Semiconductor planar microcavities significantly enhance the interaction between light and matter and are thus crucial as a fundamental research platform for investigations of quantum information ...processing, quantum dynamics, and exciton-polariton observations. Microcavities also serve as a very agile basis for modern resonant-cavity light-emitting and detecting devices now in large-scale production for applications in sensing and communication. The fabrication of microcavity devices composed of both common materials now used in photonics and uncommon or arbitrary materials that are new to photonics offers great freedom in the exploration of the functionalities of novel microcavity device concepts. Here we propose and carefully investigate two unique microcavity designs. The first design uses a monolithic high-index-contrast grating (MHCG) and a distributed Bragg reflector (DBR) as the microcavity mirrors. The second design uses two MHCGs as the microcavity mirrors. We demonstrate by numerical analysis that MHCG-DBR and MHCG-MHCG microcavities, whose lateral radial dimension is 16 μm, reach very large quality factors at the level of 10
and nearly 10
, as well as purposely designed wavelength tuning ranges of 8 and 60 nm in both configurations, respectively. Our MHCG-MHCG microcavities with a very small size of 600 nm in the vertical dimension show extremely large quality factors, which can be explained by treating the optical modes as quasi-bound states in a continuum (BICs). Moreover, we verify our theoretical analysis and calibrate our simulation parameters by comparing to the experimental characteristics of an electrically injected MHCG-DBR microcavity vertical-cavity surface-emitting laser (VCSEL) emitting at a peak wavelength of about 980 nm. We use the calibrated parameters to simulate the emission characteristics of electrically injected VCSELs in various MHCG-DBR and MHCG-MHCG microcavity configurations to illustrate the influence of microcavity designs and their quality factors on the predicted lasing properties of the devices.
Here, we describe in detail a procedure for the numerical design of planar focusing mirrors based on monolithic high contrast gratings. We put a special emphasis on the reconstruction of the ...hyperbolic phase of these mirrors and we conclude that the phase does not have to be perfectly mimicked to obtain a focusing reflector. We consider here the grating mirrors that focus light not in the air but in the GaAs substrate and we compare them with conventional parabolic reflectors of corresponding dimensions. The light intensity at the focal point of the focusing grating mirrors was found to be comparable to that of the parabolic reflector. Moreover, the reflectivity of the focusing grating mirrors is almost as high as that of parabolic mirrors covered with an additional reflecting structure, if the ratio of the reflector width to the focal length is less than 0.6. Planar focusing grating mirrors offer a good alternative to parabolic mirrors, especially considering the complexity of fabricating three-dimensional structures compared to planar structures.
We present an experimental and theoretical analysis of chromatic aberration in a monolithic metasurface focusing mirror. The planar focusing mirror is based on a monolithic high contrast grating made ...from GaAs, designed for a wavelength of 980 nm. Light is focused on the high refractive index side of the mirror. Our measurements, performed between 890 and 1050 nm, indicate a shift of the focal point position that is inversely proportional to the wavelength. The experimental results are in very good agreement with our simulations, in terms of both the position of the focal point and the spectral dependence. Based on our numerical simulations, we show that simply modifying the grating height does not lead to significant alteration of the focal length or to any noticeable reduction in chromatic aberration. Using numerical simulations, we analyze how the height of the stripes, the refractive index of the grating material, and its dispersion combine to influence the chromatic aberration of the mirror.
The design of transparent conductive electrodes (TCEs) for optoelectronic devices requires a trade‐off between high conductivity and transmittivity, limiting their efficiency. This paper demonstrates ...the best ever achieved TCEs with the novel approach to fabricating TCEs that effectively alleviates this trade‐off: a monolithic high contrast grating integrated with metal (metalMHCG). The metalMHCG enables higher electrical conductivity than other TCEs, while providing transmissive and antireflective properties. It focuses on infrared spectrum TCEs, which are essential for sensing, thermal imaging, and automotive applications. However, due to elevated free carrier absorption, they are much more demanding than TCEs for the visible spectrum. It demonstrates a record 75% absolute transmittiance of unpolarized light, resulting in a record 108% transmittance relative to plain GaAs substrate. It achieves even larger absolute transmittance of polarized light, reaching 92% or 133% relative transmittance. Despite the record high transmittance, the sheet resistance of the metalMHCG is the best ever reported, several times lower than any other TCE, ranging from 0.5 to 1 Ω Sq−1.
The best ever achieved transparent conductive electrode (TCE) effectively alleviating trade‐off between high conductivity and transmittivity. Applicable to any transparent substrate, it attains a remarkable relative transmittance of 108% for unpolarised and 133% for polarized light. Additionally, the sheet resistance reported is the lowest ever documented, surpassing other TCEs by several times.
We report the first experimental parametric analysis of subwavelength monolithic high-contrast grating (MHCG) mirrors. To date, subwavelength grating mirrors have been fabricated by suspending a thin ...grating membrane in the air or placing it on a low refractive index material – a scheme that requires sophisticated processing and makes the gratings sensitive to mechanical stress, impeding current injection, and heat dissipation if used in active devices. Inherently MHCGs are well suited for optoelectronic devices because they can be fabricated in all possible material systems. Here we demonstrate above 90% optical power reflectance, strong polarization discrimination. Based on experimental analysis aided by numerical simulations, we demonstrate the possibility of tuning the spectral characteristics of MHCGs reflectance for more than 200 nm via modification of the duty cycle of the MHCG stripes. We show our MHCG tuning method is convenient to define the properties of MHCG devices during the device processing.
Highly reflective mirrors are indispensable components in a variety of state-of-the-art photonic devices. Typically used, bulky, multi-layered distributed Bragg (DBR) reflectors are limited to ...lattice-matched semiconductors or nonconductive dielectrics. Here, we introduce an inverted refractive index-contrast grating (ICG) as compact, single-layer alternative to DBR. In the ICG, a subwavelength one-dimensional grating made of a low-refractive-index material is implemented on a high-refractive-index cladding. Our numerical simulations show that the ICG provides nearly total optical power reflectance for the light incident from the side of the cladding whenever the refractive index of the grating exceeds 1.75, irrespective of the refractive index of the cladding. Additionally, the ICG enables polarization discrimination and phase tuning of the reflected and transmitted light, the property not achievable with the DBR. We experimentally demonstrate a proof-of-concept ICG fabricated according to the proposed design, using the technique of sub-µm 3D laser lithography in which thin stripes of IP-Dip photoresist are micro-printed on a Si cladding. This one-step method avoids laborious and often destructive etching-based procedures for grating structuration, making it possible to implement the grating on any arbitrary cladding material.
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