Eskildsenbeasley1156

We demonstrate a hybrid silicon tunable laser with wide tunability and rapid switching speed for applications in sensing and optical networks. By implementing an optimized carrier injection phase shifter design, the filters of the silicon laser cavity may be efficiently controlled, enabling both fine and broad wavelength tuning across a 56 nm range, in addition to a rapid 10 ns switching time. The laser emits up to 10 dBm output power, and the linewidth is near 200 kHz. The fast wavelength switching demonstrated here may be employed in data center and access networks, while the potential for rapid wavelength sweeping is attractive for optical sensing and imaging applications.Cryogenic operation, in conjunction with new test-mass materials, promises to reduce the sensitivity limitations from thermal noise in gravitational-wave detectors. Currently, the most advanced materials under discussion are crystalline silicon as a substrate with amorphous silicon-based coatings. However, they require operational wavelengths around 2 µm to avoid laser absorption. Here we present a light source at 2128 nm based on a degenerate optical parametric oscillator to convert light from a 1064 nm nonplanar ring-oscillator. We achieve an external conversion efficiency of (87.1±0.4)% at a pump power of 52 mW in periodically poled potassium titanyl phosphate (internal efficiency was 93%). With our approach, light from the established and existing laser sources can be efficiently converted to the 2 µm regime while retaining the excellent stability properties.We report a photonic scheme to generate multiband and multi-format microwave signals based on a commercial dual-polarization Mach-Zehnder modulator (DP-MZM). The key novelty of this work is the compact signal generator benefitting from the single modulator and the flexible multi-format signals at the multiband. The upper Mach-Zehnder modulator (MZM) of the DP-MZM is used to generate an optical frequency comb, while the lower MZM is driven by baseband electrical coding or single-chirp signal to obtain the multi-format modulated optical signal. The proposed scheme is theoretically analyzed and experimentally demonstrated. A multiband phase-coded microwave signal with a bit rate of 2 Gb/s and complementary linearly chirped microwave waveform pairs with a time duration of 1 µs and a bandwidth of 2 GHz have been successfully generated. The performance of pulse compression of generated signals is also demonstrated.A parallel structured optical fiber Fabry-Perot interferometer sensor is proposed and demonstrated for refractive index and strain sensing with low temperature cross sensitivity. The device consists of two Fabry-Perot cavities fabricated by a femtosecond laser one is inscribed in the fiber surface waveguide and used for sensing, and the other one is located in the fiber core for referencing. Part of the light propagating in the fiber core can be directed to the fiber surface waveguide via an X coupler. selleck chemicals llc Because of the evanescent field, the light traveling along the fiber surface waveguide interacts with the surrounding medium and enables external refractive index sensing. The measurement sensitivity of the device is enhanced due to the Vernier effect associated with the parallel structured two Fabry-Perot interferometers. The sensitivities of ∼843.3nm/RIU and ∼101.8pm/µε have been obtained for refractive index and strain, respectively, and the corresponding temperature cross sensitivities are ∼9.6×10-6RIU/∘C and ∼7.956×10-2µε/∘C, respectively. The device is featured with high robustness, compact size, and large sensitivity.Imaging with high angular resolution requires large apertures and long focal lengths. This has prevented the integration of telephoto lenses into thin devices such as modern mobile phones. We report a camera module employing multiple rotated rectangular apertures and folding of the optical system into the plane of the camera, enabling an order-of-magnitude reduction in depth compared to traditional telephoto lenses. Multiple images are fused in the frequency domain to yield a single high-resolution image equivalent to that yielded by a single circular aperture. The diameter of this equivalent aperture may be several times wider than the depth of the camera module. We propose two architectures and present illustrative optical designs to demonstrate the concept. Simulations of raytraced image acquisition and computational image reconstruction demonstrate the potential for high-quality, high-resolution imaging from thin, flat lens modules.We propose and experimentally demonstrate a joint equalization scheme to recover a zero-guard band dual-single sideband (dual-SSB) four-level pulse amplitude modulation (PAM4) signal in a system with moderate bandwidth limitation. In the joint equalization scheme, a multiple-input multiple-output feedforward equalizer (MIMO-FFE) is first used to mitigate the residual crosstalk resulting from non-ideal optical filtering. Then, a modified post filter (PF) is placed after the MIMO-FFE to suppress the MIMO-FFE-enhanced low-frequency noise, whereas the known inter-symbol interference introduced by the modified PF is further eliminated with the maximum likelihood sequence estimation algorithm. Based on the proposed scheme, we experimentally demonstrate a 112-Gb/s zero-guard band dual-SSB PAM4 signal transmission over an 80-km single mode fiber with the averaged bit error ratio of two sidebands below 3.8×10-3. We also achieve, to the best of our knowledge, a record electrical spectral efficiency of 7.1 b/s/Hz for single polarization direct detection systems using a dual-SSB PAM4 or dual-SSB 16-quadrature amplitude modulation format.In this Letter, we numerically propose a temperature-tunable, ultra-narrowband one-way perfect near-infrared radiation absorber with high transmission in the longer wavelength neighboring spectral range. We obtained this functionality by using a guided-mode resonance-based grating-waveguide metamirror that is comprised of silicon, a spacer dielectric, an absorbing semiconductor, and germanium. Within the ultra-narrow bandwidth of the guided-mode resonance excited at 1.16 µm with a full width at half-maximum of 3.3 nm, we confirmed perfect absorption when light is incident from one of the two opposite directions. Excitation from the opposite direction resulted in perfect reflection. The thickness of the entire structure is limited to about one third the operating wavelength. Furthermore, due to the temperature tunability of silicon and germanium the thermo-optical sensitivity was found to be approximately 0.068 nm/K. In addition to this spectral tunability, our proposed device supports transparency windows with 80% transmission in the higher wavelength ranges.