Bi-domain two-mode single crystal fiber devices

Details Bi-domain two-mode single crystal fiber devices Bi-domain two-mode single crystal fiber devices

1990-06-20

1992-01-21

Ullah, Akm

Optical waveguides

Temporal optical modulation within an optical waveguide

Electro-optic

385 16, 385 28, G02B 610, G02B 628, G02B 602, G02B 616

Patent

active

050823493

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.

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