Patent ID: 9268195
Filing Date: 2016-02-23
CPC Classification: G02F

Claim Text:
1. An apparatus for generating entangled photons by four-wave mixing, comprising a resonator and an output waveguide for the resonator, wherein: the resonator is an optical disk microresonator or an optical ring microresonator; the resonator has an operating frequency range; the resonator comprises a silicon nitride waveguide clad with a cladding material, the silicon nitride waveguide having a radius dimension r, a thickness dimension h, and a disk diameter dimension or ring width dimension w; an angular wavenumber m represents a number of wavelengths of pump radiation that fit around the resonator when the resonator is pumped by a pump beam of light at a pump frequency, such that each value of m corresponds to a mode having a respective mode frequency; the respective modes are spaced apart in frequency by a Free Spectral Range FSR that varies with frequency, according to a dispersion curve, in a manner that depends on r, h, and w; the dimensions r, h, and w are selected to place a zero-dispersion frequency, where the dispersion curve is at a minimum, within the operating frequency range; the dimensions r, h, and w are further selected to make the dispersion curve steeper on a low-wavenumber side of the zero-dispersion frequency and less steep on a high-wavenumber side of the zero-dispersion frequency; and the apparatus further comprises a broadband optical filter coupled to the output waveguide and configured to separate a first and a second spectral region from a spectral region that intervenes between said first and second spectral regions, and to pass entangled photons in the first and second spectral regions forward for further disposition.