In this work, a silicon nitride waveguide‐integrated photodetector based on a transferred graphene/MoS2 heterostructure has been reported, where photo‐generated electron–hole pairs are produced in the CVD‐grown MoS2 monolayer and rapidly separated at the heterostructure interface, followed by electrons continuously transferring to the graphene layer induced by an effective built‐in electrical field. By tuning the back‐gate voltage to control the Fermi‐level in graphene layer, a competitive photoresponsivity of 440 mA W−1 at 532 nm is achieved. Furthermore, these exhibit a photoresponse rate with a rise time of 80 ms and a fall time of 30 ms. It is believed that the 2D heterostructure has potentials for future applications in integrated optoelectronic circuits.
The monolithic integration of soliton microcomb devices with active photonic components and high-frequency electronics is highly desirable for practical applications. Among many materials, silicon nitride (
SiN
x
) waveguide layers prepared by low-pressure chemical vapor deposition (LPCVD) have been the main platform for on-chip optical frequency comb generation. However, the high temperatures involved in LPCVD render it incompatible as a back-end process with complementary metal oxide semiconductor (CMOS) or active III-V compound semiconductor fabrication flows. We report the generation of coherent soliton frequency combs in micro-ring resonators fabricated in deuterated silicon nitride (
SiN
x
:
D
) waveguides with a loss of 0.09 dB/cm. Deposited at 270°C by an inductance-coupled plasma chemical vapor deposition (ICP-CVD) process, the material preparation and fabrication flow are fully CMOS-compatible. These results enable the integration of silicon-nitride-based optical combs and photonic integrated circuits (PICs) on prefabricated CMOS and/or III-V substrates, therefore marking a major step forward in
SiN
x
photonic technologies.
In order to overcome the challenge of obtaining high modulation depth due to weak graphene-light interaction, a graphene-on-silicon nitride (SiN x ) microring resonator based on graphene's gate-tunable optical conductivity is proposed and studied. Geometrical parameters of graphene-on-SiN x waveguide are systematically analyzed and optimized, yielding a loss tunability of 0.04 dB/μm and an effective index variation of 0.0022. We explicitly study the interaction between graphene and a 40-μm-radius microring resonator, where electro-absorptive and electro-refractive modulation are both taken into account. By choosing appropriate graphene coverage and coupling coefficient, a high modulation depth of over 40 dB with large fabrication tolerance is obtained.
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