  This paper presents several component prototypes towards a low-latency,
small-form-factor optical link designed for the ATLAS Liquid Argon Calorimeter
Phase-I trigger upgrade. A prototype of the custom-made dual-channel optical
transmitter module, the Miniature optical Transmitter (MTx), with separate
transmitter optical sub-assemblies (TOSAs) has been demonstrated at data rates
up to 8 Gbps per channel. A Vertical-Cavity Surface-Emitting Laser (VCSEL)
driver ASIC has been developed and is used in the current MTx prototypes. A
serializer ASIC prototype, operating at up to 8 Gbps per channel, has been
designed and tested. A low-latency, low-overhead encoder ASIC prototype has
been designed and tested. The latency of the whole link, including the
transmitter latency and the receiver latency but not the latency of the fiber,
is estimated to be less than 57.9 ns. The size of the MTx is 45 mm x 15 mm x 6
mm.
