Low-cost microoptical modules for mcm level optical interconnections

Abstract

A multi-channel free-space micro-optical module for dense MCM-level optical interconnections has been designed and fabricated. Extensive modeling proves that the module is scalable with a potential for multi-Tb/s.cm 2 aggregate bit rate capacity while alignment and fabrication tolerances are compatible with present-day mass replication techniques. The micro-optical module is an assembly of refractive lensletarrays and a high-quality micro-prism. Both components are prototyped using deep lithography with protons and are monolithically integrated using vacuum casting replication technique. The resulting 16-channel high optical-grade plastic module shows optical transfer efficiencies of 46% and interchannel cross talks as low as-22 dB, sufficient to establish workable multi-channel MCM-level interconnections. This micro-optical module was used in a feasibility demonstrator to establish intra-chip optical interconnections on a 0.6µm CMOS opto-electronic field programmable gate array. This opto-electronic chip combines fully functional digital logic, driver and receiver circuitry and flip-chipped VCSEL and detector arrays. With this test-vehicle multi-channel on-chip data-communication has been achieved for the first time to our knowledge. The bit rate per channel was limited to 10Mb/s because of the limited speed of the chip tester.

Device Requirements for Optical Interconnects to Silicon Chips

“…Though random interconnect patterns are difficult for free-space optics, regular structures such as busses or even strongly interleaved patterns such as perfect shuffles that are suited to operations such as Fourier transforms or switching networks could be quite viable. Micro-optical systems can make free-space connections from chip to chip or within a chip [112], and a planar optics technology has been demonstrated that could make entire pre-aligned "free-space" optical systems based on lithography on a planar substrate [111].…”

Deep proton writing: a rapid prototyping polymer micro-fabrication tool for micro-optical modules

“…• C. The detailed physics behind technological processing steps have been published before [26]- [28]. We demonstrated that DPW is a flexible technology to fabricate 2D matrices of spherical microlenses with different diameters between 120 and 200 µm and focal numbers ranging from 1 to 7 on the same PMMA substrate.…”

“…We have shown that this type of interconnect modules has the potential to provide the highly desirable massive parallel highspeed interconnects needed for future generations intra-MCM level interconnections [28]. We are currently working towards a massively parallel intra-chip interconnect demonstrator that will carry a channel density above 4000 channels cm −2 and hence provide us with low-cost, chip compatible, plug-and-play, commercially viable interconnect solutions [39].…”

Collective Micro-Optics Technologies for VCSEL Photonic Integration

“…One can cite, for example, passive alignment of micro-Fresnel lens arrays with side-mounted VCSELs [19]. A low-cost plastic multichannel interconnection module including a lenslet and a high-quality microprism was also successfully developed for increasing misalignments tolerances to ±40 µm (Figure 4) [20].…”