Refractive Index

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A Cusano - One of the best experts on this subject based on the ideXlab platform.

  • mode transition in high Refractive Index coated long period gratings
    Optics Express, 2006
    Co-Authors: A Cusano, Agostino Iadicicco, S Campopiano, A Cutolo, P Pilla, Luigi Contessa, Michele Giordano
    Abstract:

    In this work, the numerical and experimental investigation of the cladding modes re-organization in high Refractive Index (HRI) coated Long Period Gratings (LPGs) is reported. Moreover, the effects of the cladding modes re-organization on the sensitivity to the surrounding medium Refractive Index (SRI) have been outlined. When azimuthally symmetric nano-scale HRI coatings are deposited along LPGs devices, a significant modification of the cladding modes distribution occurs, depending on the layer features (Refractive Index and thickness) and on the SRI. In particular, if layer parameters are properly chosen, the transition of the lowest order cladding mode into an overlay mode occurs. As a consequence, a cladding modes re-organization can be observed leading to relevant improvements in the SRI sensitivity in terms of wavelength shift and amplitude variations of the LPGs attenuation bands.

  • thinned fiber bragg gratings as Refractive Index sensors
    IEEE Sensors Journal, 2005
    Co-Authors: Agostino Iadicicco, S Campopiano, A Cutolo, A Cusano, M Giordano
    Abstract:

    In this work, highly sensitive Refractive Index measurements have been experimentally demonstrated by using thinned fiber Bragg grating (FBG) sensors. When the cladding diameter is reduced, significant changes in the effective Refractive Index occur due to surrounding medium Refractive Index modifications, leading to Bragg wavelength shifts. Uniformly thinned FBGs have been obtained by using wet chemical etching in hydrofluoric acid solutions. In order to prove sensor sensitivity, experimental tests have been carried out by using glycerine solutions with well-known Refractive indices. Obtained results agree well with the numerical analysis carried out by using the three-layer fiber model. If the cladding layer is completely removed, resolutions of /spl ap/10/sup -5/ and /spl ap/10/sup -4/ for the outer Refractive Index around 1.450 and 1.333, respectively, are possible. Finally, a novel approach based on the selective etching along the grating region has been analyzed, leading to high-sensitivity Refractive Index sensors based on intensity measurements.

  • cladding mode reorganization in high Refractive Index coated long period gratings effects on the Refractive Index sensitivity
    Optics Letters, 2005
    Co-Authors: A Cusano, Agostino Iadicicco, S Campopiano, A Cutolo, P Pilla, Luigi Contessa, M Giordano
    Abstract:

    We theoretically and experimentally investigated the reorganization of cladding modes in high-Refractive-Index- (HRI-) coated long-period gratings (LPGs), focusing on the influence of Refractive-Index sensitivity. When azimuthally symmetric nanoscale HRI coatings are deposited along LPG devices, a significant modification of the distribution of cladding modes occurs, depending on the layers’ features (Refractive Index and thickness) and on the external Refractive Index. In particular, if these parameters are properly chosen, a transition between cladding modes and overlay modes occurs. Numerical and experimental effects of the mode transition on the sensitivity of the surrounding Refractive Index are described.

  • Refractive Index sensor based on microstructured fiber bragg grating
    IEEE Photonics Technology Letters, 2005
    Co-Authors: Agostino Iadicicco, S Campopiano, A Cutolo, M Giordano, A Cusano
    Abstract:

    In this work, an all-fiber high-resolution Refractive Index sensor based on a microstructured fiber Bragg grating is presented. The proposed structure relies on a partial and localized etching of the cladding layer along a standard grating. The main spectral changes of the structured grating are the increasing of the stopband and the formation of a narrow allowed band strongly dependent on the etching features and the surrounding Refractive Index. A sensor prototype has been fabricated by using wet etching and a proper masking procedure; experimental results reveal the possibility to carry out low-cost Refractive Index measurements with a resolution of 4/spl middot/10/sup -5/.

Agostino Iadicicco - One of the best experts on this subject based on the ideXlab platform.

  • mode transition in high Refractive Index coated long period gratings
    Optics Express, 2006
    Co-Authors: A Cusano, Agostino Iadicicco, S Campopiano, A Cutolo, P Pilla, Luigi Contessa, Michele Giordano
    Abstract:

    In this work, the numerical and experimental investigation of the cladding modes re-organization in high Refractive Index (HRI) coated Long Period Gratings (LPGs) is reported. Moreover, the effects of the cladding modes re-organization on the sensitivity to the surrounding medium Refractive Index (SRI) have been outlined. When azimuthally symmetric nano-scale HRI coatings are deposited along LPGs devices, a significant modification of the cladding modes distribution occurs, depending on the layer features (Refractive Index and thickness) and on the SRI. In particular, if layer parameters are properly chosen, the transition of the lowest order cladding mode into an overlay mode occurs. As a consequence, a cladding modes re-organization can be observed leading to relevant improvements in the SRI sensitivity in terms of wavelength shift and amplitude variations of the LPGs attenuation bands.

  • thinned fiber bragg gratings as Refractive Index sensors
    IEEE Sensors Journal, 2005
    Co-Authors: Agostino Iadicicco, S Campopiano, A Cutolo, A Cusano, M Giordano
    Abstract:

    In this work, highly sensitive Refractive Index measurements have been experimentally demonstrated by using thinned fiber Bragg grating (FBG) sensors. When the cladding diameter is reduced, significant changes in the effective Refractive Index occur due to surrounding medium Refractive Index modifications, leading to Bragg wavelength shifts. Uniformly thinned FBGs have been obtained by using wet chemical etching in hydrofluoric acid solutions. In order to prove sensor sensitivity, experimental tests have been carried out by using glycerine solutions with well-known Refractive indices. Obtained results agree well with the numerical analysis carried out by using the three-layer fiber model. If the cladding layer is completely removed, resolutions of /spl ap/10/sup -5/ and /spl ap/10/sup -4/ for the outer Refractive Index around 1.450 and 1.333, respectively, are possible. Finally, a novel approach based on the selective etching along the grating region has been analyzed, leading to high-sensitivity Refractive Index sensors based on intensity measurements.

  • cladding mode reorganization in high Refractive Index coated long period gratings effects on the Refractive Index sensitivity
    Optics Letters, 2005
    Co-Authors: A Cusano, Agostino Iadicicco, S Campopiano, A Cutolo, P Pilla, Luigi Contessa, M Giordano
    Abstract:

    We theoretically and experimentally investigated the reorganization of cladding modes in high-Refractive-Index- (HRI-) coated long-period gratings (LPGs), focusing on the influence of Refractive-Index sensitivity. When azimuthally symmetric nanoscale HRI coatings are deposited along LPG devices, a significant modification of the distribution of cladding modes occurs, depending on the layers’ features (Refractive Index and thickness) and on the external Refractive Index. In particular, if these parameters are properly chosen, a transition between cladding modes and overlay modes occurs. Numerical and experimental effects of the mode transition on the sensitivity of the surrounding Refractive Index are described.

  • Refractive Index sensor based on microstructured fiber bragg grating
    IEEE Photonics Technology Letters, 2005
    Co-Authors: Agostino Iadicicco, S Campopiano, A Cutolo, M Giordano, A Cusano
    Abstract:

    In this work, an all-fiber high-resolution Refractive Index sensor based on a microstructured fiber Bragg grating is presented. The proposed structure relies on a partial and localized etching of the cladding layer along a standard grating. The main spectral changes of the structured grating are the increasing of the stopband and the formation of a narrow allowed band strongly dependent on the etching features and the surrounding Refractive Index. A sensor prototype has been fabricated by using wet etching and a proper masking procedure; experimental results reveal the possibility to carry out low-cost Refractive Index measurements with a resolution of 4/spl middot/10/sup -5/.

H C Yang - One of the best experts on this subject based on the ideXlab platform.

  • origin and applications of magnetically tunable Refractive Index of magnetic fluid films
    Applied Physics Letters, 2004
    Co-Authors: Shieh-yueh Yang, Herng-er Horng, Jenje Chieh, Chin Yin Hong, H C Yang
    Abstract:

    When an external field was applied, the Refractive Index of the magnetic fluid film was observed to be modulated as the field exceeded a critical strength. We found that the stronger the magnetic field, the higher the Refractive Index. By taking both the formation of the columns and the variation in the concentration of the liquid phase in magnetic fluid films under external magnetic fields into account, the Refractive Index was calculated and compared with experimental data. When we did this, we noticed a consistency that implies that the phase separation leads to the variation in the Refractive Index of the magnetic fluid film as the magnetic field strength is changed. With such a property as a tunable Refractive Index, the feasibility of using a magnetic fluid in a tunable optical device is worthy of investigation.

  • thermal effect on the field dependent Refractive Index of the magnetic fluid film
    Applied Physics Letters, 2003
    Co-Authors: Yingchung Chen, Shieh-yueh Yang, Chin-yih Hong, Herng-er Horng, H C Yang
    Abstract:

    The field-dependent Refractive Index (nMF–H curve) of the magnetic fluid film (MFF) is measured at various temperatures to investigate the thermal effect on the Refractive Index. It was found, at a certain temperature, that the Refractive Index becomes higher under higher magnetic fields. This nMF–H curve is moved toward the region with lower nMF when the temperature is raised. Since the variation in the Refractive Index of the MF under external fields is due to the formation of the magnetic columns, the structural patterns are then examined to clarify the origin of the change in the nMF–H curve with the temperature. Under a given field strength, the particles of columns are dispersed into the liquid carrier at a higher temperature. This depresses the phase separation in the MFF under fields, and in turn, reduces the Refractive Index of the MFF. The observed results also reveal that the temperature exhibits a compensation effect on the Refractive Index of the MFF with respect to the magnetic field.

  • magnetically modulated Refractive Index of magnetic fluid films
    Applied Physics Letters, 2002
    Co-Authors: Shieh-yueh Yang, Chin-yih Hong, Herng-er Horng, Yute Chen, W S Tse, H C Yang
    Abstract:

    We developed a setup to probe the Refractive Index of the magnetic fluid films under external magnetic fields. This setup possesses a high resolution of 0.0001 in the measured Refractive Index. It was found that the Refractive Index of the magnetic fluid depends linearly on the concentration of the dilute magnetic fluid under zero field. For a given magnetic fluid film, the Refractive Index increases with the increasing field strength over a critical value, and then becomes saturated as the field reaches around 200 Oe. It is noteworthy that the magnetically modulated Refractive Index of the magnetic fluid films could have great potential in electro-optical applications.

M Giordano - One of the best experts on this subject based on the ideXlab platform.

  • thinned fiber bragg gratings as Refractive Index sensors
    IEEE Sensors Journal, 2005
    Co-Authors: Agostino Iadicicco, S Campopiano, A Cutolo, A Cusano, M Giordano
    Abstract:

    In this work, highly sensitive Refractive Index measurements have been experimentally demonstrated by using thinned fiber Bragg grating (FBG) sensors. When the cladding diameter is reduced, significant changes in the effective Refractive Index occur due to surrounding medium Refractive Index modifications, leading to Bragg wavelength shifts. Uniformly thinned FBGs have been obtained by using wet chemical etching in hydrofluoric acid solutions. In order to prove sensor sensitivity, experimental tests have been carried out by using glycerine solutions with well-known Refractive indices. Obtained results agree well with the numerical analysis carried out by using the three-layer fiber model. If the cladding layer is completely removed, resolutions of /spl ap/10/sup -5/ and /spl ap/10/sup -4/ for the outer Refractive Index around 1.450 and 1.333, respectively, are possible. Finally, a novel approach based on the selective etching along the grating region has been analyzed, leading to high-sensitivity Refractive Index sensors based on intensity measurements.

  • cladding mode reorganization in high Refractive Index coated long period gratings effects on the Refractive Index sensitivity
    Optics Letters, 2005
    Co-Authors: A Cusano, Agostino Iadicicco, S Campopiano, A Cutolo, P Pilla, Luigi Contessa, M Giordano
    Abstract:

    We theoretically and experimentally investigated the reorganization of cladding modes in high-Refractive-Index- (HRI-) coated long-period gratings (LPGs), focusing on the influence of Refractive-Index sensitivity. When azimuthally symmetric nanoscale HRI coatings are deposited along LPG devices, a significant modification of the distribution of cladding modes occurs, depending on the layers’ features (Refractive Index and thickness) and on the external Refractive Index. In particular, if these parameters are properly chosen, a transition between cladding modes and overlay modes occurs. Numerical and experimental effects of the mode transition on the sensitivity of the surrounding Refractive Index are described.

  • Refractive Index sensor based on microstructured fiber bragg grating
    IEEE Photonics Technology Letters, 2005
    Co-Authors: Agostino Iadicicco, S Campopiano, A Cutolo, M Giordano, A Cusano
    Abstract:

    In this work, an all-fiber high-resolution Refractive Index sensor based on a microstructured fiber Bragg grating is presented. The proposed structure relies on a partial and localized etching of the cladding layer along a standard grating. The main spectral changes of the structured grating are the increasing of the stopband and the formation of a narrow allowed band strongly dependent on the etching features and the surrounding Refractive Index. A sensor prototype has been fabricated by using wet etching and a proper masking procedure; experimental results reveal the possibility to carry out low-cost Refractive Index measurements with a resolution of 4/spl middot/10/sup -5/.

S Campopiano - One of the best experts on this subject based on the ideXlab platform.

  • mode transition in high Refractive Index coated long period gratings
    Optics Express, 2006
    Co-Authors: A Cusano, Agostino Iadicicco, S Campopiano, A Cutolo, P Pilla, Luigi Contessa, Michele Giordano
    Abstract:

    In this work, the numerical and experimental investigation of the cladding modes re-organization in high Refractive Index (HRI) coated Long Period Gratings (LPGs) is reported. Moreover, the effects of the cladding modes re-organization on the sensitivity to the surrounding medium Refractive Index (SRI) have been outlined. When azimuthally symmetric nano-scale HRI coatings are deposited along LPGs devices, a significant modification of the cladding modes distribution occurs, depending on the layer features (Refractive Index and thickness) and on the SRI. In particular, if layer parameters are properly chosen, the transition of the lowest order cladding mode into an overlay mode occurs. As a consequence, a cladding modes re-organization can be observed leading to relevant improvements in the SRI sensitivity in terms of wavelength shift and amplitude variations of the LPGs attenuation bands.

  • thinned fiber bragg gratings as Refractive Index sensors
    IEEE Sensors Journal, 2005
    Co-Authors: Agostino Iadicicco, S Campopiano, A Cutolo, A Cusano, M Giordano
    Abstract:

    In this work, highly sensitive Refractive Index measurements have been experimentally demonstrated by using thinned fiber Bragg grating (FBG) sensors. When the cladding diameter is reduced, significant changes in the effective Refractive Index occur due to surrounding medium Refractive Index modifications, leading to Bragg wavelength shifts. Uniformly thinned FBGs have been obtained by using wet chemical etching in hydrofluoric acid solutions. In order to prove sensor sensitivity, experimental tests have been carried out by using glycerine solutions with well-known Refractive indices. Obtained results agree well with the numerical analysis carried out by using the three-layer fiber model. If the cladding layer is completely removed, resolutions of /spl ap/10/sup -5/ and /spl ap/10/sup -4/ for the outer Refractive Index around 1.450 and 1.333, respectively, are possible. Finally, a novel approach based on the selective etching along the grating region has been analyzed, leading to high-sensitivity Refractive Index sensors based on intensity measurements.

  • cladding mode reorganization in high Refractive Index coated long period gratings effects on the Refractive Index sensitivity
    Optics Letters, 2005
    Co-Authors: A Cusano, Agostino Iadicicco, S Campopiano, A Cutolo, P Pilla, Luigi Contessa, M Giordano
    Abstract:

    We theoretically and experimentally investigated the reorganization of cladding modes in high-Refractive-Index- (HRI-) coated long-period gratings (LPGs), focusing on the influence of Refractive-Index sensitivity. When azimuthally symmetric nanoscale HRI coatings are deposited along LPG devices, a significant modification of the distribution of cladding modes occurs, depending on the layers’ features (Refractive Index and thickness) and on the external Refractive Index. In particular, if these parameters are properly chosen, a transition between cladding modes and overlay modes occurs. Numerical and experimental effects of the mode transition on the sensitivity of the surrounding Refractive Index are described.

  • Refractive Index sensor based on microstructured fiber bragg grating
    IEEE Photonics Technology Letters, 2005
    Co-Authors: Agostino Iadicicco, S Campopiano, A Cutolo, M Giordano, A Cusano
    Abstract:

    In this work, an all-fiber high-resolution Refractive Index sensor based on a microstructured fiber Bragg grating is presented. The proposed structure relies on a partial and localized etching of the cladding layer along a standard grating. The main spectral changes of the structured grating are the increasing of the stopband and the formation of a narrow allowed band strongly dependent on the etching features and the surrounding Refractive Index. A sensor prototype has been fabricated by using wet etching and a proper masking procedure; experimental results reveal the possibility to carry out low-cost Refractive Index measurements with a resolution of 4/spl middot/10/sup -5/.