MEMS-based tunable terahertz wire-laser over 330 GHz.

Area of Science:

• Terahertz (THz) Photonics
• Semiconductor Lasers
• Optoelectronics

Background:

• Terahertz (THz) quantum cascade lasers (QCLs) are crucial for spectroscopy and imaging.
• Achieving wide, continuous tuning in single-mode THz QCLs remains a significant challenge.
• Existing tuning methods often suffer from limited range, discrete steps, or mechanical complexity.

Purpose of the Study:

• To demonstrate a novel, continuous tuning mechanism for terahertz quantum cascade wire lasers.
• To achieve a broad tuning range with single-mode operation.
• To investigate the influence of different tuning elements on the laser's frequency output.

Main Methods:

• Fabrication of a narrow terahertz quantum cascade wire laser ridge (approximately λ(o)/8).
• Integration of a movable microelectromechanical systems (MEMS) side object (plunger) to manipulate the transverse optical mode.
• Utilizing silicon and metal plungers to induce redshift and blueshift tuning, respectively.

Main Results:

• Demonstrated continuous, single-mode tuning over a broad range of ~330 GHz (~8.6% of the 3.85 THz center frequency).
• Achieved ~30 GHz redshift tuning with a silicon plunger.
• Achieved ~300 GHz blueshift tuning with a metal plunger, limited by the gain medium bandwidth.

Conclusions:

• The frictionless MEMS plunger enables continuous and reversible tuning of THz QCLs.
• The demonstrated tuning mechanism offers a wide frequency adjustment range for THz laser applications.
• The blueshift tuning range is primarily limited by the gain bandwidth of the laser medium.