Thermal Phase Modulator and Method of Modulation of Light Beams by Optical Means.
Patent, Filed 31 Oct 91, patented 24 Nov 92,
DEPARTMENT OF THE NAVY WASHINGTON DC
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Apparatus is provided for modulating the phase of a coherent light beam propagating through the core of a single-mode waveguide. A light-absorbing element is connected to a portion of the cladding of the waveguide such that there is a thermal interface therebetween. A means is provided for launching light into the portion of the cladding of the waveguide having the light-absorbing element connected thereto. The light-absorbing element absorbs the light and produces beat in proportion to the lights energy. The heat thus produced is transferred to the waveguide, changing its optical path length and varying the phase of the light propagating therethrough. The intensity of the light launched into the cladding is variable and is controlled by a power supply. The modulator may be used in an interferometer in which a signal is directed to the power supply to control the light intensity for various purposes.
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