Extinction ratio

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

A Tunable Polarization Beam Splitter Based on Magnetic Fluids-Filled Dual-Core Photonic Crystal Fiber

Abstract: A tunable polarization beam splitter (PBS) is proposed based on a dual-core photonic crystal fiber (DCPCF). The DCPCF is filled with magnetic fluids in the air holes, whose refractive index varies with the magnetic field strength. The two polarized modes are separated into the two cores at the output ports in a magnetic-free condition. When magnetic field is applied, the output intensities of the two polarized modes would fluctuate. The polarized modes can be ported out with arbitrary proportion by adjusting the magnetic field intensity. Moreover, the polarized mode would be completely converted at some magnetic field strength. The properties of the DCPCF are investigated by the finite element method (FEM), including mode-conversion magnetic field strength, extinction ratio, fabrication tolerance of the PBS, and the performance of PBS at various temperatures. The numerical results show that at 1550-nm wavelength, the length of the tunable PBS is 8.13 mm. The polarized mode converts at a magnetic intensity of 25 mT with a high extinction ratio greater than −100 dB. In addition, the tunable PBS sustains a fabrication tolerance of at least 0.5% and works well at temperatures in the range of 0–55 °C by adjusting the magnetic field strength.

Subwavelength-grating-assisted silicon polarization rotator covering all optical communication bands

Abstract: We propose an ultra-broadband and ultra-compact polarization rotator (PR) structure on the silicon-on-insulator platform. The subwavelength gratings (SWGs) are introduced at the waveguide corner in order to excite the hybridized modes and realize the polarization rotation. The dispersion-engineered SWG can dramatically reduce the polarization conversion length deviation. High polarization extinction ratio > 20 dB and low excess loss < 1 dB can be achieved over 1.26-1.675 μm wavelength range, which covers O-, E-, S-, C-, L-, and U-bands. The total device size is as small as 4.8 × 0.34 μm2. To the best of our knowledge, the proposed structure is the first silicon PR that could cover all of the optical communication bands.

Tunable erbium-doped fiber ring laser precisely locked to the 50-GHz ITU frequency grid

Abstract: A discretely tunable, single-frequency erbium-doped fiber ring laser demonstrates frequency locking to the 50-GHz ITU frequency grid with an accuracy of /spl plusmn/03 GHz and stability of /spl plusmn/005 GHz over a 50-nm tuning range An output power of 7 mW and an extinction ratio of 45 dB make this single-frequency laser useful for a variety of DWDM applications

Wireless optical communications via diversity reception and optical preamplification

Abstract: Atmospheric optical communication systems that use optical preamplifiers and diversity reception to combat the effects of atmospheric turbulence are addressed. The effects of atmospheric turbulence, background light, source extinction ratio, amplified spontaneous emission, and receiver thermal noise are considered in a context of a semiclassical photon-counting approach. The particular diversity techniques that are investigated include aperture averaging, linear combining, and adaptive optics. Numerical results, obtained using a conditional Gaussian approximation, quantify the link margin improvement due to optical preamplification and diversity reception.

Semiconductor optical modulation device

Abstract: The invention provides a semiconductor optical modulation device which has low power dissipation, high extinction ratio and high speed response features. An n-type InP clad layer, an n - -type InAlAs-InAlGaAs composition inclination multiple layer, a p-type InP clad layer and a p + -type InGaAs contact layer are layered on an n-type InP substrate. The layers are etched up to an intermediate location of the n-type clad layer to form a rib waveguide, and a positive electrode is formed on an upper portion of the rib waveguide. Further, a negative electrode is formed on the substrate.