Solid-state organic amplifiers and lasers are attractive for hybrid integration due to their compatibility with different material platforms, straightforward processing, and possibility to optimize easily their optical and electronic properties by molecular engineering. Advances in the gain medium design and synthesis in combination with new resonator architectures led to tremendous improvements in temporal and spectral properties, lifetime stability, gains produced and operating threshold powers, which triggered interest in their use for a broad range of integrated photonic applications. In this contribution, the current state-of-the-art in the field of organic solid-state amplifiers and lasers is reviewed from the aspects of fabrication technology, gain materials, and device performance. Furthermore, examples of the progress of this technology from a laboratory curiosity to one that demonstrates practical integrated photonic applications are highlighted. An outlook is also provided on research areas and applications that are likely to shape further developments of this technology. (Figure reprinted from [296],

Whispering-gallery-mode resonators have been extensively used in conjunction with different materials for the development of a variety of photonic devices. Among the latter, hybrid structures, consisting of dielectric microspheres and colloidal core/shell semiconductor nanocrystals as gain media, have attracted interest for the development of microlasers and studies of cavity quantum electrodynamic effects. Here we demonstrate single-exciton, single-mode, spectrally tuned lasing from ensembles of optical antenna-designed, colloidal core/shell CdSe/CdS quantum rods deposited on silica microspheres. We obtain single-exciton emission by capitalizing on the band structure of the specific core/shell architecture that strongly localizes holes in the core, and the two-dimensional quantum confinement of electrons across the elongated shell. This creates a type-II conduction band alignment driven by coulombic repulsion that eliminates non-radiative multi-exciton Auger recombination processes, thereby inducing a large exciton–bi-exciton energy shift. Their ultra-low thresholds and single-mode, single-exciton emission make these hybrid lasers appealing for various applications, including quantum information processing.

The authors present the deposition of nanoscale droplets of Cr using femtosecond Ti:sapphire laser-induced forward transfer. Deposits around 300 nm in diameter, significantly smaller than any previously reported, are obtained from a 30 nm thick source film. Deposit size, morphology, and adhesion to a receiver substrate as functions of applied laser fluence are investigated. The authors show that deposits can be obtained from previously irradiated areas of the source material film with negligible loss of deposition quality, allowing subspot size period microarrays to be produced without the need to move the source film. © 2006 American Institute of Physics. ͓DOI: 10.1063/1.2386921͔The laser-induced forward transfer ͑LIFT͒ technique exists as a method for the direct writing of a wide variety of materials with a minimum achievable resolution around 1 m. 1 It is of particular interest due to the ability to pattern material in air and at room temperature onto virtually any substrate. 2 In recent years, significant study has been directed towards extending the range of materials that can be deposited using LIFT; metals, 3 oxides, 2 superconductors, 4 DNA, 5 proteins, 6 fungal spores, 7 polycrystalline Si, 8 and various important electronic and sensing materials 9 have all been transferred. In contrast, efforts to reduce the minimum achievable deposition dimensions have received comparatively little attention. LIFT using nanosecond pulsed lasers ͑ns-LIFT͒ typically produces depositions which at best reproduce the shape and size of the laser focal spot. 10 Femtosecond-LIFT ͑fs-LIFT͒ using an UV excimer laser has been shown to be capable of subspot size depositions with diameters around 0.5 m. 3 Recently, it was demonstrated that ns-LIFT could also be used to produce subspot size deposits by carefully controlling the laser fluence just above the threshold for material transfer. 11 In LIFT, a thin film of the material to be deposited ͑the "source film"͒ is coated onto one face of a transparent substrate ͑the "carrier"͒ and brought into close contact with another substrate ͑the "receiver"͒. A single laser pulse is then focused through the carrier onto the carrier-film interface, where it is absorbed in a shallow layer of the film ͓Fig. 1͑a͔͒. Conventionally, LIFT then occurs by vaporization of film material at the constrained interface, with the resultant pressure buildup propelling film material to the receiver. However, this is the case only for thicker films and high laser fluence; for thin films and fluence just above the threshold for material transfer, it is possible for LIFT to occur solely by melt-through of the source film ͓Fig. 1͑b͔͒. With precise control of the laser fluence, only the center of the melt front reaches the free surface of the film ͓Fig. 1͑c͔͒, allowing molten material under pressure to expand through an unconstrained, subspot size region. With ns-LIFT this process has been shown to facilitate sublaser spot size printing. 11 In this letter we demonstrate that the same process can occur with fs-LIFT...

Abstract:The tremendous interest in the field of waveguide lasers in the past two decades is largely attributed to the geometry of the gain medium, which provides the possibility to store optical energy on a very small dimension in the form of an optical mode. This allows for realization of sources with enhanced optical gain, low lasing threshold, and small footprint and opens up exciting possibilities in the area of integrated optics by facilitating their on-chip integration with different functionalities and highly compact photonic circuits. Moreover, this geometrical concept is compatible with high power diode pumping schemes as it provides exceptional thermal management, minimizing the impact of thermal loading on laser performance. The proliferation of techniques for fabrication and processing capable of producing high optical quality waveguides has greatly contributed to the growth of waveguide lasers from a topic of fundamental research to an area that encompasses a variety of practical applications. In this first part of the review on optically pumped waveguide lasers the properties that distinguish these sources from other classes of lasers will be discussed. Furthermore, the current state-of-the art in terms of fabrication tools used for producing waveguide lasers is reviewed from the aspects of the processes and the materials involved. 2 1.IntroductionOver the last two decades the field of solid-state planar waveguide lasers has experienced a steady growth, progressing from a laboratory curiosity to an area that demonstrates a broad spectrum of applications, from multiwavelength laser channel arrays for telecommunications to diode-pumped planar structures with multiwatt output powers for sensing and ranging applications. Waveguide lasers are by no means a new field and the first report on such a source dates back in 1961, when laser operation of a waveguide based on an active glass core rod embedded in a low refractive index cladding was demonstrated [1]. However research efforts in the years that followed this report focused primarily on the development of optically pumped laser sources based on high optical quality bulk dielectric laser media in the form of rods and slabs. The merits of the waveguide geometry and the associated optical confinement have been first highlighted in single mode glass optical fibers. Fibers have proven an enabling technology for realization of highly efficient amplifier and laser sources owing to their unrivalled low loss performance and ability to maintain a small spot size and hence high intensities over lengths that are orders of magnitude longer than would normally be allowed by diffraction, [2,3]. Er-doped fiber amplifiers (EDFAs) in particular have directly contributed to the enormous expansion of the optical communications networks that underpin today's internet infrastructure by allowing for signal regeneration and optical data transmission over long distances. The excellent performance of fiber lasers and amplifiers provided motivation and triggered a major techn...