Enhancing the Linear Dynamic Range in Multi-Channel Single Photon Detector beyond 7OD.

Area of Science:

• Photonics and Instrumentation
• Biophysics
• Optical Sensing

Background:

• Accurate photon detection is crucial for various scientific applications, including fluorescence microscopy and particle counting.
• Existing single photon detectors often face limitations in dynamic range and speed, hindering high-throughput measurements.
• Photomultiplier tube (PMT) sensors offer high sensitivity but require specialized electronics for high count rate applications.

Purpose of the Study:

• To design, implement, and characterize a high-speed single photon detector system.
• To evaluate the linear dynamic range (LDR) and performance limitations of a 32-channel PMT sensor.
• To demonstrate the detector's capability in a biological application, such as microbead detection.

Main Methods:

• Development of a custom high-speed electronic readout system for a 32-channel PMT sensor (Hamamatsu H7260-20).
• Experimental characterization of the detector's performance, including its linear dynamic range (LDR) and count rate capabilities.
• Monte Carlo simulations to understand the factors limiting the LDR.
• Testing the detector's functionality in a capillary flow system for detecting fluorescence-labeled microbeads.

Main Results:

• The developed single photon detector achieves a linear dynamic range (LDR) of up to 10^8 counts/s per channel.
• Key limitations to the LDR were identified as the 900 ps photon pulse width and amplitude decrease at high count rates.
• The multi-channel architecture and associated firmware/software enable a 32-fold dynamic range expansion through beam shaping.
• Successful detection of fluorescence-labeled microbeads in capillary flow was demonstrated.

Conclusions:

• The designed single photon detector system offers high speed and a significant linear dynamic range (LDR) for photon counting applications.
• Understanding the limitations imposed by pulse width and count rate is essential for optimizing PMT sensor performance.
• The multi-channel design and beam shaping provide a scalable solution for extending the dynamic range.
• The detector is a viable tool for sensitive and high-throughput biological measurements, such as analyzing microbead flow.