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Coupled Mode Switching Device

IP.com Disclosure Number: IPCOM000096018D
Original Publication Date: 1964-Nov-01
Included in the Prior Art Database: 2005-Mar-07
Document File: 2 page(s) / 40K

Publishing Venue

IBM

Related People

Hardy, WA: AUTHOR

Abstract

In contrast to prior devices which have modulated the quantity of light energy transfer between closely coupled optical fibers by controlling the magnitude of the coupling, this apparatus functions to modulate the energy transfer by controlling the propagation constants of the fibers. This difference in the mode of operation yields a marked improvement in the efficiency of operation in that a far greater degree of modulation is possible with less applied control energy.

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Coupled Mode Switching Device

In contrast to prior devices which have modulated the quantity of light energy transfer between closely coupled optical fibers by controlling the magnitude of the coupling, this apparatus functions to modulate the energy transfer by controlling the propagation constants of the fibers. This difference in the mode of operation yields a marked improvement in the efficiency of operation in that a far greater degree of modulation is possible with less applied control energy.

Fibers 1 and 2 are either separated by or embedded in dielectric compound 3 which is preferably transparent, but at least translucent to the passage of light energy. This compound should have an index of refraction which is lower than that of the optical fibers. The fibers themselves must have matched propagation constants at least within the control range. Preferably, their propagation constants should be equal in the absence of any applied control. If fiber 2 is fabricated of a single crystal of ferroelectric material, e. g., barium titanate, and with two electrodes 4 and 5 placed near it, then a potential applied across 4 and 5 alters the propagation constants of fiber 2. Since the distribution of energy transferred to fiber 2 is sinusoidal, any unbalance in the propagation constant of fiber 2 relative to fiber 1 causes a beating of the propagating waveform with the energy transferred. the characteristics of fiber 2 are altered to effect a 180 degree phase shift, c...