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Time-Magnified Photon Counting in Femtosecond Regime

Time-magnified single-photon counting with femtosecond resolution and 97% conversion efficiency without the need for cryogenic cooling

Published: 28th April 2022
Time-Magnified Photon Counting in Femtosecond Regime
Source: Yurok Aleksandrovich,,


Time-correlated single-photon counting (TCSPC) is the key enabling technology for applications such as low-light fluorescence lifetime spectroscopy, time-gated Raman spectroscopy, and photon counting time-of-flight (ToF) 3D imaging. For these applications, the most important figure- of-merit is the single-photon timing resolution that directly affects the measurement accuracy and precision on important parameters such as the fluorescence-decay lifetime, Raman spectral resolution, ToF distance, and spatial resolution. The TCSPC single-photon time resolution is currently limited by the available single-photon detector technology.

Technology Overview

CU Boulder researchers have demonstrated a time-magnified TCSPC (TM-TCSPC) that achieves an unprecedentedly short single-photon timing resolution of 550 femtoseconds using an off-the-shelf single photon detector. The key component is a quantum temporal magnifier. A temporal magnification of 130x with a 97% photon conversion efficiency has been achieved while maintaining the quantum coherence of the signal under test. When applied to photon counting ToF 3D imaging, the TM-TCSPC greatly suppresses the range walk error by 99.2 % and thus provides high depth measurement accuracy and precision of 26 μm and 3 μm, respectively.


  • Sub-picosecond resolution
  • Enhanced resolution for ToF 3D imaging
  • No need for cryogenic cooling


  • Photon counting time-of-flight imaging
  • Low-light fluorescence lifetime spectroscopy and microscopy
  • Time-gated Raman spectroscopy
IP Status
  • Patent application submitted
  • Provisional patent
  • Licensing
  • University spin out