Open AccessTunable Doppler shift using a time-varying epsilon-near-zero thin film near 1550 nm
Author(s) -
Cong Liu,
M. Zahirul Alam,
Kai Pang,
Karapet Manukyan,
Joshua R. Hendrickson,
Evan M. Smith,
Yiyu Zhou,
Orad Reshef,
Haoqian Song,
Runzhou Zhang,
Fatemeh Alishahi,
Ahmad Fallahpour,
Ahmed Almaiman,
Robert W. Boyd,
Moshe Tur
Publication year - 2021
Publication title -
optics letters/optics index
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.524
H-Index - 272
eISSN - 1071-2763
pISSN - 0146-9592
DOI - 10.1364/ol.430106
Subject(s) - analytical chemistry (journal) , materials science , chemistry , chromatography
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.