Ion trap electric field characterization using slab coupled optical fiber sensors.

This paper presents a method for characterizing electric field profiles of radio frequency (rf) quadrupole ion trap structures using sensors based on slab coupled optical-fiber sensor (SCOS) technology. The all-dielectric and virtually optical fiber-sized SCOS fits within the compact environment required for ion traps and is able to distinguish electric field orientation and amplitude with minimal perturbation. Measurement of the fields offers insight into the functionality of traps, which may not be obtainable solely by performing simulations. The SCOS accurately mapped the well-known field profiles within a commercially available three-dimensional quadrupole ion trap (Paul trap). The results of this test allowed the SCOS to map the more complicated fields within the coaxial ion trap with a high degree of confidence as to the accuracy of the measurement. Figure ᅟ

Frequency dependence of slab coupled optical sensor sensitivity.

This paper presents the frequency-dependent sensitivity of slab-coupled optical fiber sensors (SCOSs). This dependence is caused by the frequency characteristics of the relative permittivity. We show experimentally the frequency dependence of SCOS sensitivity for frequencies in the range of 1 kHz to 1 MHz for SCOS fabricated with both potassium titanyl phosphate (KTP) and lithium niobate (LiNbO(3)). We conclude that x-cut KTP SCOSs are preferred for measuring fields above 300 kHz as they are 1.55× more sensitive than x-cut LiNbO(3) SCOSs to the higher frequency fields. However, since KTP SCOSs experience increasing permittivity for low frequencies, SCOSs made with LiNbO(3) may be used for low frequency sensing applications due to their flat sensitivity response. For a 10 kHz electric field, an x cut LiNbO(3) SCOS is approximately 3.43× more sensitive than an x-cut KTP SCOS.

Improvements in electric-field sensor sensitivity by exploiting a tangential field condition.

This paper presents improvements to slab-coupled optical fiber sensors for electric-field sensing. The sensors are comprised of a potassium titanyl phosphate (KTP) crystal mounted on a D-fiber. The improvements are based on changing the crystal orientation, which enhances sensitivity due to a combined increase in the effective electro-optic coefficient and electric-field penetration into the KTP crystal. The paper provides a detailed comparison of the improved sensor, which uses x-cut KTP to the previous sensor design using z-cut KTP. The measurements show an 8.6× improvement in the sensitivity.

Single tunable laser interrogation of slab-coupled optical sensors through resonance tuning.

This paper describes a method for tuning the resonant wavelengths of slab-coupled optical fiber sensors (SCOSs). This method allows multiple sensors to be interrogated simultaneously with a single tunable laser. The resonances are tuned by rotating a biaxial slab waveguide relative to an optical D-fiber. As the slab waveguide rotates, its effective index of refraction changes causing the coupling wavelengths of the slab waveguide and D-fiber to shift. A SCOS fabricated with potassium titanyl phosphate crystal as the slab waveguide is shown to have resonance tuning ranges of 6.67 and 22.24 nm, respectively, for TM and TE polarized modes.

Multiaxis electric field sensing using slab coupled optical sensors.

This paper provides the details of a multiaxis electric field sensor. The sensing element consists of three slab coupled optical-fiber sensors that are combined to allow directional electric field sensing. The packaged three-axis sensor has a small cross-sectional area of 0.5 cm×0.5 cm by using an x-cut crystal. A method is described that uses a sensitivity-matrix approach to map the measurements to field components. The calibration and testing are described, resulting in an average error of 1.5°.

Electric-field sensors utilizing coupling between a D-fiber and an electro-optic polymer slab.

This paper provides a detailed analysis of electric field sensing using a slab-coupled optical fiber sensor (SCOS). This analysis explains that the best material for the slab waveguide is an inorganic material because of the low RF permittivity combined with the high electro-optic coefficient. The paper also describes the fabrication and testing of a SCOS using an AJL chromophore in amorphous polycarbonate. The high uniform polymer slab waveguide is fabricated using a hot embossing process to create a slab with a thickness of 50 µm. The fabricated polymer SCOS was characterized to have a resonance slope of ΔP/Δλ=6.83E5 W/m and a resonance shift of Δλ/E=1.47E-16 m(2)/V.