23 February 2012 Improved performance of traveling wave directional coupler modulator based on electro-optic polymer
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Proceedings Volume 8267, Optoelectronic Interconnects XII; 82671B (2012) https://doi.org/10.1117/12.907744
Event: SPIE OPTO, 2012, San Francisco, California, United States
Polymer based electro-optic modulators have shown great potentials in high frequency analog optical links. Existing commercial LiNibO3 Mach-Zehnder modulators have intrinsic drawbacks in linearity to provide high fidelity communication. In this paper, we present the design, fabrication and characterization of a traveling wave directional coupler modulator based on electro-optic polymer, which is able to provide high linearity, high speed, and low optical insertion loss. A silver ground electrode is used to reduce waveguide sidewall roughness due to the scattering of UV light in photolithography process in addition to suppressing the RF loss. A 1x2 multi-mode interference 3dB-splitter, a photobleached refractive index taper and a quasi-vertical taper are used to reduce the optical insertion loss of the device. The symmetric waveguide structure of the MMI-fed directional coupler is intrinsically bias-free, and the modulation is obtained at the 3-dB point regardless of the ambient temperature. By achieving low RF loss, characteristic impedance matching with 50Ω load, and excellent velocity matching between the RF wave and the optical wave, a travelling wave electrode is designed to function up to 62.5GHz. Domain-inversion poling with push-pull configuration is applied using alternating pulses on a 2-section directional-coupler to achieve a spurious free dynamic range of 110dB/Hz2/3. The 3-dB electrical bandwidth of device is measured to be 10GHz.
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Xingyu Zhang, Xingyu Zhang, Beomsuk Lee, Beomsuk Lee, Che-Yun Lin, Che-Yun Lin, Alan X. Wang, Alan X. Wang, Amir Hosseini, Amir Hosseini, Xiaohui Lin, Xiaohui Lin, Ray T. Chen, Ray T. Chen, } "Improved performance of traveling wave directional coupler modulator based on electro-optic polymer", Proc. SPIE 8267, Optoelectronic Interconnects XII, 82671B (23 February 2012); doi: 10.1117/12.907744; https://doi.org/10.1117/12.907744

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