Efficient Planar-Integrated Free-Space Optical Interconnects Fabricated by a Combination of Binary and Analog Lithography

Abstract

Abstract-Design, fabrication, and experimental testing of an integrated microoptical module for interconnection are reported. The systems integration is based on the concept of planar-integrated free-space optics. The module combines diffractive-reflective and refractive microoptics. The diffractive elements were fabricated by binary lithography and reactive ion etching. The refractive elements were made by analog lithography using a high-energy beam sensitive mask and replication in Ormocer. The fabricated module implemented a simple one-dimensional optical interconnect. Two versions were implemented for which insertion losses of approximately 8 and 4.5 dB were measured, respectively.

Micro‐ and nanooptics – an overview

“…This suggests the following design approach: the use of refractive elements for simple functionality but high efficiency, for example, for coupling, and the use of diffractive optics where specific functionality is required (e.g., beam splitting, wavefront correction). Recently, an integrated microoptical system was built and demonstrated based on this design concept [31]. It implements an optical interconnect between two MT-fiber connectors (Fig.…”

Silicon micromirrors with three-dimensional curvature enabling lensless efficient coupling of free-space light

“…By contrast, free-space coupling elements are usually designed to mitigate optical beam divergence phenomena associated with Gaussian beam (GB) propagation and achieve phase/mode matching. [4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23] Photonic applications in which the sources and destinations are separated by a free-space optical path (OP) such as fiber to fiber, 4 laser to fiber, 5-7 photonic crystal to fiber, 8 waveguide to fiber, [9][10][11] laser to laser [12][13][14][15][16] and intra chip coupling 17 have been reported. In many applications, a high coupling efficiency over a relatively long OP, within the submillimeter range and sometimes extending up to the centimeter range, is critical.…”

“…For example, the coupling efficiency has a direct impact on the output power and tunable range of external cavity tunable lasers, 14 the finesse and free spectral range of Fabry-Pérot resonators 18 and the insertion loss and number of the input/output ports in optical switches, 19 as well as in optical interconnects. 17,20 Micro lenses in the form of lens array, 19 ball lenses, 21 graded-index lenses 4,11 or lensed fibers 22 are the most commonly used optical components for focusing and matching GBs. The use of lenses, however, increases the system complexity and cost due to the required assembly process, a major obstacle to system integration.…”