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.

As40S59Se1/As2S3 step index fiber for 1–5 μm supercontinuum generation

Abstract: A high-purity As 40 S 59 Se 1 /As 2 S 3 core/cladding step-index fiber for supercontinuum generation was fabricated in this study. The glass rods were obtained by using a relatively effective and inexpensive method of modified physical and chemical purification. Then, the multi-material fiber preform was fabricated through a modified laboratory using one-step co-extrusion process. Moreover, the fiber preform with a Polyether Sulfone (PES) polymer was drawn with a core diameter of ~ 22 μm. The core/cladding ratio of the fiber was approximately 1:17, and the minimum loss was approximately 1 dB/m between 4 and 6 μm. By pumping a 13 cm-long fiber with different laser powers and another two different lengths (20 cm and 50 cm, respectively) of fiber at 4.8 μm, a supercontinuum covering 1–5 μm could be recorded in all fibers. This study attained a 1–5 μm supercontinuum that covered the second atmospheric window. Result of this study can be a promising reference in the production of mid-infrared light source.

Method to determine the crystalline properties of an interface of two materials by an optical technique

Abstract: Crystalline quality of a semiconductor material at its interface with an insulator is optically evaluated by a reflected light beam scanned in wavelength. The refractive index of the material at or near the interface is determined by calculation from the measured values of reflectivity extrema and compared, if desired, to the bulk refractive index of the material. This index is an indicia of the crystalline quality at the interface.

System and method for inspection of a substrate that has a refractive index

Abstract: A system and method for inspection of a substrate having a first refractive index, the method including the steps of: (i) defining an apodization scheme in response to a characteristic of the layer; (ii) applying an apodizer to apodize a beam of radiation in response to the apodization scheme; (iii) directing the apodized beam of radiation to impinge on the substrate, whereby a plurality of rays are reflected from the substrate; whereas the apodized beam of radiation propagates through an at least partially transparent medium having a third refractive index and an at least partially transparent layer having a second refractive index and is subsequently reflected from the substrate; whereas the second refractive index differs from the first refractive index and from the third refractive index; and (iv) detecting at least some of the plurality of reflected rays.

A Revisit of Refractive Index Profiles Design for Reduction of Positive Dispersion, Splice Loss, and Enhancement of Negative Dispersion in Optical Transmission Lines

Abstract: Loss and dispersion are two crucial parameters to be determined as low as possible while designing optical fibers as optical transmission lines. In designing dispersion shifted fibers, one has to reduce the core diameter to smaller than unshifted single mode fiber (USMF) at 1550 nm wavelength region. This issue causes the nonlinear phenomenon of four wave mixing (FWM) to appear at 1550 nm. One of the approaches to reduce the effectiveness of the FWM is to shift the zero dispersion wavelength (ZDW) to some other wavelength in the third window of optical fiber communication. Dispersion compensating fibers (DCFs) with high negative dispersion are used in wavelength division multiplexing systems for neutralization of pulse spread in transmission fibers for higher system capacity. One of the approaches of securing a high negative dispersion is to change the refractive index profile of DCFs. In this paper, by using Optifiber software, the shifting of the ZDW is made by varying the refractive index profile of a USMF, then the designed profile is optimized for low dispersion and splice loss. The obtained results show that in designed profile the effective mode field diameter is reduced, which can effectively reduce the splice loss. In another attempt, the parameters of different DCF profiles are optimized to enhance negative dispersion of about -710 ps/nm.km, which is 5 times higher than the reported experimental results.