High-speed vertically emitting lasers in the spectral range of 1550 nm, implemented in the framework of wafer sintering method

We report the results of studies of the characteristics of vertically emitting lasers in the spectral range of 1550 nm with an active region based on InGaAs quantum wells, implemented within the framework of the wafer sintering technology. The current and optical confinement is provided by the overgrown n⁺/p⁺-InAlGaAs tunnelling junction. Over a wide temperature range, lasers with an overgrown tunnel junction mesa diameter of 7 μm demonstrate efficient single-mode lasing with a side-mode suppression factor of more than 30 dB. At a temperature of 20°C, the lasers have a threshold current of ∼1.5 mA, a differential efficiency of ∼0.49 W·A^-1, a maximum output optical power of more than 4 mW, and an effective modulation frequency (at the level of –3 dB) of about 9 GHz. It is found that with an increase in the length of the optical communication line, the chromatic dispersion of an SMF-28 fibre and the spurious frequency modulation of the laser cause significant distortions in the shape of the output optical pulses, as well as an increase in intersymbol interference, which ultimately leads to the disappearance of the opening region of the eye diagram. The maximum data rate in direct current modulation regime using the NRZ amplitude format reaches 30 Gbps at 20°C for a short communication line (BTB configuration), and for a 2-km-long communication line, the maximum optical data transmission rate is no more than 25 Gbps.