By Topic

Selected Topics in Quantum Electronics, IEEE Journal of

Issue 5 • Date Sept.-Oct. 1998

Filter Results

Displaying Results 1 - 10 of 10
  • Introduction to the Issue on Advanced Optical Storage Technologies

    Page(s): 813 - 814
    Save to Project icon | Request Permissions | PDF file iconPDF (70 KB)  
    Freely Available from IEEE
  • Characteristics of spectral-hole burning of InAs self-assembled quantum dots

    Page(s): 880 - 885
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (148 KB)  

    Spectral-hole burning of InAs self-assembled quantum dots (QDs) embedded in pin-diode was observed. At 5 K, a narrow hole with width of less than 1 mm was observed and the hole depth increased as electric field increased with the writing light power of 8 mW. The hole was observed up to 40 K. The spectral hole was broadened as the writing light power increases from 8 to 20 mW. Spectral-hole width at the 8 mW was well fitted with the convolution integral of Gaussian distribution for reading light and Lorentzian distribution for absorption change taking into account homogeneous broadening of InAs QDs of ⩽80 μeV. Spectral-hole lifetime at the 8 mW was estimated to be in the order of 10-6 s. Optical absorption spectrum of 15-stacked InAs QD structure was also observed at 77 K and 300 K View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Holographic memory with correlator based readout

    Page(s): 849 - 855
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (604 KB)  

    The investigation of an inverted hybrid digital/optical VanderLugt type correlator based on a holographic memory is reported in this paper. A set of reference templates is stored in a photorefractive crystal (PRC) by angular hologram multiplexing. In the filter plane, a phase-modulating liquid crystal television (LCTV) serves as a phase-only input device. During the recognition process, which is based on the pure phase correlation, the reference templates are correlated sequentially with the input object. This correlator shows high sensitivity to object rotation, sharp correlation peaks, high light efficiency, and is fully shift-invariant in spite of the PRC thickness. The influences of the LCTV on the performance of the system are discussed and experimental results are shown View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Analysis of mark-formation process for phase-change media

    Page(s): 826 - 831
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (740 KB)  

    The objective of this study was to determine the mechanism of a phenomenon peculiar to phase-change recording regarding the mark shape or mark-forming process. The following results were obtained from our simulation of mark shapes, transparency electron microscope observations, and analysis of reproduced signals. A method of calculating a mark shape by calculating the holding-time profile was devised and its appropriateness was confirmed. We found there were close relationships between the cooling pulse shape, the effective erase ratio, the reproduced signal amplitude, and the noise level, and that the temperature change when the mark edge was cooled has a great influence on the stability of the mark shape and crystallized regions View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Near-optimal parallel distributed data detection for page-oriented optical memories

    Page(s): 866 - 879
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (496 KB)  

    Volume optical storage systems suffer from numerous sources of noise and interference, the effects of which can seriously degrade retrieved data fidelity and produce unacceptable bit-error rates (BERs). We examine the problem of reliable two-dimensional data retrieval in the context of recently developed soft-decision methods for iterative decoding. We describe a novel near-optimal algorithm in which each pixel on the page is treated as a starting point for a simple iterative procedure so that a highly parallel, locally connected, distributed computational model emerges whose operation is well suited to the page-oriented memory (POM) interface format. We study the use of our two-dimensional distributed data detection (2D4) algorithm with both incoherent (linear) and coherent (nonlinear) finite-contrast POM channel models. We present BER results obtained using the 2D4 algorithm and compare these with three other typical methods [i.e., simple thresholding (THA), differential encoding (DC) and the decision feedback Viterbi algorithm (DFVA)]. The BER improvements are shown to have a direct impact on POM storage capacity and density and this impact is quantified for the special case of holographic POM. In a Rayleigh resolved holographic POM system with infinite contrast, we find that 2D4 offers capacity improvements of 84%, 56%, and 8% as compared with DC, THA, and DFVA respectively, with corresponding storage density gains of 85%, 26%, and 9%. In the case of finite contrast (C=4), similar capacity improvements of 93%, 18%, and 4% produce similar density improvements of 98%, 21%, and 6%. Implementational issues associated with the realization of this new distributed detection algorithm are also discussed and parallel neural and focal plane strategies are considered. A 2 cm2 λ=0.1 μm digital VLSI real estate budget will support a 600×600 pixel 2D4 focal plane processor operating at 40 MHz with less than 1.7 W/cm2 power dissipation View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • The characteristics of a dual-layer optical disk with read-only and erasable functions

    Page(s): 821 - 825
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (152 KB)  

    A dual-layer optical disk comprised of a read only layer and a phase-change layer was designed to perform the read-only and erasable dual-functionality in an optical disk. With the properly designed dual-layer disk structure, 23 mW of write power was adequate to write data marks on the erasable phase-change layer; simultaneously, equal magnitude of sufficient radiofrequency readout signals could be obtained on both its data layers. The analyzes of its recording characteristics demonstrated the feasibility of the dual-functional optical disk View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Requirements and constraints for the design of smart photodetector arrays for page-oriented optical memories

    Page(s): 856 - 865
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (320 KB)  

    We discuss the feasibility of smart photodetector arrays (SPDAs) as the optoelectronic interface in page-oriented optical memory systems. In contrast to charge-coupled device arrays, SPDA's can combine fast parallel access with some processing capabilities, such as data decoding and error control. We develop a framework for SPDA design by defining their operational requirements and by delineating their scalability constraints with respect to pixel complexity, electrical power dissipation, and optical power limits. In the case of volume holographic memories, the low-diffraction efficiency of photorefractive crystals will ultimately determine page size, while for other storage technologies the primary constraint will be the circuit complexity. We also present our implementation of an experimental SPDA designed to perform parallel error correction on an entire page of data and satisfy the sustained data rates of parallel optical memories. Our prototype, fabricated in 0.35-μm complementary metal-oxide-semiconductor, integrates a differential photoreceiver with a cluster error correction code capable of achieving corrected output data rates scalable to hundreds of gigabits-per-second in the current technology View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Volume holographic storage demonstrator based on phase-coded multiplexing

    Page(s): 832 - 839
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (704 KB)  

    We present the design and realization of a compact volume holographic memory based on phase-coded multiplexing. Due to the use of nonmechanical reference beam changes in this multiplexing technique, rapid access of the stored data pages is achieved. Our system can reach a maximum storage capacity up to 480 data pages with a resolution of 640×480 pixels in a single interaction region of a photorefractive LiNbO3 crystal. We present the implementation of the system and first experimental results of both, high-resolution analog image storage and digital data storage. The storage of 180 data pages is demonstrated as well as the application of the system to real-time optical image processing View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • High-density disk storage by multiplexed microholograms

    Page(s): 840 - 848
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (844 KB)  

    We propose a concept of holographic data storage which promises storage capacities of more than 100-Gbyte on a digital versatile disk (DVD)-sized disk. The information is stored bitwise in form of microscopic reflection holograms. High storage densities can be achieved by combining multiplexing methods and multilayer storage. A theoretical model for microscopic reflection holograms generated by focused Gaussian beams is proposed. Experimental results are presented for the recording and characterization of microholograms in DuPont's HRF-800 photopolymers. The local distribution of the diffraction efficiency was investigated by applying a confocal scanning microscope setup. Single-color holograms with a radius of 1.8 and 12 μm depth have been recorded. We observe a blue shift in the spectral response of the microholograms of less than 2% due to shrinkage of the polymer. In the case of threefold wavelength multiplexing, all wavelengths are clearly resolved in the spectral response having spectral width Δλ of less than 10 nm (FWHM). Baking the holograms for 1 h at 120°C nearly doubted the diffraction efficiency while the spectral response of the microholograms broadened by a factor two. We showed that 80-ps pulses are sufficient for holographic recording in the photopolymers. An optimized pre-illumination allows a significant increase in diffraction efficiency View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Magnetooptical recording technology toward 100 Gb/in2

    Page(s): 815 - 820
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (212 KB)  

    Concerning areal recording density, magnetooptical (MO) disk possesses an advantage compared to another optical disks and also magnetic hard disk (HDD), since the linear density of MO disk can be increased by using a perpendicular magnetic recording, and the track density also can be increased by using an optical tracking method. On the other hand, in the region of high density HDD, demagnetization problem is discussed for archival data storage. However, since the coercive force of MO recording material is over five times larger than that of HDD, it does not become such a severe problem for MO recording. In case of very-high-density recording, the readout signal is drastically reduced due to decreasing both the recorded domain size and the optical resolution. However, in the case of MO, the small readout signal can be enhanced by using a novel readout technique named as magnetic amplifying MO system and the extremely small signal also can be detected. Thus, it is found that the MO has probability of achieving an extremely high density storage such as 100 Gb/in2 View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.

Aims & Scope

Papers published in the IEEE Journal of Selected Topics in Quantum Electronics fall within the broad field of science and technology of quantum electronics of a device, subsystem, or system-oriented nature.

Full Aims & Scope

Meet Our Editors

Editor-in-Chief
John Cartledge
Queen's University