Graphene photodetectors have been demonstrated for high-speed optical communications. Researchers at IBM have developed a 10 Gbits/s optical data link using a graphene-based photodetector. This photodetector, an interdigitated metal-graphene-metal (MGM) structure, achieves a high external photo-responsivity of 6.1 mA/W at 1.55 μm wavelength, a significant improvement over previous graphene photodetectors. The device utilizes an asymmetric metallization scheme to break the mirror symmetry of the built-in electric-field profile, enabling efficient photo-detection across the entire illuminated area. The photodetector was deployed in a 10 Gbits/s optical data link, demonstrating error-free detection of the optical bit stream, highlighting the potential of graphene in light detection applications. The MGM photodetector has a geometry similar to traditional metal-semiconductor-metal (MSM) detectors. It is fabricated on a highly-resistive silicon wafer with a 300 nm thick thermal oxide. Single-, bi-, and tri-layer graphene are identified and confirmed by Raman spectroscopy, and interdigitated electrodes with 1 μm spacing and 250 nm width are fabricated using electron beam lithography. The active layer is bi-layer graphene, and the detector area is 6 × 6 μm. The detector is connected to 80 × 80 μm contact pads, separated by 40 μm. In traditional graphene field-effect-transistor (FET) photodetectors, the built-in electric-field responsible for carrier separation exists only in a narrow region near the electrode/graphene interface. In the MGM photodetectors, multiple interdigitated metal fingers are used, leading to a greatly enlarged high E-field light detection region. An asymmetric metallization scheme is used to break the mirror symmetry of the built-in potential profile, allowing for summing up their individual contributions to the total photocurrent. The photodetector was tested with a He-Ne laser at various gate biases, showing a linear response up to 10 mW of optical incidence power. The 3-dB bandwidth of the photodetector is 16 GHz, limited by the RC constant rather than carrier transit time. The photodetector was also tested with a 1550 nm wavelength light, demonstrating a completely opened eye pattern at 10 Gbits/s, indicating successful operation as a high-speed detector. The external responsivity can be further improved by applying a bias within the photocurrent generation path. The responsivity was found to be 6.1 mA/W, a 15-fold improvement over previous demonstrations. The responsivity can also be increased by using thicker graphene flakes. However, increasing the number of layers beyond two does not significantly improve the responsivity due to screening effects. The photodetector was also tested with light at multiple wavelengthsGraphene photodetectors have been demonstrated for high-speed optical communications. Researchers at IBM have developed a 10 Gbits/s optical data link using a graphene-based photodetector. This photodetector, an interdigitated metal-graphene-metal (MGM) structure, achieves a high external photo-responsivity of 6.1 mA/W at 1.55 μm wavelength, a significant improvement over previous graphene photodetectors. The device utilizes an asymmetric metallization scheme to break the mirror symmetry of the built-in electric-field profile, enabling efficient photo-detection across the entire illuminated area. The photodetector was deployed in a 10 Gbits/s optical data link, demonstrating error-free detection of the optical bit stream, highlighting the potential of graphene in light detection applications. The MGM photodetector has a geometry similar to traditional metal-semiconductor-metal (MSM) detectors. It is fabricated on a highly-resistive silicon wafer with a 300 nm thick thermal oxide. Single-, bi-, and tri-layer graphene are identified and confirmed by Raman spectroscopy, and interdigitated electrodes with 1 μm spacing and 250 nm width are fabricated using electron beam lithography. The active layer is bi-layer graphene, and the detector area is 6 × 6 μm. The detector is connected to 80 × 80 μm contact pads, separated by 40 μm. In traditional graphene field-effect-transistor (FET) photodetectors, the built-in electric-field responsible for carrier separation exists only in a narrow region near the electrode/graphene interface. In the MGM photodetectors, multiple interdigitated metal fingers are used, leading to a greatly enlarged high E-field light detection region. An asymmetric metallization scheme is used to break the mirror symmetry of the built-in potential profile, allowing for summing up their individual contributions to the total photocurrent. The photodetector was tested with a He-Ne laser at various gate biases, showing a linear response up to 10 mW of optical incidence power. The 3-dB bandwidth of the photodetector is 16 GHz, limited by the RC constant rather than carrier transit time. The photodetector was also tested with a 1550 nm wavelength light, demonstrating a completely opened eye pattern at 10 Gbits/s, indicating successful operation as a high-speed detector. The external responsivity can be further improved by applying a bias within the photocurrent generation path. The responsivity was found to be 6.1 mA/W, a 15-fold improvement over previous demonstrations. The responsivity can also be increased by using thicker graphene flakes. However, increasing the number of layers beyond two does not significantly improve the responsivity due to screening effects. The photodetector was also tested with light at multiple wavelengths