Development of Highly Homogenous Quantum Dot Micropillar Arrays for Optical Reservoir Computing

Abstract

Neuromorphic computing has received considerable attention as promising alternatives to classical von Neumann computing architectures. An attractive concept in this field is reservoir computing which is based on coupled non-linear elements to enable for instance ultra-fast pattern recognition. We focus on the development of microlasers in a dense regular array for the implementation of photonic reservoir computing based on the diffractive coupling. The coupling relies on injection locking of microlasers and sets stringent requirements on the spectral homogeneity of the array, which needs to be on the order of the achievable locking range. We realize GaAs/AlGaAs micropillar arrays with InGaAs quantum dots as active medium. To achieve the high spectral homogeneity on the order of 100 µeV, as determined by injection locking experiments, the emission energy of each individual micropillar is adjusted to compensate for local inhomogeneities of order ∼1.3 meV in the underlying microcavity structure. The realized micropillar arrays have a spectral inhomogeneity as low as 190 µeV for an 8 × 8 array and down to 118 µeV for a 5 × 5 sub-array. The arrays have high potential to enable the implementation of powerful photonic reservoir computing, which can be extended to a reservoir of hundreds of microlasers in the future.

Nanolasers with Feedback as Low-Coherence Illumination Sources for Speckle-Free Imaging: A Numerical Analysis of the Superthermal Emission Regime

“…Obtaining uniform features across the nanolaser matrix, ensuring the same operating regime, is a challenge, but similar issues are already being addressed for neuromorphic computing [41], where locking capabilities impose more stringent constraints than those imposed by lighting. Arrays with 100 × 100 elements could provide illumination in the range of 10 mW, offering alternative, compact sources whose tunable properties differ from those of LEDs.…”

Stabilizing nanolasers via polarization lifetime tuning

“…Coupled nanophotonic semiconductor lasers are a prototypical model for on-chip laser networks 1 , 2 , which have attracted considerable attention as an optical solution for neuromorphic realizations in the recent years 3 – 5 . Due to their small footprint, high speed and low power consumption, they are promising light sources for a wide range of nanophotonic applications such as photonic integrated circuits, on-chip optical computing, and optical communication 4 , 6 – 9 .…”

Stabilizing Nanolasers via Polarization Lifetime Tuning

“…Coupled nanophotonic semiconductor lasers are a prototypical model for on-chip laser networks 1,2 , which have attracted considerable attention as an optical solution for neuromorphic realizations in the recent years [3][4][5] . Due to their small footprint, high speed and low power consumption, they are promising light sources for a wide range of nanophotonic applications such as photonic integrated circuits, on-chip optical computing or optical communication 4,[6][7][8][9] .…”