Michal Szymanski

Experimental study of dispersion characteristics for a series of microstructured fibers for customized supercontinuum generation

We demonstrate an experimental study of the chromatic dispersion properties for a series of microstructured fibers (MSFs) dedicated for a supercontinuum generation. With white-light interferometry application we analyze experimentally how the small variations of structural parameters, i.e. an air-hole diameter and a lattice constant, influence dispersion characteristics in different groups of MSFs. Our study provides useful information on how to design the fiber which is less sensitive to the fabrication imperfections. Moreover those investigations are the initial step to the development of the customized or tunable supercontinuum light sources based on MSFs with slightly changed structural parameters which can generate light with a different spectrum range, adapted to a proper application.

Fiber Bragg gratings in hole assisted multicore fiber for space division multiplexing

In this Letter we present, for the first time to our knowledge, the results of fiber Bragg grating (FBG) inscription in a novel microstructured multicore fiber characterized by seven single-mode isolated cores. A clear Bragg reflection peak can be observed in all of the 7 cores after one inscription process with a KrF nanosecond laser in a Talbot interferometer set up. We furthermore perform a numerical analysis of the effective refractive indices of the particular modes and compare it with the FBG inscription results. An experimental analysis of the strain and temperature sensitivities of all of the Bragg peaks is also included.

Low-Loss Patch Cords by Effective Splicing of Various Photonic Crystal Fibers With Standard Single Mode Fiber

We report on low-loss patch cords composed of a highly reproducible low-loss fusion splicing of photonic crystal fibers (PCFs) with a standard single mode fiber (SMF). Distinct from other papers in this area we report on the results for different types of PCFs, including LMA fibers with similar to a SMF core size and a mode field diameter (MFD), as well as polarization maintaining (PM) Bow-Tie PCF with an elliptical GeO 2 doped core and also a suspended-core (SC) PCF with a tiny core. We show that all studied splices between SMF and PCFs exhibit dispersive and non-reciprocal, in view of a light propagation direction, transmission losses. Defined as a larger decrease of a transmitted optical power comparing both propagation directions, achieved splicing losses, are equal to 0.46 ±0.03 dB, 0.34±0.01 dB, 0.67 ±0.17 dB and 3.09 ±0.36 dB at 1550 nm for LMA8, LMA10, Bow-Tie PCF and SC PCFs, respectively. Moreover, additionally to developed low-loss splicing, we report on low-loss patch cords for all mentioned above PCFs spliced on both ends with SMF pigtails ended with FC/APC connectors achieving the total losses at 1550 nm equal to 1.07 ±0.07 dB for LMA8, 0.72 ±0.20 dB for LMA10, 1.30 ±0.06 dB for Bow-Tie PCF, and 9.36 ±0.20 dB for SC PCF.

Fiber Bragg grating inscription in few-mode highly birefringent microstructured fiber

In this Letter, we present the technology of fiber Bragg grating (FBG) inscription in highly birefringent (HB) few-mode microstructured fibers (MSFs) with two different (nanosecond and femtosecond) lasers in a Talbot interferometer setup. The spectral characteristics of FBGs written in the core region of the investigated fiber, with particular modes represented by dual peaks, are presented and discussed. Furthermore, we calculate the fundamental fiber parameters (mode effective refractive index and phase modal birefringence) from the spectral characteristics and show very good agreement with the performed numerical fiber characterization. We expect the results of our experiments to be very useful in future development of FBG sensors based on novel HB MSFs, with enhanced strain sensitivity of higher-order modes.

Fibre Bragg gratings written in highly birefringent microstructured fiber as very sensitive strain sensors

The possibility of manufacturing highly birefringent (HB) microstructured optical fibers (MOF) made these fiber types very attractive for use in sensing applications. In contrary to traditional optical fibre sensors, properly designed MOF based components do not need temperature compensation as their birefringence remains insensitive to temperature changes. Furthermore the polarimetric strain sensitivity can significantly increase (even two orders of magnitude according to our previously reported results) for higher order modes, as their mode maxima get closer to the holey region of the fiber, hence are subjected to higher strain distribution. In this paper we present the results of numerical modeling of the propagation conditions in the HB dual-mode MOF including effective refractive index, confinement losses and birefringence calculations. Furthermore we show and discuss the spectral characteristics of fiber Bragg grating (FBG) structures written in the dedicated fiber with two technologies (with a nanosecond and femtosecond UV laser sources). A comparison of the theoretical and experimental values of effective refractive index and birefringence of the fundamental and second order modes is also included. We show the preliminary results of the fabricated structures strain response measurements and discuss ideas of increasing the structures strain sensitivity.

Polymer Microtips at Different Types of Optical Fibers as Functional Elements for Sensing Applications

In this paper, we report on a simple process of fabrication of micrometer-sized polymer elements (microtips) at the extremities of different type optical fibers, including: standard single mode (SMF-28E+, SM-450), photonic crystal (LMA-10), and polymer (GIPOF-62) ones. The method of microtips manufacturing is based on the phenomenon of photopolymerization which is successfully used for the first time, to the best of our knowledge, to manufacture microtips at photonic crystal and polymer fibers. We discuss the influence of the initial process parameters on the final microtip characteristics (i.e., length, diameter, and profile). The potential applications of such polymer microtips are near-field scanning optical microscopy, coupling light sources with fibers, and sensing.

Fiber optic gas sensor for on-line CO2 monitoring

An optical fiber CO2 gas sensor is reported in this work. Sensor is based on the change of absorption of a selected dye dissolved in an organically modified silica coating of an optical fiber. CO2 in the atmosphere decreases the pH of the deposited active layer, which eventually leads to the change of the fiber transmittance. Elaborated sensor exhibits high sensitivity, short response time and good stability, which makes it suitable for potential industrial, agricultural and household use. Described method can also be used for sensing other gases in sensor matrices.

Low loss coupling and splicing of standard single mode fibers with all-solid soft-glass microstructured fibers for supercontinuum generation

In this work we would like to present the results of low loss coupling of a novel soft glass fiber for super continuum generation with standard single mode fiber by a filament splicing method. For our experiment we used an all solid soft glass microstructured fiber (MSF) made from a composition of F2 lead-silicate glass and NC21 borosilicate glass. The structure and material properties of the fiber were optimized to achieve all normal dispersion (ND) flattened around 1560 nm, which offers two general advantages for supercontinuum generation. The ND supercontinuum avoids soliton dynamics, hence it is less sensitive to pump laser shot noise and has larger degree of coherence than supercontinuum in the anomalous dispersion range. Furthermore flattening around 1560 nm indicates optimal supercontinuum pump wavelength, which is readily available from erbium doped femtosecond fiber lasers. Using Vytran splicing station (GPX3400) we were able to achieve repeatable splice loss between a standard fused-silica single mode fiber (SMF28) and the low-melting-temperature soft glass MSF as low as 2.12 dB @1310 nm and 1.94 dB @ 1550 nm. The developed very low loss splicing technology together with the above mentioned all solid soft glass MSF advantages give very promising perspectives for commercial applications.

Microtips at photonic crystal fibers as functional elements for near-field scanning optical microscopy probes

We present the process of the microtip fabrication at the LMA-10 fiber designed for near-field scanning optical microscopy probes. Facilitation of manufacturing procedure as well as proper focusing conditions of such elements are the main advantages of such microelements production.

Low power and inexpensive microstructured fiber Mach Zehnder interferometer as temperature insensitive mechanical sensor

Microstructured fibres (MSFs) reveal unique properties including endlessly single-mode operation from ultraviolet to infrared wavelengths, very high birefringence or nonlinearity, very large or very small effective mode field area, and many others. The size, shape and the location of the air holes allow for tailoring MSF parameters in a very wide range, way beyond the classical fibres, what opens up the possibilities for various applications. Due to their advantages MSFs obtain growing attention for their perspectives in sensing applications. Different MSF sensors have already been investigated, including interferometric transducers for diverse physical parameters. Until now, there have not been any publications reporting on the sensing applications of MSF Mach-Zehnder interferometers, targeting the mechanical measurements of vibrations, dynamic or static pressure, strain, bending and lateral force. Moreover, a critical feature opening the prospective of optical fibre transducer to successfully accomplish a particular sensing task remains its cross-sensitivity to temperature. Studied MSF is made of pure silica glass in the entire cross-section with a hexagonal structure of the holes. Consequently, there is no thermal stress induced by the difference in thermal expansion coefficients between the doped core region and the pure silica glass cladding, in contrast to standard fibres. In this paper we present the experimental comparison of mechanical and temperature sensitivities of Mach- Zehnder interferometer with replaceable FC connectorized sensing fibre arm, such as: off-the-shelf endlessly single mode MSF or standard telecom single mode fibre. Experimental results clearly show very low cross-sensitivity to temperature of studied MSF compared with standard fibre. Additionally, microstructured fibre Mach-Zehnder interferometer with standard FC receptacles allows using different fibres as sensors with the same device. Moreover, investigated interferometer consumes in total extremely low electric power (< 20 mW) due to the implementation of exceptionally effective data analysis electronics and VCSEL as the light source.