Silicon-organic hybrid (SOH) modulators for intensity-modulation / direct-detection links with line rates of up to 120 Gbit/s

Abstract

High-speed interconnects in data-center and campus-area networks crucially rely on efficient and technically simple transmission techniques that use intensity modulation and direct detection (IM/DD) to bridge distances of up to a few kilometers. This requires electrooptic modulators that combine low operation voltages with large modulation bandwidth and that can be operated at high symbol rates using integrated drive circuits. Here we explore the potential of silicon-organic hybrid (SOH) Mach-Zehnder modulators (MZM) for generating high-speed IM/DD signals at line rates of up to 120 Gbit/s. Using a SiGe BiCMOS signalconditioning chip, we demonstrate that intensity-modulated duobinary (IDB) signaling allows to efficiently use the electrical bandwidth, thereby enabling line rates of up to 100 Gbit/s at bit error ratios (BER) of 8.5 × 10 −5 . This is the highest data rate achieved so far using a silicon-based MZM in combination with a dedicated signal-conditioning integrated circuit (IC). We further show four-level pulse-amplitude modulation (PAM4) at lines rates of up to 120 Gbit/s (BER = 3.2 × 10 −3 ) using a high-speed arbitrary-waveform generator and a 0.5 mm long MZM. This is the highest data rate hitherto achieved with a sub-millimeter MZM on the silicon photonic platform.

Ultra-high electro-optic activity demonstrated in a silicon-organic hybrid modulator

“…In general, static extinction ratios of better than 30 dB lead to a chirp parameter α ≤ 0.1, assuming perfect push-pull operation. This estimation is in good accordance with direct chirp measurements of similar SOH devices [24] and compares favorably with typical pn modulators featuring chirp parameters in the range of 0.8 [60].…”

“…We hence expect that the SOH concept will have major impact on future implementations of optical communication systems and may also open new opportunities in ultra-fast photonic-electronic signal processing, where highly efficient low-loss devices can, e.g., enable advanced electro-optic sampling. SOH devices have previously been demonstrated to enable high-speed coherent [47,48] and non-coherent [24,49] transmission with singlepolarization line rates of up to 400 Gbit/s (100 GBd 16QAM) [50].…”

“…In contrast to that, OEO materials are widely applicable and compatible to a wide variety of integration platforms and device structures, enabling high-speed modulators with record performance parameters [23][24][25][26] and data rates of up to 400 Gbit/s [5]. The materials can be easily spin-coated, micro-dispensed or printed in high-throughput processes.…”

High‐Speed Modulator Based on Electro‐Optic Polymer Infiltrated Subwavelength Grating Waveguide Ring Resonator

“…Compared to plasma dispersion, electro‐optic (EO) polymers have a remarkable EO coefficient (r33 > 400pm/V), ultrafast response speed (< 1 f s), small dispersion, and spin‐casting compatibility, which promise low‐power consumption, ultra‐high speed modulation, and ease of fabrication . Modulators with bandwidth over 100 GHz have been demonstrated, but their millimeter long device length defeats the purpose of chip‐scale integration . Structural slow light, such as slot photonic crystals and plasmonic devices, can effectively shrink the phase shifter size but at the price of significantly increased insertion loss .…”

Electrically packaged silicon-organic hybrid (SOH) I/Q-modulator for 64 GBd operation

“…SOH integration allows to realize high-speed modulators with sub-millimeter device lengths. The modulators offer line rates up to 120 Gbit/s for intensity modulation and direct detection (IM/DD) [12], and up to 400 Gbit/s for coherent 16QAM signaling [13].…”