Mapping of Fabry–Perot and whispering gallery modes in GaN microwires by nonlinear imaging

Abstract

Engineering nonlinear optical responses at the microscale is a key topic in photonics for achieving efficient frequency conversion and light manipulation. Gallium nitride (GaN) is a promising semiconductor material for integrated nonlinear photonic structures. In this work, we use epitaxially grown GaN microwires as nonlinear optical whispering gallery and Fabry-Perot resonators. We demonstrate an effective generation of second-harmonic and polarizationdependent signals of whispering gallery and Fabry-Perot modes under near-infrared excitation. We show how the rotation of the excitation polarization can be used to control and switch between Fabry-Perot and whispering gallery modes in tapered GaN microwire resonators. We demonstrate the enhancement of two-photon luminescence in the yellow-green spectral range due to efficient coupling between whispering gallery, Fabry-Perot modes, and excitonic states in GaN. This luminescence enhancement allows us to conveniently visualize whispering gallery modes excited with a near-infrared source. Such microwire resonators can be used as compact microlasers or sensing elements in photonic sensors.

Revealing Mie Resonances with Enhanced and Suppressed Second‐Order Nonlinear Optical Responses in a Hexagonal‐Prism‐Like MoS2 Nanoparticle

“…In this case, the enhancement of SHG relies mainly on the electric field enhancement at the wavelength of the fundamental wave. Since optical resonances in frequency domain represent the localization of electric field in spatial domain, various optical resonances have been exploited to achieve this goal, including surface plasmon resonances, [1] Mie resonances, [2] multipole resonances, [3,4] anapole mode, [5] Fabry-Perot modes, [6] whispering gallery modes, [7] epsilon-near-zero resonances, [8] and Fano resonances. [9] The state-of-the-art researches suggest that surface lattice resonances, [10] quasi-bound states in the continuum (quasi-BIC), [11][12][13][14][15] and supercavities [16,17] can not only realize electromagnetic field enhancement but also suppress radiation loss.…”

Nanoscale Electric Field Probing in a Single Nanowire with Raman Spectroscopy and Elastic Strain

“…Semiconductor nanowires (NWs) have been extensively studied for the past few decades owing to their advantageous physical properties inducing the prospects for nanophotonics . It is known that the efficiency of nanowire emitters depends on the degree of internal electric field localization in an active region, which in the case of the most common radially heterostructured geometry is located near the nanowire surface. − The approaches for nanoscale electric field imaging are being actively explored in order to provide the understanding of physical phenomena in nanophotonic structures. − In supermicrometer photonic structures the internal field can be experimentally resolved with the use of near-field scanning optical microscopy and quantum sensors based on the nitrogen vacancy in diamond. ,, An alternative way is the indirect experiment where field localization is obtained by luminescence from the specific regions or by field sensitive chemical reactions . However, the proposed techniques are still not applicable for nanowires whose lateral size is less than 300 nm.…”

“…5−7 In supermicrometer photonic structures the internal field can be experimentally resolved with the use of near-field scanning optical microscopy and quantum sensors based on the nitrogen vacancy in diamond. 5,8,9 An alternative way is the indirect experiment where field localization is obtained by luminescence from the specific regions 10 or by field sensitive chemical reactions. 4 However, the proposed techniques are still not applicable for nanowires whose lateral size is less than 300 nm.…”