Hitless wavelength-selective switch with quadruple series-coupled microring resonators using multiple-quantum-well...

Area of Science:

• Optoelectronics
• Materials Science
• Photonics

Background:

• Wavelength-selective switches (WSS) are crucial components in optical communication networks.
• Existing WSS technologies face challenges with switching speed, spectral response, and signal integrity (hitless operation).
• Quantum-confined Stark effect (QCSE) in semiconductor heterostructures offers a promising mechanism for electro-optic modulation.

Purpose of the Study:

• To demonstrate a novel hitless wavelength-selective switch (WSS).
• To leverage InGaAs/InAlAs five-layer asymmetric coupled quantum well (FACQW) structures for high-speed WSS operation.
• To investigate the performance of quadruple series-coupled microring resonators for improved switching characteristics.

Main Methods:

• Fabrication of a WSS using high-mesa waveguides on a molecular beam epitaxy-grown wafer via dry etching.
• Integration of four microring resonators with a round-trip length of 350 μm.
• Utilizing the electric-field-induced change in refractive index (QCSE) in the FACQW core for modulation.
• Employing five directional couplers with shallow grooves for resonator coupling.

Main Results:

• Successful demonstration of a hitless WSS with a boxlike spectral response.
• Achieved higher extinction ratios compared to double series-coupled microring resonators.
• Validated the high-speed operation driven by QCSE in the FACQW material.
• Proposed methods for further improvement by controlling coupling efficiencies.

Conclusions:

• The developed FACQW-based quadruple series-coupled microring resonator WSS offers superior performance for optical switching.
• The hitless switching capability and enhanced extinction ratios are significant advancements for optical networks.
• Controlling coupling efficiencies presents a viable pathway for optimizing WSS performance.