We introduce a novel method of optically inducing microsized subsurface structures using non-linear absorption of near infrared light in mono-crystalline silicon. We discuss the physical processes such as multi-photon absorption and self focussing in the material. The results presented in this paper demonstrate a new method of subsurface modifications in silicon and may open up novel avenues for optical devices embedded in silicon and optical process for the separation of wafers from their ingots.
We present a new approach for the fabrication of volume holograms in an optical nonlinear material with voxel sizes on the order of 1µm i.e., with increased degrees of freedom and thus improved multiplexing functionality.
We present a simulation study and first experimental implementations for a novel polymer three-dimensional waveguide design. The structures described here allow for new concepts of on-chip communication. By using direct laser writing, free-formed polymer structures can be realized directly on the surface of integrated circuits on wafer-or die-level. Further photonic structures like waveguides, resonators, splitters and couplers can be realized with an extended freedom of design to the third dimension. Our approach opens new possibilities for optical interconnects and routing for on-chip signal transmission with a high fill factor and CMOS compatibility.
We present micro polymer optical waveguide elements fabricated using femtosecond laser and two-photon absorption (TPA) process. The POWs are constructed by tightly focusing a laser beam in SU-8 based resists transparent to the laser wavelength for single-photon absorption. The TPA process enables the patterning of the resist in three dimensions at a resolution of 100-200 nm, which provides a high degree of freedom for POW designs. Using this technology, we provide a novel approach to fabricate Three dimensional Polymer Optical Waveguides (3D-POW) and coupling with single mode fibers in the visible wavelength regions. Our research is also focused on fabricating passive micro optical elements such as splitters, combiners and simple logical gates. For this reason we are aiming to achieve optimum coupling efficiency between the 3D-POW and fibers. The technology also facilitates 3D-POW fabrication independent of the substrate material. We present these fabrication techniques and designs, along with supporting numerical simulations and its transmission properties. With a length of 270 µm and polymer core diameter of 9 µm with air cladding, the waveguides possess a total loss of 12 dB. This value also includes the external in and out mode coupling and in continuously being improved upon by design optimization and simulations. We verify the overall feasibility of the design and coupling mechanisms that can be exploited to execute waveguide based optical functions such as filtering and logical operations.
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