Tow C. Chong

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Phase-change random-access memory (PCRAM) is one of the leading candidates for next-generation data-storage devices, but the trade-off between crystallization (writing) speed and amorphous-phase stability (data retention) presents a key challenge. We control the crystallization kinetics of a phase-change material by applying a constant low voltage via(More)
UV laser ablation of polymers was discovered 20 years ago.1,2 This effect has many fascinating applications in lithography, micromechanics, and medicine. For the last 20 years, more than 103 papers describing this phenomenon were published (see, e.g., comprehensive reviews, refs 3-7). Despite the high research activity, the nature of UV laser ablation of(More)
Planar hybrid metamaterial with different split ring resonators (SRR) structure dimensions are fabricated on silicon substrates by femtosecond (fs) laser micro-lens array (MLA) lithography and lift-off process. The fabricated metamaterial structures consist of: (a) uniform metamaterial with 4 SRRs at same design and dimension as a unit cell and (b) hybrid(More)
A new class of superlattice, crystalline amorphous superlattice (CASL), by alternatively depositing two semiconductor materials, is proposed. CASL displays three states depending on the component materials' phase: both polycrystalline phases, both amorphous phases, and one polycrystalline phase while another amorphous phase. Using materials capable of(More)
Magnetic recording technology has come a long way, since the introduction of the first hard disk drives (HDD) in 1956. The areal density has grown by a factor of 200 million times and the HDD has stayed as a main candidate for mass storage of information. In order to maintain its lead over other competing technologies, HDD industry continues to invent(More)
For bit-patterned media, media with low remanent magnetization (M(r)) and high M(r) regions are needed for storing information, which is usually achieved by lithographically defining magnetic and non-magnetic regions. In this work, we have investigated the use of ion beam modification of media surface to define the low and high M(r) states using a medium(More)
A two-dimensional in-plane displacement-sensitive electronic speckle pattern interferometer has been developed. With a fiber coupler with one input and four outputs, two sets of dual-beam interferometric configurations in orthogonal directions are constructed to determine in-plane displacements completely. When a CCD camera with a zoom lens is located at an(More)
Numerical analyses were conducted to simulate the effects of different Gaussian-weighted beams and disk geometries on the read-out signal cross talk of land and groove recording of phase-change optical disk systems. The optimized groove depth, which yields a minimum cross-talk noise, differs for different Gaussian-weighted beams and different track pitches.(More)
We have demonstrated, for the first time to our knowledge, a coupled tandem optical parametric oscillator (OPO) configuration in which a second ZnGeP(2) OPO is placed within the resonator of the first, KTiOPO(4), OPO. A significant enhancement in the overall cascaded efficiency of this OPO compared with standard two-stage OPO's was observed. With a(More)