Researchers from Singapore's Agency for Science, Technology and Research (A*STAR) in the Institute of Microelectronics (IME) and Nanyang Technological University (NTU; also in Singapore) have demonstrated a chip-based (10X smaller than commercial designs) wavelength-tunable laser fabricated using microelectromechanical system (MEMS) technology. The laser features a wide tuning range that enables telecommunications providers to cost-effectively expand system capacity in advanced optical networks to support high data packets at ultrafast speed.
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By having one laser instead of several that 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.
In fiber-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. However, commercial tunable lasers typically require multiple components in their setup 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 A*STAR 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 nm to 1579.5 nm in the near-infrared region relevant to optical telecommunications. Compared to MEMS tunable lasers based on external-cavity designs, the new laser significantly improves the coupling efficiency of 50% to more than 75% 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 for spectroscopy applications.
Cai Hong, the IME scientist who is leading the research project, said, "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 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 cm by 1 cm 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."
SOURCE: A*STAR; http://www.a-star.edu.sg/Media/News/Press-Releases/articleType/ArticleView/articleId/2575.aspx