Christian Mai

High bandwidth, high responsivity waveguide-coupled germanium p-i-n photodiode

A novel waveguide-coupled germanium p-i-n photodiode is demonstrated which combines high responsivity with very high -3 dB bandwidth at a medium dark current. Bandwidth values are 40 GHz at zero bias and more than 70 GHz at -1 V. Responsivity at 1.55 µm wavelength ranges from 0.84 A/W at zero bias to 1 A/W at -1 V. Room temperature dark current density at -1 V is about 1 A/cm2. The high responsivity mainly results from the use of a new, low-loss contact scheme, which moreover also reduces the negative effect of photo carrier diffusion on bandwidth.

Monolithic photonic-electronic QPSK receiver for 28Gbaud

The paper presents the first fully monolithic photonic-electronic single-polarization QPSK receiver for 56Gbps (28Gbaud). The receiver sub-system was realized in photonic BiCMOS technology and demonstrates integration capabilities for state-of-the-art coherent systems.

Novel Ring Resonator Combining Strong Field Confinement With High Optical Quality Factor

Slot waveguide ring resonators appear promising candidates for several applications in silicon photonics. Strong field confinement, high device tunability, and low power consumption are beneficial properties compared with strip waveguides. Slot waveguide ring resonators suffer, however, from rather low optical quality factors due to optical losses. This letter proposes and experimentally demonstrates a novel concept based on a partially slotted ring and a strip-to-slot mode converter. An exceptional high quality factor of ~105 has been measured.

Partially slotted silicon ring resonator covered with electro-optical polymer

In this work, we present for the first time a partially slotted silicon ring resonator (PSRR) covered with an electro-optical polymer (Poly[(methyl methacrylate)-co-(Disperse Red 1 acrylate)]). The PSRR takes advantage of both a highly efficient vertical slot waveguide based phase shifter and a low loss strip waveguide in a single ring. The device is realized on 200 mm silicon-on-insulator wafers using 248 nm DUV lithography and covered with the electro-optic polymer in a post process. This silicon-organic hybrid ring resonator has a small footprint, high optical quality factor, and high DC device tunability. A quality factor of up to 105 and a DC device tunability of about 700 pm/V is experimentally demonstrated in the wavelength range of 1540 nm to 1590 nm. Further, we compare our results with state-of-the-art silicon-organic hybrid devices by determining the poling efficiency. It is demonstrated that the active PSRR is a promising candidate for efficient optical switches and tunable filters.

Monolithically Integrated High-Extinction-Ratio MZM With a Segmented Driver in Photonic BiCMOS

In this letter, a dual-drive Si depletion-type Mach-Zehnder modulator (MZM) monolithically integrated with a segmented driver using 0.25-μm SiGe:C photonic bipolar complementary metal-oxide-semiconductor technology is demonstrated. The phase shifter on each MZM arm has a total length of 6.048 mm and is divided into 16 sections, driven by the driver segments. Extinction ratio (ER) higher than 11 dB is shown at 28 and 32 Gb/s at ON-OFF keying with a differential input voltage swing of 800 mVpp (3.5 Vpp on the phase shifters). The power consumption equals to 64 pJ/b at 28 Gb/s. This is one of the highest ER values shown by a monolithically integrated Si MZM at this data rate.

Hybrid-Waveguide Ring Resonator for Biochemical Sensing

This paper proposes a hybrid-waveguide ring resonator for on-chip biochemical sensing. Consisting of a low-loss strip-waveguide and a highly sensitive slot-waveguide integrated in a silicon photonic platform, it combines advantages of both waveguide types. In this way, it provides the unique feature to increase the sensitivity while maintaining low optical losses. Thus, this resonator structure may represent a promising alternative approach for future integrated biochemical sensing applications. This is suggested by a theoretical analysis, involving numerical simulation of the hybrid-waveguide ring resonator and an optimization of the slot-waveguide structure with regard to light-analyte-interaction. It is demonstrated that the hybrid-waveguide concept may overcome limitations in terms of overall resonator sensitivity, which is described by a figure of merit, connecting the optical losses with the resonator sensitivity.

BiCMOS silicon photonics platform for fabrication of high-bandwidth electronic-photonic integrated circuits

Photonic BiCMOS is a novel technology for fabricating electronic-photonic integrated circuits. Broadband silicon photonics devices such as germanium photodiodes and depletion type Mach-Zehnder modulators were monolithically integrated in a high performance SiGe BiCMOS baseline process. Integration aspects and examples of demonstrator circuits shall be reviewed.

Design effects on the performance of high-speed Ge photo detectors

We investigate design effects on the opto-electrical frequency response of waveguide-coupled, lateral Ge p-i-n photodiodes to estimate the sensitivity of this response to diode fabrication tolerances and, in particular, to improve our understanding how diffusion of photo carriers acts on the response behavior.

A monolithically integrated Si optical single-sideband modulator

We demonstrate a monolithically integrated Si optical single-sideband modulator that contains a ring-assisted Mach-Zehnder modulator, two MMI optical couplers, and an electrical quadrature hybrid coupler. The modulator successfully produces 30-GHz single sideband with 15-dB suppression of the undesired sideband.

Thermo-optical switching in hybrid VO 2 /Sİ waveguides by lateral displaced microheaters

A lateral displaced microheater is demonstrated for switching across the VO2 phase transition in ultra-short hybrid VO2/Si waveguides for both TE and TM light polarizations. Simulation and experimental results are obtained showing a very good agreement with a switching electrical power of around 10mW.