Low-Threshold Microlasers Based on Holographic Dual-Gratings

Abstract

Among the efforts to improve the performances of microlasers, optimization of the gain properties and cavity parameters of these lasers has attracted significant attention recently. Distributed feedback lasers, as one of the most promising candidate technologies for electrically pumped microlasers, can be combined with dual-gratings. This combination provides additional freedom for the design of the laser cavity. Here, a holographic dual-grating is designed to improve the distributed feedback laser performance. The holographic dual-grating laser consists of a colloidal quantum dot film with two parallel gratings, comprising first-order (210 nm) and second-order (420 nm) gratings that can be fabricated easily using a combination of spin coating and interference lithography. The feedback and the output from the cavity are controlled using the first-order grating and the second-order grating, respectively. Through careful design and analysis of the dual-grating, a balance is achieved between the feedback and the cavity output such that the lasing threshold based on the dual-grating is nearly half the threshold of conventional distributed feedback lasers. Additionally, the holographic dual-grating laser shows a high level of stability because of the high stability of the colloidal quantum dots against photobleaching.

Lasers Based on Periodic and Quasiperiodic Planar Feedback Cavities: Designs, Principle, and Potential Applications

“…Beat structures with parallel gratings offer flexibility in adjusting laser patterns and the number of wavelengths, and in compound structures, ultralow thresholds can be achieved by balancing feedback and output coupling [127,128]. In 2020, Zhai et al fabricated a CQDs holographic dual-grating laser with first-order and second-order gratings, resulting in a lasing threshold nearly half that of conventional distributed feedback lasers [143].…”

Lasing by Template‐Assisted Self‐Assembled Quantum Dots

“…Up to now, most of the QDs-based DFB nanolasers were produced by depositing colloids onto a structured substrate. [43][44][45][46][47][48][49][50][51][52][53][54][55] Being relatively straightforward, such an approach relies on elaborated substrate preparation and does not allow for creating multicomponent systems. To circumvent that, various direct micro-and nanopatterning techniques were introduced, such as template stripping, [56] electron-beam lithography (EBL), [57][58][59][60] laser ablation, [61] photolithography on the blends of QDs and photosensitive polymer [62,63] or nanoimprinting of the composites of QDs and high-refractive index-matrixes.…”

Hybrid Microcavity Lasers: Principle, Design, and Practical Application

“…[19] Therefore, the optical microcavity has developed rapidly with its advantages of high quality (Q) factor and small mode volume, in low threshold lasers, sensors, cavity quantum electrodynamics, cavity optomechanics, and other fields. [20][21][22][23][24][25] Since the beginning of the revolution in optical microcavities, there have been a vast number of cavities, e.g., Fabry-Perot interferometers (F-P), [26][27][28][29][30] DOI: 10.1002/lpor.202300343 distributed Bragg reflectors (DFB), [31][32][33][34][35][36] distributed Bragg reflection (DBR) cavities, [37][38][39][40] whispering gallery mode (WGM) resonators, [41][42][43][44][45][46][47][48] scattering system (SS), [49][50][51][52][53] and deformation cavities. [54][55][56][57] These specific geometries endow these microcavities with, respectively, distinct lasing emission features in frequency, direction, mode, time, or angular momentum.…”