On-chip THz spectrometer for bunch compression fingerprinting at fourth-generation light sources

Area of Science:

• Physics
• Electrical Engineering
• Accelerator Science

Background:

• Terahertz (THz) spectroscopy is crucial for analyzing materials and processes.
• Existing THz spectrometers can be bulky and complex.
• Compact, integrated solutions are needed for applications like electron accelerators.

Purpose of the Study:

• To present the design and performance of an integrated millimetre-scale on-chip THz spectrometer.
• To demonstrate its capability for simultaneous multi-frequency detection in the THz range.
• To validate its use in characterizing electron bunches in accelerators.

Main Methods:

• Integration of eight Schottky-diode detectors with narrowband THz antennas on a single chip.
• Design of detector active area to match THz radiation focal spot size.
• Characterization using a quasi-continuous wave superconducting radio-frequency linear accelerator (SRF) at specific repetition rates and electron bunch charges.

Main Results:

• Successful demonstration of an integrated on-chip THz spectrometer.
• Simultaneous detection of eight distinct THz frequencies.
• Achieved pulse-resolved detection with a 3 dB bandwidth less than 10% of the center frequency.
• Performance validated at 100 kHz repetition rates with varying electron bunch charges (pC to 100 pC).

Conclusions:

• The developed on-chip THz spectrometer is a compact and effective solution for multi-frequency THz detection.
• Its performance is suitable for applications requiring pulse-resolved measurements, such as bunch compression monitoring in linear electron accelerators.
• This technology offers potential for miniaturized THz sensing and analysis.