Tunable Doppler shift using a time-varying epsilon-near-zero thin film near 1550 nm
Abstract
We experimentally investigate the tunable Doppler shift in an 80 nm thick indium-tin-oxide (ITO) film at its epsilon-near-zero (ENZ) region. Under strong and pulsed excitation, ITO exhibits a time-varying change in the refractive index. A maximum frequency redshift of 1.8 THz is observed in the reflected light when the pump light has a peak intensity of ∼ 140 G W / c m 2 and a pulse duration of ∼ 580 f s , at an incident angle of 40°. The frequency shift increases with the increase in pump intensity and saturates at the intensity of ∼ 140 G W / c m 2 . When the pump pulse duration increases from ∼ 580 f s to ∼ 1380 f s , the maximum attainable frequency shift decreases from 1.8 THz to 0.7 THz. In addition, the pump energy required to saturate the frequency shift decreases with the increase in pump pulse duration for ∼ x 1 p s and remains unchanged for ∼ x > --> 1 p s durations. Tunability exists among the pump pulse energy, duration, and incident angle for the Doppler shift of the ITO-ENZ material, which can be employed to design efficient frequency shifters for telecom applications.
Document Details
- Document Type
- Pub Defense Publication
- Publication Date
- Jul 14, 2021
- Source ID
- 10.1364/ol.430106
Entities
People
- Ahmad Fallahpour
- Ahmed Almaiman
- Alan E. Willner
- Cong Liu
- Evan M. Smith
- Fatemeh Alishahi
- Hao Song
- Haoqian Song
- Joshua R Hendrickson
- Kai Pang
- Karapet Manukyan
- M. Zahirul Alam
- Moshe Tur
- Orad Reshef
- Robert W. Boyd
- Runzhou Zhang
- Yiyu Zhou
Organizations
- Air Force Research Laboratory
- Defense Advanced Research Projects Agency
- King Saud University
- Tel Aviv University
- University of Ottawa
- University of Southern California