Optical Transmitter Based on a 1.3-μm VCSEL and a SiGe Driver Circuit for Short-Reach Applications and beyond

Long-wavelength vertical-cavity surface-emitting lasers (LW-VCSELs) with emission wavelength in the 1.3<formula><tex>$\mu$</tex></formula>m region for intensity modulation/direct detection (IM/DD) optical transmissions, enable longer fiber reach compared to C-band VCSELs, thanks to the extremely low chromatic dispersion impact at that wavelength. A lot of effort has been recently dedicated to novel cavity designs in order to enhance LW-VCSELs modulation bandwidth to allow higher data rates. Another approach to further improve VCSEL-based intensity modulation speed consists of making use of dedicated driver circuits implementing feed forward equalization (FFE). In this manuscript we present a transmitter assembly incorporating a 4-channel 0.13-<formula><tex>$\mu$</tex></formula>m SiGe driver circuit wire-bonded to a novel dual 1.3<formula><tex>$\mu$</tex></formula>m-VCSEL array. The short-cavity Indium Phosphide (InP) Buried Tunnel Junction (BTJ) VCSEL design minimizes both the photon lifetime and the device parasitic currents. The integrated driver circuit requires 2.5 V supply voltage only due to the implementation of a pseudo-balanced regulator, it includes a 2-tap asymmetric FFE where magnitude, sign, relative delay and pulse width distortion (PWD) of the taps can be modified. Through the proposed transmitter, standard single-mode fiber reach of 20 km and 4.5 km respectively for 28 Gb/s and 40 Gb/s data rate has been demonstrated with state-of-the-art power consumption. Transmitter performance has been analyzed through pseudorandom bit sequences of both 27-1 and 231-1 length and the additional benefit due to the use of the driver circuit has been discussed in detail. A final comparison with state-of-the-art VCSEL drivers is also included.