The integration of nanophotonics components with advanced complementary metal-oxide-semiconductor (CMOS) electronics requires drive voltages as low as 1 V for enabling next-generation CMOS electrophotonics transceivers. Slow-light propagation has been recently demonstrated as an effective mechanism to enhance the modulation efficiency in free-carrier-based electrooptical silicon modulators. Here, we exploit the use of slow light to reduce the driving voltage of carrier-depletion-based Mach-Zehnder modulators. The slowlight phase shifter consists of a p-n junction positioned in the middle of a corrugated waveguide. A modulation efficiency as high as V L $ 0:6 V Á cm is achieved, thus allowing data transmission rates up to 10 Gb/s with a 1.5-V pp drive voltage and an insertion loss of $12 dB. The influence of the drive voltage on the modulation speed as well as the variation of the insertion losses with a group index is also analyzed and discussed.

Abstract-A polarization rotator in silicon-on-insulator technology based on breaking the symmetry of the waveguide cross section is reported. The 25-µm-long device is designed to be integrated with standard grating couplers without the need for extra fabrication steps. Hence, fabrication is carried out by a 2-etch-step complementary metal-oxide-semiconductor compatible process using 193-nm deep ultraviolet lithography. A polarization conversion efficiency of more than −0.85 dB with insertion losses ranging from −1 to −2.5 dB over a wavelength range of 30 nm is demonstrated.

Abstract-In this study, an analytical model for calculating the nonlinear harmonic/intermodulation distortion for RF signals in silicon-based electro-optic modulators is investigated by considering the nonlinearity on the effective index change curve with the operation point and the device structure simultaneously. Distortion expressions are obtained and theoretical results are presented showing that optimal modulator parameters can be found to linearize it. Moreover, the harmonic distortion of a 1 mm silicon-based asymmetric MZI is RF characterized and used to corroborate the theoretical results. Based on the present model, the nonlinear distortion in terms of bias voltage or operating wavelength is calculated and validated by comparing with the experimental data, showing a good agreement between measurements and theory. Analog photonic link quality parameter like carrier-todistortion is one of the parameters that can be found with that model. Finally, the modulation depth is measured to assure that no over-modulation is produced.

We describe and demonstrate experimentally a method for photonic mixing of microwave signals by using a silicon electro-optical Mach-Zehnder modulator enhanced via slow-light propagation. Slow light with a group index of ∼11, achieved in a one-dimensional periodic structure, is exploited to improve the upconversion performance of an input frequency signal from 1 to 10.25 GHz. A minimum transmission point is used to successfully demonstrate the upconversion with very low conversion losses of ∼7 dB and excellent quality of the received I∕Q modulated QPSK signal with an optimum EVM of ∼8%.

We experimentally demonstrate a high-speed differential phase shift keying (DPSK) modulation using a silicon push-pull operated dualdrive Mach Zehnder modulator (MZM) based on carrier depletion. 5 Gbit/s and 10 Gbit/s error-free modulation is demonstrated by demodulating the generated DPSK modulated signal using a demodulation circuit based on a polarization delay interferometer through the use of a differential group delay (DGD). Furthermore, the potential for higher DPSK modulation speeds up to 20 Gbit/s is also demonstrated. The obtained results validate the potential to achieve higher order modulation formats, such as quadrature phase shift keying (QPSK), by arranging the MZM in a nested configuration.2013 Elservier B.V. All rights reserved.