Tunable laser expands system capacity in advanced optical networks
A team of researchers from A*STAR's Institute of Microelectronics (IME) and Nanyang Technological University (NTU) have showcased what they say is the smallest wavelength-tunable laser fabricated by microelectromechanical system (MEMS) technology. According to them, the laser has a wide tuning range that enables telecommunications providers to cost-effectively expand system capacity in advanced optical networks to support high data packets at extremely fast speed.
By having one laser, instead of several, which can generate light over a range of wavelengths, the network infrastructure is greatly simplified, and inventory and operational costs are dramatically reduced, thus strengthening the capability of telecommunications providers to deliver bandwidth-on-demand services at higher profit margins.
To keep up with increasing consumer demands for faster internet connectivity and greater network coverage, service providers need to revamp their network architectures. In fibre-optic communications, advanced wavelength division multiplexing (WDM) networks typically rely on single wavelength laser sources, making them expensive, time-intensive, energy-inefficient and logistically impractical for service providers to increase their system capacity.
On the other hand, commercial tunable lasers require multiple components in their set-up in order to achieve the necessary wide tuning range, thereby contributing to the bulkiness of these lasers and rendering them unsuitable for system integration.
To tackle these challenges, the joint team from IME and NTU has demonstrated an on-chip integrated laser, the smallest reported tunable laser fabricated by MEMS technology that can generate light from 1531.2-1579.5nm of the near-infrared region, relevant to optical telecommunications. Compared to MEMS tunable laser based on external cavity design, the laser significantly improves the coupling efficiency of 50 per cent to more than 75 per cent to offer wide tuning range using processing steps that are more streamlined and amenable to mass production.
The design uses simple packaging and provides ease of fabrication for mass production. This miniature on-chip system can also be readily integrated into high-density photonic circuits to achieve smaller form-factor. These distinct functionalities and highlights make the laser an attractive light source for next generation optical telecommunications, as well as in other spectroscopy applications.
Cai Hong, the IME scientist who is leading the research project, commented, "Our laser exploits the superior light converging ability of the rod lens and parabolic mirror of the 3D micro-coupling system to achieve both wide wavelength tuning range and small form factor. In external cavity tunable lasers, wide tuning range is traditionally at the expense of small form factor."
Liu Ai Qun, professor from the school of electrical and electronic engineering, NTU, said: "This new chip is very attractive to communications and biomedical device companies because of its small size and low cost. Our prototype, a 1 x 1cm microchip, is the smallest tunable laser which can be easily manufactured as it is ten times smaller than most commercially available tunable laser devices. The key innovation was that our tunable laser is integrated onto a microchip using MEMs technology, made possible only through NTU's strong expertise in MEMs, backed by a decade of solid research into single-chip solutions."