Spectral Beam Combining

Input fibre array to spectral combiner
The variety of lasers and wavelengths available from them has grown exponentially in recent years. This has been reciprocated by a similar growth in applications of lasers, including: material processing, remote sensing, medical, free space optical communications, cosmetic and lighting, amongst many others.

There is an increasing number of applications where lasers covering more than one wavelength are required for a single application. For closely spaced wavelengths, combining such lasers to form a single beam is relatively straightforward, by employing dichroic mirrors for example. However, as the number of wavelengths increases or as the spectral separation between them increases, traditional methods become limited and in some cases do not provide a solution.

To solve this problem, the team at LumOptica developed a concept based on spectral beam combining. More technical information can be found here.

Based on fibre optics and diffractive optical elements, the solution is compact and completely passive. The figure below shows the optical fibres of each channel (the other ends being coupled to the lasers) positioned very accurately both laterally and longitudinally. Upon emerging from the fibres, the radiation from each fibre is collimated by a lens system and co-aligned to its neighbours by a diffractive optical element.

The result is that we are able to offer technology which enables almost any number of lasers to be combined into a single co-aligned, collimated output beam. The approach enables an extraordinary spectral bandwidth to be utilised; it has been demonstrated combining five distinct wavelengths ranging from 355 nm in the ultraviolet, through visible, near-infrared to 4.3 microns in the mid-infrared. The spectral limits are governed by the glass materials employed and can extend even further below and beyond the quoted wavelengths. Laboratory tests revealed that the technology is suitable at individual laser power levels of at least several watts.

If you have a requirement to combine lasers covering ultra-broad wavebands, then this approach is likely to meet it. Contact us to find out how we could assist you in making this happen.