Solid State Optical Microlasers Fabrication via Microfluidic Channels

Maurizio Manzo,Omar Cavazos

doi:10.3390/opt1010007

Abstract

In this paper, we propose the use of a microfluidic channel with flow focusing technique to fabricate solid state polymeric microlasers to precisely control sizes for mass production. Microlasers are made from a solution of UV curable polymer, namely polyethylene glycol diacrylate (PEGDA) with a molecular weight of 700 and rhodamine 6G laser dye at two different volumetric ratios (polymer to dye) of 4:1 and 2:1, respectively, which are used as the dispersed phase. A reservoir filled with liquid polydimethylsiloxane (PDMS) was used to cure the microlasers via UV lamp. A microchannel made of (PDMS) and size of 200 µm was used in this paper; mineral oil was selected as the continuous phase. Two experiments are conducted by fixing the pressure flow for the dispersed phase to 188 mbar and 479.9 mbar, respectively. In both experiments, the pressure of the continuous phase (mineral oil) was varied between 1666.9 mbar and 1996.9 mbar. The measurement of the fabricated microlasers’ size was performed with the aid of the MATLAB Image Processing Toolbox by using photographs taken with a CMOS camera. The tunability of the highest size, ranging from 109 µm to 72 µm, was found for the PEGDA to dye ratio of 2:1 (188 mbar) and average standard deviation of 1.49 µm, while no tunability was found for the 4:1 ratio (188 mbar). The tunability of the microlaser’s size, ranging from 139 µm to 130 µm and an average standard deviation value of 1.47 µm, was found for the 4:1 ratio (479.9 mbar). The fabricated microlasers presented a quality factor Q of the order 104, which is suitable for sensing applications. This technique can be used to control the size of the fabrication of a high number of solid state microlaser based UV polymers mixed with laser dyes.

Highlights

Microscale circular structures that enable whispering gallery modes (WGMs) have been employed as passive and active elements for different applications such as non-linear optics, low threshold microlasers, filters, and sensors [1,2,3,4,5,6,7,8,9,10,11,12]
WGM resonators have been used for building quantum optomechanical devices where the radiative pressure is used to drive mechanical resonances that can be used for extreme sensing applications [19,20,21]
The flow parameters of the water phase (dispersed phase corresponding size of the particles was adjusted byeither changing the flow parameters of either to thethe water curable polymer and dye solution) or the oil phase

Summary

Introduction

Microscale circular structures that enable whispering gallery modes (WGMs) have been employed as passive and active elements for different applications such as non-linear optics, low threshold microlasers, filters, and sensors [1,2,3,4,5,6,7,8,9,10,11,12]. Assuming spherical symmetry and a wavelength of the light that is much larger than the radius of the WGM structure, an approximate ray optic solution can be used to find the optical modes generated. Assuming spherical symmetry and a wavelength of the light that is much larger than the radius of the WGM structure, an approximate ray optic solution can be used to find the optical modes inside these resonators; the trappedthe raytrapped propagates due to the total internal reflection the surface. In all previous works, the fabricated microlasers were tested in the liquid phase, from inside microchannels or by trapping the droplet opticalvia tweezers. PDMS, thenliquid were PDMS, tested for thewere emission and quality factor.and quality factor

Methods

Figure

Experimental

Discussion

Photograph

Conclusions