Simultaneous detection of intensity and polarization at the pixel-level has many important applications in the mid-infrared
region. In this work a large-format aluminum wire grid micro polarizer array has been fabricated and tested on
silicon substrates. The arrays were made on 150mm silicon wafers using a 193nm deep-UV stepper, with each array
spanning over 1-million pixels. A unique multilayer design and a large-area nanoscale projection lithography combined
with high-aspect ratio wire-grid structures were utilized to achieve optimum extinction coefficient and transmission.
Measured extinction coefficients on test samples exceeded 30-dB, with maximum transmission around 90%. These
arrays could be designed to match the focal-plane array geometry for integration with mid-IR imagers.
Past work with polarimetry in the mid-wave infrared (MWIR) has yielded mixed results. In order to better characterize
polarimetric content in the MWIR and short-wave infrared (SWIR) atmospheric windows, we are developing focal
plane array (FPA) technology that will address shortcomings in earlier devices. In particular, our efforts are focusing on
placing micro-polarizing grids in very close proximity to the P-N junction of the detector. By placing these micropolarizers
very close to the photodetector junction, the opportunity for polarimetric cross talk between pixels is
minimized. CE's unique process for fabricating FPAs is well suited for implementing this approach. Since a
polarimetric FPA consisting of a standard FPA and micro-wire grid polarizers reduces the effective FPA format by a
factor of two in both dimensions, the ability to produce extremely large format FPAs are critical to obtain high
resolution polarimetric imagery. CE's FPA fabrication process is also highly scalable and has successfully fabricated
FPAs as large as 2k by 2k. This paper describes the progress we've made towards developing these unique polarimetric
We present experimental results of second harmonic generation enhancement through the resonance of the band edge in a photonic crystal based on lithium niobate. Proton exchange technique was used to fabricate a waveguide near the surface of the lithium niobate substrate. The photonic crystal structure over the waveguide was made by UV laser interferometry. Subsequently experiments were designed to quantify the Cerenkov second-harmonic generation (CSHG) radiated into the substrate. The SHG radiated inside the waveguides was also experimentally investigated. In our experiments, the second guided mode of the waveguide was tuned to the band edge resonance to enhance the second harmonic generation. The highest conversion efficiency of CSHG using photonic band gap (PBG) was around 50 times compared to SHG emission from non-patterned lithium niobate. A numerical model was used to corroborate the experimental result. It was also found that the SHG signal in the waveguides is quenched compared to the CSHG signal.
The photoluminescence (PL) and amplified spontaneous emission (ASE) spectra of the conjugated polymer [2-methoxy-5-(2'- ethylhexyloxy)-1, 4-phenylenevinylene] (MEH-PPV) is study under different conditions such as thin film and solution, solvent type and concentration. Experiments indicate that aggregation has a pronounced effect on the measured spectra of both the PL and the ASE. In solution form, the ASE emission bandwidth decreases with the increment on concentration as well as a red shift of the ASE peak. For the thin film samples, the ASE spectra show two emission bands corresponding to the emission of the inner and the outer polymer chains. These two emission bands were associated with the gas to crystal effect, previously reported for PL.
Conference Committee Involvement (1)
Nano- and Microphotonics: Materials, Devices, Processing, and Applications