Publications by authors named "Sina Foroutan-Barenji"

2 Publications

  • Page 1 of 1

Self-Resonant Microlasers of Colloidal Quantum Wells Constructed by Direct Deep Patterning.

Nano Lett 2021 Jun 24;21(11):4598-4605. Epub 2021 May 24.

Department of Electrical and Electronics Engineering Department of Physics, UNAM-Institute of Materials Science and Nanotechnology, Bilkent University, Ankara 06800, Turkey.

Here, the first account of self-resonant fully colloidal μ-lasers made from colloidal quantum well (CQW) solution is reported. A deep patterning technique is developed to fabricate well-defined high aspect-ratio on-chip CQW resonators made of grating waveguides and in-plane reflectors. The fabricated waveguide-coupled laser, enabling tight optical confinement, assures in-plane lasing. CQWs of the patterned layers are closed-packed with sharp edges and residual-free lifted-off surfaces. Additionally, the method is successfully applied to various nanoparticles including colloidal quantum dots and metal nanoparticles. It is observed that the patterning process does not affect the nanocrystals (NCs) immobilized in the attained patterns and the different physical and chemical properties of the NCs remain pristine. Thanks to the deep patterning capability of the proposed method, patterns of NCs with subwavelength lateral feature sizes and micron-scale heights can possibly be fabricated in high aspect ratios.
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June 2021

Optical Gain in Ultrathin Self-Assembled Bi-Layers of Colloidal Quantum Wells Enabled by the Mode Confinement in their High-Index Dielectric Waveguides.

Small 2020 Nov 20;16(45):e2004304. Epub 2020 Oct 20.

Department of Electrical and Electronics Engineering, Department of Physics, UNAM - Institute of Materials Science and Nanotechnology, Bilkent University, Ankara, 06800, Turkey.

This study demonstrates an ultra-thin colloidal gain medium consisting of bi-layers of colloidal quantum wells (CQWs) with a total film thickness of 14 nm integrated with high-index dielectrics. To achieve optical gain from such an ultra-thin nanocrystal film, hybrid waveguide structures partly composed of self-assembled layers of CQWs and partly high-index dielectric material are developed and shown: in asymmetric waveguide architecture employing one thin film of dielectric underneath CQWs and in the case of quasi-symmetric waveguide with a pair of dielectric films sandwiching CQWs. Numerical modeling indicates that the modal confinement factor of ultra-thin CQW films is enhanced in the presence of the adjacent dielectric layers significantly. The active slabs of these CQW monolayers in the proposed waveguide structure are constructed with great care to obtain near-unity surface coverage, which increases the density of active particles, and to reduce the surface roughness to sub-nm scale, which decreases the scattering losses. The excitation and propagation of amplified spontaneous emission (ASE) along these active waveguides are experimentally demonstrated and numerically analyzed. The findings of this work offer possibilities for the realization of ultra-thin electrically driven colloidal laser devices, providing critical advantages including single-mode lasing and high electrical conduction.
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November 2020