Rapid progresses in nano-sciences and bio-applications, such lab-on-a-chip or drug screening technique, have stimulated enormous interest in micro-scaled coherent light sources. Among others, solid-state dye lasers offer a vast set of the required features: high brightness and coherence, narrow line width of radiation, broad wavelength tunability, easy operation, and inexpensive manufacturing. Recent achievements in polymer physics and improvements of dye properties make such lasers good candidates for micro- and nano-photonics applications.
In this paper, we report a model of a microcavity solid-state dye laser using Rh6G dye embedded in a PMMA polymer host matrix as a gain material. As a reference stage, we take a model of the liquid dye microcavity laser demonstrated recently [1]. It consisted of two triangle-shaped polymer (PMMA) parts with a micro-fluidic dye channel. In our model, we substitute the micro-fluidic dye channel with a solid bar containing dye-polymer composition. Several hundreds of point excitation sources simulating dye molecules are randomly allocated inside the bar. Such an approach corresponds better to real dye lasers which typically are excited by optical pumping of the gain material. The structure was of a typical size required for micro-(nano-)photonics applications, 4-10 µm. The wavelength is chosen to correspond real dye lasers, within 500-600 nm bandwidth. With this modified dye laser layout, we have obtained noticeable features not observed in the original model: higher out-coupling efficiency and depletion of odd modes inside the laser microcavity. We demonstrate that the axial symmetry of the microcavity with the inserted gain section is responsible for the odd modes depletion. Better out-coupling can be explained by more homogeneous and efficient allocation of the excitation sources.
Additionally, we discuss how different cavity geometries and the material properties, such as gain, attenuation, and dispersion can affect the lasing properties and output coupling efficiency of the solid-state dye laser.
References
1. M. Gersborg-Hansen, S. Balslev, and N.A. Mortensen, Finite-element simulation of cavity modes in a micro-fluidic dye ring laser, J. Opt. A: Pure Appl. Opt. 8, 17-20 (2006).
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