Compact optoelectronic modules are described that, in some implementations, can have reduced heights, while at the same time having very little optical crosstalk or detection of stray light. An optoelectronic module having optical channel can include a support on which is mounted an optoelectronic device arranged to emit or detect light at a particular one or more wavelengths. The module has a cover including an optically transmissive portion over the optoelectronic device. The optically transmissive portion is surrounded laterally by sections of the cover that are substantially non-transparent to the one or more wavelengths. A passive optical element is present on a surface of the optically transmissive portion. A spacer separates the support from the cover. The cover can be relatively thin so that the overall height of the module is relatively small.