A novel packaging solution is discussed where both optical and electrical connectivity can be fabricated using ion-exchange (IOX) waveguides integrated into a glass with thin film metallization for an electrical redistribution layer. Design and process aspects are discussed to support silicon photonic flip-chip assembly directly to the glass substrate. Low-loss evanescent coupling occurs between the IOX waveguides embedded in the glass and the photonic chips with high-density silicon nitride optical I/Os. This design enables low-cost assembly methods involving the pick and place alignment of optical components and offers connectivity with low-profile mechanical transfer (MT) ferrule-based fiber connectors.
Co-packaged optical modules aim to meet the increasing bandwidth and power reduction requirements in next-generation datacenter switches. Meeting the cost per capacity targets requires new and innovative wafer-scale manufacturing solutions. In this work, glass with low-loss (<0.1 dB/cm) single-mode ion-exchanged waveguides is proposed as an optoelectronic substrate for co-packaged optics. High-speed ultrafast laser processes are developed to fabricate through glass vias for electrical connections, ablated features to enable passive alignment of MPO-connector to chip coupling, and for the singulation of glass wafers into individual optical circuits with optical quality end-facets for low-loss edge coupling without subsequent post-polishing or finishing steps.
There are significant advantages for on-board and co-packaged optics in next-generation data centers. However, the highvolume manufacturing of the photonic circuits that underpin the technology will require the fabrication of large quantities on a wafer- or panel-scale, which must then be singulated into individual devices. A major challenge is the requirement for low-loss edge coupling to optical fibers (optical-quality and vertical end-facets) which typically requires expensive and time-consuming post-processing steps such as mechanical polishing. In this work, an ultrafast laser is employed to singulate glass substrates using a non-diffracting beam that creates a localized material modification through the entire glass thickness via nonlinear laser-material interactions. By controlling the placement of the laser modifications, the regions around the waveguides could be strategically avoided. This leaves optical-quality regions around the waveguides which provide the same low-loss edge coupling as the polished end-facets. This process can be applied to optical circuits containing planar ion-exchanged waveguides and 3D ultrafast laser-inscribed waveguides in the bulk glass without the need for post-polishing the end-facet and thus opens the opportunity for more rapid device prototyping and lower-cost high-volume manufacturing.
Co-packaged optics for next-generation data center switches require novel photonic packaging and optical interconnect solutions to increase bandwidth and decrease manufacturing costs. An optoelectronic glass substrate with integrated ion-exchanged (IOX) single-mode waveguides for photonic integrated circuit (PIC) packaging and fiber cable connectivity is demonstrated in an effort to reduce the overall packaging complexity. The single-mode glass waveguides were fabricated and evaluated to be thermally stable at 110ºC for more than 5 years. Laser singulated optical end-facets and laser-formed passive alignment features yield an average connector loss of 0.68 dB when end-coupled to standard MTP- 16™ connectors.
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