Highly efficient and ultracompact InP/InGaAsP three-port trench-based couplers

Area of Science:

• Photonics
• Integrated Optics
• Waveguide Devices

Background:

• Existing photonic couplers face limitations in footprint and interaction length.
• There is a need for more compact and efficient optical coupling solutions.

Purpose of the Study:

• To propose and demonstrate a highly efficient and ultracompact three-port trench-based coupler (TBC).
• To optimize TBC design parameters for improved performance.

Main Methods:

• Utilized the frustrated total internal reflection principle.
• Employed the finite-difference time-domain (FDTD) numerical method for optimization.
• Fabricated and characterized a TBC on an InP platform at 1.55 µm wavelength.

Main Results:

• Achieved an ultracompact TBC with a single slash-shaped trench.
• Optimized trench dimensions, material (Al2O3), and fabrication process.
• Demonstrated low insertion loss (IL) in the range of 0.3-0.5 dB.
• Exhibited a figure of merit significantly superior (≥∼24 times) to state-of-the-art trench couplers.

Conclusions:

• The proposed TBC offers superior performance in terms of compactness and efficiency.
• The optimized fabrication process minimizes insertion loss.
• TBCs are highly promising for next-generation photonic integrated circuits.