Optical modules including customizable spacers for focal length adjustment and/or reduction of tilt, and fabrication of the optical modules

An optical module comprising:

• a plurality of active optoelectronic components each of which is mounted on a respective printed circuit board, wherein each of the active optoelectronic components is associated with a respective different optical channel;
• a plurality of optical assemblies, each of which is substantially aligned over a different respective one of the optical channels;
• and
• a spacer separating the active optoelectronic components and printed circuit boards from the optical assemblies,
• wherein the optical assemblies are attached by adhesive directly to an optical assembly-side surface of the spacer,
• wherein the spacer includes first edge features in contact with top surfaces of the active optoelectronic components and second edge features attached to top surfaces of the printed circuit boards, and
• wherein a first one of the active optoelectronic components is separated, by the spacer, from a first one of the optical assemblies by a first distance and wherein a second one of the active optoelectronic components is separated, by the spacer, from a second one of the optical assemblies by a different second distance.