Showing papers on "Photonic-crystal fiber published in 2004"
TL;DR: In this article, different properties possible to obtain in photonic crystal fibers are reviewed and fabrication and modeling methods are also discussed, and different properties of photonic bandgap effect are discussed.
Abstract: Photonic crystal fibers are a new class of optical fibers. Their artificial crystal-like microstructure results in a number of unusual properties. They can guide light not only through a well-known total internal reflection mechanism but using also photonic bandgap effect. In this paper different properties possible to obtain in photonic crystal fibers are reviewed. Fabrication and modeling methods are also discussed.
995 citations
TL;DR: It is shown that very-long ultra-low-loss tapers can in fact be produced using a conventional fiber taper rig incorporating a simple burner configuration, and the optical losses achieved are one order of magnitude lower than losses previously reported in the literature for tapers of a similar size.
Abstract: Optical fiber tapers with a waist size larger than 1microm are commonplace in telecommunications and sensor applications. However the fabrication of low-loss optical fiber tapers with subwavelength diameters was previously thought to be impractical due to difficulties associated with control of the surface roughness and diameter uniformity. In this paper we show that very-long ultra-low-loss tapers can in fact be produced using a conventional fiber taper rig incorporating a simple burner configuration. For single-mode operation, the optical losses we achieve at 1.55microm are one order of magnitude lower than losses previously reported in the literature for tapers of a similar size. SEM images confirm excellent taper uniformity. We believe that these low-loss structures should pave the way to a whole range of fiber nanodevices.
601 citations
TL;DR: Photonic crystal fibres exhibiting endlessly single-mode operation and dispersion zero in the range 1040 to 1100 nm are demonstrated.
Abstract: Photonic crystal fibres exhibiting endlessly single-mode operation and dispersion zero in the range 1040 to 1100 nm are demonstrated. A sub-ns pump source at 1064 nm generates a parametric output at 732 nm with an efficiency of 35%, or parametric gain of 55 dB at 1315 nm. A broad, flat supercontinuum extending from 500 nm to beyond 1750 nm is also demonstrated using the same pump source.
507 citations
23 Aug 2004
TL;DR: Experimental studies of gas sensing using air-guiding photonic bandgap fibers using standard single mode fibers for ease of use and improved stability are reported on.
Abstract: We report on experimental studies of gas sensing using air-guiding photonic bandgap fibers. The photonic bandgap fibers have at one end been spliced to standard single mode fibers for ease of use and improved stability
431 citations
TL;DR: In this paper, the first passively mode-locked fiber laser based on carbon nanotubes (SAINT) is presented, which offers several key advantages such as: ultrafast recovery time (<1 ps), high-optical damage threshold, mechanical and environmental robustness, chemical stability, and the ability to operate in transmission, reflection, and bidirectional modes.
Abstract: We present the first passively mode-locked fiber lasers based on a novel saturable absorber incorporating carbon nanotubes (SAINT). This device offers several key advantages such as: ultrafast recovery time (<1 ps), high-optical damage threshold, mechanical and environmental robustness, chemical stability, and the ability to operate in transmission, reflection, and bidirectional modes. Moreover, the fabrication cost and complexity of SAINT devices are potentially lower than that of conventional semiconductor saturable absorber mirror devices. Therefore, it is expected that SAINT will greatly impact future pulsed laser design and development.
372 citations
TL;DR: An air-clad large-core single-transverse-mode ytterbium-doped photonic crystal fiber with a mode-field-diameter of 35 microm allowing for the frequency up-conversion of these pulses using narrow-bandwidth phase matched nonlinear crystals.
Abstract: We report on an air-clad large-core single-transverse-mode ytterbium-doped photonic crystal fiber with a mode-field-diameter of 35 µm, corresponding to a mode-field-area of ~1000 µm2. In a first experiment this fiber is used to amplify 10-ps pulses to a peak power of 60 kW without significant spectral broadening due to self-phase modulation allowing for the frequency up-conversion of these pulses using narrow-bandwidth phase-matched nonlinear crystals.
347 citations
TL;DR: In this paper, the numerical and experimental analysis on the use of thinned fiber Bragg gratings as refractive index sensors have been carried out, where wet chemical etching in a buffered hydrofluoric acid solution was used for sensor fabrication.
Abstract: In this work, the numerical and experimental analysis on the use of thinned fiber Bragg gratings as refractive index sensors have been carried out. Wet chemical etching in a buffered hydrofluoric acid solution was used for sensor fabrication. Experimental characterization for an almost full etched cladding sensor is presented demonstrating good agreement with numerical results and resolutions of /spl ap/10/sup -5/ and /spl ap/10/sup -4/ for outer refractive index around 1.45 and 1.333, respectively.
327 citations
TL;DR: In this paper, a tunable light switch using a photonic crystal fiber filled with nematic liquid crystal is demonstrated, where the original band-gap-guiding fiber structure was transformed to a total internal reflection-guided photonic-crystal fiber by filling liquid crystal into the air core and cladding air holes.
Abstract: Tunable light switch using a photonic crystal fiber filled with nematic liquid crystal is demonstrated. The original band-gap-guiding fiber structure was transformed to a total internal reflection-guiding photonic crystal fiber by filling liquid crystal into the air core and cladding air holes. By applying external voltage to the liquid-crystal-filled fiber, we have demonstrated an electrically tunable fiber-optical switch with over 30dB attenuation at 60Vrms for a He-Ne laser beam. This liquid-crystal-filled photonic crystal fiber will find useful applications in fiber-optic communication systems.
315 citations
TL;DR: It is demonstrated that highly efficient evanescent-wave detection of fluorophore-labeled biomolecules in aqueous solutions positioned in the air holes of the microstructured part of a photonic crystal fiber even at wavelengths in the visible range is demonstrated.
Abstract: We demonstrate highly efficient evanescent-wave detection of fluorophore-labeled biomolecules in aqueous solutions positioned in the air holes of the microstructured part of a photonic crystal fiber. The air-suspended silica structures located between three neighboring air holes in the cladding crystal guide light with a large fraction of the optical field penetrating into the sample even at wavelengths in the visible range. An effective interaction length of several centimeters is obtained when a sample volume of less than 1 µL is used.
309 citations
TL;DR: The supercontinuum generation in a highly nonlinear photonic crystal fiber with two closely lying zero dispersion wavelengths is demonstrated, which has high spectral density and is extremely independent of the input pulse over a wide range of input pulse parameters.
Abstract: We demonstrate supercontinuum generation in a highly nonlinear photonic crystal fiber with two closely lying zero dispersion wavelengths. The special dispersion of the fiber has a profound influence on the supercontinuum which is generated through self-phase modulation and phasematched four-wave mixing and not soliton fission as in the initial photonic crystal fibers. The supercontinuum has high spectral density and is extremely independent of the input pulse over a wide range of input pulse parameters. Simulations show that the supercontinuum can be compressed to ultrashort pulses.
305 citations
TL;DR: In this paper, a method for the fabrication of functional microstructured optical fibers (MOFs) by selectively filling the air holes with liquid phase materials, where the dependence of filling speed on the size of the air hole was exploited.
Abstract: We develop a method for the fabrication of functional microstructured optical fibers (MOFs) by selectively filling the air holes with liquid phase materials, where we utilize the dependence of filling speed on the size of the air holes. As a demonstration, we construct a hybrid MOF by filling the center hollow core of a triangular lattice photonic crystal fiber with dye-doped curable polymer, and experimentally observe the two-photon fluorescence from the hybrid MOF.
TL;DR: An all-optical modulator is demonstrated, which utilizes a pulsed 532nm laser to modulate the spectral position of the bandgaps in a photonic crystal fiber infiltrated with a dye-doped nematic liquid crystal.
Abstract: Photonic crystal fibers (PCFs) have attracted significant attention during the last years and much research has been devoted to develop fiber designs for various applications, hereunder tunable fiber devices. Recently, thermally and electrically tunable PCF devices based on liquid crystals (LCs) have been demonstrated. However, optical tuning of the LC PCF has until now not been demonstrated. Here we demonstrate an all-optical modulator, which utilizes a pulsed 532nm laser to modulate the spectral position of the bandgaps in a photonic crystal fiber infiltrated with a dye-doped nematic liquid crystal. We demonstrate a modulation frequency of 2kHz for a moderate pump power of 2–3mW and describe two pump pulse regimes in which there is an order of magnitude difference between the decay times.
TL;DR: A Sagnac loop interferometer based on polarization-maintaining photonic crystal fiber was built and analyzed, and an unambiguous temperature dependent birefringence coefficient was deduced.
Abstract: A Sagnac loop interferometer based on polarization-maintaining photonic crystal fiber was built and analyzed. Mainly the temperature dependence of the Sagnac loop filter function was measured and analyzed. By measuring the filtering function of the Sagnac loop as a function of the temperature over 200 degrees C, we deduced an unambiguous temperature dependent birefringence coefficient, d n/dT = 2.0 x 10-9 /K. Over the full temperature swing, the maximum peak shifts was less than 10% of the filter period. For comparison, a standard Sagnac loop was built with the exact same length and experimental condition, where we deduced d n/dT = 7.0 x 10-8 /K.
TL;DR: The fusion-splicing of a bismuth holey fiber to silica fibers is demonstrated, which has resulted in reduced coupling loss and robust single mode guiding at 1550 nm.
Abstract: We report on the progress of bismuth oxide glass holey fibers for nonlinear device applications. The use of micron-scale core diameters has resulted in a very high nonlinearity of 1100 W-1 km-1 at 1550 nm. The nonlinear performance of the fibers is evaluated in terms of a newly introduced figure-of-merit for nonlinear device applications. Anomalous dispersion at 1550 nm has been predicted and experimentally confirmed by soliton self-frequency shifting. In addition, we demonstrate the fusion-splicing of a bismuth holey fiber to silica fibers, which has resulted in reduced coupling loss and robust single mode guiding at 1550 nm.
TL;DR: In this paper, the authors demonstrate the construction of reasonably long and non-polarization changing photonic fiber waveguide using Teflon which is a readily available and highly flexible material.
Abstract: We demonstrate the construction of reasonably long and non-polarization changing photonic fiber waveguide using Teflon which is a readily available and highly flexible material. Due to its relatively low loss coefficient, the possibility of preparing longer photonic fiber waveguide, which has the potential of guiding intense THz radiation, can be easily attained.
TL;DR: It is shown through numerical results that the novel microstructured optical fiber with small normal group-velocity dispersion and nearly zero dispersion slope offers the possibility of efficient supercontinuum generation in the telecommunication window using a few ps pulses.
Abstract: We propose a new structure of highly nonlinear dispersion-flattened (HNDF) photonic crystal fiber (PCF) with nonlinear coefficient as large as 30 W(-1)km(-1) at 1.55 microm designed by varying the diameters of the air-hole rings along the fiber radius. This innovative HNDF-PCF has a unique effective-index profile that can offer not only a large nonlinear coefficient but also flat dispersion slope and low leakage losses. It is shown through numerical results that the novel microstructured optical fiber with small normal group-velocity dispersion and nearly zero dispersion slope offers the possibility of efficient supercontinuum generation in the telecommunication window using a few ps pulses.
TL;DR: The fabrication of what is believed to be the first microstructured optical fibers with uniformly oriented elliptical holes with a high degree of hole ellipticity is reported with a simple technique that relies on hole deformation during fiber draw.
Abstract: We report the fabrication of what are believed to be the first microstructured optical fibers with uniformly oriented elliptical holes. A high degree of hole ellipticity is achieved with a simple technique that relies on hole deformation during fiber draw. Both form and stress-optic birefringence are characterized over a broad wavelength range. These measurements are in excellent agreement with numerical modeling and demonstrate a birefringence as high as 1.0×10-4 at a wavelength of 850 nm.
TL;DR: In this article, a temperature-insensitive interferometer made from a HiBi-PCF fiber loop mirror (FLM) is achieved for the wavelength spacing of 0.43 nm, a wavelength spacing variation with temperature of only 0.05 pm/spl deg/C, and a transmission peak shift of
Abstract: Utilizing the high birefringence and the low-temperature coefficient of birefringence of the highly birefringent photonic crystal fiber (HiBi-PCF), a temperature-insensitive interferometer made from a HiBi-PCF fiber loop mirror (FLM) is achieved. For the wavelength spacing of 0.43 nm, a wavelength spacing variation with temperature of only 0.05 pm//spl deg/C, and a transmission peak shift of 0.3 pm//spl deg/C is demonstrated. The stability of the FLM is improved dramatically when it uses a HiBi-PCF, as compared to FLMs using conventional HiBi fibers.
TL;DR: A model is developed that connects the experimental observations of high losses in the middle of the transmission spectrum to the presence of surface modes supported at the core-cladding interface and a new PBGF design is proposed that avoids these surface modes and produces single-mode operation.
Abstract: We present a detailed description of the role of surface modes in photonic band-gap fibers (PBGFs). A model is developed that connects the experimental observations of high losses in the middle of the transmission spectrum to the presence of surface modes supported at the core-cladding interface. Furthermore, a new PBGF design is proposed that avoids these surface modes and produces single-mode operation.
TL;DR: It is demonstrated that the simultaneous excitation of the microstuctured fiber in its normal and anomalous dispersion regimes using the fundamental and second harmonic signals of a passively Q-switched microchip laser leads to a homogeneous supercontinuum in the visible range.
Abstract: We report on the experimental demonstration of a white-light supercontinuum generation in normally dispersive singlemode air-silica microstructured fiber. We demonstrate that the simultaneous excitation of the microstuctured fiber in its normal and anomalous dispersion regimes using the fundamental and second harmonic signals of a passively Q-switched microchip laser leads to a homogeneous supercontinuum in the visible range. This pumping scheme allows the suppression of the cascaded Raman effect predominance in favor of an efficient spectrum broadening induced by parametric phenomena. A flat supercontinuum extended from 400 to 700 nm is achieved.
TL;DR: The generation of pure rotational stimulated Raman scattering in a hydrogen gas hollow-core photonic crystal fiber is reported, permitting pure conversion to the rotational Stokes frequency in a single-pass configuration pumped by a microchip laser.
Abstract: We report on the generation of pure rotational stimulated Raman scattering in a hydrogen gas hollow-core photonic crystal fiber. Using the special properties of this low-loss fiber, the normally dominant vibrational stimulated Raman scattering is suppressed, permitting pure conversion to the rotational Stokes frequency in a single-pass configuration pumped by a microchip laser. We report 92% quantum conversion efficiency (40 nJ pulses in 2.9 m fiber) and threshold energies (3 nJ in 35 m) more than 1 x 10(6) times lower than previously reported. The control of the output spectral components by varying only the pump polarization is also shown. The results point to a new generation of highly engineerable and compact laser sources.
TL;DR: The dispersion and loss in microstructured fibers are studied using a full-vectorial compact-2D finite-difference method in frequency-domain and a dielectric constant averaging technique using Ampere's law across the curved media interface is presented.
Abstract: The dispersion and loss in microstructured fibers are studied using a full-vectorial compact-2D finite-difference method in frequency-domain. This method solves a standard eigen-value problem from the Maxwell’s equations directly and obtains complex propagation constants of the modes using anisotropic perfectly matched layers. A dielectric constant averaging technique using Ampere’s law across the curved media interface is presented. Both the real and the imaginary parts of the complex propagation constant can be obtained with a high accuracy and fast convergence. Material loss, dispersion and spurious modes are also discussed.
TL;DR: In this article, an optical fiber that guides only one polarization mode of a light signal was realized by using highly birefringent pure silica photonic crystal fiber at wavelengths longer than 1450 nm.
Abstract: An optical fiber that guides only one polarization mode of a light signal is realized by using highly birefringent pure silica photonic crystal fiber. The fiber guides only one polarization mode at wavelengths longer than 1450 nm. A polarization dependent loss of 196 dB/km with a 28 dB/km transmission loss is achieved at a wavelength of 1550 nm.
Patent•
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10 Nov 2004
TL;DR: In this paper, a reflective optical element on one end of a modelocked fiber resonator having a relatively low reflectivity is employed to couple light from the resonator to the amplifier.
Abstract: Modelocked fiber laser resonators may be coupled with optical amplifiers. An isolator optionally may separate the resonator from the amplifier. A reflective optical element on one end of the resonator having a relatively low reflectivity may be employed to couple light from the resonator to the amplifier. Enhanced pulse-width control may be provided with concatenated sections of both polarization-maintaining and non-polarization-maintaining fibers. Apodized fiber Bragg gratings and integrated fiber polarizers may also be included in the laser cavity to assist in linearly polarizing the output of the cavity. Very short pulses with a large optical bandwidth may be obtained by matching the dispersion value of the grating to the inverse of the dispersion of the intra-cavity fiber. Frequency comb sources may be constructed from such modelocked fiber oscillators. Low dispersion and an in-line interferometer that provides feedback may assist in controlling the frequency components output from the comb source.
TL;DR: In this paper, a fiber optic sensing system for simultaneous measurement of temperature and salinity based on fiber Bragg grating technology is presented, which relies on chemical etching of the fiber and its performance is evaluated.
Abstract: A fiber optic sensing system for simultaneous measurement of temperature and salinity based on fiber Bragg grating technology is presented. The fabrication process, which relies on chemical etching of the fibre, is described and its performance is evaluated. Theoretical and experimental results are given, which are summarized on the obtained resolutions of 60.06°C/AHz and 60.2‰/ AHz for temperature and salin- ity, respectively. © 2004 Society of Photo-Optical Instrumentation Engineers.
TL;DR: It is concluded that 7-unit-cell cores are currently most suitable for transmission of femtosecond and sub-picosecond pulses, whereas larger cores are better for delivering nanosecond pulsed and continuous-wave beams.
Abstract: Hollow-core photonic crystal fibers have unusual properties which make them ideally suited to delivery of laser beams. We describe the properties of fibers with different core designs, and the observed effects of anti-crossings with interface modes. We conclude that 7-unit-cell cores are currently most suitable for transmission of femtosecond and sub-picosecond pulses, whereas larger cores (e.g. 19-cell cores) are better for delivering nanosecond pulsed and continuous-wave beams.
TL;DR: The bending influence on the modal characteristics shows that it is possible to tune the phase-matching wavelength over the C band by adjusting the diameter of the fiber.
Abstract: A photonic crystal fiber based on a particular periodic arrangement of airholes and pure silica is designed for chromatic dispersion compensation. A two-concentric-core structure is obtained by introducing two different sizes of capillaries (for the airholes) and exhibits very high negative chromatic dispersion [-2200 ps/(nm km) at 1550 nm]. The variation of optogeometric parameters is also investigated to evaluate the tolerance of the fabrication. Finally, the bending influence on the modal characteristics shows that it is possible to tune the phase-matching wavelength over the C band by adjusting the diameter of the fiber.
TL;DR: The dispersion properties of large hole photonic crystal fibers (PCFs) are tailored by changing the diameter of the air-holes belonging to the first three rings, in order to obtain fibers with a small effective area and low dispersion values in a wide wavelength range around 1550 nm as mentioned in this paper.
Abstract: The dispersion properties of large-hole photonic crystal fibers (PCFs) are tailored by changing the diameter of the air-holes belonging to the first three rings, in order to obtain fibers with a small effective area and low dispersion values in a wide wavelength range around 1550 nm. Highly nonlinear triangular PCFs with effective area of a few square micrometers, flattened dispersion curve, and zero-dispersion wavelength around 1500 nm have been designed.
TL;DR: The all-PCF Mach-Zehnder interferometer was formed by mechanically inducing two identical long-period fiber gratings (LPGs) in the PCF by mechanically induced two identicalLong-period Fiber gratings in thePCF to investigate the spectral properties of a LPG and a LGas pair.
Abstract: We demonstrate implementation of an all-fiber Mach–Zehnder interferometer formed in a photonic crystal fiber (PCF). We formed the all-PCF Mach–Zehnder interferometer by mechanically inducing two identical long-period fiber gratings (LPGs) in the PCF. The spectral properties of a LPG and a LPG pair were investigated. The interference fringe formed within the stop band of the LPG pair varied with the period and the strength of the gratings, and the fringe spacing was decreased with increasing grating separation. From the fringe spacing measurement the differential effective group index of the PCF was calculated to be Δm≈2.8×10-3.
TL;DR: This work reports on a polarization maintaining large mode area photonic crystal fiber, which is both single mode at any wavelength and have a practically constant birefringence for any wavelength.
Abstract: We report on a polarization maintaining large mode area photonic crystal fiber Unlike, previous work on polarization maintaining photonic crystal fibers, birefringence is introduced using stress applying parts This has allowed us to realize fibers, which are both single mode at any wavelength and have a practically constant birefringence for any wavelength The fibers presented in this work have mode field diameters from about 4 to 65 micron, and exhibit a typical birefringence of 15·10-4