Quadrature outputs from fiber interferometer with 4 x 4 coupler

Area of Science:

• Photonics and Optical Engineering
• Waveguide Optics
• Integrated Optics

Background:

• Directional couplers are fundamental components in integrated optics.
• Self-imaging phenomena offer precise light manipulation capabilities.
• Mach-Zehnder interferometers are widely used for optical sensing and signal processing.

Purpose of the Study:

• To investigate the self-imaging properties of a broad stripe waveguide.
• To demonstrate its functionality as a 4x4 directional coupler.
• To analyze the output power behavior when coupled with a fiber-optic Mach-Zehnder interferometer.

Main Methods:

• Theoretical analysis of a broad stripe waveguide with width W and length L.
• Derivation of the condition for self-imaging: L = NW(2)/lambda, where N is the effective index.
• Simulation or experimental setup connecting the waveguide coupler to a Mach-Zehnder interferometer.

Main Results:

• The broad stripe waveguide acts as a self-imaging 4x4 directional coupler under specific conditions.
• Output powers at the four ports exhibit variations in phase quadrature when interfaced with a Mach-Zehnder interferometer.

Conclusions:

• Broad stripe waveguides can be engineered as efficient self-imaging directional couplers.
• This configuration enables novel optical signal manipulation with phase-quadrature outputs.
• Potential applications in optical signal processing and interferometry.