A Laser Source for Biosensors

Organic laser on a silicon photonics chip: Optical excitation from above generates laser light in the waveguide (Source: KIT)

In the area of nano photonics, scientists for the first time succeeded in integrating a laser with an organic gain medium on a silicon photonic chip. This approach is of enormous potential for low-cost biosensors that might be used for near-patient diagnosis once and without any sterili­zation expenditure similar to today’s strips for measuring blood sugar.

This is the first time organic lasers were integrated on a single silicon photonic chip, Christian Koos, researcher of KIT’s Institute of Photonics and Quantum Electronics and Institute of Micro­structure Techno­logy, reports. “The main advantage of the lasers consists in the fact that production of large series is associated with low costs. In the long term, manu­facture at a price of some cents per laser might be feasible.”

One of the major challenges associated with the fabrication of optical microchips consists in integrating a number of different components on one substrate at low cost. For some years now, it has been possible to produce optical components from silicon. This so-called silicon photonics uses highly developed nano­technological fabri­cation processes of microelectronics and allows for the inexpensive production of large numbers of high-perfor­mance photonic components. Such components of fractions of a micrometer in size can contribute to making infor­mation technology more energy-efficient and are highly suited for compact biosensors.

The problem of integrating light sources on the chip, however, still remained unsolved, as the silicon semi­conductor is hardly suited as a light emitter due to its electronic structure. During electron transfer between energe­tically different states, the energy is preferably released in the form of heat rather than light.

Researchers of KIT have now developed a new class of lasers in the infrared range. For this purpose, they combine silicon nano wave­guides with a polymer doped with an organic dye. The energy to operate this “organic” laser is supplied from above, vertically to the chip surface, by a pulsed light source. The laser light produced is directly coupled into a silicon nano waveguide. The resear­chers succeeded in generating pulsed laser radiation with a wavelength of 1310 nm and a peak power of more than one Watt on one chip. By the use of various dyes and laser reso­nators, the wavelength of laser radiation can be varied over a wide range. (Source: KIT)

Reference: D. Korn et al.: Lasing in silicon-organic hybrid waveguides, Nat. Comm. 7, 10864, DOI: 10.1038/ncomms10864

Link: Institute of Photonics and Quantum Electronics (IPQ, C. Koos), Karlsruhe Institute of Technology (KIT), Karlsruhe, Germany

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