Our results might imply that the intervention of RVE retarded bone loss induced by simulated microgravity in humans that was mainly attributed to its anabolic effects.

We study whether helium ion implantation can reduce the carrier lifetime and thus reduce the density of two-photon-absorption-generated free carriers. Our experiments and theoretical model show that helium ion implantation into silicon waveguides can successfully reduce the free-carrier losses and allow net gain to be attained by cw-pumped stimulated Raman scattering without requiring reverse bias to remove the photogenerated free carriers.

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In this demonstration, we propose and experimentally investigate the quaternary-amplitude-shift-keying (4-ASK) modulation with digital filtering to enhance the direct modulation speed of white-light lightemitting-diode (LED) in visible light communication (VLC) system. Here, an ordinary LED commercially available for lighting application with a direct modulation speed of 1 MHz is used. Data rate of 20 Mbit/s can be achieved in a 1 m free space transmission without using optical blue filter. In the previous studies, the transmission rate of LED VLC could only be increased by 2 to 10 times of the direct modulation speed of the white-light LED if using electrical equalization only. Moreover, the adaptive-controlled FIR filter makes the system closer to the matched filtering condition for reducing the inter-symbol-interference (ISI) for the LED VLC. A recorded 20 times enhancement of the direct modulation speed of white-light LED VLC system is demonstrated by using digital filter only and without using optical blue filter.

Carrier diffusion and recombination are considered in calculating the time dependent density of free carriers generated by two photon absorption in silicon waveguides. The calculations are compared to experimental results from optical pump-probe measurements of the induced loss from free carrier absorption. A generalized definition of nonlinear effective length is proposed to describe the effects of nonlinear loss. The authors experimentally demonstrate that helium-ion implantation can reduce the effective carrier lifetime and report on the observation of enhanced self-phase modulation in the helium implanted silicon waveguide.