Recently, indium tin oxide has been very attractive for thermo-optic (TO)-controlled silicon photonic devices, due to its high transparency, strong TO phase dependency, high conductivity, and CMOS compatibility. These properties enable the reduction of the gap between the silicon core and the heater, leading to a considerably low electric power consumption and high switching speed. We present an investigation of a numerical simulation to design and optimize a compact ITO microheater for tuning the TO phase shift in a proof-of-concept of a three-mode converter (TMC) with broadband and ultralow loss properties. We show that the TMC can operate the 3-dB bandwidth up to 100 nm. In addition, the designed device can attain relatively large fabrication tolerances for width and height of ±50 and ±5 nm, respectively. In addition, the proposed mode converter consumes a total power of less than 90 mW and obtains a fast switching time of less than 8 μs. Moreover, the device can be integrated into an estimated compact footprint of 8 μm × 2160 μm. Such excellent performances make ITO a strong candidate for low-loss TO phase shifters and open up an alternative method for realizing ultrafast and high-speed mode division multiplexing systems and large-scale applications.
We present the first observation of nonlinear optical response mediated by ultrafast magneto-electric (ME) rectification. The control of magnetic properties of materials by ultrafast optical field enable novel sensing technology, energy conversion, terahertz emission, and ultrafast data storage. However, the interaction of the magnetic field of light with materials is normally ignored due to low magnetic susceptibilities at high frequencies. Optical nonlinearities driven jointly by electric and magnetic field components of light provide a new route in controlling magnetic properties of bulk media. Several novel physical phenomena arise from curved motion of bound electrons driven jointly by electric and magnetic fields such as longitudinally polarized second harmonic radiation, induced transverse magnetization at the optical frequency, and charge separation along the propagation direction. We investigate an ME charge separation in pentacene semiconductors using a time-resolved second harmonic generation technique. A femtosecond laser beam acted as an optical pump with photon energy well below the bandgap of the material to induce ME charge separation. The DC electric field from the ME charge separation interacted with the optical field from a second laser beam, the probe, in a four-wave-mixing interaction that induced second harmonic (M-EFISH) generation. We also sought evidence of ME charge separation by searching for THz emission. By monitoring time-resolved M-EFISH and THz emission, we were able to study the ME charge separation dynamics for the first time.
In this work, we report three-dimensional memory by recording optical bits with irradiation of near-infrared femtosecond laser pulses and by reading photoluminescence change in the blue due to permanent reduction of Eu3+ to Eu2+ in sodium borate glasses. We produced a multilayered micro-bit pattern which was read out by detecting the blue emission from the 405 nm excitation with a high S/N ratio. The readout was performed by using a scanning reflection-type confocal microscope.
We report ultraviolet-induced transient and stable absorption and two-color holographic recording at 514, 633, and 830 nm in thulium doped stoichiometric LiNbO3 crystal. The gating light at 355 nm increased the diffraction efficiency and sensitivity. We found the optimum gating-recording intensity ratio for maximum diffraction efficiency and weak nonvolatile holographic storage with gating.
From the ultraviolet induced absorption, we have found a broad blue band and little involvement of Pr ions in ultraviolet illumination. Ultraviolet excited photoluminescence and the excitation spectra for visible emission were also measured in Pr:LiNbO3. We estimated photovoltaic constant and photoconductivity by measuring photovoltaic current and voltage with different boundary conditions. With ultraviolet gated short-circuit holographic recording, we have measured enhanced sensitivity and diffraction efficiency.
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