Optoelectronic Bidirectional Transceiver Chips: Crosstalk and Alignment Issues

We present the static operation properties of monolithically integrated 850 nm wavelength AlGaAs/GaAs-based vertical-cavity surface-emitting lasers (VCSELs) and PIN (p-doped– intrinsic–n-doped) photodiodes (PDs). Devices with three different epitaxial layer structures of the PDs are investigated. PDs with a 3μm thick intrinsic region show a responsivity of > 0.6A/W and have the lowest dark currents. We investigate the mutual influence between the closely integrated optoelectronic devices. The optical crosstalk is below −11 dB and the maximum electrical crosstalk between VCSEL and PIN PD of around −50 dB is nearly negligible. Butt-coupling to a multimode fiber with a core diameter of 50 μm has maximum fiber alignment tolerances in the range of 14–26 μm.