Guided wave methods and apparatus for nonlinear frequency generation

A method for nonlinear generation of a signal, comprising:

• providing a waveguide that defines a waveguide cavity the waveguide having a propagation constant k.sub.mode ;
• mixing a plurality of fluid components to produce a nonlinear material having an index of refraction n and a propagation constant k.sub.material ;
• disposing the nonlinear material in the waveguide cavity;
• directing electromagnetic radiation into the waveguide cavity to produce a signal;
• and
• satisfying a phase-matching condition for the signal by adjusting the propagation constant k.sub.material with respect to k.sub.mode, wherein the phase-matching condition is satisfied by adjusting the refractive index n of the nonlinear material by adjusting the relative proportions of the fluid components.

A method for nonlinear generation of a signal, comprising:

• selecting a nonlinear material, the nonlinear material having an index of refraction n and a propagation constant k.sub.material ;
• providing a waveguide that defines a waveguide cavity, the waveguide having a propagation constant k.sub.mode and being selected to satisfy a phase-matching condition for the signal;
• disposing a nonlinear material in the waveguide cavity;
• and
• directing electromagnetic radiation into the waveguide cavity to produce a signal.

A method for multistage nonlinear generation of a signal, comprising:

• providing first and second waveguides defining respective first and second waveguide cavities and having first and second waveguide propagation constants;
• selecting first and second nonlinear materials having respective first and second material propagation constants;
• disposing the first and second nonlinear materials into the first and second waveguide cavities, respectively;
• directing an input electromagnetic radiation into the first waveguide;
• phase-matching a first nonlinear generation process in the first waveguide by adjusting the first waveguide propagation constant or the first nonlinear material propagation constant with respect to the first waveguide propagation constant, thereby generating an intermediate signal;
• directing the intermediate signal to the second waveguide;
• phase-matching a second nonlinear generation process using the intermediate signal in the second waveguide, wherein phase-matching is achieved by adjusting the second waveguide propagation constant or adjusting the second nonlinear material propagation constant with respect to the second waveguide propagation constant, thereby generating the signal.

A method for phase matching nonlinear generation, comprising:

• providing a waveguide defining a waveguide cavity;
• disposing an ionized gas in the waveguide cavity, the ionized gas having a free electron density;
• and
• selecting frequencies for input electromagnetic radiation to the waveguide such that a phase-matching condition is satisfied substantially independently of the free electron density.

A method for nonlinear generation of a signal from a pump and an idler, the signal, pump, and idler having frequencies .omega..sub.s, .omega..sub.p, .omega..sub.i and free space wavelengths .lambda..sub.p, .lambda..sub.s, .lambda., respectively, wherein .omega..sub.s =N.omega..sub.p -M.omega..sub.i, and N, M are integers, the method comprising:

• providing a waveguide that defines a waveguide cavity having waveguide modes;
• disposing a nonlinear material in the cavity, the nonlinear material having a refractive index;
• directing the pump and idler into the waveguide cavity to produce a signal;
• and
• satisfying a phase-matching condition with a combination of the refractive index and the waveguide modes.

An apparatus for nonlinear generation of a signal, comprising:

• a waveguide defining a waveguide cavity, the waveguide having a waveguide mode and an associated propagation constant k.sub.mode ;
• a nonlinear material disposed in the waveguide cavity, the nonlinear material having an index of refraction n and a propagation constant k.sub.material ;
• and
• the propagation constants k.sub.mode and k.sub.material satisfying a phase-matching condition for the signal frequency.

An apparatus for nonlinear generation of a signal, comprising:

• a waveguide having a propagation constant and comprising first and second waveguide sections aligned on an axis, the waveguide sections defining respective waveguide cavities;
• a gas chamber;
• gas seals through which the first and second waveguide cavities communicate with the gas chamber;
• a gas supply that delivers gas to the gas chamber, whereby gas flows through the first and second waveguide cavities and exits the gas chamber;
• a regulator that adjusts the gas pressure to achieve phase matching with respect to the waveguide propagation constant;
• and
• a vacuum enclosure in communication with the second waveguide cavity.

An apparatus for nonlinear generation of a signal, comprising:

• a waveguide having a propagation constant and comprising first, second, and third waveguide sections aligned on an axis, the waveguide sections defining respective waveguide cavities;
• a gas chamber containing the second waveguide section;
• gas seals through which the first and third waveguide cavities communicate with the chamber;
• a gas supply that delivers gas to the gas chamber, whereby gas flows through the first and third waveguide cavities and exits the gas chamber;
• a regulator that adjusts the gas pressure to achieve phase matching with respect to the waveguide propagation constant;
• and
• a vacuum enclosure in communication with the first and third waveguide cavities.