Influence of grating characteristics on the operation of circular-grating distributed-feedback polymer lasers

Abstract

We explore the influence of grating characteristics on the lasing performance of polymer circular-grating distributed-feedback lasers. A range of circular-grating sizes and profiles were fabricated on a single silica substrate, which was coated with a thin film of the conjugated polymer poly͓2-methoxy-5-͑2'ethylhexyloxy͒-1,4-phenylene vinylene͔. Variations in lasing threshold and surface-emitted slope efficiency were determined as a function of grating outer diameter and duty cycle. The experimental lasing results are compared with predictions from a theoretical analysis based on an adaptation of the transfer matrix method. We find that an outer diameter of at least 200 m is required to minimize the threshold and optimize the surface-emitted slope efficiency. A groove-to-period duty cycle of ϳ25% gives the lowest lasing thresholds by optimizing the in-plane feedback. We also find that the structure of the polymer-air surface varies substantially with substrate duty cycle, which has implications for optimum device design.

All-polymer organic semiconductor laser chips: Parallel fabrication and encapsulation

“…Aiming for top emitting devices we have chosen second order linear DFB gratings. A duty-cycle of ~25% is used which is known to give low thresholds for second order gratings [22].…”

Effect of gain localization in circular-grating distributed feedback lasers

“…There has been growing interest in recent years in semiconductor lasers based on two-dimensional distributed feedback ͑DFB͒ resonators. Various laser structures have been explored experimentally in both III-V and organic semiconductors, including photonic crystals, [1][2][3][4][5][6] circular-grating DFB ͑CDFB͒, [7][8][9][10][11] and quasicrystals. 12 Such two-dimensional structures can significantly improve the operating characteristics of surface-emitting DFB lasers, compared with conventional one-dimensional gratings.…”

Surface-emitting circular DFB, disk- and ring- Bragg resonator lasers with chirped gratings: a unified theory and comparative study

“…Among the various grating coupled schemes, circular grating lasers with large emission apertures possess the additional advantage of producing circularly-symmetric, narrow-divergence laser beams, making them convenient for coupling to fibers [7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26]. In such lasers, the grating serves two purposes: confining the in-plane fields to form a radial resonator and secondly acting as a broadside output coupler.…”