IDYLIC

IDYLIC is a research project, dedicated to the development and demonstration of a new concept of an ultra-stable coherent dual frequency laser for microwave photonic applications at telecommunication wavelength. It covers applications from radio-over-fiber communications, delivery and detection of radar signals, up to THz wave signal generation. When most of dual frequency lasers demonstrated so far are based on complex and bulky solid state lasers which require optical excitation, some attempts have been done to propose a compact, electrically excited dual frequency lasers using semiconductors. Nevertheless their fabrication and/or manipulation are still complex mainly limited by the semiconductor active layer itself (quantum well) behaving as a homogeneous medium. This implies that simultaneous dual frequency generation is not feasible within the same volume because of mode competition. As a consequence, complex architectures have been proposed based on phase locked edge emitting lasers (with external electronics or coupled waveguides), or using two different and spatially separated and slightly coupled oscillating modes. In the first case, such laser cavities suffer from a well-known low spectral purity, far from their solid state counterpart, which severely limits the beatnote linewidth of the two frequencies. In the second case, the spatial separation lying on a two axis optical configuration implies complex optical alignment rules to avoid mode competition, and make it very difficult to use electrical injection in such devices. In IDYLIC project, we propose to combine a semiconductor based active layer behaving as an inhomogeneous medium like solid state material by using quantum dot (QD), and a vertical external cavity surface emitting laser (VECSEL) cavity design ensuring a high output power, class-A laser regime, and a high spectral purity. This unique union will enable a dual frequency emission without spatial separation (single axis configuration) of the two lasing mode which is highly suitable for a better compactness and a simplified pumping scheme, making electrical injection possible. As a preliminary and essential step, first demonstrations of coherent dual frequency emission at 1.5 µm will be carried out with single axis optically pumped QD VECSEL, exploiting QD potentialities to cover frequency difference from 100 GHz up to 4 THz, with very narrow lasing and beatnote linewidth ( 50-100 µm) is very challenging, such a pumping scheme is more promising for integration in an optoelectronic system, but above all may enable to decrease low frequency noise These two main IDYLIC challenges are the key points to develop a device with performances without any equivalent at the moment. To succeed in these ambitious objectives, the IDYLIC project will address material optimizations (QD issues), which will define, in close collaboration with QD modelization, the best QD structural properties for the dual frequency emission. Also state of the art VECSEL processing will be considered and developped, prior to device characterization. At the end of the project, coherent dual frequency lasers developed in IDYLIC project will be tested and evaluated in microwave photonic applications, including the generation of THz radiation for medical imaging and sensing systems.