Integrated injection seeded terahertz source and amplifier for time-domain spectroscopy.

Area of Science:

• Optics and Photonics
• Quantum Electronics
• Spectroscopy

Background:

• Terahertz (THz) time-domain spectroscopy (TDS) requires robust and efficient THz sources.
• Quantum cascade lasers (QCLs) offer a compact and tunable platform for THz generation.
• Developing integrated THz QCL sources for spectroscopy enhances experimental capabilities.

Purpose of the Study:

• To utilize a terahertz (THz) quantum cascade laser (QCL) as an integrated injection seeded source and amplifier.
• To investigate the performance of the THz QCL in an injection seeded configuration for THz-TDS.
• To confirm the operational regime of the THz QCL through output power characteristics.

Main Methods:

• Generating THz input pulses within a QCL by illuminating its facet with a near-infrared (near-IR) femtosecond laser pulse.
• Amplifying the generated THz pulses using gain switching in the QCL.
• Operating the QCL in an injection seeded configuration by coupling external THz radiation.

Main Results:

• The THz output from the QCL demonstrated saturation as the THz input power was increased.
• This saturation behavior is a key indicator of the QCL operating in an injection seeded regime.
• The integrated THz QCL successfully functioned as both a source and amplifier.

Conclusions:

• A terahertz (THz) quantum cascade laser (QCL) can effectively serve as an integrated injection seeded source and amplifier.
• The observed output saturation confirms the injection seeded operation of the THz QCL.
• This approach provides a promising pathway for advanced THz time-domain spectroscopy systems.