Dencker Friedrichsen (pastorform68)

Time-domain analysis (TDA) is useful for measuring optical devices along with a link and for diagnosing a long device. In this Letter, an optical vector analyzer with TDA capability is proposed and experimentally demonstrated. The key to realizing TDA is a low-coherence optical carrier, which is achieved by modulating an electrical broadband signal on a continuous-wave light via acousto-optic modulation. Then, optical single-sideband modulation and vector balanced detection are used to measure the total frequency response of multiple devices under test (DUTs). Through an inverse Fourier transform, the obtained DUT impulses are distinguished in the time domain. Finally, time-domain gating and Fourier transform are applied to extract the frequency response of each DUT. An experiment is performed in which a fiber link comprising three DUTs and an H 13 C 14 N gas cell with a breakpoint inserted is characterized. The frequency setting resolution is 5 MHz, and a time-domain resolution of 30.84 ns is proved, which can reach 14.881 ns in theory.All-dielectric metamaterials conforming to an optical reflectionless potential (ORP) offer broadband, omni-directional suppression of reflection. Though they are predicted to possess broadband negative group velocity dispersion (GVD), ultrashort pulse propagation through such materials has not been studied so far, to the best of our knowledge. In this work, we demonstrate negative GVD and group delay dispersion over broadband covering visible to near-infrared wavelengths. We investigate the role of ORP in supercontinuum generation (SC), which is observed to be polarization independent. The negative GVD in ORPs is interesting for pulse compression, phase compensation, dispersion engineering, and controlled SC generation.We demonstrate a novel method to optically tune the pulse advancement and delay based on stimulated Raman gain in hydrogen. With a frequency-chirped pump, the generated signal pulse is selectively amplified at the leading or trailing edge of the pump pulse, depending on whether the frequency difference between the pump and the signal beam is blue or red detuned from the Raman transition, which results in advancement or delay of the signal peak. Different from the method of slow/fast light, where advancement and delay are accompanied with power loss and gain, respectively, for a single resonance, both the advancement and delay are realized in the gain region for the method here. With a piece of 48-mm-long optical nanofiber in hydrogen, the time-shift for a signal peak ranging from 3.7 to -3.7 ns is achieved in a Raman-generated pulse with width of ∼12n s.We report the first, to the best of our knowledge, observation of cross-phase modulational instability (XPMI) of circularly polarized helical Bloch modes carrying optical vortices in a twisted photonic crystal fiber with a three-fold symmetric core, formed by spinning the fiber preform during the draw. When the fiber is pumped by a superposition of left-circular polarization (LCP) and right-circular polarization (RCP) modes, a pair of orthogonal circularly polarized sidebands of opposite topological charge is generated. When, on the other hand, a pure LCP (or RCP) mode is launched, the XPMI gain is zero, and no sidebands are seen. This observation has not been seen before in any system and is unique to chiral structures with N-fold rotational symmetry. The polarization state and topological charge of the generated sidebands are measured. By decomposing the helical Bloch modes into their azimuthal harmonics, we are able to deduce the selection rules for the appearance of modulational instability sidebands. We showed that the four waves in the nonlinear mixing process must exhibit the same set of azimuthal harmonic orders.This Letter reports a demonstration of integrating a tiny GaN-based photonic chip with a PDMS microfluidics system. The photonic chip containing InGaN/GaN quantum wells is responsible for light emission and photo