This paper demonstrates the value of D-type optical fibers (D-fibers) in a variety of sensing applications. The principal
advantage of the D-fiber is that it allows for interaction with light traveling in the core of an optical fiber with materials
or structures placed in contact with the fiber. This permits stimulus sensitive materials to be placed on the D-fiber to
interact with the light in the core of the fiber. The presentation shows that this feature of D-fibers can be used to create
alternatives to sensors formed in standard optical fibers for measuring temperature, strain, and shape change. In addition,
D-fiber sensors have been fabricated to measure chemical concentrations, and electric fields.
Modern electronics are often shielded with metallic packaging to protect them from harmful electromagnetic
radiation. In order to determine the effectiveness of the electronic shielding, there is a need to perform non-intrusive
measurements of the electric field within the shielding. The requirement to be non-intrusive requires
the sensor to be all dielectric and the sensing area needs to be very small. The non-intrusive sensor is attained
by coupling a slab of non-linear optical material to the surface of a D shaped optical fiber and is called a slab
coupled optical fiber sensor (SCOS). The sensitivity of the SCOS is increased by using an organic electro-optic
High powered microwave weapons use electric fields to overload electronics. We developed a non-intrusive sensor
using a technology based on slab coupled optical sensing (SCOS). Each sensor detects the electric field component
normal to the surface of the slab. By mounting two of these sensors orthogonally to each other, a more complete
image of the electrical field can be obtained. One of the major hurdles of creating a multi-axial SCOS is keeping the
size of the sensor small. The size is limited by (1) the size of the sensing material and (2) the ability to package the
sensor to maintain its structural integrity and orientation. Good sensitivity is attained with SCOS with a length less
than 3 mm and the D-fiber platform has a small core which allows for much less bending loss than standard single
mode fiber. We have developed a mounting system that is heat resistant and structurally robust to protect the sensor
that is extremely small when compared to traditional electric field sensors.
We develop an electric field sensor array based on optical fiber interrogation with electro-optic crystals to measure high
energy electromagnetic pulses. The D-shaped optical fiber used in this work provides the platform for resonant coupling
with multiple electro-optic crystals to allow an array of sensing points on a single strand of optical fiber. Because of its
uniquely small size, this sensor array is suitable for performing electric-field analysis at multiple points within an
electronic device due to its flexibility and dielectric composition. Using Lithium Niobate and Potassium Titanyl
Phosphate crystals, the sensor array in this work is sensitive to fields as low as 100 V/m.
We recently reported on a new fiber Bragg grating etched into the flat surface of a D-fiber and its potential use as a high temperature sensor. Since then we have investigated more in depth many of the characteristics that are unique due to the surface relief nature of the grating. In this paper we show that a surface relief fiber Bragg grating exhibits some significant advantages when compared to standard fiber Bragg gratings including: high temperature operation, polarization selectivity, and the ability for multi axis strain sensing. We also show the uniqueness of these gratings for bend sensing with two degrees of freedom.