Single-mode 1.5-µm VCSELs with small-signal bandwidth beyond 20 GHz

In this work, we present three different approaches with the objective of increasing the small-signal modulation bandwidth of InP-based VCSELs beyond 20 GHz. The intrinsic bandwidth limitations are overcome thanks to a highly-strained active region, and an ultra-short cavity design. The parasitic cut-off frequency is enhanced by a double-mesa VCSEL design.