Appl. Phys. Lett. 107, 211105 (2015)

Credit: AIP

An on-chip optofluidic laser that is tunable across the visible wavelength band has been fabricated by scientists from Israel and Denmark. Avraham Bakal and co-workers from The Hebrew University of Jerusalem and the Technical University of Denmark made their laser from a periodic linear array of droplets of benzyl alcohol containing the dye R6G that are located inside a microfluidic channel filled with mineral oil. The droplets form due to the immiscibility of the alcohol and the oil. The R6G dye serves as an optical gain medium for the laser while refractive index corrugation associated with the droplet array acts like a distributed grating that provides optical feedback. When pumped with 532-nm nanosecond pulses from a frequency-doubled Nd:YAG laser, the device lases with the emission wavelength determined by the periodicity of the droplet array. The team demonstrated lasing that is tunable between about 570 nm and 640 nm by simply changing the pressure of the oil and alcohol reservoirs that feed the device.