Optical waveguide and coupler devices and methods include a trench formed in a bulk semiconductor substrate, for example, a bulk silicon substrate. A bottom cladding layer is formed in the trench, and a core region is formed on the bottom cladding layer. A reflective element, such as a distributed Bragg reflector can be formed under the coupler device and/or the waveguide device. Because the optical devices are integrated in a bulk substrate, they can be readily integrated with other devices on a chip or die in accordance with silicon photonics technology. Specifically, for example, the optical devices can be integrated in a DRAM memory circuit chip die.