Photonic device assembly:where technology and expertise align

PHOTONICS HAS revolutionised the telecommunications sector by removing the bottlenecks in data transfer speed and bandwidth associated with traditional electronics, and allowing superior processing power to be squeezed into ever-smaller envelopes. However, device miniaturisation is making it harder for manufacturers that use manual techniques to work at the required assembly tolerances. This article looks at the challenges involved in photonic device production and the automation solutions that ensure perfect alignment every time.

Manual manoeuvring

Photonic device assembly generally involves the precise alignment, gluing and curing of a combination of light sources, fibres, lenses and chips. Component positioning is crucial to ensure that the final product functions as intended, since even miniscule misalignments can dramatically decrease device efficiency. However, time-consuming manual alignment methods - such as the use of shims and retaining hardware - continue to be the norm for the majority of manufacturers. This not only requires specialised labour - which is both expensive and hard to find - but it can also take up to 20 minutes to assemble complex devices, creating a production bottleneck. Since shims and jigs also struggle to satisfy the tight tolerances of some modern devices, a more accurate indicator of component alignment is needed.

A complex balance

An advantage of photonic devices is that their efficiency is directly related to the alignment of their individual parts, meaning that the strength of their output will fluctuate in real time as component positions are changed. The varying magnitude of this signal can be used to guide an iterative process of positional adjustment, culminating in a perfectly aligned assembly. This output strength can also be tracked during the gluing and curing process to assess component drift. However, this method is almost impossible to carry out manually on complex devices with multiple inputs and outputs, since any movement during the optimisation of one connection will cause the alignment of others to shift, requiring constant re-adjustment to reach a global consensus. This is clearly not practical in a production environment, and a degree of automation is required to solve the issue.

Active alignment

One solution is to close the feedback loop between the device output and positioning hardware, allowing the adjustment process to be automated using intelligent software solutions and control modules. These systems use algorithms to characterise the assembly and locate the approximate location of peak photonic output, culminating in multiple gradient searches to pinpoint the global optimum. Specialised piezo nanopositioners are then used to guide the components into position in a process known as active alignment, optimising several connections at once and eliminating the need for constant iterative readjustment. There are now complete modular solutions available that can vastly reduce photonic device manufacturing times while maintaining sub-micron precision, something that would simply not be possible with manual alignment. For example, Physik Instrumente’s Fast Multichannel Photonic Alignment (FMPA) technology is capable of performing multiple alignments in parallel, reducing assembly time by a factor of 100 or more. 

Moving with the market

The photonics market is moving at such a pace that these devices could soon contain hundreds - or thousands - of individual components and connections that require parallel optimisation, making production impossible without active alignment. The rising adoption of photonics across almost all sectors is leading to the development of increasingly specialised devices, all requiring bespoke production processes. It is therefore crucial for manufacturers to future proof themselves by implementing agile combinations of hardware and software that can be reconfigured if and when required. This is where modular alignment solutions excel, offering the flexibility and scalability needed for operations to keep up with market demand and position themselves for continued success.

Warren Harvard is  country manager UK at Physik Instrumente and Scott Jordan is head of photonics at Physik Instrumente

For more information: 

www.physikinstrumente.co.uk

Tel: 01234 756 360