A compact 100 GHz femtojoule silicon-organic hybrid modulator based on a novel Mach–Zehnder interferometer design

In this paper a high speed, low power and compact silicon-organic hybrid (SOH) modulator operating at the telecom wavelength is presented. The modulator is based on the mature and widespread silicon–on-insulator (SOI) technology with device layer of 220nm. The proposed design utilize slot waveguide in a loop-terminated MZI (LT-MZI) configuration. LT-MZI is two times more compact than the conventional MZI. Accordingly, LT-MZI modulator exhibit two times lower capacitance which enhances the modulator speed and power consumption by a factor of two. Electro-optic polymer is used as it exhibit fast and strong electro-optic effect. Finite element and finite difference simulations show that for driving voltage of only 0.5 V our modulator arms' length is as low as 167 µm resulting in Vπ×L product of only 0.084 V.mm, 10.41 fF capacitance and up to 100 GHz speed with corresponding energy consumption of only 6.755 fJ/bit. Results based on 3D Finite difference time domain (FDTD) simulation show that our modulator can work over a large optical bandwidth of 60nm with extinction ratio (ER) greater than 23 dB and insertion loss (IL) less than 1.7 dB reaching ER = 40 dB and IL = 1.15 dB at λ=1.55 µm.