Abstract: The present invention generally relates to lasers comprising fluidic channels, such as microfluidic channels. In some instances, the channel contains two or more fluids. The fluids may remain non-mixed within the channel, for example, due to immiscibility and/or laminar flow within the channel. The fluids may be arranged in the channel such that light propagating in a first fluid is prevented by the second fluid from exiting the first fluid, for example, due to differences in the indexes of refraction (e.g., causing internal reflection of the fluid to occur). Thus, in one embodiment, a first fluid may be at least partially surrounded by a second fluid having a second index of refraction lower than the index of refraction of the first fluid. In some embodiments, the fluidic channel is used as a laser, for instance, a dye laser, i.e., a laser created by directing light at a dye to produce coherent light. The dye may be present in one or more fluids within the fluidic channel.

Abstract: The invention relates to methods and apparatuses for guiding and emitting electromagnetic radiation from a fluid waveguide. Various methods for changing optical properties (e.g., refractive index, absorption, and fluorescence) and/or physical properties (e.g., magnetic susceptibility, electrical conductivity, and temperature) of either the waveguide core or the cladding, or both, are provided herein. In one embodiment, electromagnetic radiation is guided and/or emitted at multiple distinct wavelengths, including emission in the form of an essentially continuous band, in some cases covering at least 150 nanometers. In another embodiment, methods for splitting a waveguide core and/or the joining of at least two waveguide cores in a waveguide are provided. In yet another embodiment, the invention includes the use of thermal gradients to generate a waveguide and/or to change the properties of waveguides. Embodiments of the waveguides may be used for optical detection or spectroscopic analysis.