Silicon-organic hybrid (SOH) Mach-Zehnder modulators for 100 GBd PAM4 signaling with sub-1 dB phase-shifter loss

Abstract

We report on compact and efficient silicon-organic hybrid (SOH) Mach-Zehnder modulators (MZM) with low phase shifter insertion loss of 0.7 dB. The 280 µm-long phase shifters feature a π-voltage-length product of 0.41 Vmm and a loss-efficiency product as small as aUπL = 1.0 VdB. The device performance is demonstrated in a data transmission experiment, where we generate on-off-keying (OOK) and four-level pulse-amplitude modulation (PAM4) signals at symbol rates of 100 GBd, resulting in line rates of up to 200 Gbit/s. Bit error ratios are below the threshold for hard-decision forward error correction (HD-FEC) with 7 % coding overhead, leading to net data rates of 187 Gbit/s. This is the highest PAM4 data rate ever achieved for a sub-1 mm silicon photonic MZM.

Taking silicon photonics modulators to a higher performance level: state-of-the-art and a review of new technologies

“…Recent years have seen growing efforts to integrate materials with strong electro-optic effects on SiPh platforms. [192][193][194][195][196][197][198][199][200][201][202][203][204][205][206][207][208]228 The integration of new materials provides routes for optically broadband and energy-efficient high-speed modulation with little or no current flow. 176,181,184,188,202 Furthermore, in some cases, these new materials provide an excellent decoupling between amplitude and phase modulation, which is difficult to achieve with contemporary all-silicon plasma dispersion modulation schemes.…”

“…[186][187][188]197 The underlying organic materials in SOH modulators are designed to provide high electrooptic activity with experimentally demonstrated values of n 3 r > 2000 pm∕V. 190 This results in modulators with a lowloss, 194 a low-chirp parameter of α ¼ −0.02, 193 and a high modulation efficiency (V π • L ≈ 0.03 V • cm), 190 high modulation bandwidth (>100 GHz) 191,259 and low-energy consumption of a few fJ/bit. 192,228 With π-voltages below 1 V, SOH modulators may be directly driven by standard CMOS circuits without the need for any additional drive amplifiers, 260 thereby opening a path toward greatly reduced power dissipation in highly integrated transceivers.…”

“…Table 1 shows a rich landscape of SiPh modulators, where SiPh is incorporating a variety of other materials for implementing performant high-speed modulators. Modulation of amplitude by the Franz-Keldysh (FK) effect, 20,38,128,[133][134][135][136][137][138][139][140] quantum-confined Stark (QCS) effect, [141][142][143][144][145][146][147][148][149][150][151][152] and electrical gating, [153][154][155][156][157][158][159][160] or the modulation of phase by employing the plasma dispersion effect, [161][162][163][164][165][166] Pockels effect, [192][193][194][195][196][197][198][199][200] and inter-band transitions,…”

Organic Electro‐Optic Mach–Zehnder Modulators: From Physics‐Based to System‐Level Modeling

“…A typical coplanar electrode setup for SOH modulators is shown in Figure . [ 32 ] Slot widths are around 100 nm, whereas the Si ribs are moderately doped not to increase optical losses. As the EO polymer refractive index is lower than the Si index, the optical field is not strongly (laterally) confined to the slot, whereas the RF field is, leading to an only partial overlap.…”

Photonic-Electronic Ultra-Broadband Signal Processing: Concepts, Devices, and Applications

“…This approach is complemented by hybrid on-chip integration of silicon photonic circuits together with plasmonic structures and/or with advanced electro-optic materials. Combining silicon photonic waveguides with plasmonic structures allows for ultra-broadband optical-to-electrical conversion in so-called plasmonic internal photoemission devices (PIPED) [7], [8], whereas silicon-organic hybrid (SOH) integration [9], [10] offers an attractive route towards low-loss electro-optic (EO) modulators that can be operated at high data rates [11], [12] and low voltage levels [13], [14], [15]. Plasmonic-organic hybrid (POH) integration finally combines silicon-plasmonic circuits with advanced organic materials, thereby boosting the bandwidth of EO modulators to hundreds of gigahertz [16].…”