Pseudomorphic Si1−xGex/Si multi‐quantum well structures for waveguide applications have been grown on (110) Si by molecular beam epitaxy. In a series of samples the Ge fractionxhas been varied fromx=0.25 tox=0.37 andx=0.50, respectively. We have used photocurrent spectroscopy on mesa diodes to demonstrate that the absorption edge of the strained Si1−xGexquantum wells can be tuned from 1.3 to 1.55 &mgr;m by the Ge fractionx. Realization and characterization of single‐mode (110) Si1−xGexrib waveguides with end facets of high optical quality, prepared by cleaving, is reported. ©1995 American Institute of Physics.