Long-Wavelength Tunable Detector Using High-Contrast Grating

We report a tunable 1550-nm detector using a monolithic high-contrast grating (HCG) vertical-cavity surface-emitting laser. The detector is resonance enhanced, with a responsivity demonstrated as large as 1 A/W. It features a strong wavelength selectivity over a wide tuning range, enabled by the highly reflective microelectromechanically actutable HCG mirror. A tuning range of 33.5 nm and a spectral width of 1.2 nm are demonstrated. We show that it can select a specific data channel with 1 Gb/s data rate and reject adjacent channels 4 nm away. Higher detection speed at 10 Gb/s is also demonstrated. We show three special functionalities of this tunable detector. The first one is dual functionality-not only as a receiver but also a transmitter-with a simple change of its bias polarity. Though long sought after, a tunable bifunctional device had not been realized before. An error-free high-speed link over 25 km single-mode-fiber is demonstrated between two such devices. The second special property is its wavelength-self-tracking configuration, i.e., its resonance wavelength can automatically track the input light´s wavelength. Finally, we demonstrate its use as a fast on-chip optical spectrometer, with an operation speed at 200 kHz. This tunable detector would be useful for a variety of wavelength-division-multiplexing network and lab-on-a-chip systems.