Step-index profile

About: Step-index profile is a research topic. Over the lifetime, 3104 publications have been published within this topic receiving 53199 citations.

Multilayer antireflective coating with a graded base layer

Abstract: An antireflectance coating is disclosed comprising a first graded layer wherein the composition is varied throughout the thickness of the layer such that the refractive index of the graded layer varies from a low refractive index approximately matching the refractive index of the substrate at the interface of the graded layer and the substrate to a higher refractive index at the surface of the graded layer opposite the interface with the substrate, and a second substantially homogeneous layer of a composition selected to have a refractive index which is approximately the square root of the product of the higher refractive index of the graded layer and the refractive index of the incident medium at the surface of the second layer opposite the interface of the second layer with the graded layer, having an optical thickness of approximately at least one quarter of a selected design wavelength. The antireflectance properties of the coating of the present invention can be expanded to a broader range of reflected wavelengths by incorporating, between the graded layer and the second substantially homogeneous layer, an intermediate layer having a relatively high refractive index and an optical thickness of about half the design wavelength.

Optimization of cascaded fiber tapered Mach–Zehnder interferometer and refractive index sensing technology

Abstract: A novel refractive index sensor with high sensitivity based on Mach–Zehnder interferometer formed by cascaded two single-mode fiber tapers was proposed and experimentally demonstrated The dip of the measured spectrum signal caused by Mach–Zehnder interference shifted obviously when the surrounding refractive index changed The approximate linear relationship between surrounding refractive index and spectrum dip wavelength shift was obtained experimentally The measurement sensitivity up to 1584 nm/RIU was showed with the surrounding RI ranged from 133 to 13792, which meant the measurement resolution about 63 × 10 −6 could be implemented if wavelength shift measurement resolution of the optical spectrum analyzer is 1 pm Meanwhile, its ease of fabrication makes itself a low-cost alternative to existing sensing applications

Temperature-insensitive refractive index sensor based on in-fiber Michelson interferometer

Abstract: A novel intensity-modulated refractive index sensor based on an in-fiber Michelson interferometer is demonstrated by splicing a section of thin core fiber between two standard single mode fibers. Such a refractive index sensor exhibits an ultrahigh sensitivity of −208.24 and 125.44 dB/RIU at the refractive index of 1.440 and 1.500, respectively. The refractive index sensor is insensitive to temperature and thus solves the cross-sensitivity problem between temperature and surrounding refractive index. Moreover, the promising RI sensor has the advantages of short size (less than 2 mm) and easy fabrication.

Fiber Cavity Ring-Down Refractive Index Sensor

Abstract: An exploratory study on a novel fiber long-period grating (LPG) cavity ring-down refractive index sensor is conducted. By detecting the ring-down curves at different ambient refractive index levels, the performances of the LPG sensor are investigated. The experimental results demonstrate by using this sensing setup the change of the refractive index in 1.35-1.43 region could be effectively detected.