High Performance Electric-Field Sensor Based on Enhanced Electro-Optic Polymer Refilled Slot Photonic Crystal Waveguides

Period of Performance: 05/15/2012 - 02/15/2013


Phase 1 STTR

Recipient Firm

Omega Optics, Inc.
8500 Shoal Creek Road, Bldg4/Ste200 Array
Austin, TX 78757
Principal Investigator
Firm POC

Research Institution

University of Texas at Austin
10100 Burnet Road, Bldg 160 J. J. Pickle Research Campus
Austin, TX 78758
Institution POC


ABSTRACT: In this program, we propose to develop a miniaturized Electromagnetic (EM) wave sensor based on defect engineered slotted photonic crystal waveguide (PCW) Mach Zehnder interferometer (MZI). EO polymers with large EO coefficient (r33>150pm/V) will be designed and synthesized to refill the slot PCW in order to take advantage of high field concentration in the narrow slots. Band engineered slot PCW slows down the light propagation, and thus increases the light-EO polymer intraction over its optical bandwidth, while maintaining a constant group index of ~22 (low dispersion). Low dispersion propagation and inverted domain poling for EO polymer are adopted to enhance the linearity of sensor operation, and thus its dynamic range (1V/m-1000kV/m) with an RF band coverage from 1 MHz to 40 GHz. Input/ouput PCW couplers consisting of optical mode convertor and adiabatic group index tapers will be used to minimize the device optical insertion loss. The slot dimensions and poling electrodes are designed for maximum poling efficiency. This device will benefit from three enhancement mechanisms: 1. large EO coefficient from polymer (>~150pm/V), 2. slow light effect (10X to 100X enhancement) and 3. high concentration of photon energy in the slot region (50X enhancement). This unique combination, can provide an integrated hybrid silicon-EO polymer based modulator/sensor chip with an in-device effective r33 of >75000pm/V (150pm/V*10*50) for different RF photonics applications requiring low power, linearized high speed operation. EO polymer synthesis techniques for potential mass-production will pave a smooth transition to increase the RF performance while reducing the cost of future dual-use RF photonic systems. BENEFIT: Electromagnetic (EM) wave measurements are required in various scientific and technical areas, including process control, EM-field monitoring in medical apparatuses, ballistic control, electromagnetic compatibility measurements, microwave integrated circuit testing, and detection of directional energy weapon attack. Conventional EM wave measurement systems use active metallic probes (small anteneas), which disturb the EM waves to be measured and render the sensor very sensitive to electromagnetic noises. Photonic EM-field sensors exhibit significant advantages with respect to the electronic ones due to their smaller size, lighter weight, higher sensitivity, and extremely broad bandwidth. However, photonic EM-field sensors using Mach-Zehnder Interferometer (MZI) or ring resonators are facing significant challenges in their spurious free dynamic range (SFDR) for high fidelity measurement of the EM waves (typical 70% linearity with conventional MZIs). The proposed MZI based EM sensor is the most compact-size (less than 2mm total device length) that provides large dynamic range (1V/m-10MV/m) and linearity (over 90%) and has the potential for use in wide range of defense and civilian applications.