Fiberless multicolor optoelectrodes using Injection Laser Diodes and Gradient-index lens coupled optical waveguides

We present an integrated optoelectrode that can deliver multicolor light from a waveguide coupled to an optical mixer. Such a device can provide spatial precision and scalability needed to enable independent activation and silencing of local neural circuits, allowing study of brain activities such as memory consolidation networks in the hippocampus. We have demonstrated successful implementation of fiber-less optoelectrodes in a highly compact form by achieving efficient end-fire coupling between a side-emitting injection laser diode (ILD) and a dielectric channel waveguide via a Gradient-index (GRIN) lens. Total optical efficiency achieved for 405nm and 635nm wavelengths through an optical mixer was 12.2% and 5.4%, respectively. This approach also provides robust thermal packaging by efficiently managing thermal power loss of ILDs.