No abstract

A red-green-blue random laser is fabricated on an optical fiber facet by the dip-coating method.

In this study, high-order distributed-feedback (DFB) polymer lasers were comparatively investigated. Their performance relies on multiple lasing directions and their advantages include their high manufacturing tolerances due to the large grating periods. Nine laser cavities were fabricated by spin-coating the gain polymer films onto a grating structure, which was manufactured via interference lithography that operated at the 2nd, 3rd, and 4th DFB orders. Low threshold lasing and high slope efficiency were achieved in high-order DFB polymer lasers due to the large grating groove depth and the large gain layer thickness. A high-order DFB configuration shows possible advantages, including the ability to control the lasing direction and to achieve multiple-wavelength lasers. Furthermore, our investigation demonstrates that the increase in threshold and decrease in slope efficiency with an increase in the feedback order can be limited by controlling the structural parameters.

A fanshaped structure is proposed to achieve a continuously tunable polymer laser. The structure with gradual periods is fabricated by electron beam lithography, which acts as a distributed feedback cavity for the polymer laser. A light-emitting polymer is spin-coated on the cavity to form an active layer. The pump beam is focused by a cylindrical lens to a narrow stripe on the sample surface. When the position of the pump stripe on the fanshaped cavity is changed from long period (370 nm) to short period (340 nm) and vice versa, the output wavelength of the laser is continuously tuned from 584 nm to 552 nm. Tuning behavior can be interpreted by the Bragg condition. These results can be used to explore compact laser sources.

No abstract