Amit Lakhani

Subwavelength metal-optic semiconductor nanopatch lasers

We report on near infrared semiconductor nanopatch lasers with subwavelength-scale physical dimensions (0.019 cubic wavelengths) and effective mode volumes (0.0017 cubic wavelengths). We observe lasing in the two most fundamental optical modes which resemble oscillating electrical and magnetic dipoles. The ultra-small laser volume is achieved with the presence of nanoscale metal patches which suppress electromagnetic radiation into free-space and convert a leaky cavity into a highly-confined subwavelength optical resonator. Such ultra-small lasers with metallodielectric cavities will enable broad applications in data storage, biological sensing, and on-chip optical communication.

Plasmonic crystal defect nanolaser

Surface plasmons are widely interesting due to their ability to probe nanoscale dimensions. To create coherent plasmons, we demonstrate a nanolaser based on a plasmonic bandgap defect state inside a surface plasmonic crystal. A one-dimensional semiconductor-based plasmonic crystal is engineered to have stopbands in which surface plasmons are prohibited from travelling in the crystalline structure. We then confine surface plasmons using a three-hole defect in the periodic structure. Using conventional III-V semiconductors, we achieve lasing in mode volumes as small as V(eff) = 0.3(λ₀/n)³ at λ₀ = 1342 nm, which is 10 times smaller than similar modes in photonic crystals of the same size. This demonstration should pave the way for achieving engineered nanolasers with deep-subwavelength mode volumes and attractive nanophotonics integration capabilities while enabling the use of plasmonic crystals as an attractive platform for designing plasmons.

Efficient waveguide-coupling of metal-clad nanolaser cavities

Many remarkable semiconductor-based nanolaser cavities using metal have been reported in past few years. However, the efficient coupling of these small cavities to waveguides still remains a large challenge. Here, we show highly efficient coupling of a semiconductor-based metal-clad nanolaser cavity operating in the fundamental dielectric cavity mode to a silicon-on-insulator waveguide. By engineering the effective refractive index and the field distribution of the cavity mode, a coupling efficiency as high as 78% can be achieved for a metal-clad nanolaser with a modal volume of 0.28 (λ/n)³ while maintaining a high optical quality factor of > 600.

Optical antenna design for nanophotodiodes

Guidelines for designing an optical antenna for optimizing the performance of a nanophotodiode are proposed. A nanopatch design is simulated with over 70% absorption efficiency using germanium as the absorber.

Optical antenna based nanoLED

An optical antenna based nanoLED design that enhances photoluminescence of a semiconductor emitter by more than 10× is presented. The small mode (0.015 (λ₀/2n)³) and physical (3×10^-4 λ₀³) volumes are attractive for on-chip optical interconnect applications.

Lasing in a one-dimensional plasmonic crystal

We report on the experimental demonstration of laser based on one-dimensional plasmonic crystals. Plasmon radiation has been engineered to create subwavelength mode-volumes smaller than photonic crystals. The device operates with quasi-CW pumping at 77 Kelvin.

Recent advances in semiconductor nanolasers

Nanolasers that integrate metal into the cavity design have pushed laser volumes much below one cubic wavelength λ₀³. In this paper, we review this growing field and highlight recent work on the nanopatch laser.

Ultra sensitive surface-enhanced Raman scattering detection using uniform sub-5 nm gap optical antennas

Arch-dipole optical antennas with uniform 5nm gaps have been fabricated on Si substrate using deep-UV “spacer” lithography. Strong surface-enhanced Raman scattering (SERS) signals with an enhancement factor of 1.1×10⁸ have been measured.

Subwavelength semiconductor nanocavity laser

We report the smallest metallo-dielectric cavity semiconductor laser to our knowledge operating at near-infrared frequencies. The laser consists of an InGaAsP patch sandwiched by gold. We observe lasing in electric and magnetic dipole modes.

Nanoscale light sources for on-chip optical interconnects

Near-infrared semiconductor lasers with nanoscale physical dimensions and effective mode volumes using metallodielectric cavities are discussed. Such ultra-small lasers will find various applications in on-chip optical communication, data storage, and sensing.