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A stimulated Brillouin fiber ring laser with a spectral width of 2 kHz and an intrinsic linewidth of less than 30 Hz has been demonstrated. Applications of such a laser include laser linewidth narrowing, microwave frequency generation, high-rate amplitude modulation, and optical inertial rotation sensing.

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This paper demonstrates that the molding of a sol-gel precursor against an elastomeric replica of the desired features (a form of soft lithography) [1] is a convenient method to generate submicrometer patterns of glasses on a substrate. We were able to fabricate glass (silicon dioxide doped with boron oxide, titanium oxide, or aluminum oxide) structures with micrometer-scale features supported on a flat Si/SiO 2 substrate, as well as free-standing membranes.In molding, an initially fluid material is allowed to acquire its final geometry by solidifying in a mold. This technique allows the reproduction of the fine details of the mold: replica molding of structures in polymers has generated structures with 10 nm sized features.[2] The molding of sol-gel precursor solutions has produced monolithic silica pieces [3] as well as Fresnel lenses or gratings with sub-micrometer periods.[4] Replica molding is a method that has several potentially useful features. It does not require photolithography and can be used without access to a clean room. Once the mold is fabricated, many replicas can be produced.[2] It has a theoretical limit to resolution that is much below that that can be achieved by photolithography. It can be used to make patterns on curved substrates. The throughput of a process based on molding can be high and its cost low. Unlike electron-beam or scanning tunneling microscopy (STM) writing, molding allows parallel fabrication. We believe that micro-molding is a type of process that will be widely useful in microfabrication. The sol-gel process is a versatile method for synthesizing many inorganic oxides.[5] This method generates materials with controlled chemical composition and low levels of impurities. Most common glasses, with the exception of some halide glasses, have been successfully synthesized; these compositions range from high purity silica to an eight-component glass ceramic. [6] Other materials that have been prepared by sol-gel process include PZT ceramics (i.e., Pb(Zr,Ti)O 3 ), [7,8] electro-optic films, [9] high efficiency phosphors, [10] and electrochromic glasses.[11]The use of sol-gel chemistry to prepare materials has one unattractive characteristic: the shrinkage induced in the drying stage gives rise to high stresses in the structures. These stresses can cause the deformation and breaking of the structures. In order to reduce these stresses, drying additives can be used.[12] The incorporation of non-hydrolyzing organic groups in the material (methyl or phenyl) gives structures with higher compliance and allows structural relaxation during the drying stage.[13] Controlled slow drying can also decrease the risk of cracking of the glass; it will, however, result in long process times. Good adhesion of the glass to the substrate is necessary to prevent the delamination of the structure. We wished to fabricate glass structures with dimensions in the range of 0.1 mm to several micrometers by non-lithographic methods, and have examined the molding of solgels in an elastomeric mold. This pape...

Mechanisms of bacterial pathogenesis have become an increasingly important subject as pathogens have become increasingly resistant to current antibiotics. The adhesion of microorganisms to the surface of host tissue is often a first step in pathogenesis and is a plausible target for new antiinfective agents. Examination of bacterial adhesion has been difficult both because it is polyvalent and because bacterial adhesins often recognize more than one type of cell-surface molecule. This paper describes an experimental procedure that measures the forces of adhesion resulting from the interaction of uropathogenic Escherichia coli to molecularly well defined models of cellular surfaces. This procedure uses selfassembled monolayers (SAMs) to model the surface of epithelial cells and optical tweezers to manipulate the bacteria. Optical tweezers orient the bacteria relative to the surface and, thus, limit the number of points of attachment (that is, the valency of attachment). Using this combination, it was possible to quantify the force required to break a single interaction between pilus and mannose groups linked to the SAM. These results demonstrate the deconvolution and characterization of complicated events in microbial adhesion in terms of specific molecular interactions. They also suggest that the combination of optical tweezers and appropriately functionalized SAMs is a uniquely synergistic system with which to study polyvalent adhesion of bacteria to biologically relevant surfaces and with which to screen for inhibitors of this adhesion.polyvalency ͉ optical tweezers ͉ self-assembled monolayers A dhesion of microorganisms to biological surfaces often correlates with pathogenicity (1). This observation suggests blocking adhesion as a strategy for limiting pathogenicity. Polyvalency is a tactic often used by microorganisms to remain attached to host cells when exposed to shear forces from flowing liquid (2). For example, Escherichia coli [the primary causative agent of urinary tract infections (3, 4)] use the FimH adhesin located on the tips of its type 1 pili to bind to mannose groups in oligosaccharides present on the surface of bladder epithelial cells (5-7). The small number of techniques that can be used to study adhesion of complex, polyvalent systems in biologically relevant circumstances has limited understanding of microbial adhesion and has slowed the development of new medicinal agents whose mechanism involves blocking adhesion.We have quantified successfully the forces of adhesion of uropathogenic E. coli to mannose-presenting surfaces by using gradient force optical traps-better known as optical tweezers-in conjunction with self-assembled monolayers (SAMs). Several characteristics of optical tweezers make them particularly well suited for studies of polyvalent adhesion involving bacteria: (i) they generate an optical trap (a focal region Ϸ0.1-0.3 m in size) that has dimensions similar to those of a typical bacterial cell (Ϸ0.5-1.0 m) (8, 9); (ii) they can be used in biological media (so long as these...