Extinction ratio

About: Extinction ratio is a research topic. Over the lifetime, 8541 publications have been published within this topic receiving 111908 citations.

Dynamic behavior of wavelength converters based on FWM in SOAs

Abstract: As wavelength converters based on four-wave mixing (FWM) in semiconductor optical amplifiers (SOAs) attract more attention, dynamic effects and wavelength dependent performance become key aspects to be investigated. Such issues are particularly important, as complex configurations are likely to be used to overcome challenges like tunability and polarization dependence. In this paper a numerical model is used to predict the dynamic performance of three FWM configurations and an analytical model is used to derive design rules. First, the wavelength dependent behavior of a wavelength converter is investigated and the requirement for a widely tunable converter is identified. Secondly, a configuration for extinction ratio (ER) improvement is studied and novel design rules are obtained analytically, tested experimentally and explained by the numerical model; experimental results with ER improvement at 10 Gb/s were achieved for the first time. The third configuration studied is a dual-pump arrangement enabling wide tunability. Fixed input/tunable output and tunable input/fixed output configurations are discussed in terms of optical signal-to-noise ratio and tunability. Design rules are extracted and verified for all three configurations that are likely to be deployed: simple wavelength converters, regenerating converters and tunable wavelength converters.

High-extinction ratio and low-loss silica-based 8/spl times/8 thermooptic matrix switch

Abstract: A high-extinction ratio and low-loss silica-based 8/spl times/8 thermooptic matrix switch is demonstrated. The 8/spl times/8 matrix switch is realized by using a double Mach-Zehnder interferometer switching unit and a matrix arrangement which reduces the total waveguide length. The average extinction ratio and the average insertion loss are 60.3 and 5.2 dB, respectively.

Generation of Terahertz Vortices Using Metasurface With Circular Slits

Abstract: We propose a metal device containing circular slits to generate a terahertz (THz) orbital angular momentum beam with numerical simulations. The estimation of the polarization extinction ratio is above 20 dB over the bandwidth ranging from 0.3 to 3 THz, and a mode purity of ${\rm TC}=1$ or $-$ 1 is close to 1 over a wide bandwidth range, except for the area near the deteriorated valley. We analyze the OAM spectrum and find that the main noise comes from an OAM mode of ${\rm TC}=-3$ or 3. When multiple concentric circular slits are employed, a larger transmittance is obtained without the sacrifice of mode purity. The design of such a device is simple with a size of micrometer order, revealing an option to generate a broadband THz vortex beam.

Photon probe fault locator for single-mode optical fiber using an acoustooptical light deflector

Abstract: A new backscattering technique for diagnosing the attenuation characteristics, spatial imperfections with length (fault location), and splice loss in a single-mode optical fiber has been developed by using a TeO 2 acoustooptical light deflector operating at 120 MHz. Due to the small insertion loss and high extinction ratio of the deflector, the dynamic range of the backscattered signal has been increased by at least 10 dB, which corresponds to the extension of 5 km in measurable length for fiber loss of 1 dB/km, compared with the conventional back-scattering technique in which the beam splitter and polarizer-analyzer combination are utilized. Another advantage of this technique is in that the saturation of the amplifier is avoided by arbitrarily cutting off a large power in the early stage of the Rayleigh scattering signal. A single-mode fiber of 19.2 km in length has been examined, and the distance for fault location up to 18.4 km was obtained.

Integrated optical intensity modulator and method for fabricating the same

Abstract: An integrated optical intensity modulator and a method for fabricating the same are provided. The integrated optical intensity modulator includes a substrate having spontaneous polarization, cut in a predetermined direction, an optical waveguide formed on the substrate, a plurality of domain-inversion areas having domains in the reverse direction of the spontaneous polarization, arranged in a staggered pattern around the optical waveguide, and a first electrode formed on the optical waveguide and second and third electordes formed on the substrates on the right and left of the optical waveguide, wherein if a predetermined voltage is applied to the electrode, a light wave is deflected and scattered in a domain-inversion area in accordance with a change of the refractive index of thedomain-inversion area in the optical waveguide and the refractive index of the spontaneous polarization area. According to the optical intensity modulator of the present invention, the domain-inversion structure of a ferroelectric material isformed in a staggered pattern around the optical waveguide, and an optical guided mode is deflected by an applied voltage, to thereby half driving voltage of the optical waveguide, and an area for deflecting the optical guided mode to the right and left can be formed in multiple stages, to thereby increase the extinction ratio.