Effective in-device r_33 of 735 pm/V on electro-optic polymer infiltrated silicon photonic crystal slot waveguides

Abstract

We design and fabricate a 320 nm slot for an electro-optic (E-O) polymer infiltrated silicon photonic crystal waveguide. Because of the large slot width, the poling efficiency of the infiltrated E-O polymer (AJCKL1/amorphous polycarbonate) is significantly improved. When coupled with the slow light effect from the silicon photonic crystal waveguide, an effective in-device r(33) of 735 pm/V, which to our knowledge is a record high, is demonstrated, which is ten times higher than the E-O coefficient achieved in thin film material. Because of this ultrahigh E-O efficiency, the V(π)L of the device is only 0.44 V mm, which is to our knowledge the best result of all E-O polymer modulators.

Electro-optic polymer/TiO2 multilayer slot waveguide modulators

“…Because of the lower poling efficiency of EO polymers when compared with our previous hybrid EO polymer/sol-gel silica waveguide modulators, 2,3 the highest in-device EO coefficient for EO polymers in coplanar Si-EO polymer slot waveguides was limited to 59 pm/V. 8 Additionally, the dielectric constant of TiO 2 was higher (i.e., >30) than that of the EO polymers used (e.g., $2). When the TiO 2 thin layer was used with an EO polymer layer, the enhanced effective field in the EO polymer layer reduced V p .…”

“…To realize the potential of EO polymers for large 3-dB bandwidths of more than 100 GHz, we used metallic upper and lower electrodes rather than the previously demonstrated highly doped Si electrodes. [4][5][6][7][8] This slot waveguide approach aims to reduce V p and optical insertion loss while maintaining a large 3-dB bandwidth.…”

“…Determining the butt coupling process from a cleaved SM fiber to a SM passive Si waveguide on a SiO 2 insulator (e.g., MFD < 0.4 lm) has been challenging 10 because the coupling from the SM fiber to SM Si waveguide usually involves mode converters or grating couplers. In contrast to these active EO polymer/Si slot waveguides [5][6][7][8] and passive Si waveguides, 10 our slot waveguide enabled butt coupling while maintaining EO activity and low insertion loss. An EO modulator using this all-dielectric waveguide would have an EO modulation bandwidth (e.g., >60 GHz) larger than that of previously reported Si slot/EO polymer waveguide modulators [5][6][7][8] because of its highly conductive Au electrode (without using a highly doped Si conductor as the electrode), which is easily modified to act as a microstrip line for millimeter-wave propagation.…”

“…In contrast to these active EO polymer/Si slot waveguides [5][6][7][8] and passive Si waveguides, 10 our slot waveguide enabled butt coupling while maintaining EO activity and low insertion loss. An EO modulator using this all-dielectric waveguide would have an EO modulation bandwidth (e.g., >60 GHz) larger than that of previously reported Si slot/EO polymer waveguide modulators [5][6][7][8] because of its highly conductive Au electrode (without using a highly doped Si conductor as the electrode), which is easily modified to act as a microstrip line for millimeter-wave propagation. The type II waveguide had better mode confinement, which permitted a thinner lower cladding because of the thinner EO polymer and thicker TiO 2 layers.…”

Thermo-optic switch based on transmission-dip shifting in a double-slot photonic crystal waveguide

“…5,8,9 Another one is photonic crystal waveguide (PCWG) with the help of slow light effect, which could be achieved with a flexible design of the photonic band structure. [10][11][12][13] There are two operating mechanisms reported for the PCWG based optical switches. One is applying PCWGs on the conventional Mach-Zehnder interferometers (MZIs) 5,6 or directional couplers, 3 where PCWGs are used to realize p phase-shift with a small size, a low operating power.…”