Marcus Antonius Verschuuren

Hybrid plasmonic-photonic modes in diffractive arrays of nanoparticles coupled to light-emitting optical waveguides

We study the hybridized plasmonic-photonic modes supported by two-dimensional arrays of metallic nanoparticles coupled to light-emitting optical waveguides. Localized surface plasmon polaritons in the metallic nanoparticles can couple to guided modes in the underlying waveguide, forming quasi-guided hybrid modes, or to diffracted orders in the plane of the array, forming surface lattice resonances. We consider three kinds of samples: one sustains quasi-guided modes only, another sustains surface lattice resonances only, and a third sample sustains both modes. This third sample constitutes the first demonstration of simultaneous coupling of localized surface plasmons to guided modes and diffracted orders. The dispersive properties of the modes in the samples are investigated through light extinction and emission spectroscopy. We elucidate the conditions that lead to the coexistence of surface lattice resonances and quasi-guided hybrid modes, and assess their potential for enhancing the luminescence of emitters embedded in the coupled waveguide. We find the largest increase in emission intensity for the surface lattice resonances, reaching up to a factor of 20.

Improved performance of polarization-stable VCSELs by monolithic sub-wavelength gratings produced by soft nano-imprint lithography

We present a novel method for fabricating polarization-stable oxide-confined single-mode GaAs based vertical cavity surface emitting lasers (VCSELs) emitting at 850 nm using a new soft-lithography nano-imprint technique. A monolithic surface grating is etched in the output mirror of the laser cavity using a directly imprinted silica-based sol-gel imprint resist as an etch mask. The opto-electronic performance of these devices is compared to VCSELs fabricated by state-of-the-art electron-beam lithography. The lasers made using the soft nano-imprint technique show single-mode TM lasing at a threshold and laser slope similar to that of devices made by e-beam lithography. The soft nano-imprint technique also enables the fabrication of gratings with sub-wavelength pitch, which avoids diffraction losses in the laser cavity. The resulting single-mode VCSEL devices exhibit 29% enhanced efficiency compared to devices equipped with diffractive gratings.

SCIL nanoimprint solutions: high-volume soft NIL for wafer scale sub-10nm resolution

Nano-patterning materials and surfaces can add unique functionalities and properties which cannot be obtained in bulk or micro-structured materials. Examples range from hetro-epitaxy of semiconductor nano-wires to guiding cell expression and growth on medical implants. [1] Due to the cost and throughput requirements conventional nano-patterning techniques such as deep UV lithography (cost and flat substrate demands) and electron-beam lithography (cost, throughput) are not an option. Self-assembly techniques are being considered for IC manufacturing, but require nano-sized guiding patterns, which have to be fabricated in any case.[2] Additionally, the self-assembly process is highly sensitive to the environment and layer thickness, which is difficult to control on non-flat surfaces such as PV silicon wafers or III/V substrates. Laser interference lithography can achieve wafer scale periodic patterns, but is limited by the throughput due to intensity of the laser at the pinhole and only regular patterns are possible where the pattern fill fraction cannot be chosen freely due to the interference condition.[3] Nanoimprint lithography (NIL) is a promising technology for the cost effective fabrication of sub-micron and nano-patterns on large areas. The challenges for NIL are related to the technique being a contact method where a stamp which holds the patterns is required to be brought into intimate contact with the surface of the product. In NIL a strong distinction is made between the type of stamp used, either rigid or soft. Rigid stamps are made from patterned silicon, silica or plastic foils and are capable of sub-10nm resolution and wafer scale patterning. All these materials behave similar at the micro- to nm scale and require high pressures (5 – 50 Bar) to enable conformal contact to be made on wafer scales. Real world conditions such as substrate bow and particle contaminants complicate the use of rigid stamps for wafer scale areas, reducing stamp lifetime and yield. Soft stamps, usually based on silicone rubber, behave fundamentally different compared to rigid stamps on the macro-, micro- and nanometer level. The main limitation of traditional silicones is that they are too soft to support sub-micron features against surface tension based stamp deformation and collapse [4] and handling a soft stamp to achieve accurate feature placement on wafer scales to allow overlay alignment with sub-100nm overlay accuracy.

Plasmonic Crystals for Solid-State Lighting

Herein we demonstrate a very large emission increase (up to 60-fold for unpolarized emission in defined directions) using emitters developed for solid-state lighting (SSL) applications with an intrinsic quantum efficiency (QE) close to one