Ultra‐Compact High‐Speed Polarization Division Multiplexing Optical Receiving Chip Enabled by Graphene‐on‐Plasmonic Slot Waveguide Photodetectors

Abstract

Polarization multiplexing technology is widely adopted for increasing the capacity in optical communication systems. Especially, silicon‐based integrated polarization division multiplexing (PDM) optical receivers with large bandwidth therein play an important role, which are crucial for on‐chip large‐capacity optical interconnection. Here, a silicon‐based PDM optical receiving chip is enabled by two‐dimensional grating couplers and graphene‐on‐plasmonic slot waveguide photodetectors. Utilizing the advantages of the designed focusing two‐dimensional grating couplers and plasmonic‐slot‐waveguide‐enhanced graphene–light interaction, the optical receiving chip is achieved with an ultra‐small footprint, a bandwidth exceeding 70 GHz and a reception of PDM signals in a line rate of 128 Gbit s−1 non‐return‐to‐zero and 224 Gbit s−1 four‐level pulse‐amplitude‐modulation at 1550 nm, accompanied by the bit error rates lower than the KP4 forward error correction threshold and 15% soft‐decision forward error correction threshold, respectively. Comparing with receiving the single‐polarization state, simultaneous receiving dual‐polarization state introduces about 1 dB additional power penalty because of inter‐polarization crosstalk. The graphene‐plasmonic PDM optical receiving chip can greatly improve the line rate of the system, showing its unique advantages of small footprint, high speed, large bandwidth, low crosstalk and complementary metal–oxide–semiconductor compatibility, which can be potentially used in the next generation silicon‐based high‐speed optical communication.

Ultrahigh-speed graphene-based optical coherent receiver

“…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.…”

“…Here, we present a single-polarization graphene-based OCR enabled by plasmonic slot waveguides (PSWs) with compact active detection sections of 4 × 15 μm × 100 nm (four graphene-on-PSW PDs 26 with an active detection area of 15 μm × 100 nm each (see Supplementary Note 1 and Supplementary Fig. 3 )) and a simple fabrication process.…”

Graphene photodetector employing double slot structure with enhanced responsivity and large bandwidth

“…3(b) and 3(c). We could see that the current decreases with light injection, which is a direct phenomenon indicating that the dominant photodetection mechanism within the proposed device should be the photobolometric effect 21,22,48 . Based on the measured I-V curve, the relationship between the photocurrent and the bias voltage (V B ) is depicted in Fig.…”

Plasmonic Photovoltaic Double-Graphene Detector Integrated Into TiN Slot Waveguides

“…TiN is a refractory metal nitride that has optical properties that are similar to Au [21], an electrical conductivity higher than Titanium (Ti) [22], but unlike Au, TiN is CMOS-compatible [20], [23]- [25]. A strong plasmonic enhancement of the optical mode has been reported for photodetectors that are based on plasmonic slot waveguides [5], [11], [13], [26], including the aforementioned graphene photodetector with a record-high responsivity of 0.67 A/W. By incorporating these design elements, we report a photodetector device that achieves a high responsivity of 2.18 A/W and more at 0.5 V bias, across the telecom C-band and beyond.…”