Broad-Band Ultrafast All-Optical Switching Based on Enhanced Nonlinear Absorption in Corrugated Indium Tin Oxide Films

Abstract

Ultrafast all-optical switches based on epsilon-near-zero (ENZ)-enhanced nonlinear refraction in transparent conducting oxides have achieved exciting results in realizing large absolute modulations. However, broad-band, polarization-independent, and wide-angle ultrafast all-optical switches have been challenging to produce, due to the inherent narrow band, polarization-dependent, and angle-dependent characteristics of the ENZ effect. To this end, we propose an ultrafast all-optical switch based on the enhanced nonlinear absorption of corrugated indium tin oxide (ITO) thin films. Taking advantage of the perfect absorption and localized field enhancement of the ENZ and localized surface plasmon resonance modes, we significantly enhanced the nonlinear absorption of the corrugated ITO film in the 1450–1650 nm telecom band. The experimental results show that the nonlinear saturable absorption coefficient of the corrugated ITO film at 1450 nm was as high as −1.5 × 105 cm GW–1, enabling all-optical switching to obtain an extinction ratio of 14.32 dB and an ultrafast switching time of 350 fs at a pump fluence of 18.51 mJ cm–2. Furthermore, the all-optical switch achieved an extinction ratio of over 15 dB and an insertion loss of approximately 2.6 dB within the 200 nm absorption band and exhibited polarization-independent and wide-angle features. The ultrafast temporal response can be attributed to intraband transient bleaching of the corrugated ITO film. Our findings demonstrate that corrugated ENZ films can overcome the inherent narrow-band, polarization-dependent, and angle-dependent problems of natural ENZ materials without increasing the response time, making them a potential ENZ ultrafast all-optical switching material platform.

A tunable perfect absorber based on a black phosphorus/bowtie shaped cavity hybrid metasurface

“…Additionally, the insertion loss (IL = 10 log 10 (1/ A on )) is introduced to represent the loss caused by the light propagation. 43 It is concluded that to the triple-frequency switch, IL are 0.01 dB, 8.46 dB and 0.003 dB, to the dual-frequency switch, IL are 0.03 dB and 4.59 dB, respectively. To sum up, this polarization-tunable optical switch has high ON/OFF ratio and modulation depth, as well as low insertion loss.…”

Flexible optical limiters based on Cu3VSe4 nanocrystals

“…In addition, dielectric resonance leads to the enhancement of the electric field in the epsilon-near-zero region and thus giant optical nonlinearity. 45,46 Fig. S16 and Table S3 † show that the nonlinear optical responses of the spherical Cu 3 VSe 4 NC control without dielectric resonance are much weaker.…”

Indium tin oxide as a dual-band compatible stealth material with low infrared emissivity and strong microwave absorption

“…At 30.521, 35.441, 51.061 and 60.711, the peaks correspond to the (222), (400), (440) and (622) crystal planes of the ITO crystal, which is the main orientation of ITO. 23,27 There is no diffraction peak of the SnO 2 phase or other phases found in the figure, which indicates that all Sn 4+ ions are doped into In 2 O 3 lattice, forming a single cubic structure, indicating that ITO particles have high purity and crystallinity. Fig.…”

“…In addition, its moderate conductivity and the synergistic effect of In and Sn elements may play an important role in compatible stealth. 22,23 Moreover, ITO has a wide direct forbidden band gap (3.5-4.3 eV), and simply changing the doping level can adjust the total polarizability, band gap, and free carrier concentration, thereby effectively improving the optoelectronic performance. 24 It also possesses admirable thermal and chemical stability, which can adapt to apply in high temperature environments.…”