The application of nematic liquid crystal infiltrated photonic crystal fiber as a sensor for electric field intensity measurement is demonstrated. The device is based on an intrinsic sensing mechanism for electric fields. The sensor probe, which consists of a $1\mathrm{cm}$ infiltrated section of photonic crystal fiber with a lateral size of $\sim 125\mathrm{\mu m}$, is very compact with small size and weight. A simple all-fiber design for the sensor is employed in an intensity based measurement scheme. The transmitted and reflected power of the infiltrated photonic crystal fiber is shown to have a linear response with the applied electric field. The sensor is operated in the telecommunication window at $1550\mathrm{nm}$. The temperature dependence of the device at this operating wavelength is also experimentally studied and discussed. These structures can be used to accurately measure electric field intensity and can be used for the fabrication of all-fiber sensors for high electric field environments as both an in-line and reflective type point sensor.

Intravascular imaging in percutaneous coronary interventions can be an invaluable tool in the treatment of coronary artery disease. It is of significant interest to provide molecular imaging contrast that is complementary to structural contrast provided by optical coherence tomography (OCT) and intravascular ultrasound imaging (IVUS). In this study, we developed a dual-modality intravascular imaging probe comprising a commercial OCT catheter and a high sensitivity fiber optic ultrasound sensor, to provide both photoacoustic (PA) and OCT imaging. With PA imaging, the lateral resolution varied from 18 μm to 40 μm; the axial resolution was consistently in the vicinity of 45 μm. We demonstrated the clinical potential of the probe with 2-D circumferential PA and OCT imaging, and with multispectral PA imaging.

The directional sensitivity of nematic liquid crystal infiltrated polarization-maintaining photonic crystal fiber to an externally applied electric field is evaluated for two-dimensional electric field sensing. Selectively infiltrated and infiltration length optimized polarization-maintaining photonic crystal fiber is used as a probe. Using a polarimetric scheme, the polarized transmission properties of the infiltrated fiber are evaluated in terms of the orientation of the fiber polarization axis in an electric field. It is shown that the sensor has varying sensitivity to electric fields oriented at different angles with respect to the fiber polarization axis. The proposed low-cost all-fiber sensor can be used for two-dimensional directional electric field sensing.

The electronic tunability of ferroelectric liquid crystal filled photonic crystal fibres is demonstrated for the first time. The tunability is obtained in the wavelength range of 1500–1600 nm, with a free spectral range of∼20 nm. The electronic tunability is achieved by applying an electric field onto the infiltrated photonic crystal fibre which facilitates the photonic bandgap tuning owing to the microsecond-order switching speeds of ferroelectric liquid crystals. The polarised transmission spectrum shows the behaviour of a tunable notch filter with a change in applied voltage. The results obtained could pave the way for the fabrication of fast tunable all-in-fibre devices in the telecom wavelength range.