Planarised optical fiber composite using flame hydrolysis deposition demonstrating an integrated FBG anemometer

Holmes, Christopher; Gates, James C.; Smith, Peter G. R.

doi:10.1364/oe.22.032150

Cited by 25 publications

(18 citation statements)

References 27 publications

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“…The results clarified that the refractive index changes were monitored successfully by the system function. [7] used cladding-mode-recoupling-based hybrid long period grating (LPG)/fiber Bragg grating (FBG) sensors for the simultaneous measurement of temperature and strain is proposed. A set of counter-propagation cladding modes can be achieved through a specially fabricated hybrid LPG/FBG structure, and experimental results indicate that the intensity of cladding modes and FBG resonance show different temperature and strain response, which can be used for simultaneous measurement of temperature and strain through power-reference-based ratiometric detection.…”

Section: Introductionmentioning

confidence: 99%

Hybrid Fibre Grating Structure of an Optical Fibre Refractive Index Sensor

Benisha¹

2015

JACE

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The refractive index which is compensated with temperature by incorporating an LPG and FBG has been established and evaluated in a series configuration. As refractive index is used by Long Period Grating which allows it to be responsive to external refractive index difference ,for temperature compensation the Fibre Bragg Grating was used. For efficient interpretation of both refractive index and temperature the Long Period Grating (LPG) and Fibre Bragg Grating (FBG) wavelengths were chosen to be within suitable spectral bandwidths. For the use as a chemical sensor the hybrid sensor performance was rated by varying sodium chloride (NaCl) concentrations in temperature from 11-96 o C and water from 0.25 -2 %NaCl and by recording its related attenuation band shifts. The hybrid sensor to NaCl concentration and temperature sensitivity is found to be 0.62 nm/%NaCl and 9 pm/ o C respectively.

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Section: Introductionmentioning

confidence: 99%

Hybrid Fibre Grating Structure of an Optical Fibre Refractive Index Sensor

Benisha¹

2015

JACE

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“…The increase in applications requiring robust laser systems (e.g. space borne gravitational wave measurements) has led to a need for alternatives at frequencies where free space lasers have previously been utilised.We have previously demonstrated a novel planar platform using flamed hydrolysis deposition (FHD) to bond optical fibers to silicon wafers and form integrated optical fiber (IOF) into which Bragg gratings can be written at precisely selected wavelengths using a direct UV writing technique [1]. Low noise, narrow linewidth external cavity diode lasers have been constructed in a bench-top system built on translation stages using these IOF gratings as the external cavity for gain chips at wavelengths corresponding to selected gas absorption lines, e.g.…”

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confidence: 99%

Frequency doubling a compact stable external cavity diode laser using a novel PPLN waveguide

Lynch

Carpenter

Berry

et al. 2017

2017 Conference on Lasers and Electro-Optics Europe &Amp; European Quantum Electronics Conference (CLEO/Europe-EQEC)

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There is increasing demand for low noise, narrow linewidth lasers for applications including spectroscopy, ion traps for optical clocks and gravitational waves measurements. External cavity diode lasers (ECDL) can provide a compact, low cost solution; however these are typically available at a limited range of optical frequencies. The increase in applications requiring robust laser systems (e.g. space borne gravitational wave measurements) has led to a need for alternatives at frequencies where free space lasers have previously been utilised.We have previously demonstrated a novel planar platform using flamed hydrolysis deposition (FHD) to bond optical fibers to silicon wafers and form integrated optical fiber (IOF) into which Bragg gratings can be written at precisely selected wavelengths using a direct UV writing technique [1]. Low noise, narrow linewidth external cavity diode lasers have been constructed in a bench-top system built on translation stages using these IOF gratings as the external cavity for gain chips at wavelengths corresponding to selected gas absorption lines, e.g. acetylene [2]. Here we present results for an IOF-based ECDL that has been constructed into a compact and portable 1560 nm laser, see Fig. 1(a) and (b), with reduced susceptibility to low frequency RIN to offer higher stability. Frequency doubling is achieved by a periodically poled magnesium doped lithium niobate (PPLN) waveguide, see Fig. 1(c). The PPLN waveguides are fabricated via a bonding, thinning and ultra precision dicing route, this creates a LiNbO3-on-Si structure. Second harmonic generation is achieved with a 19.6 µm period grating. This laser has been frequency doubled to 780 nm, see Fig. 1(d), so it can be temperature tuned to a rubidium absorption line for locking. The FHD and UV writing techniques used to build this laser enable significant flexibility for the wavelengths achievable from these stable lasers which, with the use of PPLN for frequency up/down conversion, can offer stable sources for applications at optical and IR frequencies not previously accessible with compact, low-cost laser systems. The low frequency intensity noise (sub-100 Hz) was significantly reduced when compared with previous lasers [2], and we will present further results demonstrating the low noise and high stability that can be achieved for the output of a frequency doubled IOF-based ECDL. We will also show locking of the ECDLs for increasing long-term stability.

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“…The binding medium is of optical quality and mechanically robust, illustrated in fig 1 (a). Although non-trivial seamless on/off-chip coupling has also been demonstrated, which could further act to minimise coupling losses typically associated with integrated optics.Thus far, developments in IOF have largely utilised either environmental stability [1] and/or physical robustness [2] and not realised the formats potential for optical integration. This work reports for the first time an integrated optical fibre coupler, illustrated in figure 1(b)-(e).…”

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confidence: 99%

“…Thus far, developments in IOF have largely utilised either environmental stability [1] and/or physical robustness [2] and not realised the formats potential for optical integration. This work reports for the first time an integrated optical fibre coupler, illustrated in figure 1(b)-(e).…”

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Integrated optical fibre coupler

Holmes

Jantzen

Lynch

et al. 2017

2017 Conference on Lasers and Electro-Optics Europe &Amp; European Quantum Electronics Conference (CLEO/Europe-EQEC)

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Integrated Optical Fibre (IOF) is a low-loss photonic platform that directly integrates optical fibre to a planar substrate. The platform possess advantages associated with optical fibre including low propagation loss, whilst at the same time enabling planar functionality associated with integrated optics. IOF fabrication is achieved through a modified Flame Hydrolysis Deposition (FHD) technique that forms a robust glass alloy between the fibre and substrate. The binding medium is of optical quality and mechanically robust, illustrated in fig 1 (a). Although non-trivial seamless on/off-chip coupling has also been demonstrated, which could further act to minimise coupling losses typically associated with integrated optics.Thus far, developments in IOF have largely utilised either environmental stability [1] and/or physical robustness [2] and not realised the formats potential for optical integration. This work reports for the first time an integrated optical fibre coupler, illustrated in figure 1(b)-(e). The proof-of-concept device could be scaled and serve as a building block for future large-scale low-loss integrated architectures. For example it could be feasible to concatenate multiple coupler components with integrated functionality e.g. a thermo-optic tuning capability. To achieve this proof-of-concept component it was necessary to expose the evanescent field of the optical fibre, such that two fibres could optically couple. Exposure was achieved through use of a wet etching, using a buffered HF solution. In the etching of this structure the diameter of SMF-28 fibre was brought down to 8 µm. After etching a pair of such fibres were layered-up upon a silicon wafer. The silicon wafer had a thick thermally grown oxide (15 µm) that acted as an optical buffer (clad), ensuring a guided mode did not leak into the silicon substrate. The layer-up stage brought the two etched fibres into physical contact and thus enabled directional coupling. In this initial demonstration a 0.5 µm thick FHD layer was deposited and consolidated about the fibre(s), illustrated in Fig 1(b)-(e). The FHD silicate was doped with boron and phosphorus such that the refractive index matched that of the thermal oxide and it had a consolidation temperature below 1250 o C. It is noted that due to meniscus effects during consolidation the thickness of FHD varies about the respective fibres. The component demonstrated brought two fibres together at an angle of 3-degrees, after which they are in physical proximity for ~1mm and then depart at an angle similar to input, illustrated in Figure 1 (c)-(e). Upon single arm input illumination at 780 nm wavelength a 34:66 splitting ratio was attained, illustrated in Figure 1 (f)-(g). Improvements to surface roughness of the etched fibres, optimised FHD thickness and refractive index and fibre diameter insertion losses should be further reduced.This work will report the latest results for propagation losses in etched fibre after IOF layer-up and the insertion losses brought about for optimised coupler design...

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Planarised optical fiber composite using flame hydrolysis deposition demonstrating an integrated FBG anemometer

Cited by 25 publications

References 27 publications

Hybrid Fibre Grating Structure of an Optical Fibre Refractive Index Sensor

Hybrid Fibre Grating Structure of an Optical Fibre Refractive Index Sensor

Frequency doubling a compact stable external cavity diode laser using a novel PPLN waveguide

Integrated optical fibre coupler

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