Millimeter wave photonics with terahertz semiconductor lasers

Area of Science:

• Optoelectronics
• Quantum Cascade Lasers
• Terahertz Technology

Background:

• Photonic millimeter wave (mmWave) generation typically uses near-infrared lasers, facing limitations in monolithic architecture and quantum defect-related efficiency losses.
• Terahertz (THz) quantum cascade lasers (QCLs) offer potential for integrated mmWave generation due to their low-energy photons, ultrafast gain relaxation, and high nonlinearities.

Purpose of the Study:

• To demonstrate intracavity mmWave generation within THz QCLs.
• To explore the integration of laser action and mmWave generation in a single device.
• To achieve mmWave generation over an unprecedented frequency range.

Main Methods:

• Utilized miniaturized THz quantum cascade lasers (QCLs) for integrated mmWave generation.
• Employed ultrafast time-resolved techniques to investigate the underlying physical processes.
• Analyzed the role of modal phases, giant second-order nonlinearity, and phase-matched processes.

Main Results:

• Successfully demonstrated intracavity mmWave generation within THz QCLs.
• Achieved mmWave generation across an unprecedented frequency range from 25 GHz to 500 GHz.
• Identified the critical role of modal phases and nonlinear optical processes in efficient mmWave generation.

Conclusions:

• Intracavity mmWave generation in THz QCLs is feasible and highly efficient.
• This approach overcomes limitations of traditional photonic methods, enabling monolithic device integration.
• The findings pave the way for compact, low-noise mmWave sources using mode-locked THz frequency combs.