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Fabry-Perot etalons using electro-optic (EO) organic materials can be used for devices such as tunable
filters and spatial light modulators (SLM's) for wavelength division multiplexing (WDM) communication
systems1-5 and ultrafast imaging systems. For these applications the SLM's need to have: (i) low insertion
loss, (ii) high speed operation, and (iii) large modulation depth with low drive voltage. Recently, there have
been three developments which together can enhance the SLM performance to a higher level. First, low
loss distributed Bragg reflector (DBR) mirrors are now used in SLM's to replace thin metal mirrors, resulting
in reduced transmission loss, high reflectivity (>99%) and high finesse. Second, EO polymer materials
have shown excellent properties for wide bandwidth optical modulation for information technology due to
their fabrication flexibility, compatibility with high speed operation, and large EO coefficients at
telecommunication wavelengths. For instance, the EO polymer AJL8/APC (AJL8: nonlinear optical
chromophore, and APC: amorphous polycarbonate has recently been incorporated into waveguide
modulators and achieved good performance for optical modulation. Finally, very low loss transparent
conducting oxide (TCO) electrodes have drawn increasing attention for applications in optoelectronic devices.
Here we will address how the low loss indium oxide (In2O3) electrodes with an absorption coefficient
~1000/cm and conductivity ~204 S/cm can help improve the modulation performance of EO polymer
Fabry-Pérot étalons using the advanced electro-optic (EO) polymer material (AJL8/APC). A hybrid etalon
structure with one highly conductive indium tin oxide (ITO) electrode outside the etalon cavity and one
low-absorption In2O3 electrode inside etalon cavity has been demonstrated. High finesse (~234), improved
effective applied voltage ratio (~0.25), and low insertion loss (~4 dB) have been obtained. A 10 dB
isolation ratio and ~10% modulation depth at 200 kHz with only 5 V applied voltage have been achieved.
These results indicate that such etalons are very promising candidates for ultrafast spatial light modulation in
information technology.
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