Vertical forward coupler based channel‐dropping photodetector

We demonstrated an integrated channel‐dropping photodetector in which a desired wavelength channel of the optical power is selectively coupled to a detector element. Based on a codirectionally grating‐coupled GaAs/AlGaAs filter structure, a 1.2‐nm‐wide photocurrent response was obtained in an 800‐nm‐wavelength region with a device length shorter than 1 mm. Light passing through the device exhibited an alternate notch response, promising not to terminate the unselected channels.