Increase in the modulation bandwidth of the high-speed VCSEL 1550 nm by active region p-type doping

The effect of active region p-type doping on the static and dynamic parameters of vertical cavity surface-emitting lasers (VCSEL) operating at a wavelength of 1550 nm is investigated. The p-type doped active region heterostructures of the lasers exhibits a two-fold increase in the peak photoluminescence intensity, compared to the undoped heterostructure. This increase can be attributed to an increase in differential gain. The VCSELs demonstrate single-mode operation with a nearly identical threshold current of 1.9 to 2.0 mA at room temperature, producing a maximum output power of 5.5 mW for the undoped device and 3.5 mW for the p-type doped laser. This reduction in output power can be attributed to increased free carrier absorption. As a result of p-doping, an increase in the modulation bandwidth from 7.2 GHz to 8.9 GHz was achieved.