Planar and channel optical waveguide structures formed on silicon substrates using the fabrication techniques of sputtering, thermal oxidation, and chemical vapor deposition are discussed. Losses in the various waveguide structures are reported and related to the fabrication procedure used. The use of polycrystalline silicon deposited by chemical vapor deposition onto any waveguide substrate to form integrated photodetector arrays is discussed. Laser recrystallization of the deposited silicon is used to allow fabrication of high quality devices. Measured values of photodiode reverse current of less than 10-9 A and breakdown voltages of 24 V are respectable values for small photodiodes incorporated into a dense array.