Modal analysis of β-Ga₂O₃:Cr widely tunable luminescent optical microcavities



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Alonso Orts, Manuel and Nogales Díaz, Emilio and San Juan, J. M. and Nó, M. L. and Piqueras de Noriega, Javier and Méndez Martín, Bianchi (2018) Modal analysis of β-Ga₂O₃:Cr widely tunable luminescent optical microcavities. Physical review applied, 9 (6). ISSN 2331-7019

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Optical microcavities are key elements in many photonic devices, and those based on distributed Bragg reflectors (DBRs) enhance dramatically the end reflectivity, allowing for higher quality factors and finesse values. Besides, they allow for wide wavelength tunability, needed for nano-and microscale light sources to be used as photonic building blocks in the micro- and nanoscale. Understanding the complete behavior of light within the cavity is essential to obtaining an optimized design of properties and optical tunability. In this work, focused ion-beam fabrication of high refractive-index contrast DBR-based optical cavities within Ga₂O₃:Cr microwires grown and doped by the vapor-solid mechanism is reported. Room-temperature microphotoluminescence spectra show strong modulations from about 650 nm up to beyond 800 nm due to the microcavity resonance modes. Selectivity of the peak wavelength is achieved for two different cavities, demonstrating the tunability of this kind of optical system. Analysis of the confined modes is carried out by an analytical approximation and by finite-difference-time-domain simulations. A good agreement is obtained between the reflectivity values of the DBRs calculated from the experimental resonance spectra, and those obtained by finite-difference-time-domain simulations. Experimental reflectivities up to 70% are observed in the studied wavelength range and cavities, and simulations demonstrate that reflectivities up to about 90% could be reached. Therefore, Ga₂O₃:Cr high-reflectivity optical microcavities are shown as good candidates for single-material-based, widely tunable light emitters for micro- and nanodevices.

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© 2018 American Physical Society.
This work has been supported by MINECO (Projects No. MAT 2015-65274-R-FEDER, No. MAT2016-81720-REDC). M. A.-O. acknowledges financial support from MECD (FPU Contract No. FPU15/01982). The authors would like to thank Steven A. Hindmarsh and Ana M. Sánchez from the University of Warwick for the first trials with FIB milling.

Uncontrolled Keywords:Gallium oxide; Wave-guides; Emitting phosphors; Ga₂O₃ nanowires; Semiconductor; Lasers; Photonics; Mirrors; Memory; Cavity
Subjects:Sciences > Physics > Materials
Sciences > Physics > Solid state physics
ID Code:48155
Deposited On:29 Jun 2018 15:24
Last Modified:03 Jul 2018 08:12

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