Waveguiding at 1.3 μm has been observed in a submicrometer strained layer of Si1-xGex sandwiched between a Si capping layer and a Si substrate. This structure is a precursor of the waveguided Si/Si1-xGex/Si heterojunction bipolar transistor. The buried alloy layer, grown by chemical vapor deposition, had a Ge content of either 8% or 18%. The SiGe layer was ∼1500 Å thick beneath a 2-μm Si cap. The observed TE0 mode profile agreed with theory.