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.

Stimulated brillouin scattering suppressed optical fiber

Abstract: The invention provides a stimulated Brillouin scattering suppressed optical fiber which is easy to be produced, has an almost zero chromatic dispersion over the entirety of an optical fiber in the lengthwise direction, and has a low light loss. That is, in an optical fiber having a property, by which the chromatic dispersion with respect to optical communication signals becomes zero, obtained by changing the relative refractive index difference of the optical fiber and core diameter in the same increase or decrease direction, the relative refractive index difference of the core and the core diameter R are changed in the lengthwise direction of the optical fiber, and the core diameter R is made smaller in line a decrease the relative refractive index difference of the core while the core diameter R is made larger in line with an increase of the refractive index difference, whereby the chromatic dispersion the designated wavelength band is made nearly equal to zero in the entirety of the optical fiber in the lengthwise direction.

Optical component and method of manufacture of optical component

Abstract: An optical component or optical low-pass filter has two or more regions demarcated by differences in refractive indexes, in which a region having a refractive index different from the refractive index of the continuous region with the largest volume among the two or more regions is formed in the interior of a transparent material. This optical component or optical low-pass filter has regions with different refractive indexes formed in the interior by pulsed laser irradiation or focused irradiation of the transparent material.

Optical interferometric approach for measuring the geometrical dimension and refractive index profiles of a double-sided polished undoped Si wafer

Abstract: In this investigation, we propose a technique to obtain not only the dimensional profile of an undoped double-side polished silicon (Si) wafer but also its refractive index profile simultaneously. This technique is based on low coherence scanning interferometry using a near-infrared light around 1 µm wavelength, for which transmission is non-zero for undoped silicon and also detectable by the typical visible CCD camera. As the experimental results show, the profiles of optical thicknesses, geometrical thicknesses, group refractive indices and phase refractive indices were successfully obtained by the proposed technique, and the mean values were 1869.6 µm, 490.45 µm, 3.8121 and 3.516, respectively. Compared to the reference values of the group refractive index and the phase refractive index of the Si wafer given by the previous researches, the deviations were 0.055 and 0.04, respectively. The deviations were attributed to the position error of the scanning stage. In addition, the combined technique with spectrally-resolved interferometry was also discussed to improve the measurement accuracy of the system.

A monolithic pump signal multiplexer for air-clad photonic crystal fiber amplifiers

Abstract: We report on the performance of a monolithic 6+1X1 fiber pump signal multiplexer for use in fiber amplifiers. The key component of this coupler design is an etched taper that transforms the low-numerical aperture large diameter pump radiation into a high numerical aperture small diamter format for injection into the pump cladding of an air-clad fiber while maintaining a constant refractive index profile in the core for efficient signal coupling. This taper was then fused onto the 6+1 fiber bundle at the large end and to the air-clad large mode area polarization maintaining photonic crystal fiber at the small end. We employed 6 pump delivery fibers in a 200/220/0.22 core/clad/NA format and a 25/250 polarization maintaining step index signal delivery fiber for the bundle. The large end of the taper had a cladding diameter of 650 μm while the small end had a cladding diameter of 300 μm to match the pump cladding diameter of the PCF which was 314 μm. The core within the taper had a constant diameter of 40 μm and NA of 0.07 achieved through a step index profile. The mode field diameter of the PCF was 54 μm. Signal coupling efficiency at 1550 nm was measured to be 90% with a polarization extinction ratio > 20dB while pump coupling efficiency was measured to be 87% at 1532nm. The low pump coupling efficiency was found to be due to pump delivery fibers that had a numerical aperture of 0.24, higher than the specification of 0.22. A simple calculation shows that with 0.22 NA pump fibers, the pump coupling efficiency would increase to 94%.

Self-fabricated single mode waveguide in fluoride glass excited by self-channeled plasma filaments

Abstract: Self-fabricated permanent structure of single mode waveguide in optical fluoride glasses was demonstrated using the self-channeled plasma filament excited by a femtosecond (130fs) Ti:sapphire laser (λp=790nm) The photoinduced refractive index modification in ZrF4–BaF2–LaF3–AlF3–NaF glasses reached a length of approximately 10–15mm from the input surface of the optical glass with the diameters ranging from 5to8μm at the input intensities of more than 10×1012W∕cm2 The graded refractive index profiles were fabricated to be a symmetric form from the center of optical fluoride glass, and a maximum value of refractive index change (Δn) was measured to be 13×10−2 The beam profile of the output beam transmitted through the modified region showed that the photoinduced refractive index modification produced a permanent structure of single mode waveguide