Showing papers on "Step-index profile published in 1972"
TL;DR: In this article, a multimode optical fiber consisting of glass cladding and liquid core has been constructed and a loss of 0.140 dB/m has been measured over lengths of about 50 m.
Abstract: Multimode optical fibers consisting of glass cladding and liquid core have been constructed. For a cladding index of refraction of 1.52 and a core of bromobenzene, index of 1.560, a loss of 0.140 dB/m has been measured over lengths of about 50 m. The loss measured with incoherent light is higher due to the presence of higher order modes. Strong absorption in the near infrared occurs in narrow wavebands associated with overtones of the C-H fundamental vibration frequency.
39 citations
Patent•
11 Sep 1972TL;DR: In this article, the faster propagating, higher order modes are selectively removed from a multimode optical fiber by either attenuating said modes or coupling the modes out of the fiber core and into the surrounding cladding.
Abstract: The faster propagating, higher order modes are selectively removed from a multimode optical fiber by either attenuating said modes or by coupling the modes out of the fiber core and into the surrounding cladding. In one embodiment the fiber core is surrounded by a low-loss cladding of prescribed thickness, and a refractive index that is no greater than that of any portion of the core. In an alternate embodiment, the core is surrounded by a low-loss cladding whose refractive index is greater than that at the periphery of the core.
31 citations
17 citations
16 citations
TL;DR: First, a closed-form analysis of the problem for a long transition region is given, followed by a computer analysis applicable to transition regions of any length.
Abstract: Abeles’s method of determining the refractive index of a thin film is discussed. Attention is directed to the effect of a graded index transition between the film and the substrate on the measured index. First, a closed-form analysis of the problem for a long transition region is given. This is followed by a computer analysis applicable to transition regions of any length.
15 citations
TL;DR: A focusing critical angle refractometer has been constructed to measure the one-dimensional refractive index profile immediately adjacent to the glass wall of a liquid container as discussed by the authors, which is capable of resolving concentration differences of 10−4 M (10−5 refractive units) and distances of 0.02 mm.
Abstract: A focusing critical angle refractometer has been constructed to measure the one‐dimensional refractive index profile immediately adjacent to the glass wall of a liquid container. The instrument displays a graphic image of the entire refractive index profile. It is capable of resolving concentration differences of 10−4 M (10−5 refractive index units) and distances of 0.02 mm.
2 citations
TL;DR: The importance of thermal effects on the refractive indices of laser host materials operating under conditions of high heat loading has been known for some time; changes of refractive index with temperature can cause complicated lensing effects that, if not corrected, increase beam divergence.
Abstract: The importance of thermal effects on the refractive indices of laser host materials operating under conditions of high heat loading has been known for some time; changes of refractive index with temperature can cause complicated lensing effects that, if not corrected, increase beam divergence. It has also been realized that similar thermal effects in windows used for laser beams of high average power can cause distortions serious enough to degrade system performance, even when the power density is well below the optical damage threshold for the window material.
1 citations
TL;DR: Flaky crystals of hematite showed apparent index 4.52, in agreement with theory, compared with the true ordinary index around 3.09, which is in line with theory.
Abstract: The refractive index of a particle can be determined with microscope equipment for measuring interference in transmitted light. If the path difference is several wavelengths, white illumination will be used. If the particle has strong dispersion, measurements made with white light give an apparent refractive index much higher than the true one. The apparent index is related to the group velocity of light waves in the substance in the same way that the true index is related to phase velocity. Flaky crystals of hematite showed apparent index 4.52, in agreement with theory, compared with the true ordinary index around 3.09.
1 citations
TL;DR: The alternating component of the refractive index of the gas-discharge medium of a CO2 laser (λ = 10.6 μ) was determined during the modulation of the discharge current, at a modulation frequency of 0-2 kHz, the alternating component was governed by the periodic expulsion of the neutral gas into a ballast chamber, whereas at frequencies exceeding 2 kHz it was due to variations in the freeelectron density as mentioned in this paper.
Abstract: The alternating component of the refractive index of the gas-discharge medium of a CO2 laser (λ = 10.6 μ) was determined during the modulation of the discharge current. At a modulation frequency of 0–2 kHz, the alternating component was governed by the periodic expulsion of the neutral gas into a ballast chamber, whereas at frequencies exceeding 2 kHz it was due to variations in the free-electron density.
1 citations