Observing mode-dependent wavelength-to-time mapping in few-mode fibers using a single-photon detector array

Harikumar K. Chandrasekharan*, Katjana Ehrlich, Michael G. Tanner, Dionne M. Haynes, Sebabrata Mukherjee, Tim A. Birks, Robert R. Thomson

*Corresponding author for this work

Research output: Contribution to journalLetterpeer-review

13 Citations (Scopus)
59 Downloads (Pure)


Wavelength-to-time mapping (WTM)-stretching ultrashort optical pulses in a dispersive medium such that the instantaneous frequency becomes time-dependent-is usually performed using a single-mode fiber. In a number of applications, such as time-stretch imaging (TSI), the use of this single-mode fiber during WTM limits the achievable sampling rate and the imaging quality. Multimode fiber based WTM is a potential route to overcome this challenge and project a more diverse range of light patterns. Here, we demonstrate the use of a two-dimensional single-photon avalanche diode (SPAD) array to image, in a time-correlated single-photon counting (TCSPC) manner, the time-and wavelength-dependent arrival of different spatial modes in a few-mode fiber. We then use a TCSPC spectrometer with a one-dimensional SPAD array to record and calibrate the wavelength-dependent and mode-dependent WTM processes. The direct measurement of the WTM of the spatial modes opens a convenient route to estimate group velocity dispersion, differential mode delay, and the effective refractive index of different spatial modes. This is applicable to TSI and ultrafast optical imaging, as well as broader areas such as telecommunications.

Original languageEnglish
Article number061303
JournalAPL Photonics
Issue number6
Early online date9 Jun 2020
Publication statusPublished - Jun 2020

ASJC Scopus subject areas

  • Atomic and Molecular Physics, and Optics
  • Computer Networks and Communications


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