Electro-optic phase modulator with no residual amplitude modulation

Abstract

An optical phase modulator includes an input source that is configured to receive a light source. There is an output operative to provide a phase modulated output signal based on the received light source. There is a first optical coupler configured to split the light source into a first optical path of a Mach Zehnder Interferometer (MZI) and a second optical path of the MZI. A static phase shifter is configured to provide a static phase shift to the first optical path. There is a phase modulator in the second optical path. There is a second optical coupler configured to combine the first optical path and the second optical path. The first and second optical couplers are tuned such that the phase modulated optical signal at the output provides a substantially constant amplitude that is independent of a change in loss introduced by the phase modulator.

Description

BACKGROUNDTechnical Field[0001]The present application generally relates to optical modulators to control light signals, and more particularly, to optical phase modulators with controlled residual amplitude modulation.Description of the Related Art[0002]An electro-optic modulator is an optoelectronic device where a signal-controlled element having an electro-optic effect is used to modulate a beam of light. The modulation may be with respect to the phase, frequency, amplitude, or polarization of the beam of light. Electro-optic phase modulators are largely used in fiber optical communication systems for realizing high-speed phase modulation of optical signals. Various technologies and material platforms can be used to realize a phase modulator. The structure generally includes an optical waveguide that has a refractive index that is modulated by applying an RF electrical field that spatially overlaps with an optical mode of the waveguide.[0003]After propagating through an L-long pha...

AI Technical Summary

Benefits of technology

The patent text is submitted to allow the reader to quickly understand the nature of the invention. It is not meant to constrain the claims or the scope of the invention. The text explains that various features are grouped together in different embodiments to make the disclosure easier to read. This method of disclosure does not suggest that all features are present in each claim. Inventive subject matter is primarily described in the claims, which are each individually claimed as separate subject matter. The patent text aims to make it easier for R&D personnel to understand the invention without adding additional information.

Problems solved by technology

It is generally desirable to provide pure phase modulation without any residual amplitude modulation, which could be detrimental to the system.

The residual amplitude modulation of phase modulators is a salient issue for several applications including, without limitation, optical isolators, optical switches, and advanced imaging techniques such as optical coherence tomography.

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