Tunable optofluidic distributed feedback dye lasers

Abstract

We demonstrated a continuously tunable optofluidic distributed feedback (DFB) dye laser on a monolithic poly(dimethylsiloxane) (PDMS) elastomer chip. The optical feedback was provided by a phase-shifted higher order Bragg grating embedded in the liquid core of a single mode buried channel waveguide. We achieved nearly 60nm continuously tunable output by mechanically varying the grating period with two dye molecules Rhodamine 6G (Rh6G) and Rhodamine 101 (Rh101). Single-mode operation was obtained with <0.1nm linewidth. Because of the higher order grating, a single laser, when operated with different dye solutions, can provide tunable output covering from near UV to near IR spectral region. The low pump threshold (< 1uJ) makes it possible to use a single high energy pulsed laser to pump hundreds of such lasers on a chip. An integrated array of five DFB dye lasers with different lasing wavelengths was also demonstrated. Such laser arrays make it possible to build highly parallel optical sensors on a chip. The laser chip is fully compatible with PDMS based soft microfluidics.

Highly Accurate Pneumatically Tunable Optofluidic Distributed Feedback Dye Lasers

“…However, the need for the frequent replacement of dye solutions and grating periods severely hampers real-time dynamic tuning in optofluidic dye lasers. Li et al reported a method of continuously stretching and compressing a microfluidic chip on a mechanical stage [ 31 , 32 ]. Nevertheless, the deformation of the entire device using a mechanical stage impedes integration with more complex microfluidic systems.…”

“…Li et al reported a method of continuously stretching and compressing a microfluidic chip on a mechanical stage [31,32]. Nevertheless, the deformation of the entire device using a mechanical stage impedes integration with more complex microfluidic systems.…”

Diffusion dynamics in microfluidic dye lasers

“…Typically, the problem of dye bleaching is accounted for by a continuous convective flow of liquid-dissolved dye molecules, thus compensating the bleaching dynamics caused by the external optical pump. The required, convective dye-replenishing flow has been achieved by external fluid-handling apparatus (syringe pumps), 4, 6-8 on-chip micro-fluidic pumps, 9,10 or by means of capillary effect. 11 In this paper we find supporting evidence that such opto-fluidic devices may potentially be operated for days by diffusion without the need for a convective flow.…”