Photo thermal effect graphene detector featuring 105 Gbit s−1 NRZ and 120 Gbit s−1 PAM4 direct detection

Abstract

One of the main challenges of next generation optical communication is to increase the available bandwidth while reducing the size, cost and power consumption of photonic integrated circuits. Graphene has been recently proposed to be integrated with silicon photonics to meet these goals because of its high mobility, fast carrier dynamics and ultra-broadband optical properties. We focus on graphene photodetectors for high speed datacom and telecom applications based on the photo-thermo-electric effect, allowing for direct optical power to voltage conversion, zero dark current, and ultra-fast operation. We report on a chemical vapour deposition graphene photodetector based on the photo-thermoelectric effect, integrated on a silicon waveguide, providing frequency response >65 GHz and optimized to be interfaced to a 50 Ω voltage amplifier for direct voltage amplification. We demonstrate a system test leading to direct detection of 105 Gbit s−1 non-return to zero and 120 Gbit s−1 4-level pulse amplitude modulation optical signals.

High-responsivity graphene photodetectors integrated on silicon microring resonators

“…For our GPDs, we estimate = Q v n / R [V/W] ~ −16 dBm for same BER and BW, where v n = , and R G ~ 800 Ω is the total device resistance. Thus, in contrast to previous reports of both PTE 25 – 27 , 29 , 33 , 76 and non-PTE 30 – 32 GPDs for integrated photonics, of our GPD-based receiver is on par with mature semiconductor technology, and could be further improved by reducing R contact , which dominates the total device resistance, thus being the primary source of thermal noise. The natural generation of a voltage makes the need for a TIA obsolete, with a reduction of energy-per-bit cost and system foot-print.…”

“…The six-fold pattern, with the highest photoresponse for bipolar (p-n, n-p) junctions, and a sign-change across the diagonal ( V G1 = V G2 ) for unipolar (n-n, p-p) junctions in the SLG channel, confirms that the PTE effect dominates the conversion of photons into electrical signal (rather than a photovoltaic conversion with a two-fold pattern in photovoltage over the same measurement range) 43 , 44 . Our R [V/W] outperforms the current state-of-the-art for waveguide-integrated PTE-GPDs, R [V/W] ~ 3–12 V/W 25 , 29 , 33 , 76 , by around one order of magnitude.…”

Ultrahigh-speed graphene-based optical coherent receiver

“…The overall performances of our OCR in terms of bandwidth and receiving capacity (Gbaud) are comparable to the traditional silicon-germanium 48 or III-V-based 49 OCRs. The larger shot noise caused by the dark current of this graphene-based OCR may reduce the sensitivity of the OCR (See Supplementary Note 4), which can be further vanished by the unbiased photothermoelectric-effect graphene-based PDs 27 . Furthermore, the responsivity of the plasmonic waveguide-integrated graphene-based PD can be further improved by other structures 20,21 , which is closer to that of the silicon-germanium PDs.…”

“…Currently, plasmonic waveguide-integrated graphene-based PDs with a compact size of a few microns 20 , 21 show a high responsivity up to 0.7 A/W 21 , a large bandwidth of 110 GHz 20 , 22 , and a high receiving capacity of 100–120 Gbit/s 20 , 26 , 27 . However, graphene-based PDs are still difficult to be applied in 200-Gbit/s, 400-Gbit/s, or even higher 800-Gbit/s optical interconnections 28 , while direct detection mode is exploited.…”

Silicon/2D-material photodetectors: from near-infrared to mid-infrared

“…Figure 3 shows the representative metal-2DM-metal PDs with various materials as well as different mechanisms. Among them, it can be seen that the M-G-M PDs 58,60,[106][107][108][109][110][111][112][113][114][115][116][117][118][119] are very popular because the fabrication process is relatively easy. For M-G-M PDs, the PV effect is hardly observed because the life time of the photogenerated carriers in graphene is very short (~2 ps 120 ).…”