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

Planar feedback micro-nanoscale cavities, shaped by advances in nanofabrication, have revolutionized laser technology, giving rise to chip-scale, low-threshold lasers with wide-ranging applications, spanning from atmospheric investigation to incorporation into central devices such as smartphones and computer chips. The complicated designs of these cavities, shaped by the physics of periodic and quasiperiodic structures, empower efficient manipulation of light-matter interaction and coherent light coupling, minimizing losses. This review thoroughly explores the underlying concepts and crucial parameters of planar feedback microcavities, shedding light on the photophysical behavior of recent gain materials pivotal for realizing optimal lasing properties. The examination extends to photonic crystal bandgap (PhC BG) microcavity lasers, specifically with periodic and quasiperiodic architectures. In-depth assessments probe into the principles and designs of each architecture, exploring features such as wavelength selectivity, tuneability, lasing patterns, and the narrow linewidth characteristics inherent in distributed feedback (DFB) microcavity lasers. The review highlights the intriguing characteristics of non-radiative bound states in the continuum (BIC) within periodic architectures, emphasizing trends toward high-quality factors, low thresholds, and directional and vortex beam lasing. It also explores the nascent field of Quasiperiodic (QP) microcavity lasers, addressing challenges related to disorder in traditional periodic structures. Comparative inquiries offer insights into the strengths and limitations of each architecture, while discussions on challenges and future directions aim to inspire innovation and collaboration in this dynamic field. [ABSTRACT FROM AUTHOR]