MicroLEDs may be used in providing intra-chip optical communications and/or inter-chip optical communications, for example within a multi-chip module or semiconductor package containing multiple integrated circuit semiconductor chips. In some embodiments the integrated circuit semiconductor chips may be distributed across different shelves in a rack. The optical interconnections may make use of optical couplings, for example in the form of lens(es) and/or mirrors. In some embodiments arrays of microLEDs and arrays of photodetectors are used in providing parallel links, which in some embodiments are duplex links.