"High-sensitivity high-resolution refractometry with twin turn-around-point long-period gratings in a photonic crystal fiber"@en . "RIV/67985882:_____/13:00396688!RIV14-MSM-67985882" . . . . "978-0-8194-9577-8" . "Prague" . "I, P(LD11030)" . "High-sensitivity high-resolution refractometry with twin turn-around-point long-period gratings in a photonic crystal fiber"@en . . . "77436" . "SPIE-INT SOC OPTICAL ENGINEERING" . . . . . "[5771D5726430]" . "MICRO-STRUCTURED AND SPECIALTY OPTICAL FIBRES II" . . "1"^^ . . "RIV/67985882:_____/13:00396688" . "1"^^ . "Ka\u0148ka, Ji\u0159\u00ED" . . "BELLINGHAM" . "9"^^ . . "0277-786X" . "High-sensitivity high-resolution refractometry with twin turn-around-point long-period gratings in a photonic crystal fiber" . "000323548700020" . "We present the numerical design of a turn-around-point long-period grating in a photonic crystal fiber (TAP PCF-LPG) for high-sensitivity, high-resolution refractometry of gases. High refractive-index sensitivity is achieved by operating LPGs in the vicinity of the dispersion turning point of the optimized PCF. Despite the resonant wavelength of the optimized PCF-LPG is highly sensitive to the refractive index of analytes, its large shifts could be monitored with a reduced resolution because the resonance dip in the TAP LPG transmission spectrum is broad. To provide also high refractive-index resolution, twin TAP-LPGs have been proposed to be used as 3 dB broadband mode converters in the interferometric scheme. The first LPG couples a portion of the light in the core mode to a forward propagating cladding mode and the second LPG couples the light back to the core mode. The resulting interference fringes within the envelope of LPG attenuation dip provide a means for higher resolution sensing. Instead of monitoring the wavelength shift as a result of a refractive index change, the transmission spectrum can also be analyzed in terms of the shift in phase suffered by the fringe pattern. This is a more accurate way of interpreting the interferometric sensor measurements, since the phase shift is a direct result of an analyte-induced change in optical path length"@en . . . . "High-sensitivity high-resolution refractometry with twin turn-around-point long-period gratings in a photonic crystal fiber" . . . "10.1117/12.2017335" . "We present the numerical design of a turn-around-point long-period grating in a photonic crystal fiber (TAP PCF-LPG) for high-sensitivity, high-resolution refractometry of gases. High refractive-index sensitivity is achieved by operating LPGs in the vicinity of the dispersion turning point of the optimized PCF. Despite the resonant wavelength of the optimized PCF-LPG is highly sensitive to the refractive index of analytes, its large shifts could be monitored with a reduced resolution because the resonance dip in the TAP LPG transmission spectrum is broad. To provide also high refractive-index resolution, twin TAP-LPGs have been proposed to be used as 3 dB broadband mode converters in the interferometric scheme. The first LPG couples a portion of the light in the core mode to a forward propagating cladding mode and the second LPG couples the light back to the core mode. The resulting interference fringes within the envelope of LPG attenuation dip provide a means for higher resolution sensing. Instead of monitoring the wavelength shift as a result of a refractive index change, the transmission spectrum can also be analyzed in terms of the shift in phase suffered by the fringe pattern. This is a more accurate way of interpreting the interferometric sensor measurements, since the phase shift is a direct result of an analyte-induced change in optical path length" . "fibre design; Photonic crystal fibres; interferometric sensor"@en . "2013-04-15+02:00"^^ .