Topic
Extinction ratio
About: Extinction ratio is a research topic. Over the lifetime, 8541 publications have been published within this topic receiving 111908 citations.
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TL;DR: A spectrally clean kHz-linewidth single-polarization single-frequency distributed Bragg reflector Yb-doped phosphate fiber (YPF) laser at 1120 nm (> 1100 nm) for the first time is demonstrated.
Abstract: A spectrally clean kHz-linewidth single-polarization single-frequency distributed Bragg reflector Yb-doped phosphate fiber (YPF) laser at 1120 nm (> 1100 nm) for the first time is demonstrated. By enhancing the reflectivity of output fiber Bragg grating and optimizing the length of YPF to implement the effective ASE suppression and single-longitudinal-mode long-wavelength lasing, a stable output power of over 62 mW is achieved from a 31-mm-long highly YPF with a linewidth of 5.7 kHz. The signal to noise ratio of > 67 dB, the polarization extinction ratio of > 25 dB, and the relative intensity noise of < –150 dB/Hz for the frequencies above 10.0 MHz are obtained in such single-frequency fiber laser. This narrow linewidth fiber laser is an ideal laser source to generate the coherent single-frequency 560 nm light via frequency doubling for biochemical analysis application.
33 citations
TL;DR: In this paper, a tri-coupled waveguide-based silicon electro-optical modulator is proposed, which is designed such that it will both change the coupling conditions and introduces additional intrinsic losses at the telecommunication wavelength (1550 nm).
Abstract: Silicon based electro-optical modulators are essential for optical communication systems. In this paper, we present a silicon electro-optical modulator, which is based on tri-coupled waveguides. Two of these waveguides are silicon-on-insulator slot waveguides separated by a hybrid Indium Tin Oxide intermediate waveguide. The silicon-on-insulator slot waveguides reaps the advantages of the high mode confinement. The power-splitting mechanism can be electrically tuned through applying external electric field to the intermediate plasmonic waveguide. The tuning mechanism is designed such that it will both change the coupling conditions and introduces additional intrinsic losses at the telecommunication wavelength (1550 nm). The modulator was optimized by three-dimensional full finite difference time domain electromagnetic simulations. Extinction ratio of 6.14 dB and insertion losses of 0.06 dB are realized at 21 μm modulator length; as well as, extinction ratio of 11.43 dB and insertion losses of 1.65 dB are realized at 34 μm modulator length. The proposed silicon electro-optical modulator can potentially play a key role in the next generation of the onchip electronic-photonic integrated circuits.
33 citations
TL;DR: In this article, the authors present an experimental analysis and phenomenological modeling of single and multistage wavelength converters using cross-gain modulation in polarization insensitive multiquantum-well optical amplifiers.
Abstract: Extinction ratio conservation, wide dynamic range, and large operating wavelength window are important features for all-optical wavelength converters. Practical converters may probably be multistage devices and have to be precisely modeled. We present an experimental analysis and phenomenological modeling of single- and multistage wavelength converters using cross-gain modulation in polarization insensitive multiquantum-well optical amplifiers. One of the studied double-stage converters is able to produce a large extinction ratio improvement with a regeneration factor higher than 1.5 for any conversion in the 1.53-1.56-/spl mu/m window. The phenomenological model yields a very good agreement with the experimental results.
33 citations
TL;DR: The fabricated active terahertz wave hybrid grating structure of Au/Ti metallic grating on VO2/Al2O3 was fabricated and evaluated and it is shown that the metallic gratings on the VO2 layer strengthen the metallic characteristics to enhance the contrast of the metallic and dielectric phases of a VO2-based device.
Abstract: An active terahertz (THz) wave hybrid grating structure of Au/Ti metallic grating on VO2/Al2O3 (0001) was fabricated and evaluated. In our structure, it is shown that the metallic gratings on the VO2 layer strengthen the metallic characteristics to enhance the contrast of the metallic and dielectric phases of a VO2-based device. Especially, the metal grating-induced optical conductivity of the device is greatly enhanced, three times more than that of a metallic phase of bare VO2 films in the 0.1-2.0 THz spectral range. As an illustrative example, we fabricated an actively on/off switchable THz linear polarizer. The fabricated device has shown commercially comparable values in degree of polarization (DOP) and extinction ratio (ER). A high value of 0.89 in the modulation depth (MD) for the transmission field amplitude, superior to other THz wave modulators, is achieved. The experimental results show that the fabricated device can be highly useful in many applications, including active THz linear polarizers, THz wave modulators and variable THz attenuators.
33 citations
TL;DR: Ridge waveguide 1.3 mum GaInNAs lasers were fabricated from high quality double quantum well material grown by molecular beam epitaxy, and an extinction ratio larger than 6 dB and a spectral rms-width smaller than 2 nm are obtained.
Abstract: Ridge waveguide 1.3 μm GaInNAs lasers were fabricated from high quality double quantum well material grown by molecular beam epitaxy. Short cavity (250 μm) lasers have low threshold currents and small temperature dependencies of threshold current and slope efficiency, with a characteristic temperature of the threshold current as high as 200 K. The temperature stability allows for uncooled 2.5 Gb/s operation up to temperatures as high as 110 °C with a constant modulation voltage and only the bias current adjusted for constant average output power. Under these conditions, an extinction ratio larger than 6 dB and a spectral rms-width smaller than 2 nm are obtained.
33 citations