Showing papers by "Periklis Petropoulos published in 2005"

Extruded singlemode, high-nonlinearity, tellurite glass holey fibre

Abstract: The fabrication of the first singlemode tellurite glass holey fibre produced from an extruded preform is reported. Robust singlemode guidance was observed at 1047 nm in the fabricated small core holey fibre. An effective mode area of 2.6 /spl mu/m/sup 2/ and high effective nonlinearity of 580 W/sup -1/ km/sup -1/ at 1047 nm were predicted. The fibre loss was measured to be 3.5 dB/m at 1050 nm, and 5.8 dB/m at 1550 nm.

Microstructured fibres for sensing applications

Abstract: Microstructured fibres (MOFs) are among the most innovative developments in optical fibre technology in recent years. These fibres contain arrays of tiny air holes that run along their length and define the waveguiding properties. Optical confinement and guidance in MOFs can be obtained either through modified total internal reflection, or photonic bandgap effects; correspondingly, they are classified into index-guiding Holey Fibres (HFs) and Photonic Bandgap Fibres (PBGFs). MOFs offer great flexibility in terms of fibre design and, by virtue of the large refractive index contrast between glass/air and the possibility to make wavelength-scale features, offer a range of unique properties. In this paper we review the current status of air/silica MOF design and fabrication and discuss the attractions of this technology within the field of sensors, including prospects for further development. We focus on two primary areas, which we believe to be of particular significance. Firstly, we discuss the use of fibres offering large evanescent fields, or, alternatively, guidance in an air core, to provide long interaction lengths for detection of trace chemicals in gas or liquid samples; an improved fibre design is presented and prospects for practical implementation in sensor systems are also analysed. Secondly, we discuss the application of photonic bandgap fibre technology for obtaining fibres operating beyond silica's transparency window, and in particular in the 3µm wavelength region.

Extruded single-mode high-index-core one-dimensional microstructured optical fiber with high index-contrast for highly nonlinear optical devices

Abstract: We report the fabrication of a high-index-core one-dimensional microstructured optical fiber incorporating with high index-contrast layers, using extrusion technique for preform fabrication. Single mode guidance and a high effective nonlinearity of 260±30W−1km−1 were observed in the fiber at 1.55μm, highlighting the potential of such fibers for use in nonlinear optical devices.

A Lead Silicate Holey Fiber with γ = 1820 W -1 km -1 at 1550 nm

Abstract: We report the fabrication of lead silicate holey fibers with record nonlinearities of up to 1860 W-1km-1 at 1.55 µm. Broadband supercontinuum generation is obtained in a dispersion optimized fiber variant at ~100 pJ pulse energies for 1.06 µm pumping.

Advances in microstructured fiber technology

Abstract: We review our recent progress in the area of microstructured fiber design, fabrication and applications with particular emphasis on the control of both the nonlinearity and dispersion.

Towards zero dispersion highly nonlinear lead silicate glass holey fibres at 1550 nm by structured-element-stacking

Abstract: We report the fabrication of lead-silicate holey fibres with a high nonlinearity up to 414 W-1km-1 and low dispersion at 1550 nm using a new fabrication technique based on the stacking of extruded structured elements. (2 pages)

A lead silicate holey fiber with /spl gamma/=1860 W/sup -1/km/sup -1/ at 1550 nm

Abstract: We report the fabrication of lead silicate holey fibers with record nonlinearities of up to 1860 W/sup -1/m/sup -1/ at 1.55 /spl mu/m. Broadband supercontinuum generation is obtained in a dispersion optimized fiber variant at /spl sim/100 pJ pulse energies for 1.06 /spl mu/m pumping.

Direct characterization of the spatial effective refractive index profile in Bragg gratings

Abstract: We propose a pulse response method to directly characterize the phase of the spatial index modulation, including the dc refractive index distribution (distributed phase shift), discrete phase, and chirp of fiber Bragg gratings (FBGs). This method is based on the observation that the spatial phase of gratings is directly related to the temporal phase of its pulse response. Therefore, the phase of the spatial index modulation can be characterized directly by measuring the temporal phase of the pulse response of FBGs. This method is then used to characterize an FBG with a current-induced phase shift.

Generation of ultra-flat SPM-broadened spectra in a highly nonlinear fiber using pulse pre-shaping in a fiber Bragg grating

Abstract: We propose a new approach to generating spectrally flat supercontinuum pulses based on seeding a commercial nonlinear fibre with pump pulses shaped using a superstructured fiber Bragg grating. Experimental results confirm the viability of the approach.

Heavy metal oxide glass holey fibers with high nonlinearity

Abstract: We report on the development of small-core high-NA lead silicate and bismuth glass holey fibers. We measured high nonlinearity (1100 W/sup -1/ km/sup -1/ in bismuth holey fiber) and predicted near-zero or anomalous dispersion at 1550 nm.

Direct sequence OCDMA systems based on fibre grating technology

Abstract: Fibre Bragg grating technology enables all-optical encoding and decoding of short pulses at ultrafast chip rates. Such code sequences can be used to implement both all-optical code division multiple access and packet switched systems operating at Gbit/s data rates.

Single-mode high-index-core one-dimensional microstructured fiber with high nonlinearity

Abstract: We report the first fabrication of a high-index-core one-dimensional microstructured optical fiber with high index-contrast layers. Extrusion is utilized to fabricate the microstructured preform. Single mode guidance and high nonlinearity were observed in the fiber.

Full characterisation of the temporal response of phase-shifted SSFBGs using electroabsorption modulator based frequency resolved optical gating

Abstract: We report the use of electro-absorption modulator based frequency resolved optical gating (EAM-FROG) to characterise the temporal phase and amplitude response of phase-shifted fibre Bragg gratings.

Full characterisation of the temporal response of complex phase shifted Bragg gratings for OCDMA using frequency resolved optical gating

Abstract: We report on the use of frequency resolved optical gating based on sampling with an electro-absorption modulator to characterise the phase and intensity of multichip encoded OCDMA pulses generated with fibre Bragg gratings. (2 pages)

A novel XPM based pulse retiming system incorporating a fibre grating based parabolic pulse shaper

Abstract: A novel all-optical, all-fibre pulse retiming system is experimentally demonstrated. Our technique relies on converting the timing jitter into frequency shift using XPM switching of the data signal with parabolic pulses shaped using a SSFBG. (2 pages)

High quality pulse and device characterisation using EAM-based frequency resolved optical gating

Abstract: We report on the versatility of frequency resolved optical gating using an electro-absorption modulator to accurately characterise the pulse shape and phase of high speed telecommunication pulses, as well as properties of optical components.

High Nonlinearity Holey Fibers: Design, Fabrication and Applications

Abstract: We describe our recent progress in the development of next-generation small-core holey fibers (HFs) with unique dispersive and nonlinear properties. We report the use of Genetic Algorithms to optimize the dispersion characteristics of silica-based HFs, and report progress in soft-glass HF fabrication which has resulted in fibers with record values of nonlinearity.

Direct accurate determination of the spatial refractive index profile in Bragg gratings

Abstract: We show that by measuring the temporal phase of the pulse response of a fibre Bragg grating with a current-induced phase-shift, the magnitude of the phase-shift and the corresponding refractive index distribution can be accurately determined.

Amplitude and timing jitter reduction using a fiber NOLM incorporating a fiber Bragg grating based pulse shaper

Abstract: We demonstrate the simultaneous removal of amplitude and timing jitter from an RZ data-stream using a superstructured fiber grating pulse shape converter and subsequent gating of a clean optical clock in a NOLM.

Applications of superstructured fibre Bragg gratings in OCDMA systems

Abstract: Superstructured fibre Bragg gratings enable the encoding and decoding of short pulses into long code sequences at ultrafast chip rates. Such code sequences can be used for the implementation of all-optical code division multiple access systems operating at Gbit/s data rates.

Broadband supercontinuum generation in an extremely nonlinear extruded lead silicate holey fiber using weak fs pulses

Abstract: Broadband supercontinuum generation at 1.06µm spanning > 1000nm and extending to the visible is observed in a dispersion optimized holey fiber with a record-high nonlinearity (1860W at 1.55µm), for launched pulse energies < 100pJ.

Reconfigurable all-optical header recognition for packet switched networks

Abstract: We report on an optical packet switching system with a code-reconfigurable switching node. Packet headers are generated and decoded in an all-optical fashion using fiber Bragg gratings (FBGs). The reconfigurable 15-chip, 25ps/chip quaternary phase coding decoder is based on a uniform FBG, the code of which can be changed dynamically by thermally inducing appropriate phase shifts. We present characterization results on the code-reconfigurable FBG device as well as performance evaluation of the switching system.