High-speed, widely tunable bidirectional 1310 nm MEMS VCSELs for OCT imaging

Area of Science:

• Optoelectronics
• Photonics
• Microelectromechanical Systems (MEMS)

Background:

• Tunable lasers are crucial for applications like optical coherence tomography (OCT).
• Microelectromechanical Systems (MEMS) tunable Vertical-Cavity Surface-Emitting Lasers (VCSELs) offer compact and potentially low-cost solutions.
• Silicon photonics platforms provide a robust base for integrating optoelectronic devices.

Purpose of the Study:

• To demonstrate the first bidirectional 1310 nm MEMS VCSELs fabricated on a silicon platform.
• To analyze two different device configurations for optimizing performance.
• To assess the suitability of these MEMS VCSELs for OCT applications.

Main Methods:

• Wafer bonding of Indium Phosphide (InP) epitaxy onto a silicon-on-insulator (SOI) wafer.
• Fabrication of two MEMS VCSEL device configurations: one semiconductor cavity dominant via vacuum bonding, and another incorporating an anti-reflection coating at the bonding interface.
• Characterization of tuning range and resonant frequency for both device types.

Main Results:

• Achieved MHz-range sweep rates for the MEMS VCSELs.
• A semiconductor cavity dominant MEMS VCSEL exhibited a continuous tuning range of 58 nm at 2.4 MHz.
• A device with an anti-reflection coating showed a continuous tuning range of 30.5 nm at 2.48 MHz.
• Projected tuning ranges exceeding 100 nm for both configurations.

Conclusions:

• Successfully demonstrated bidirectional 1310 nm MEMS VCSELs on a silicon platform.
• The developed MEMS VCSELs exhibit wide tuning ranges and high sweep rates, suitable for OCT.
• Device configuration significantly impacts tuning range and performance.