Joseph A. Matteo

Spectral analysis of strongly enhanced visible light transmission through single C-shaped nanoapertures

We designed, fabricated, and characterized single C-shaped apertures in an Au film, resonant in the visible regime. Our C-shaped apertures showed transmission enhancement of 13–22 times over a square aperture of the same area and suggest as high as 106 enhancement over square apertures that are designed to produce the same near-field spot size. Spectra from individual apertures demonstrate the ability to tune this resonance over 70nm by scaling the dimensions of the apertures. This shows the C aperture to be a versatile tool for gaining high-resolution, enhanced transmission through single subwavelength apertures at optical wavelengths.

C-shaped nanoaperture-enhanced germanium photodetector

We present a C-shaped nanoaperture-enhanced Ge photodetector that shows 2-5 times the photocurrent enhancement over that from a square aperture of the same area at 1310 nm wavelength. We demonstrate the polarization dependence of the C-aperture photodetector over a wide wavelength range. Our experimental observation agrees well with finite-difference time-domain simulation results.

Fractal extensions of near-field aperture shapes for enhanced transmission and resolution

Families of fractals are investigated as near-field aperture shapes. They are shown to have multiple transmission resonances associated with their multiple length scales. The higher iterations exhibit enhanced transmission, and spatial resolution exceeding the first order. Near-field enhancements of greater than 400 times the incident intensity and resolutions of better than ?/20 have been shown with apertures modeled after third iteration prefractals. Enhancements as large as 1011 have been shown, when compared with conventional square apertures that produce the same spot size. The effects of the complex permittivity values of the metal film are also addressed.

High-intensity C-shaped nanoaperture vertical-cavity surface-emitting laser with controlled polarization

The authors designed and demonstrated a C-shaped nanoaperture (C aperture) vertical-cavity surface-emitting laser (VCSEL) with a maximum far-field power of 157μW coming from a 70nm C aperture. Simulation shows that the near-field full width at half maximum spot size at 30nm away from the C aperture is 94×108nm2 in X and Y directions. The authors estimate the peak near-field intensity from the C-aperture VCSEL to be as high as 19mW∕μm2. This high intensity and small spot size are promising for realizing near-field applications such as near-field imaging and ultradense near-field optical data storage.

A C-shaped nanoaperture Vertical-Cavity Surface-Emitting Laser for high-density near-field optical data storage

We designed and demonstrated a unique C-shaped nanoaperture (C-aperture) Vertical-Cavity Surface-Emitting Laser with an estimated maximum net power of 113 μW coming from a 70nm C-aperture. Simulation shows the near-field FWHM spot size at 30nm away from the C-aperture is 94nm and 108nm in X and Y direction. We estimate the peak near-field intensity from the C-aperture VCSEL to be as high as 13.7mW/μm2. This high intensity and small spot size is promising to realize high-density near-field optical data storage.

Electromagnetic phenomena in advanced photomasks

The adoption of resolution enhancement techniques (RET) for subwavelength lithography relies on performing accurate simulation of mask effects. Although topography effects have been successfully used in RET flows, the impact of electromagnetic effects such as surface plasmons tend to be ignored. It is known, however, from the performance of “C-shaped” apertures that extraordinary transmission and opacity can be achieved using these electromagnetic effects. We have examined simulations for representative 45nm features using both conventional and novel finite difference time domain simulators. When the mask material is assumed to be conducting chromium, we found that electromagnetic effects appear to be significant and highly dependent on polarization. This may place additional constraints on the specification of mask material composition for these integrated circuit generations.

A high-intensity bowtie nano-aperture vertical-cavity surface-emitting laser for near-field optics

We demonstrated a record-high-intensity bowtie nano-aperture vertical-cavity surfaceemitting laser (VCSEL) with near-field spot size of 65 nm. The bowtie aperture VCSEL is very promising to realize near-field applications such as ultradense optical data storage.

A High-intensity Nano-aperture Vertical-Cavity Surface-Emitting Laser With Controlled Polarization

near-field optical data storage. Also, data transfer rates canbegreatly increased iftheVCSELsareapplied inparallel arrays[11. Previous workonnanoaperture VCSELsutilize conventional circular apertures whichsuffer fromlowpoweroutput through thenanoaperture whentheaperture size becomes muchsmaller thanonewavelength[23]. We propose toapply aunique C-shaped nano-aperture (C-aperture) ontoVCSELs.Fromsimulation, theC-aperture showsthree orders of magnitude higher powertransmission efficiency thanaconventional square orcircular aperture producing thesame near-field spotsize[41. We report herearecord-high near-field intensity of15.4mW/[tm2 achieved fromournanoaperture VCSELwitha70nmC-aperture. Ourtop-emitting VCSELsaredesigned tooperate around 970nmandconsist of9.5pairs ofp-type distributed Bragg reflectors (DBR),three strain-compensated InGaAs/GaAsP quantumwellsand38.5pairs ofn-DBRs.The reflectivity ofthetopmirror isenhanced witha150nmthick Aucoating. We insert ahalf-wavelength thick SiO2 filmbetween theAucoating andthetopDBR pairs toenhance thetransmission through thenano-aperture. We use wetoxidation ofAlGaAstoobtain a2.8pim-diameter oxide aperture forcurrent andmodeconfinement. Thenanoapertures areetched through theAucoating using aFocused IonBeam(FIB). Thetransmission oflight through theC-aperture ispolarization-dependent. Forthematched polarization, theCaperture produces awell-confined near-field spotwithhighintensity. However, fortheorthogonal mismatched polarization, theresulted near-field spotispoorly confined andtheintensity istwoorders ofmagnitude lower. Since VCSELsnormally havetwodegenerate orthogonal polarization states, weneedtocontrol thepolarization ofthe VCSELsinorder toapply theC-aperture ontheVCSELs.We openfour50*1500nm slits surrounding a70nmCaperture intheAu coating using FIBtocontrol thepolarization. Sincethetransmission oflight polarized perpendicular totheslit ismuchhigher thanthatoflight polarized parallel totheslit, thepolarization ofthe VCSELsiseffectively controlled tobeparallel totheslit duetolower loss inthis direction. Toidentify howmuchnetpowercomesoutoftheC-aperture, weblock thelight transmitted through theslits by depositing 150nmthick Pttofill theslits using electron-beam assisted chemical vapordeposition onaFIB/SEM dual-beam system. Pthasreflectivity of73%at1ptm, compared withreflectivity of95%forAu.Sothepolarization selectivity bytheslits ismaintained after theslits arefilled withPt.We measured thepolarization-resolved power

Consequences of Plasmonic Effects in Photomasks

For 45nm lithography and beyond, polarization and other electromagnetic effects such as surface plasmons may begin to affect the transmission through a photomask. Such phenomena are highly polarization sensitive, and may amplify the effects of line-edge roughness (LER) and variations in mask composition. A reduction in the mask material conductivity can mitigate the impact of these effects, but more accurate simulation is required to predict these effects well.

Ultra-high density optical data storage

Results on the use of C-shaped nano-apertures for optical data storage are reported. This type of aperture have a highly concentrated nanometer sized spot with a power throughput 1,000,000 times higher than for a square or round aperture producing the same spot size. Optical recording using contact media and conventional optical read-write media in DVD technology is also described.