US 5,082,349 A · Bi-domain two-mode single crystal fiber devices

Abstract

A mode converter comprises an a-axis LiNbO.sub.3 optical fiber exhibiting a ferroelectric bi-domain structure. The fiber is subject to an electrical field that induces a +.pi./2 phase retardation in one domain of the fiber and a -.pi./2 phase retardation in the other domain. A light signal launched in the fundamental mode of the fiber is converted into a light signal propagating in the second order mode. When the electrical field is selected so that the phase retardations are not multiples of .pi./2, the mode conversion is partial and the LiNbO.sub.3 fiber can operate as an optical switch or as an amplitude modulator. The mode converter can also be operated as a second harmonic generator. The fiber is heated to a phase matching temperature so that a signal launched in the fundamental mode of the fiber and at a frequency .omega. is converted to the second order mode at a frequency 2.omega.. The LiNbO.sub.3 fiber can also simultaneously operate as an optical switch and as a second harmonic generator. Other non-linear interactions are possible such as sum or difference frequency generation or parametric generation. The various embodiments of the present invention are reciprocal.

Claims34

Dependent claims

An apparatus, comprising:

an optical waveguide comprising a material having electro-optic properties, said optical waveguide including a first domain and a second domain, said domains collectively supporting a first optical propagation mode and a second optical propagation mode for optical energy propagating in said waveguide, said modes corresponding to first and second energy distribution patterns;
and
a generator for producing a perturbation in the refractive index of one of said domains relative to the refractive index of the other of said domains of said optical waveguide, said perturbation altering the energy distribution of said optical energy to shift at least a portion of said optical energy from one of said patterns to the other of said patterns.

A method of coupling optical energy in an optical waveguide, comprising the steps of:

providing a single crystal waveguide having electro-optic properties, said single crystal waveguide comprising a first and a second domain having first and second refractive indices, respectively, said waveguide including at least first and second spatial modes in said first and second domains, said first and said second refractive indices being equal when no perturbation is applied within said single crystal waveguide and changing differently upon applying a perturbation in said single crystal waveguide;
inputting a first optical signal having a first frequency into said single crystal waveguide, so that the first optical signal propagates in said first mode in said first domain and in said first mode in said second domain;
and
perturbing the refractive index in said first and second domains to provide an output optical signal propagating at least in said second propagation mode.

1 more element

Dependencies are inferred from the claim text.

Bi-domain two-mode single crystal fiber devices

Life of this patent

Bi-domain two-mode single crystal fiber devices

Life of this patent

Abstract

Claims34