Abstract
An 850-nm-band transverse-coupled-cavity vertical-cavity surface-emitting laser (VCSEL) is demonstrated for the first time, showing a 3 dB modulation bandwidth of over 30 GHz, which is the record for VCSELs. The transverse-coupled cavity is formed by making lithography-defined, battledore-shaped mesas. The coupling strength can be increased by reducing the absorption loss in a passive feedback cavity. Further increase in the coupling strength and/or mode selection via current injection into the feedback cavity shows the possibility of overclocking the device by optical equalization. Large-signal measurement shows eye-opening at 40 Gb/s. After the coupled mode is stabilized, higher bitrate modulation can be expected. (C) 2015 The Japan Society of Applied Physics