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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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21 Dec 1992TL;DR: In this paper, a circuit for controlling an extinction ratio of a laser whose temperature can change over time includes first and second feedback loops which monitor a LOW output power of the laser during a first frame training pulse and a HIGH laser output power during a second-frame training pulse.
Abstract: A circuit for controlling an extinction ratio of a laser whose temperature can change over time includes first and second feedback loops which monitor a LOW output power of the laser during a first frame training pulse and a HIGH laser output power during a second frame training pulse. The LOW power output is compared to a preset dynamic LOW power reference, and a LOW bias current applied to the laser is incrementally increased or decreased so as to keep this LOW power output toggling about this LOW reference. Similarly, the HIGH power output is compared to a HIGH power reference, and a modulation current for the laser is incrementally increased or decreased to keep the HIGH laser output power toggling about this HIGH reference. Preferably, the training pulse is sent once per frame thus enabling both the LOW and HIGH laser output powers to be kept constant regardless of whatever dynamic variables may change over time thus keeping the laser extinction ratio constant.
34 citations
TL;DR: The results indicate that the aperture dimension significantly impacts the polarizer transmission behavior and that the extinction of the unwanted polarization is often limited by depolarizing scattering that is due to the finite aperture size.
Abstract: The transmission characteristics of wire grid polarizers fabricated in finite apertures are investigated by using a three-dimensional finite-difference time-domain formulation Specifically, the optical transmissivity and extinction ratio are characterized for a wide variety of geometrical parameters including aperture size in both dimensions, conducting wire fill factor, and polarizer thickness A dispersive material model is used to investigate the performance of polarizers fabricated by using realistic metals at infrared wavelengths The results indicate that the aperture dimension significantly impacts the polarizer transmission behavior and that the extinction of the unwanted polarization is often limited by depolarizing scattering that is due to the finite aperture size
34 citations
TL;DR: Low-loss SiN/SiON waveguides for wavelength-division-multiplexing filters on a Si platform have been proposed in this paper, where the key technology is a low-temperature deposition of refractive-index-controllable SiN and SiON films by using a hydrogen-free gas source (SiD4), which avoids the strong optical absorption due to N-H bond.
Abstract: We describe low-loss SiN/SiON waveguides for wavelength-division-multiplexing filters on a Si platform. The key technology is a low-temperature deposition of refractive-index-controllable SiN/SiON films by using a hydrogen-free gas source (SiD4), which avoids the strong optical absorption due to N-H bond. Using this technology, we demonstrate a low-loss ring resonator with a SiN waveguide, whose loss is 0.47 dB/cm at 1550 nm. It shows excess loss of 2.7 dB, a 3-dB bandwidth of 0.13 nm, and an extinction ratio of 27 dB in the entire C band. In addition, we also demonstrate a polarization-insensitive arrayed-waveguide grating with a SiON waveguide, whose loss is 0.29 dB/cm at 1550 nm. It shows insertion loss of 5.3 dB, crosstalk of less than −27 dB, and polarization insensitivity in the entire C band.
34 citations
TL;DR: Error-free all-optical packet switching is demonstrated by use of a multiwavelength mutual injection-locked Fabry-Perot laser diode.
Abstract: Error-free all-optical packet switching is demonstrated by use of a multiwavelength mutual injection-locked Fabry-Perot laser diode. A 10-Gbit/s data signal is switched on and off with an extinction ratio of 16.9 dB when an optical control signal is turned off and on with a power difference of only 3 dB.
34 citations
TL;DR: The designed SPP launcher exhibits a simulated extinction ratio reaching up to 495 at a wavelength of 618 nm and 283 in the experiment and may pave a new way for the directional excitation of SPPs and can be useful in compact plasmonic circuits and other photonic integrated devices.
Abstract: Controlling the propagation direction of surface plasmon polaritons (SPPs) at will using planar structures has been investigated in recent years. However the realization of a high extinction ratio of a SPP directional launcher in a densely integrated and miniaturized way, especially at the wavelength scale, still remains a challenge. To the best of our knowledge, the maximum value of the extinction ratio of a unidirectional SPP launcher based on the planar metasurface in experiment is nearly 250, which relies on the combined effect of several gap-plasmon resonator blocks with a lateral dimension much larger than the incident wavelength. Here, we design and experimentally demonstrate a polarization-controlled unidirectional SPP launcher based on a single column catenary aperture array with a lateral dimension as small as 552 nm, which is even smaller than the working wavelength. Under the illumination of circularly polarized light, our designed SPP launcher exhibits a simulated extinction ratio reaching up to 495 at a wavelength of 618 nm and 283 in the experiment. The compact size and distinctive extinction ratio may pave a new way for the directional excitation of SPPs and can be useful in compact plasmonic circuits and other photonic integrated devices.
34 citations