Thermal and spectroscopic studies of polymer protective coatings used in optical fibers technology

An important factor determining the quality of optical fibers is their mechanical reliability. The control of the mechanical reliability allows define the lifetime of a fiber, which was under the stress during the work. Decisive influences on the mechanical and optical properties of the optical fibers have the protective coatings. Optical fiber technology requires that the coatings were applied on them on-line, directly after they have been drawn. So far, little attention has been paid to optimizing the conditions of coatings curing. In this work, the comparison of a thermoanalytical and spectroscopic analysis of coatings that were cured in an UV oven in which the power of the UV lamps was changed will be shown. As part of the research tasks, completed mechanical strength measurements were made with a silica fiber of 0.125 mm diameter

Plug&Play Fiber‐Coupled 73 kHz Single‐Photon Source Operating in the Telecom O‐Band

A user‐friendly, fiber‐coupled, single‐photon source operating at telecom wavelengths is a key component of photonic quantum networks providing long‐haul, ultra‐secure data exchange. To take full advantage of quantum‐mechanical data protection and to maximize the transmission rate and distance, a true quantum source providing single photons on demand is highly desirable. This great challenge is tackled by developing a ready‐to‐use semiconductor quantum‐dot‐based device that launches single photons at a wavelength of 1.3 µm directly into a single‐mode optical fiber. In the proposed approach, the quantum dot is deterministically integrated into a nanophotonic structure to ensure efficient on‐chip coupling into a fiber. The whole arrangement is integrated into a 19ʺ compatible housing to enable stand‐alone operation by cooling via a compact Stirling cryocooler. The realized source delivers single photons with a multiphoton events probability as low as 0.15 and a single‐photon emission rate of up to 73 kHz into a standard telecom single‐mode fiber.BMBF, 05M20ZBM, Forschungscampus MODAL - Mathematical Optimization and Data Analysis Laboratories - zweite Förderphase (Stabilisierung)TU Berlin, Open-Access-Mittel – 202

Chromatic dispersion measurement of holey fibres using a supercontinuum source and a dispersion balanced interferometer

Chromatic dispersion of polarization modes in short-length holey fibres is measured by a spectral interferometric technique employing a broad-band supercontinuum source. The technique utilizes a dispersion balanced Mach–Zehnder interferometer with a fibre under test of known length inserted in one of the interferometer arms and the other arm with adjustable path length. We record a series of spectral interferograms to measure the equalization wavelength as a function of the path length difference, or equivalently the differential group index dispersion of the fibre. A five-term power series fit is applied to the measured data to obtain the chromatic dispersion over a broad spectral range (500–1600 nm). We measured by this technique the chromatic dispersion of polarization modes in four air-silica holey fibres and revealed the dependence of the position of the zero-dispersion wavelength on the geometrical parameters of the fibre.Web of Science201351421

TG/DTG/MS COUPLED METHODS FOR THERMAL ANALYSIS OF NEW MATERIALS FOR OPTICAL FIBER TECHNOLOGY

In this study bulk polymerization of methacrylic derivative of thiophenol (PSM) with commercial monomers styrene (St) and methyl methacrylate (MMA) was presented. This monomers had been chosen because of their good thermal and optical properties, which make them useful in optical fibres technology. Copolymerization MMA or St with PSM in glass form, with different weight ratio of monomers (1:10, 1:20; MMA or St : PSM) was performed. As a initiator α,α’-azoiso-bis-butyronitrile (AIBN) was used. This process was carried out in water bath at 60 oC for 2 h and 90 oC for 12 h. As an analytical method coupled TG/DTG/QMS was used

Temperature sensing using the spectral interference of polarization modes in a highly birefringent fiber

The spectral interference of polarization modes in a highly birefringent (HB) fiber to measure temperature is analyzed theoretically and experimentally. A tandem configuration of a birefringent delay line and a sensing HB fiber is considered and the spectral interferograms are modelled for the known birefringence dispersion of the HB fiber under test. As the delay line, a birefringent quartz crystal of a suitable thickness is employed to resolve a channeled spectrum. The channeled spectra are recorded for different temperatures and the polarimetric sensitivity to temperature, determined in the spectral range from 500 to 850 nm, is decreasing with wavelength. It is demonstrated that the temperature sensing is possible using the wavelength interrogation, i.e., the position of a given interference maximum is temperature dependent. The temperature sensitivity of the HB fiber under test is −0.25 nm/K and the resolution is better than 0.5 K.Web of Science70565

An Efficient Method for the Intermodal Four-Wave Mixing Process

We demonstrate a partially degenerated intermodal four-wave mixing (FWM) process realized in a few-mode nonlinear optical fiber, leading to the effective generation of visible red and blue light from 532 nm sub-nanosecond pulses. We present a self-seeded FWM configuration with a signal beam obtained in the additional section of the same type of fiber that ensures perfect matching between the seed and the Stokes beams. Over 40% of the wavelength conversion efficiency in the FWM process was obtained using a fiber length shorter than 1 m

Intermodal Four-Wave Mixing Process in Strain-Induced Birefringent Multimode Optical Fibers

Our study investigated the partially degenerate intermodal four-wave mixing (IM-FWM) process in nonlinear multimode optical fibers with strain-induced birefringence. The difference in the refractive index along the two orthogonal directions was due to the photoelastic effect that occurred when the fiber under test (FUT) was subjected to uniformly applied diameter stress caused by winding on a cylinder of a given diameter. Our work analyzed how the nonlinear frequency conversion and the output modal field profiles depended on the degree of birefringence in FUT. The experimental results significantly affected the order of the excited moduli in fiber sections characterized by different amounts of birefringence. We also checked the efficiency of the FWM process for different polarizations of the pump beam to determine those for which the FWM process was most effective for the 532 nm sub-nanosecond pulses. More than 30% conversion efficiency was obtained for the FUTs with a length of tens of centimeters