Optical Fiber Devices Research Articles

Long-Period Fiber Grating Cascaded to an S Fiber Taper for Simultaneous Measurement of Temperature and Refractive Index

A novel, low-cost, and simple dual-parameter measurement scheme based on a cascaded optical fiber device composed of a long-period fiber grating (LPFG) and an S fiber taper Mach-Zehnder interferometer (SFT-MZI) is proposed and demonstrated. The crosstalk problem is solved as different resonance peaks of the LPFG and the MZI possess different refractive index (RI) and temperature sensitivities. Experimental results show distinctive spectral sensitivities of -52.57 nm/refractive index unit (RIU) and 45.87 pm/°C by the LPFG, and 311.48 nm/RIU (in the RI range of 1.33-1.37) and 12.87 pm/°C by the SFT-MZI. The simultaneous measurement of external RI and the temperature is experimentally demonstrated by the sensor. The RI and temperature calculated by the sensor matrix agree well with the actual RI and temperature in the experiment.

A Fiberoptic (Photodynamic Therapy Type) Device with a Photosensitizer and Singlet Oxygen Delivery Probe Tip for Ovarian Cancer Cell Killing

A portable "fiber optic-based sensitizer delivery" (FOSD) device has been developed and studied. Before there might be success in photodynamic therapy (PDT) and antibacterial ambitions, an understanding of basic factors on device performance was needed. Thus, the device was examined for the localized delivery of sensitizer molecules in ovarian cancer cells and production of high concentrations of singlet oxygen for their eradication in vitro. The device tip releases stored pheophorbide by attack of singlet oxygen from sensitized oxygen gas delivered through the hollow fiber using 669 nm laser light. The performance of the device was enhanced when configured with a fluorosilane tip by virtue of its Teflon-like property compared with a conventional glass tip (greater sensitizer quantities were photoreleased and laterally diffused, and greater amounts of ovarian OVCAR-5 cancer cells were killed). No cell damage was observed at 2.2 N of force applied by the probe tip itself, an amount used for many of the experiments described here.

Abstract 2481: Synthesis and characterization of PEGylated chlorin e6 sensitizers for the photodynamic killing of human ovarian cancer cells.

Abstract Pegylated chlorin e6 photosensitizers have been synthesized with triethylene glycol attached at the ester bond(s) for a 1:1 conjugate, a 2:1 conjugate, and a 3:1 conjugate. These chlorin sensitizers were studied for hydrolytic stability and solubility. Our studies included an analysis of ovarian OVCAR-5 cancer cell uptake, localization, and phototoxicity. Because of our interest in fiber-based photosensitizer and singlet oxygen delivery methods, desirable aspects of the 3:1 chlorin e6 conjugate make it a potential sensitizer for incorporation into a fiber optic device, particularly in the area of ovarian cancer photodynamic therapy. Citation Format: Ashwini Ghogare, Goutam Ghosh, Stanley Kimani, Dorota Bartusik, Benjamin Rudshteyn, Tayyaba Hasan, Alexander Greer. Synthesis and characterization of PEGylated chlorin e6 sensitizers for the photodynamic killing of human ovarian cancer cells. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 2481. doi:10.1158/1538-7445.AM2013-2481

Integrated Bragg gratings in spiral waveguides

Over the last two decades, many filters requiring custom spectral responses were obtained from photo-inscribed fiber Bragg gratings because of the flexibility inherent to this technology. However, Bragg gratings in silicon waveguides have the potential to provide faster and more efficient tuning capabilities when compared to optical fiber devices. One drawback is that Bragg gratings filters with elaborate spectral amplitude and phase responses often require a long interaction length, which is not compatible with current integration trends in CMOS compatible photonic circuits. In this paper, we propose to make Bragg gratings in spiral-shaped waveguides in order to increase their lengths while making them more compact. The approach preserves the flexibility of regular straight grating structures. More specifically, we demonstrate 2-mm long gratings wrapped in an area of 200 µm x 190 µm without any spectral degradation due to waveguide curvature. Furthermore, we interleave three spiral waveguides with integrated gratings thereby tripling the density and demonstrate good phase compensation for each of them. Finally, we show that this approach is compatible with phase-apodization of the grating coupling coefficient.

Surface-Enhanced Resonance Raman Scattering (SERRS) Using Au Nanohole Arrays on Optical Fiber Tips

Circular and bow tie-shaped Au nanoholes arrays were fabricated on gold films deposited on the tips of single-mode optical fibers. The nanostructures were milled using focused ion beam with a high quality control of their shapes and sizes. The optical fiber devices were used for surface-enhanced resonance Raman scattering (SERRS) measurements in both back- and forward-scattering geometries, yielding promising performance in both detection arrangements. The effect of the hole shape on the SERRS performance was explored with the bow tie nanostructures presenting a better SERRS performance than the circular holes arrays. The results present here are another step towards the development of optical fiber tips modified with plasmonic nanostructures for SERRS applications.

Distributed fiber-optic laser-ultrasound generation based on ghost-mode of tilted fiber Bragg gratings

Active ultrasonic testing is widely used for medical diagnosis, material characterization and structural health monitoring. Ultrasonic transducer is a key component in active ultrasonic testing. Due to their many advantages such as small size, light weight, and immunity to electromagnetic interference, fiber-optic ultrasonic transducers are particularly attractive for permanent, embedded applications in active ultrasonic testing for structural health monitoring. However, current fiber-optic transducers only allow effective ultrasound generation at a single location of the fiber end. Here we demonstrate a fiber-optic device that can effectively generate ultrasound at multiple, selected locations along a fiber in a controllable manner based on a smart light tapping scheme that only taps out the light of a particular wavelength for laser-ultrasound generation and allow light of longer wavelengths pass by without loss. Such a scheme may also find applications in remote fiber-optic device tuning and quasi-distributed biochemical fiber-optic sensing.

Sequential Injection Chromatography for Separation and Quantification of Chlorpromazine in Human Urine and Pharmaceutical Formulations

Sequential injection chromatography (SIC) is a recent, simple, and inexpensive green miniaturized separation technique. In the current study, SIC was exploited for the first time for biochemical analysis. A new SIC method for the separation and quantification of chlorpromazine in human urine, as well as pharmaceutical formulations, was developed and validated. Clozapine was used as an internal standard. Chlorpromazine was successfully separated on a C18 monolithic column (25x4.6 mm id). The UV detection was carried out at 250 nm using miniaturized fiber optic spectrometric devices. The optimum mobile phase composition was 30 mmol/L phosphate-acetonitrile-methanol (55.0 + 31.5 + 13.5, v/v/v) at pH 3.0. The sample volume was 40 microL and flow rate was 40 microL/s. Acceptable chromatographic results were obtained. The resolution was 2.7, peak symmetry was 1.1, and number of theoretical plates was more than 1 x 10(6). Good linearity (r = 0.9997) in the range of 25-100 microg/mL was also obtained. The method offered acceptable recovery for both human urine (89.6-93.1%) and pharmaceutical formulations (96.9-98.5%), which was sensitive enough to detect chlorpromazine. The LOD and LOQ in human urine were 61 and 204 ng/mL, respectively. The method was rapid and reagent-saving, and hence safe for the environment. The sample throughput was 26.3 samples/h and the total volume of consumed reagents was 4.0 mL.

Spectrum Analysis in Postural Strategy on Static Tests in a Healthy Population

Introduction and objectivesThe power spectral density can be used to find a hidden behaviour in a physical system. We studied postural behaviour in a healthy population, by means of power spectral density, and compared it with a situation of complete immobility. MethodsA group of healthy volunteers carried out the modified Clinical Test for Sensory Interaction in Balance. A fibre optic gyroscope device was used to record the data. We compared the power spectral density in these tests and with another recording where the device was motionless. We looked for significant differences using the ANOVA test. ResultsA power peak appeared at 8.4Hz in all static tests. The static group showed significant differences with all the other tests. We found no statistically significant differences when visual input discriminated between 2 tests. There were statistically significant differences for the proprioceptive input. ConclusionsBrief movements are needed to maintain the quiet stance. The distinctive feature of these movements is a fundamental frequency at 1.4Hz and a harmonic frequency at 8.4Hz. Proprioceptive input is essential for balance.

High-throughput sequential injection assay method for chlorpromazine

This manuscript reports the optimization and validation of a new, rapid, reagent-saving and environmentally-safe method for chlorpromazine assay in pharmaceutical formulations utilizing sequential injection analysis (SIA) technique. Despite its benefits over univariate approach, chemometrics has been rarely exploited for optimizing SIA methods. Moreover, in those methods, some conditions have not been considered in optimization process. In the current study, more conditions, namely volumes and concentrations of reagents, have been optimized by chemometrics for the first time. A developing oxidation reaction of chlorpromazine by permanganate in acidic media was adopted. A spectrophotometric detection of the reduction of permanganate was applied at 526 nm using miniaturized fiber optic devices. The 24 full-factorial design and response surface approaches were exploited for method optimization. The method was validated and realized by a British Pharmacopoeia method. Experimental conditions and analytical aspects of the current SIA method were compared with those of a previous SIA method. Some analytical aspects were comparable while other aspects demonstrated better results from the current method than those from the previous one. The current method is rapid with a sample frequency of 51.4 samples/h. It is also reagent-saving with a total volume of consumed reagents and sample of 260 μL as well as environmental-safety with a total volume of waste production of 1260 μL. The method is therefore efficient for industrial-scale pharmaceutical analysis.

A fast response variable optical attenuator based on blue phase liquid crystal

Blue phase liquid crystals (BPLCs) are promising candidates for next generation display thanks to their fast response and quasi-isotropic optical properties. By taking these advantages, we propose to introduce the material into fiber-optic applications. As an example, a BPLC based variable optical attenuator (VOA) is demonstrated with a polarization independent design. The device shows normally-off feature when no field is applied. Response time down to submillisecond scale is achieved in switching between two arbitrary attenuation states. The attenuation range is also measured from 1480 to 1550 nm, which cover the whole telecomm S-band and part of the C-band. The overall performances reach the requirements for practical use; while still have room for further improvement. Through this example, the applicability of BPLC in fiber-optic devices is presented, which may impel the development of many other photonic applications from infrared to even microwave regions.

Intracranial hyperthermia through local photothermal heating with a fiberoptic microneedle device

The fiberoptic microneedle device (FMD) seeks to leverage advantages of both laser-induced thermal therapy (LITT) and convection-enhanced delivery (CED) to increase volumetric dispersal of locally infused chemotherapeutics through sub-lethal photothermal heat generation. This study focused on determination of photothermal damage thresholds with 1,064 nm light delivered through the FMD into in vivo rat models. FMDs capable of co-delivering laser energy and fluid agents were fabricated through a novel off-center splicing technique involving fusion of a multimode fiberoptic to light-guiding capillary tubing. FMDs were positioned at a depth of 2.5 mm within the cerebrum of male rats with fluoroptic temperature probes placed within 1 mm of the FMD tip. Irradiation (without fluid infusion) was conducted at laser powers of 0 (sham), 100, 200, 500, or 750 mW. Evans blue-serum albumin conjugated complex solution (EBA) and laser energy co-delivery were performed in a second set of preliminary experiments. Maximum, steady-state temperatures of 38.7 ± 1.6 and 42.0 ± 0.9 °C were measured for the 100 and 200 mW experimental groups, respectively. Histological investigation demonstrated needle insertion damage alone for sham and 100 mW irradiations. Photothermal damage was detected at 200 mW, although observable thermal damage was limited to a small penumbra of cerebral cortical microcavitation and necrosis that immediately surrounded the region of FMD insertion. Co-delivery of EBA and laser energy presented increased volumetric dispersal relative to infusion-only controls. Fluoroptic temperature sensing and histopathological assessments demonstrated that a laser power of 100 mW results in sub-lethal brain hyperthermia, and the optimum, sub-lethal target energy range is likely 100-200 mW. The preliminary FMD-CED experiments confirmed the feasibility of augmenting fluid dispersal using slight photothermal heat generation, demonstrating the FMD's potential as a way to increase the efficacy of CED in treating MG.

Reconfigurable liquid metal fiber-optic mirror for continuous, widely-tunable true-time-delay

This paper reports the demonstration of a widely-translatable fiber-optic mirror based on the motion of liquid metal through the hollow core of a photonic bandgap fiber. By moving a liquid metal mirror within the hollow core of an optical fiber, large, continuous changes in optical path length are achieved in a comparatively small package. A fiber-optic device is demonstrated which provided a continuously-variable optical path length of over 3.6 meters, without the use of free-space optics or resonant optical techniques (i.e. slow light). This change in path length corresponds to a continuously-variable true-time delay of over 12 ns, or 120 periods at a modulation frequency of 10 GHz. Wavelength dependence was shown to be negligible across the C and L bands.

Preface to Special Issue on Optical Fiber and Optical Device Technologies to Support Space Division Multiplexing Transmission

Preface to Special Issue on Optical Fiber and Optical Device Technologies to Support Space Division Multiplexing Transmission

A fourth-order Runge-Kutta in the interaction picture algorithm for simulating coupled generalized nonlinear Schrödinger equation and its error analysis

The numerical simulation method for accurately solving the coupled generalized nonlinear Schrödinger equations (C-GNLSE) is essential for describing the dynamic behavior of ultrashort pulse propagating in optical fiber and developing the corresponding nonlinear fiber-optic devices. C-GNLSE in the normal picture is first mapped into the interaction picture by the representation transformation, and then, the two coupled nonlinear partial differential equations in the interaction picture are solved in frequency domain, with synchronous data updating in each iteration step, by using the vector form of Hult’s fourth-order Runge-Kutta iterative scheme. The proposed vector form algorithm of fourth-order Runge-Kutta in interaction picture (V-JH-RK4IP) is verified by using it in simulating the supercontinuum generation in high birefringence photonic crystal fiber. Moreover, the V-JH-RK4IP algorithm also exhibits the highest accuracy and computational efficiency as compared to other classical algorithms.

Transient global amnesia after epiduroscopy in a failed back surgery syndrome patient: Case report

Epiduroscopy (EDS) allows diagnosis and treatment of spinal nerve root pathology by a fiberoptic device inserted percutaneously in the epidural space. Transient global amnesia syndrome (TGA) is defined by an abrupt onset of an anterograde and retrograde amnesia that lasts up to 24 h, although mild subclinical neuropsychological deficits, with concomitant vegetative symptoms, can last for days after the episode. To our knowledge no cases of TGA in association with EDS have been recognized. We present a case of a 54-year-old man who was admitted for EDS, having experienced two times the failed surgery for spinal and left leg pain. During the EDS, 10 ml of non-ionic contrast media (CM) was injected to confirm the inside lesions. The epidural adhesions were gently broken down and drugs were injected around any inflamed nerve roots. Immediately after EDS, the patient experienced a TGA with loss of memory for the recent procedure and an impaired ability to retain new information. There were no signs of confusion or altered conscious level or seizure activities and neurological examination was normal. At 24 h a cranial computerized tomography (cCT) without CM showed “abnormal contrast enhancement at subarachnoid liquoral spaces levels”, then at 72 h cCT control was normal. The patient was discharged on the seventh day with perioperative lacunar amnesia persisting at this time. Herein, we sought a possible relationship between neurotoxic effect of CM and TGA in a patient emotionally stressed, even if the CM dose was given as a normal clinical range.

Nonlinear fibre-optic devices pumped by semiconductor disk lasers

Semiconductor disk lasers offer a unique combination of characteristics that are particularly attractive for pumping Raman lasers and amplifiers. The advantages of disk lasers include a low relative noise intensity (-150 dB Hz-1), scalable (on the order of several watts) output power, and nearly diffraction-limited beam quality resulting in a high (∼70 % — 90 %) coupling efficiency into a single-mode fibre. Using this technology, low-noise fibre Raman amplifiers operating at 1.3 μm in co-propagation configuration are developed. A hybrid Raman-bismuth doped fibre amplifier is proposed to further increase the pump conversion efficiency. The possibility of fabricating mode-locked picosecond fibre lasers operating under both normal and anomalous dispersion is shown experimentally. We demonstrate the operation of 1.38-μm and 1.6-μm passively mode-locked Raman fibre lasers pumped by 1.29-μm and 1.48-μm semiconductor disk lasers and producing 1.97- and 2.7-ps pulses, respectively. Using a picosecond semiconductor disk laseramplified with an ytterbium-erbium fibre amplifier, the supercontinuum generation spanning from 1.35 μm to 2 μm is achieved with an average power of 3.5 W.

Loop-mirror-based slot waveguide refractive index sensor

Loop mirror has been widely used in fiber optical devices and systems for it provides a smart way to make use of the fiber birefringence properties and can enhance the sensitivity greatly. On the other hand, slot waveguide is very promising for optical sensing applications because of their peculiar spatial mode profile. In this paper, we propose and analyze a loop-mirror-based slot waveguide (LMSW) sensor which can be routinely fabricated in modern high-volume complementary metal-oxide–semiconductor (CMOS) process. The finite element method (FEM) simulation results show that the birefringence can be as high as 0.8 which is orders of magnitude than that in conventional birefringent fiber loop mirror. High sensitivity up to 6 × 103 nm/RIU (refractive index unit) is achieved by this scheme.

Temperature-insensitive fiber-optic devices using multimode interference effect

We show theoretically that the fiber-optic devices using single-multi-single mode fiber structures can be made temperature insensitive by properly adjusting the concentration of P(2)O(5) in the core region of the multimode fiber used. Taking an example of a parabolic index multimode fiber, we obtain the temperature-insensitive transmission spectrum and fiber-optic lens action for a core composition of 1.57 mol. % P(2)O(5) and 13.5 mol. % GeO(2) in the SiO(2) host.

Review on structural, thermal, optical and spectroscopic properties of tellurium oxide based glasses for fibre optic and waveguide applications

This review focuses on the engineering of the structural, thermal, optical and spectroscopic properties of tellurium oxide (TeO2) glasses for their applications in fibre optic and waveguide devices. Unlike silica optical fibres, tellurium oxide glass fibres and light waveguides support propagation of light beyond ∼2 μm, where silica fibres become opaque. Silica fibres also have limited solubility for rare earth oxides due to silica’s structure, which is where tellurium oxide fibres and light waveguides can offer significant opportunities to engineer novel lasers and amplifiers for integrated optics. In this review, we compare the structural properties of TeO2 based glasses, modified by incorporating alkali, alkaline earth, and other oxide compounds. Based on Raman, UV, visible and infrared spectroscopic data, the structural aspects of tellurite glasses are discussed. The effects of compositional modification on the thermal and viscous flow properties are also compared and related with the resistance against devitrification. The significance of glass to crystal phase transformation during cooling and heating is explained in the context of preform and fibre fabrication. The review also reports on the characterisation of OH− impurities in tellurite glasses. Recent developments in tellurite fibre lasers and femtosecond laser inscribed waveguide fabrication are discussed.

Estudio espectral de la estrategia postural de una población sana en pruebas estáticas

Introduction and objectivesThe power spectral density can be used to find a hidden behaviour in a physical system. We studied postural behaviour in a healthy population, by means of power spectral density, and compared it with a situation of complete immobility. MethodsA group of healthy volunteers carried out the modified Clinical Test for Sensory Interaction in Balance. A fibre optic gyroscope device was used to record the data. We compared the power spectral density in these tests and with another recording where the device was motionless. We looked for significant differences using the ANOVA test. ResultsA power peak appeared at 8.4Hz in all static tests. The static group showed significant differences with all the other tests. We found no statistically significant differences when visual input discriminated between 2 tests. There were statistically significant differences for the proprioceptive input. ConclusionsBrief movements are needed to maintain the quiet stance. The distinctive feature of these movements is a fundamental frequency at 1.4Hz and a harmonic frequency at 8.4Hz. Proprioceptive input is essential for balance.