Short range optical interconnect applications suffer from the lack of suitable and cost-efficient optical amplifiers. The availability of a practical amplifier that can be inserted in optical links between chips or even on chips could help overcoming losses, increasing the sensitivity of detectors and thereby make such links more practical. The current main-stream solution for optical amplification, Erbium Doped Fiber Amplfiers or EDFA’s is too bulky to be inserted on chip and even in chip to chip applications. The alternative, a III-V semiconductor based device is often too expensive and very sensitive to temperature variations. As a side-path in the ERC-project ULPPIC we discovered that a new type of colloidal quantum dots, HgTe quantum dots, provide optical gain at much lower threshold than other types of colloidal quantum dots, on par with what would be needed in practical optical interconnect applications. These colloidal quantum dot materials are particular interesting because they are solution processed – and hence potentially cheap – and can be integrated with optical waveguides in an efficient and compact way as we demonstrated in the ERC ULPPIC project. The aim of the INTERDOT POC project was to demonstrate that HgTe, can provide suitable gain levels when deposited on a substrate, and not only when dissolved in a solvent (status before INTERDOT).
Unfortunately, early in the project unexpectedly considerable difficulties were encountered in depositing HgTe quantum dot films of sufficient quality. Excessive clustering resulted in very high radiation loss for the deposited film. Therefore we further focussed on the intrinsic characterisation of the quantum dots. In the second half of the project we finally managed to deposit films of higher quality that allowed optical characterisation. A clear signature of amplified spontaneous emission was observed in these films. Based on these results a patent application is being prepared and a journal publication has been written. These will be used to contact suitable industrial partners, active in the domain of optical interconnects.
