For reliable operation, individual cells of an STT-MRAM memory array must meet specific requirements on their performance. In this work we review some of these requirements and discuss the fundamental physical principles of STT-MRAM operation, covering the range from device level to chip array performance, and methodology for its development.

Compact parallel transmitters and receivers with an aggregate capacity of 107 Gb/s are built through hybrid integration of arrays of ten 100-GHz spaced directly modulated lasers, arrays of ten avalanche photodiodes, and high-index contrast silica arrayed waveguide grating multi- and demultiplexers. Unamplified transmission over 75 km of standard single-mode fiber and 155-km amplified links is demonstrated in the C-band, by using a modulation format based on spectral offset filtering and electronic dispersion compensation.

We report on a 10 × 11.1-Gb/s optoelectronic multiwavelength receiver with 100-GHz channel spacing and 14-dBm per-channel sensitivity. The device uses hybrid integration of separately optimized elements to achieve high optical sensitivity. A novel micromachined optical turning mirror has been developed to simplify the fabrication and assembly of the receiver.

Magnetic behavior of CoFeB at various thicknesses ranging from 2 nm to 8 nm capped with different materials, such as MgO, Ta, Ru, and V have been studied. The films were sputter-deposited and subsequently characterized by magnetometry and broadband ferromagnetic resonance (FMR). There are magnetically dead layers at the interface observed with Ru and Ta capping layers, while MgO and V have almost no effect on the magnetization of the CoFeB. As the ferromagnetic layer is made thinner, the effective magnetization decreases, indicating an interfacial perpendicular anisotropy. Particularly in the case of MgO, V/Ru, and V/Ta capping layers, interfacial perpendicular anisotropy is induced in CoFeB, and the Gilbert damping parameter is also reduced. The origin of this perpendicular magnetic anisotropy (PMA) is understood to be caused by the interface anisotropy between the free layer and the capping layer. The effect of post-deposition annealing and CoFeB thickness on the anisotropy and damping of V/Ta capped samples are reported. Doping CoFeB with vanadium (V) greatly reduced the 4πMs and 4πMeff values, resulting in an effective increase in the PMA.

STT-RAM (Spin-Transfer Torque Random Access Memory) is a second-generation magnetic random access memory (MRAM) technology that is fast, non-volatile, durable, and scalable to future technology nodes [1-2]. In this paper, we present the latest advances in in-plane and perpendicular STT-RAM development and outline STT-RAM's future prospects, applications and roadmap.

We demonstrate a 60-km CWDM-TDM PON with 40 Gb/s capacity both down and upstream. The system incorporates technologies such as volume manufacturable transmitters, burst-mode transmission, hybrid SOA-Raman amplifiers, and a cyclic CWDM multiplexer.

We demonstrate an extended reach 60 km coarse wavelength division multiplexing (CWDM)-time division multiple access (TDMA) passive optical network (PON) with 40 Gb/s capacity for both down and upstream directions. The system leverages existing 10 Gb/s TDMA PON technologies and incorporates various subsystems such as volume manufacturable optical transmitters, a prototype 10 Gb/s burst-mode receiver, hybrid semiconductor optical amplifier-Raman amplifiers, and a cyclic CWDM multiplexer. We confirm that this 32-user system has sufficient power margin to accommodate 128 users.

Spin-transfer torque random access memory (STT-RAM) is a potentially revolutionary universal memory technology that combines the capacity and cost benefits of DRAM, the fast read and write performance of SRAM, the non-volatility of Flash, and essentially unlimited endurance. In order to realize a small cell size, high speed and achieve a fully functional STT-RAM chip, the MgO-barrier magnetic tunnel junctions (MTJ) used as the core storage and readout element must meet a set of performance requirements on switching current density, voltage, magneto-resistance ratio (MR), resistance-area product (RA), thermal stability factor (¿) , switching current distribution, read resistance distribution and reliability. In this paper, we report the progress of our work on device design, material improvement, wafer processing, integration with CMOS, and testing for a demonstration STT-RAM test chip, and projections based on modeling of the future characteristics of STT-RAM.

CoFeB/MgO/CoFeB magnetic tunnel junctions (MTJs) with perpendicular magnetic anisotropy (PMA) free and reference layers composed of Co/M (where M=Pd or Ni) multilayers have been optimized for high PMA and high tunneling magnetoresistance (TMR). The effects of Co thickness, Pd thickness, and the number of Co/Pd bilayers on the anisotropy and coercivity of the [Co/Pd]n multilayer films have been studied for both free and reference layers. The damping parameter α of CoFeB capped multilayers was determined using broadband ferromagnetic resonance. The transport properties of the patterned MTJ stacks were measured from 10 to 400 K. A maximum TMR of 10% at 10 K (5%–10% at 300 K) was obtained for these perpendicular MTJs, regardless of whether or not they were magnetically annealed for MgO–CoFeB crystallization. This indicates that the fcc-bcc-fcc transitions from the fcc multilayers to the bcc CoFeB/MgO/CoFeB do not promote the “giant MgO TMR effect” caused by symmetry filtering.

A thermal oxidation fabrication technique is employed to form low-loss high-index-contrast silicon shallow-ridge waveguides in silicon-on-insulator (SOI) with maximally tight vertical confinement. Drop-port responses from weakly coupled ring resonators demonstrate propagation losses below 0.36 dB/cm for TE modes. This technique is also combined with "magic width" designs mitigating severe lateral radiation leakage for TM modes to achieve propagation loss values of 0.94 dB/cm. We discuss the fabrication process utilized to form these low-loss waveguides and implications for sensor devices in particular.

We demonstrate a 40-Gb/s hybrid CWDM-TDM PON with a novel remote node including a cyclic CWDM multiplexer/demultiplexer. The system uses commercially available 10-Gb/s 1.3-mum directly modulated laser transmitters upstream and 1.5-mum electroabsorption modulated laser transmitters downstream.

We present a compact reconfigurable 8-bit optical matching filter fabricated using 4% delta high-index-contrast silica-on-silicon waveguides. We demonstrate its working by successfully correlating 8-bit binary phase-shift keyed patterns.

An optimised ultra-low power thermo-optic waveguide switch design is presented. Under 25 mW power consumption was achieved for standard index-contrast silica-on-silicon material with reduced polarisation-dependent switching performance.

We have developed low-loss high-index-contrast designs enabling the monolithic integration of a 64 channel, 100GHz VMUX in a compact die. We reduced the power consumption of the attenuators to 20mW and increased the switching speed to 0.5mS by electrical overdriving.

Low-loss high-index-contrast designs enabling the monolithic integration of a 64 channel, 100 GHz VMUX in a compact die have been developed. The power consumption of the attenuators is reduced to 20 mW and the switching speed increased to 0.5 mS by electrical overdriving.

We present a study of ultra-low power thermo-optic waveguide switch designs. Through optimization we achieved under 25mW power consumption for standard index-contrast silica-on-silicon material with reduced polarization dependent switching performance.

We report on a novel design for a colorless wavelength adding-and-dropping module. The module comprises a cyclic demultiplexer and an optical cross connect and greatly reduces the insertion loss of this functionality, in comparison to other approaches. Implementation of ultralow-power-consumption thermo-optic switches simplifies the module thermal control.

We demonstrate the use of an optical equalizer to allow a 42.7-Gbaud (85.4-Gb/s) NRZ-DQPSK signal to tolerate the narrow optical filtering required in high-spectral-efficiency systems. The equalizer passbands are repetitive, enabling equalization of multiple channels.

We present a planar lightwave circuit tunable optical dispersion compensator that combines silica and polymer waveguides to achieve a low power consumption and low polarization dependence. We demonstrate dispersion compensation of a 10-Gb/s pluggable transceiver.

We demonstrate a silica waveguide Mach-Zehnder delay-interferometer that uses integrated switches to demodulate either 10- or 40-Gb/s differential phase-shift keyed signals. We achieved polarization insensitivity by using a half-wave plate and reducing polarization crosstalk in the couplers