50 GBit/s Photodetectors Based on Wafer-Scale Graphene for Integrated Silicon Photonic Communication Systems

Abstract

Optical data links are the backbone of today's telecommunication infrastructure. The integration of electronic and optic components on one chip is one of the most attractive routes to further increase the system performance. Here, we present the fabrication of photodetectors based on CVD-grown graphene on silicon photonic waveguides. The devices operate bias-free in the Cband at 1550 nm and show an extrinsic −3 dB bandwidth of 41 GHz. We demonstrate that these detectors work at data rates up to 50 GBit/ s with excellent signal integrity.

Graphene photodetectors with a bandwidth >76 GHz fabricated in a 6″ wafer process line

“…There, the bandwidth of the photodetector was limited by the RC component of the device, with R being the device resistance and C dominated by the capacitance of the contact pads. In this study, we reduced the pad area and thus the contact pad capacitance by approximately a factor of 8, while the device resistance was similar to the values in [15]. However, the measured bandwidth increased only by a factor of 2, which then cannot be explained by an RC limited device characteristic any more.…”

“…The electronic and optic properties of graphene [4], the two dimensional allotrope of carbon, were studied extensively in the last years [5][6][7][8][9]. Moreover, competitive chipintegrated electro-optical devices like electro-optical modulators [10,11], efficient waveguide heaters [12] and ultrafast photodetectors [13][14][15][16] were fabricated using graphene as active material. The performance of graphene photodetectors on integrated silicon waveguides in terms of speed and sensitivity has improved significantly in the last years and the gap between the performance of graphene and competing technologies is vanishing [17][18][19][20][21].…”

Controlled Generation of a p–n Junction in a Waveguide Integrated Graphene Photodetector

“…We performed impulse response measurements, where ~1 ps long optical pulses, generated by a mode-locked erbium fiber laser with a wavelength of 1550 nm, were coupled into the device (sample B) and the impulse response was monitored with an oscilloscope (Figure 4(a)). From this measurement we extract a pulse duration at full-width at half-maximum In order to determine the cut-off frequency of our detector, we used a heterodyne measurement technique similar to the one used in reference [27]. Two laser sources with different frequencies were multiplexed, causing amplitude beating at the difference frequency.…”

Monolithic optoelectronic integrated broadband optical receiver with graphene photodetectors

“…However, the uniform 2.3% optical absorption of graphene limits GPD's photoresponsivity [35]. To solve this problem, graphene has been integrated with microcavities [36], plasmon resonators [37,38] and silicon waveguide [23,24,[39][40][41], but these methods weaken the broadband character. Another method carried out by integrating graphene layer with semiconductor quantum dots can greatly improve photoresponsivity without wavelength dependence [42], but the photoresponse speed is relatively low.…”