Fast Gating for Raman Spectroscopy

Abstract

Fast gating in Raman spectroscopy is used to reject the fluorescence contribution from the sample and/or the substrate. Several techniques have been set up in the last few decades aiming either to enhance the Raman signal (CARS, SERS or Resonant Raman scattering) or to cancel out the fluorescence contribution (SERDS), and a number of reviews have already been published on these sub-topics. However, for many reasons it is sometimes necessary to reject fluorescence in traditional Raman spectroscopy, and in the last few decades a variety of papers dealt with this issue, which is still challenging due to the time scales at stake (down to picoseconds). Fast gating (<1 ns) in the time domain allows one to cut off part of the fluorescence signal and retrieve the best Raman signal, depending on the fluorescence lifetime of the sample and laser pulse duration. In particular, three different techniques have been developed to accomplish this task: optical Kerr cells, intensified Charge Coupling Devices and systems based on Single Photon Avalanche Photodiodes. The utility of time domain fast gating will be discussed, and In this work, the utility of time domain fast gating is discussed, as well as the performances of the mentioned techniques as reported in literature.

Single Photon Avalanche Diode Arrays for Time-Resolved Raman Spectroscopy

“…A complete table comparing state-of-art SPAD arrays for different Raman spectroscopy experimental setups in terms of technology, pixel number, pixel pitch, FF, PDE, and DCR is reported in [ 42 ]. Our review instead aims at comparing the architectural choices of existing SPAD arrays, from the microelectronics design point of view, in order to provide guidelines for an improved next-generation of Raman single-photon cameras.…”

“…ICCD low frame rate is instead balanced by the ability to perform several counts per laser pulse, like any linear detector. Features, performances, and drawbacks of Kerr-gating and ICCDs are summarized in [ 42 ].…”

CMOS SPAD Line Sensor With Fine-Tunable Parallel Connected Time-to-Digital Converters for Raman Spectroscopy

“…A combination of time gating and an adjustable delay generator can also be a good alternative to a time-todigital converter (TDC) if a very high background radiation level is expected. A thorough description of time-gated Raman spectroscopy can be found in recent reviews [24], [25], [26].…”

Split-step birefringence simulation method for optical Kerr gates

“…Ultra-fast optical Kerr gates are widely used in ultra-fast spectrum measurements, 1 , 2 time-gate gating ballistic light imaging, 3 , 4 and third-order nonlinear measurements 5 . Moreover, they have immense potential in the field of quantum information 6 .…”