Warren Harvard, country manager UK, Physik Instrumente (PI)
The last six decades have seen the constant and rapid development of silicon microchips, with an exponential increase in integrated circuit (IC) transistor density leading to greater processing power being squeezed into ever-smaller microchips. However, since transistors can only shrink so far before quantum effects start to interfere with their function, researchers and manufacturers are now reaching the limits of what can be achieved via conventional electronics. Fortunately, photonics is on hand to usher in a new age of innovation, allowing the integration of miniaturised optical devices into everything from driverless vehicles and virtual reality goggles to smart wearables and quantum computers. With the number of sectors using photonics predicted to grow rapidly over the next decade, it is crucial to identify the main production bottlenecks and novel solutions that can be used to keep up with future demand.
Device assembly
The assembly of photonic devices generally involves the precise alignment, gluing and curing of a combination of light sources, fibres, lenses and chips. The positioning of these individual components 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, it can take up to 20 minutes to assemble particularly complex devices, creating a production bottleneck. Additionally, since shims and jigs are not able to satisfy the increasingly tight tolerances required to manufacture some modern devices, a more accurate indicator of component alignment is needed.
Photonic feedback
An inherent advantage of photonic devices is that their efficiency is directly related to the alignment of their individual components, meaning that the strength of their output will fluctuate in real time as component positions are changed. Consequently, the varying magnitude of this signal can be used to guide an iterative process of positional adjustment, culminating in a perfectly aligned assembly. The strength of this photonic output can even be tracked during the gluing and curing process, giving an indication of 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 time-consuming back-and-forth is clearly not practical in a production environment, and a degree of automation is required to solve this problem.
Closing the loop
One solution is to close the feedback loop between the device output and positioning hardware, a technique known as active alignment, allowing the adjustment process to be automated using intelligent software solutions and control modules. These systems use areal scan 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 perfect alignment. There are now modular solutions available that can optimise the positioning of multiple connections simultaneously, eliminating the need for constant iterative readjustment and vastly reducing photonic device manufacturing times, while maintaining sub-micron precision. For example, Physik Instrumente’s (PI’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.
Keeping pace
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 without active alignment all but impossible. Furthermore, the rising adoption of photonics across almost all sectors is leading to the development of increasingly specialised devices, all of which necessitate 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, such as those engineered by PI, excel, offering the flexibility and scalability needed for operations to keep up with market demand and position themselves for continued success.
PI