Rolf Schmid

DA and AD converters in SiGe technology: Speed and resolution for ultra high data rate applications

DA and AD converters are key elements for implementing new modulation formats in next generation optical transport systems. Latest results and future trends are presented with a focus on SiGe devices.

Generation of 224-Gb/s multicarrier offset-QAM using a real-time transmitter

We present the first real-time transmitter generating a multicarrier offset-QAM signal at 224 Gb/s after polarization multiplexing. Low penalties are achieved in a back-to-back experiment using a novel FPGA platform including two high-speed DACs running at 32 GS/s.

Generation of a Digitally Shaped 55-GBd 64-QAM Single-Carrier Signal Using Novel High-Speed DACs

We present a novel 2-channel arbitrary waveform generator (AWG) prototype, generating complex signal constellations with 6-bit digital-to-analog conversion (DAC) of up to 72 GS/s at a 6-dB bandwidth of 23 GHz. We generate a 55-GBd root-raised cosine shaped single-carrier 64-QAM signal.

Generation of 64 GBd 4ASK signals using a silicon-organic hybrid modulator at 80°C.

We demonstrate a silicon-organic hybrid (SOH) Mach-Zehnder modulator (MZM) generating four-level amplitude shift keying (4ASK) signals at symbol rates of up to 64 GBd both at room temperature and at an elevated temperature of 80°C. The measured line rate of 128 Gbit/s corresponds to the highest value demonstrated for silicon-based MZM so far. We report bit error ratios of 10-10 (64 GBd BPSK), 10-5 (36 GBd 4ASK), and 4 × 10-3 (64 GBd 4ASK) at room temperature. At 80 °C, the respective bit error ratios are 10-10, 10-4, and 1.3 × 10-2. The high-temperature experiments were performed in regular oxygen-rich ambient atmosphere.

100 GBd Intensity Modulation and Direct Detection With an InP-Based Monolithic DFB Laser Mach–Zehnder Modulator

We demonstrate, for the first time with a DFB-MZM at 1550 nm, 100-GBd NRZ and PAM4 transmission over up to 1.2 km due to close-to-zero chirp. At 100-GBd PAM4, the DFB-MZM consumed only 0.85 pJ/bit.

A linear active combiner enabling an interleaved 200 GS/s DAC with 44 GHz analog bandwidth

A linear active combiner with an analog bandwidth of 50 GHz is presented. It is well suited for interleaving the outputs of two digital-to-analog converters (DACs), because it features almost identical forward transmission of both channels and good isolation between the inputs. Featuring a high linearity it can generate output signals up to 1.6 Vpp differential voltage swing with an effective number of bits (ENoB) of 6. The performance of the combiner is demonstrated by characterization of the standalone device and in a time interleaved DAC setup where a sampling rate of 200 GS/s with an analog bandwidth of 44 GHz and an ENoB of > 4.5 is achieved.