Browsing by Subject "Nanolaser"

Now showing 1 - 2 of 2

Open Access
Lasing action in single subwavelength particles supporting supercavity modes
(American Chemical Society, 2020-05) Mylnikov, V.; Ha, S. T.; Pan, Z.; Valuckas, V.; Paniagua-Domínguez, R.; Demir, Hilmi Volkan; Kuznetsov, A. I.
On-chip light sources are critical for the realization of fully integrated photonic circuitry. So far, semiconductor miniaturized lasers have been mainly limited to sizes on the order of a few microns. Further reduction of sizes is challenging fundamentally due to the associated radiative losses. While using plasmonic metals helps to reduce radiative losses and sizes, they also introduce Ohmic losses hindering real improvements. In this work, we show that, making use of quasibound states in the continuum, or supercavity modes, we circumvent these fundamental issues and realize one of the smallest purely semiconductor nanolasers thus far. Here, the nanolaser structure is based on a single semiconductor nanocylinder that intentionally takes advantage of the destructive interference between two supported optical modes, namely Fabry–Perot and Mie modes, to obtain a significant enhancement in the quality factor of the cavity. We experimentally demonstrate the concept and obtain optically pumped lasing action using GaAs at cryogenic temperatures. The optimal nanocylinder size is as small as 500 nm in diameter and only 330 nm in height with a lasing wavelength around 825 nm, corresponding to a size-to-wavelength ratio as low as 0.6.
Open Access
Wavelength-scale lithographic vertical-cavity surface-emitting laser (LI-VCSEL): Design, fabrication and optical characterization
(2021-05) Madigawa, Abdulmalik Abdulkadir
Vertical-cavity surface-emitting lasers (VCSEL) are the ideal light sources for optical data communication and 3D sensing due to their small size, low power consumption, high-speed modulation, and low cost. The key to meeting the ever-increasing demand for higher eﬃciency and modulation devices is scaling down the cavities to near- or sub-wavelength sizes. The current state-of-the-art commercial oxide-VCSEL technology has been very successful for micro-scale cavity diameters (>3 µm), but its processing approach is not appropriate for further miniatur-ization. Improvement in the performance of oxide-VCSELs can be achieved with smaller oxide aperture diameters. However, the high thermal resistance induced by the oxide layer signiﬁcantly degrades the device performance, especially for the smaller sizes, making this method unreliable for scaling. In this work, we investigated a lithographically deﬁned VCSEL (Li-VCSEL) method in which the transverse photonic and electrical conﬁnement can be enabled by epitaxial growth and lithography. Transverse optical conﬁnement is achieved by introducing an intracavity phase-shifting mesa that provides the conﬁnement by index guiding. Numerical simulation results show high-quality factors even for submicron sizes, which is promising for the realization of submicron size single emitter and high-density array lasers. The fabrication steps include the epitaxial growth of the bottom semiconductor DBR and the cavity, deﬁning the phase-shifting mesa us-ing optical lithographic processes, and the deposition of the top dielectric DBR using thin ﬁlm deposition techniques. We demonstrated room-temperature lasing around 980 nm from Li-VCSELs with mesa diameters ranging from 0.75 µm to 2.0 µm under continuous-wave optical pumping and presented detailed charac-terization of these devices. The results represent a signiﬁcant step towards the realization of electrically pumped small-size lasers for practical optoelectronics applications.