In this paper,we present the design,fabrication,and measurement of an evanescently coupled waveguide photodetector operating at 1.55 μm,which mainly comprises a diluted waveguide,a single-mode rib waveguide and a p–i–n photodiode with an extended optical matching layer.The optical characteristics of this structure are studied by using a three-dimensional finite-difference time-domain(3D FDTD) method.The photodetector exhibits a high 3-dB bandwidth of more than 35 GHz and a responsivity of 0.291 A/W at 1550 nm directly coupled with a cleaved fiber.Moreover,a linear response of more than 72-mW optical power is achieved,where a photocurrent of more than 21 mA is obtained at a reverse bias voltage of 3 V.
In this paper, we present the design, fabrication, and measurement of an evanescently coupled waveguide photode- tector operating at 1.55 gm, which mainly comprises a diluted waveguide, a single-mode rib waveguide and a p-i-n photodiode with an extended optical matching layer. The optical characteristics of this structure are studied by using a three-dimensional finite-difference time-domain (3D FDTD) method. The photodetector exhibits a high 3-dB bandwidth of more than 35 GHz and a responsivity of 0.291 A/W at 1550 nm directly coupled with a cleaved fiber. Moreover, a linear response of more than 72-mW optical power is achieved, where a photocurrent of more than 21 mA is obtained at a reverse bias voltage of 3 V.