Frequency division multiplexing readout of a transition edge sensor bolometer array with microstrip-type electrical...

Area of Science:

• Physics
• Cryogenics
• Sensor Technology

Background:

• Transition edge sensors (TES) are crucial for sensitive low-temperature measurements.
• Multiplexed readout systems are needed to scale up detector arrays.

Purpose of the Study:

• To demonstrate an improved frequency division multiplexing (FDM) readout system for 43 TES bolometers.
• To assess the performance of the FDM system in terms of cross talk, detector stability, and noise.

Main Methods:

• Utilized a frequency division multiplexing (FDM) readout chain with bias frequencies from 1 to 3.5 MHz.
• Replaced coplanar wires with microstrip wires to minimize mutual inductance cross talk.
• Increased the heat capacity of TES detectors to reduce thermal response speed and prevent oscillations.

Main Results:

• Achieved minimal electrical cross talk (ECT) for most pixels, dominated by carrier leakage.
• Enabled stable biasing of TES detectors below 50% in transition.
• Demonstrated less than 10% difference in noise equivalent power (NEP) and 5% difference in saturation power compared to single-pixel mode.
• Validated noise spectra against simulations, confirming phonon noise dominance.

Conclusions:

• The enhanced FDM system effectively reads out a large array of TES bolometers with high performance.
• The implemented improvements significantly reduce cross talk and improve detector stability.
• The system is suitable for sensitive cryogenic measurements where phonon noise is the limiting factor.