Leonard Gonzaga

Magnetic and electric hotspots with silicon nanodimers

The study of the resonant behavior of silicon nanostructures provides a new route for achieving efficient control of both electric and magnetic components of light. We demonstrate experimentally and numerically that enhancement of localized electric and magnetic fields can be achieved in a silicon nanodimer. For the first time, we experimentally observe hotspots of the magnetic field at visible wavelengths for light polarized across the nanodimers primary axis, using near-field scanning optical microscopy.

Generalized Brewster effect in dielectric metasurfaces.

Polarization is a key property defining the state of light. It was discovered by Brewster, while studying light reflected from materials at different angles. This led to the first polarizers, based on Brewsters effect. Now, one of the trends in photonics is the study of miniaturized devices exhibiting similar, or improved, functionalities compared with bulk optical elements. In this work, it is theoretically predicted that a properly designed all-dielectric metasurface exhibits a generalized Brewsters effect potentially for any angle, wavelength and polarization of choice. The effect is experimentally demonstrated for an array of silicon nanodisks at visible wavelengths. The underlying physics is related to the suppressed scattering at certain angles due to the interference between the electric and magnetic dipole resonances excited in the nanoparticles. These findings open doors for Brewster phenomenon to new applications in photonics, which are not bonded to a specific polarization or angle of incidence.

Air-Bearing Design Towards Highly Stable Head–Disk Interface at Ultralow Flying Height

Pushing recording density towards tera-bit per square inch and beyond requires reducing flying height to 2.5-3 nm or below. One critical challenge at such ultralow flying height is the possible head-disk crash or unstable head-disk spacing due to short-range interaction forces, such as electrostatic force, intermolecular forces, lubricant interaction force, and so on. Slider design and design strategy are investigated in this work aiming at significantly increased stability of the head-disk spacing at ultralow flying height. Nonzero surface roughness leads to a roughness-limited possible minimum flying height. A stable head-disk interface requires a full air-bearing domination even at a roughness-imposed minimum flying height. Here, the air-bearing domination means that both air-bearing force and air-bearing stiffness are larger than the combination of various short-range forces and the corresponding stiffness. Investigations presented in this paper indicate that high pressure and high-pressure concentration technology are effective approaches to extending the domination of air-bearing force towards such a roughness-limited possible minimum flying height. Slider designs, proposed by authors, exhibit satisfying flying height stability even at the roughness-limited minimum flying height

Light Delivery System for Heat-Assisted Magnetic Recording

Heat-assisted magnetic recording (HAMR) technology needs a light delivery system with an incorporated near-field transducer (NFT) as a minute heat generator. A novel system for light delivery with a triangular spot size converter (SSC) and an optical fiber is proposed. The advantages of using a triangular SSC are optical efficiency and integration tolerance between the optical fiber and the NFT. It also has good affinity to conventional head fabrication process. The optical fiber enables flexible laser location. It was confirmed that fabricated triangular SSC can propagate light and reduce beam spot. Computer simulations and experiments demonstrated possibility of integration of light delivery system between NFT, SSC, and optical fiber. Flyability of a pico slider with an optical fiber was also demonstrated. It shows that the optical fiber does not have a big impact on flyability below 10 nm flying height and off-track vibration.

Silicon NanoDimers for Magnetic and Electric Field Hotspots

Dielectric nanostructures with a high refractive index are of interest for ultimate control of light in the near-field. We demonstrate, experimentally and numerically, the existence of electric and magnetic field hotspots near silicon nanodimers.

Decoupling Adjustment of Crown and Camber for Flying Height Control

An active slider with an H-shaped PZT and a U-shaped or grooved slider body is proposed for flying height control. The active slider has a decoupled crown and camber adjustment to improve the flying height adjustment ability. It can achieve more than 2nm flying height adjustment with a 12V voltage input.Copyright

Hybrid integrated single-wavelength laser with silicon micro-ring reflector

A hybrid integrated single-wavelength laser with silicon micro-ring reflector is demonstrated theoretically and experimentally. It consists of a heterogeneously integrated III-V section for optical gain, an adiabatic taper for light coupling, and a silicon micro-ring reflector for both wavelength selection and light reflection. Heterogeneous integration processes for multiple III-V chips bonded to an 8-inch Si wafer have been developed, which is promising for massive production of hybrid lasers on Si. The III-V layer is introduced on top of a 220-nm thick SOI layer through low-temperature wafer-boning technology. The optical coupling efficiency of >85% between III-V and Si waveguide has been achieved. The silicon micro-ring reflector, as the key element of the hybrid laser, is studied, with its maximized reflectivity of 85.6% demonstrated experimentally. The compact single-wavelength laser enables fully monolithic integration on silicon wafer for optical communication and optical sensing application.

Integration of light delivery for heat assisted magnetic recording

Light delivery with spot size converter (SSC) and optical fiber for heat assisted magnetic recording is proposed. It has an advantage in optical efficiency and integration tolerance. SSC was fabricated and confirmed its operation. Fly-ability of pico slider with optical fiber was also demonstrated.

New ABS trailing pad structure with improved thermal protrusion efficiency

A new trailing pad structure with partially-etched pad is proposed. The effect of the pad shape, trench depth and width was numerically investigated and presented. The thermal protrusion efficiency of the new ABS design which has adopted the new trailing pad structure is also presented.

Effects of Surface Roughness on the Fly-Ability of a Thermal Protrusion Air Bearing Slider

A femto air bearing slider with thermal protrusion is studied based on three groups of surface roughness. It is observed that the air bearing force and the contact force are proportional to the value of average roughness in the minimum flying height region studied, while the intermolecular force or the electrostatic force is the smallest for the smoothest surfaces when the minimum flying height is above a certain value. As a result, the total force on the slider is the largest on the smoothest surfaces in a certain minimum flying height region. When the minimum flying height is designed in that region, the fly-ability of the slider is maximized.Copyright