Optical fiber-coupled InGaAs-based terahertz time-domain spectroscopy system.

Area of Science:

• Spectroscopy
• Terahertz Technology
• Optical Physics

Background:

• Terahertz time-domain spectroscopy (THz-TDS) is a powerful technique for material analysis.
• Integrating THz-TDS systems with optical fibers presents challenges in maintaining signal integrity.
• Optical feedback can degrade emitter performance in fiber-coupled systems.

Purpose of the Study:

• To demonstrate a successful optical fiber-coupled THz-TDS system.
• To enhance the terahertz output power of the emitter in a fiber-coupled setup.
• To validate the system's capability for detecting spectral features, such as water vapor absorption.

Main Methods:

• Development of an optical fiber-coupled THz-TDS system.
• Implementation of two optical band rejection filters on the emitter.
• Application of an alternating current bias to the emitter below a specific threshold.
• Characterization of terahertz output power and spectral measurements.

Main Results:

• Achieved a terahertz output power of 132 nW with optical band rejection filters.
• Demonstrated a 70% improvement in terahertz output power compared to the unfiltered system.
• Suppressed unwanted optical modulated signals generated by the emitter.
• Successfully measured water vapor absorption dips using the fiber-coupled THz-TDS system under optimal alignment.

Conclusions:

• Optical band rejection filters significantly enhance the performance of fiber-coupled THz-TDS systems.
• The developed system provides a robust platform for terahertz spectroscopy with improved output power.
• The system is capable of sensitive detection of atmospheric components like water vapor.