Terahertz difference-frequency-generation quantum cascade lasers on silicon with wire grid current injectors.

Area of Science:

• Optics and Photonics
• Semiconductor Devices
• Quantum Electronics

Background:

• Terahertz (THz) quantum cascade lasers (QCLs) are crucial for various applications.
• Efficient coupling of THz radiation from QCLs into substrates remains a challenge.
• Intra-cavity difference-frequency generation (DFG) offers a pathway for THz generation.

Purpose of the Study:

• To propose and experimentally validate a novel THz QCL source.
• To integrate intra-cavity Cherenkov difference-frequency generation (CDFG) with a silicon substrate.
• To optimize current injection and THz output coupling.

Main Methods:

• Fabrication of THz QCLs on a silicon substrate.
• Implementation of a metal wire grid as a current injection layer.
• Experimental verification of CDFG operation and THz emission.
• Characterization of TM-polarized THz radiation transmission.

Main Results:

• Successful demonstration of THz QCLs based on intra-cavity CDFG.
• The metal wire grid injector achieved high transmission of TM-polarized THz radiation.
• The configuration provided a low-resistivity contact for efficient current injection.
• Operation was verified on a silicon substrate.

Conclusions:

• The proposed THz QCL design with a wire grid injector is effective.
• This approach enhances THz output coupling into silicon substrates.
• The technology holds promise for integrated THz photonic devices.