The first ever integration of a laser source with an organic amplifier on a silicon-based photonic chip is not only a remarkable achievement in the area of nanoelectronics, it also creates an enormous potential for cost-effective biosensors that can be used in near-patient testing, much like today’s disposable blood glucose test strips that can be used without any effort for sterilisation.
“This is the first ever implementation of an organic laser on a silicon photonics chip”, says Christian Koos a researcher at the KIT institutes for photonics and quantum electronics as well as at the institute for microstructure technology. “The most striking benefit of lasers is that they can be manufactured in large quantities at low cost. In the long run, a price of a few euro cents per laser is perceivable”.
A major challenge during the implementation of organic microchips poses the requirement of integrating multiple different components on a common substrate at low cost. For some years it has been possible to manufacture optical components based on silicon. These so-called silicon photonics utilises advanced microelectronics manufacturing processes and thus makes it possible to produce sophisticated photonic components in large quantities and at low cost. These sub-micron components are suited to the implementation of compact biosensors. However, until now was not possible to implement light sources on such chips because silicon is not a good light emitter; it has a poor efficiency and tends to generate more heat than light.
The KIT researchers therefore have developed a new class of infrared laser sources. They combined silicon-based nano-scale waveguides with a polymer to which an organic pigment has been added. The operating energy for this “organic” laser source is fed from above, vertically to the chip area, by means of a pulsed light source. The laser light created this way is coupled directly into a silicon nanoscale waveguide. The researchers were able to generate a pulsed laser at a wavelength of 1310 nm (infrared) and a peak performance of more than 1W on such a chip. By applying various dyes and laser resonators it is possible to vary the wavelength of the laser beam across a wide range of the spectrum.
Such components can enable biosensors with multiple integrated laser light sources whose wavelengths are tuned to specific use cases. Typically such chips contain sensors that can determine substances relevant in medical tests. To avoid contamination it is advantageous to manufacture these devices at the lowest possible cost and use them only once, make them suited for point-of-care diagnostics.
The report on this achievement was first published in the journal Nature Communications.