Amplification Technologies (United States)

Solid State Photomultipliers (SSPM) are widely recognized as a new generation of photodetectors competitive with APD and PMT in various applications. SSPM advantages are high gain, ultra-low excess noise factor of internal amplification, good photon detection efficiency, and fast timing. SSPM drawbacks are high dark count rate, considerable probability of cross-talk and afterpulsing, and low dynamic range. Detection of scintillation light pulses in nuclear science and medical imaging is one of the most attractive and thoroughly studied SSPM applications. The key parameter of the detection is energy resolution, which is used in respect to the photodetector itself by output pulse height resolution. Resolution of SSPM is considerably affected by non-linearity of the photoresponse due to the limited number of pixels and finite reset time of the pixel. Thus, output signal resolution calibrated in photon scale or Photon Number Resolution (PNR) should be used to reflect the non-linearity. The purpose of this study is to express PNR of SSPM in an analytical form taking into account excess noise factor of cross-talk and afterpulsing, and non-linearity. The normalization of PNR relative to an ideal detector characterizes the efficiency of SSPM in terms of the total excess noise factor of photodetection or, inversely, in terms of the detective quantum efficiency. The presented PNR model is suitable for performance optimization as well as for evaluation of SSPM applicability and competitiveness.

A new family of photodetectors with a Discrete Amplification (DA) mechanism allows the realization of very high gain and low excess noise factor in the visible and near infrared spectral regions and offers an alternative to conventional photomultiplier tubes and Geiger mode avalanche photodetectors. These photodetectors can operate in linear detection mode with gain-bandwidth product in excess of 4X10¹⁴ and in photon counting mode with count rates up to 10⁸ counts/sec. Potential benefits of this technology over conventional avalanche photodetectors include ultra low excess noise factor, very high gain, and lower reset time (<< 1 μs). In the photon counting mode, the devices can be operated in the non-gated mode under a constant dc bias. Because of its unique characteristics of self-quenching and self-recovery, no external quenching circuit is needed. We present the discrete amplification design approach used for the development of a solid state photomultiplier in the near infrared wavelength region. The demonstrated device performance far exceeds any available solid state photodetectors in the near infrared wavelength range. The measured devices have the following performance characteristics: gain > 2X10⁵, excess noise factor < 1.05, rise time < 350ps, fall time < 500ps, dark current < 2X10⁶ cps, operating voltage < 60V. These devices are ideal for researchers in the field of deep space optical communication, spectroscopy, industrial and scientific instrumentation, Ladar/Lidar, quantum cryptography, night vision and other military, defence and aerospace applications.