Extinction ratio

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

Total Performance of Magneto-Optical Ceramics with a Bixbyite Structure

Abstract: High-quality magneto-optical ceramics (TbxY1−x)2O3 (x = 0.5–1.0) with a Bixbyite structure were extensively investigated for the first time. The total performances of these ceramics were far superior to those of commercial TGG (Tb3Ga5O12) crystal, which is regarded as the highest class of Faraday rotator material. In particular, the Verdet constant of Tb2O3 (when x = 1.0) ceramic was the largest—495 to 154 rad·T−1·m−1 in the wavelength range of 633 to 1064 nm, respectively. It was possible to further minimize the Faraday isolator device. The insertion loss of this ceramic was equivalent to that of the commercial TGG single crystal (0.04 dB), and its extinction ratio reached more than 42 dB, which is higher than the value for TGG crystal (35 dB). The thermal lens effect (1/f) was as small as 0.40 m−1 as measured by a 50 W fiber laser. The laser damage threshold of this ceramic was 18 J/cm2, which is 1.8 times larger than that of TGG, and it was not damaged during a power handling test using a pulsed laser (pulse width 50 ps, power density 78 MW/cm2) irradiated at 2 MHz for 7000 h.

One-volt silicon photonic crystal nanocavity modulator with indium oxide gate.

Abstract: The ever-increasing global network traffic requires a high level of seamless integration between optical interconnect systems and complementary metal–oxide–semiconductor (CMOS) circuits. Therefore, it brings stringent requirements for future electro-optic (E-O) modulators, which should be ultracompact, energy efficient, high bandwidth, and in the meanwhile, able to be directly driven by the state-of-the-art CMOS circuits. In this Letter, we report a low-voltage silicon photonic crystal nanocavity modulator using an optimized metal–oxide–semiconductor (MOS) capacitor consisting of an In2O3/HfO2/p-Si stacked nanostructure. The strong light–matter interaction from the accumulated free carriers with the nanocavity resonant mode results in holistic improvement in device performance, including a high tuning efficiency of 250 pm/V and an average modulation strength of 4 dB/V with a moderate Q factor of ∼3700 and insertion loss of ∼6 dB using an ultrashort electrode length of only 350 nm. With 1 V driving voltage over a capacitive loading of only 13 fF, the silicon photonic nanocavity modulator can achieve more than 3 dB extinction ratio with energy consumption of only 3 fJ/bit. Such a low-voltage, low-capacitance silicon nanocavity modulator provides the feasibility to be directly driven by a CMOS logic gate for single-chip integration.

2.3 picoseconds optical gate monolithically integrating photodiode and electroabsorption modulator

Abstract: A novel ultra-high-speed optical gate monolithically integrating a uni-travelling-carrier photodiode and a travelling-wave electroabsorption modulator (TW-EAM) is presented. By using the nonlinear extinction characteristics of the EAM, the minimum gate opening time of 2.3 picoseconds with an extinction ratio of 14 dB is achieved.

Photo semiconductor device having a multi-quantum well structure

Abstract: A multi-quantum well structure which is formed by laminating thin semiconductor layers is provided with means for injecting carriers in a direction which is parallel to the surface of the laminated thin semiconductor layers, whereby it is possible to obtain satisfactory changes in refractive index of the carrier injection portion. For example, if the total reflection region of an optical switch consisting of optical waveguides which cross each other is provided with a multi-quantum well structure wherein carriers are injected in a direction parallel to the surface of the well, the extinction ratio characteristics of the device can be improved.

Compact tunable electromagnetically induced transparency and Fano resonance on silicon platform

Abstract: We propose and demonstrate an on-chip coupling resonant system to generate electromagnetically induced transparency (EIT)-like effect and Fano resonance on silicon platform. It is composed of a microring resonator (MRR) and two cascaded Sagnac-loop mirrors (SLMs) assisted Fabry-Perot (FP) cavity on silicon-on-insulator. According to the coupling conditions of the MRR, two cases are studied theoretically. When the MRR is over coupling, EIT-like transmission can be observed. In contrast, Fano resonances can be generated by the condition of under coupling. In the experiment, the add-drop MRR is under coupling, leading to a sharp asymmetric line shape for Fano resonance. The resonance wavelength of the MRR can be dynamically tuned based on thermal-optic effects by tuning the micro-heater. The experiment results show Fano resonances with maximum extinction ratio (ER) of 23.22 dB and maximum slope rate (SR) of 252 dB/nm. Moreover, the wavelength of Fano resonance can be shifted widely with a tuning efficiency of 0.2335 nm/mW.