Opening of glutamate receptor channel to subconductance levels.

Ionotropic glutamate receptors (iGluRs) are tetrameric ligand-gated ion channels that open their pores in response to binding of the agonist glutamate. An ionic current through a single iGluR channel shows up to four discrete conductance levels (O1-O4). Higher conductance levels have been associated with an increased number of agonist molecules bound to four individual ligand-binding domains (LBDs).

Digital-to-analog converters for high-speed optical communications using frequency interleaving: impairments and characteristics.

Digital-to-analog converters (DACs) for high-speed optical communication systems based on CMOS technology have bandwidths lower than nowadays electro-optic components. A promising concept to circumvent this bottleneck is the frequency-interleaved DAC (FI-DAC) concept. In this paper, experimental results for the application of a 180 GS/s FI-DAC with 40 GHz analog bandwidth based on two DACs in a high-speed optical link are discussed and compared with simulation results.

Coherent UDWDM PON with joint subcarrier reception at OLT.

In this contribution, we report on the experimental investigation of an ultra-dense wavelength-division multiplexing (UDWDM) upstream link with up to 700 × 2.488 Gb/s polarization-division multiplexing differential quadrature phase-shift keying parallel upstream user channels transmitted over 80 km of standard single-mode fiber. We discuss challenges of the digital signal processing in the optical line terminal arising from the joint reception of several upstream user channels.

Initial ranging scheme based on interpolated Zadoff-Chu sequences for OFDMA-PON.

Initial access to passive optical networks (PONs) requires upstream (US) synchronization of multiple optical network units (ONUs). We propose a low-complexity scheme for orthogonal frequency division multiple access (OFDMA) based PONs and demonstrate it experimentally. The scheme is based on interpolated Zadoff-Chu sequences, to synchronize the signal of each ONU arriving at the optical line terminal (OLT).

Accurate finite-difference time-domain simulation of anisotropic media by subpixel smoothing.

Finite-difference time-domain methods suffer from reduced accuracy when discretizing discontinuous materials. We previously showed that accuracy can be significantly improved by using subpixel smoothing of the isotropic dielectric function, but only if the smoothing scheme is properly designed. Using recent developments in perturbation theory that were applied to spectral methods, we extend this idea to anisotropic media and demonstrate that the generalized smoothing consistently reduces the errors and even attains second-order convergence with resolution.