Investigation of an In-Line Slot Waveguide Sensor Built in a Tapered D-Shaped Silicon-Cored Fiber

An in-line slot waveguide sensor built in a polished flat platform of a D-shaped silicon cored fiber with a taper coupled region is proposed and investigated thoroughly. Simulation results show that the single-mode light field sustained in the silicon cored fiber can be efficiently transferred to the slot waveguides through the tapered region. The geometry parameters of the slot waveguide sensors are optimized to have the corresponding highest power confinement factors and the resultant sensor sensitivities. The three-slot waveguide sensor is found to have the best performance among one-, two- and three-slot waveguides at the mid-IR wavelength.

Preliminary study on the new wound monitoring technology using co-planar waveguide sensor: Modeling and simulation

BACKGROUND: Wound monitoring is very meaningful for the clinical research, diagnosis and treatment. But the existing wound monitoring technology is hard to meet the needs of modern medical care in terms of real-time, non-invasive and anti-interference. OBJECTIVE: To solve this problem, this paper proposed a new kind of monitoring technology based on the co-planar waveguide transmission line theory and assessed the application value of this method as a wound monitoring technology. METHODS: The simplified wound model included the skin, fat, muscle, tissue fluid and bandage and a new co-planar waveguide sensor were designed and established. All of the simulation was achieved in the electromagnetic special software. The data processing method was based on the transmission line theory. RESULTS: Detailed analyses of the results from the simulation were conducted. The sensor has a good monitoring effect in the low frequency band. The monitoring results could be influenced by the thickness of the bandage outside the wound. The thickness of the bandage should not be larger than 10 mm. The effective monitoring area of the sensor is 30 × 20 mm2. CONCLUSIONS: The proposed sensor based on the CPW transmission principle in this paper has good wound monitoring potential.

Extraordinary evanescent field confinement waveguide sensor for mid-infrared trace gas spectroscopy

Nanophotonic waveguides are at the core of a great variety of optical sensors. These structures confine light along defined paths on photonic chips and provide light–matter interaction via an evanescent field. However, waveguides still lag behind free-space optics for sensitivity-critical applications such as trace gas detection. Short optical pathlengths, low interaction strengths, and spurious etalon fringes in spectral transmission are among the main reasons why on-chip gas sensing is still in its infancy. In this work, we report on a mid-infrared integrated waveguide sensor that successfully addresses these drawbacks. This sensor operates with a 107% evanescent field confinement factor in air, which not only matches but also outperforms free-space beams in terms of the per-length optical interaction. Furthermore, negligible facet reflections result in a flat spectral background and record-low absorbance noise that can finally compete with free-space spectroscopy. The sensor performance was validated at 2.566 μm, which showed a 7 ppm detection limit for acetylene with only a 2 cm long waveguide.