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ELIMINATING COMPLEX AND EXPENSIVE ACTIVE ALIGNMENT

Is automated passive alignment the key to fully capitalizing on optical interconnect innovations?

Speaking about how the optics industry needs to change in order to help data centers cope with traffic growth, during his keynote speech at OFC 2017, Urs Hölzle – Google senior vice president of technical infrastructure – said: “Optics is still an artisan craft; if you really want improvements of 10x, then you’ve got to automate. We’re really looking forward to an optics model that looks more like the rest of the data center model and chipsets”.

Hölzle is not alone in believing that the optical components industry needs to take a leaf out of the microelectronics industry’s book by industrializing processes that are often manual and demanding.

In order to begin to reach the benchmark set by the microelectronics industry, the alignment processes inside a transceiver need to be improved.

Unfortunately, alignment and assembly are commonly conducted with specialized equipment, requiring complex and time consuming manual or semi-manual operations. A better, more scalable and reliable way forward is to introduce as much automation as possible, just as has been achieved in large volume electronics manufacturing.

However, while accuracy can be excellent, active alignment is expensive and time consuming, requiring the active components to be powered up and signals optimized during the bonding process. By enabling purely machine vision based pick-and-place equipment, the overall cost and complexity can be driven down substantially, particularly for single mode transceivers.

Innovative photonic component manufacturer Optoscribe has introduced a unique monolithic 3D glass-based photonic integrated circuit platform which is ideally suited for creating custom fiber coupling and attaching solutions that can be integrated into a wide variety of transceivers. These chips integrate V-grooves to enable high precision passive alignment of the fiber to the glass chip along with precision fiducial markers to facilitate automated vision-based alignment of the glass chip to the transceiver platform such as SiPh, VCSEL or DFB. The V-grooves and fiducial markings are micromachined directly into the chip by laser direct write technology at the company’s recently opened state-of-the-art manufacturing facility in Livingston, UK.

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