are laminated, highly efficient wavelength conversion by confining light in a cross-sectional area smaller than in the known art. The manufacturing method includes steps of forming a periodic polarization inversion structure on a first substrate made of a second-order nonlinear optical crystal and forming a damage layer in the first substrate by implanting ions from one substrate surface to obtain a first substrate for bonding, directly bonding a second substrate having a bonding surface having a smaller refractive index than the first substrate to the one substrate surface of the first substrate at the bonding surface, and peeling the first substrate directly bonded to the second substrate being the support substrate with the damage layer as a boundary to remove a part of the first substrate.

An electro-optic device may comprise a Mach-Zehnder modulator (MZM) and one or more components. The one or more components may apply a child DC bias with dither to arms of a first branch of the MZM and to arms of a second branch of the MZM, and determine a second harmonic of a first return signal. The one or more components may apply a child DC bias with phase-shifted dither to the arms of the first branch or to the arms of the second branch, and determine a second harmonic of a second return signal. The one or more components may determine, based on the second harmonics, whether the first branch and the second branch are operating at quadrature, and may selectively adjust parent DC biases, applied to the first branch and the second branch, based on whether the first branch and the second branch are operating at quadrature.

An electro-optic device may comprise a Mach-Zehnder modulator (MZM) and one or more components. The one or more components may apply a child DC bias with dither to arms of a first branch of the MZM and to arms of a second branch of the MZM, and determine a second harmonic of a first return signal. The one or more components may apply a child DC bias with phase-shifted dither to the arms of the first branch or to the arms of the second branch, and determine a second harmonic of a second return signal. The one or more components may determine, based on the second harmonics, whether the first branch and the second branch are operating at quadrature, and may selectively adjust parent DC biases, applied to the first branch and the second branch, based on whether the first branch and the second branch are operating at quadrature.

An optical wavelength conversion module including a substrate, a driving device, and a first phosphor material layer is provided. The first phosphor material layer is disposed on a first optical region of the substrate. A conversion beam generated by the first phosphor material layer is a yellowish green beam when a phosphorous temperature of the first phosphor material layer is close to or equal to an ambient temperature. The conversion beam generated by the first phosphor material layer is a yellow beam when the phosphorous temperature of the first phosphor material layer is close to or exceeds a preset temperature. The driving device is connected to the substrate. The driving device is adapted to drive the substrate to act when the optical wavelength conversion module is in an operating state, so that the yellow beam is emitted from the first optical region. An illumination module is also provided.

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 wavelength conversion device includes: a dielectric substrate having holes periodically formed in a non-linear optical crystal substrate; a line-defect optical waveguide formed in the dielectric substrate; and a periodically poled portion provided in the optical waveguide. The wavelength conversion device is configured to convert a wavelength of light traveling through the optical waveguide.

An apparatus for frequency comb generation comprises a component of second order nonlinearity, where the component is configured to interact with a laser beam or derivatives of the laser beam and thereby generate frequencies for the frequency comb. The apparatus comprises advantageously an optical manipulator, which both comprises the component but additionally is configured to introduce the beam or its derivatives in a repetitive or resonating manner to the component. The component is e.g. a monolithic or other solid optical resonator or microresonator comprising optical crystal and having said second order nonlinearity.

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 device for quasi-phase-matched frequency doubling of broadband light with uncorrelated spectral phase includes a nonlinear optical material, which in turn includes a domain-reversed grating organized in a series of sections along propagation direction of the broadband light through the nonlinear optical material. Each of the sections is characterized by a respective period of the domain-reversed grating. The period within a first connected subset of the series alternates between two discrete values along the propagation direction. A method for designing the domain-reversed grating includes determining a grating function model describing an ideal nonlinear coefficient of a domain-reversed grating, and discretizing the grating function model to a manufacturable grating function having period restricted to a discrete set of manufacturable periods.