bluuebunny/crossref_metadata_2025 huggingface dataset:
Integrated Optical Two-dimensional Time-integrating Correlator
Authors: Tayag Tristan J. , Sadler Brian M. , Pellegrino John M.
Published: February 2023

Two-dimensional (2-D) acousto-optic correlators offer large processing gains for ap­plications in wide-band signal processing systems.
Analysis of coupling efficiency in single-mode fiber components as an optical design problem
Authors: Szapiel Stanislaw , Côté Jasmin
Published: February 2023

A growing number of potential applications of laser diodes and optical fibers has increased the need to design and optimize coupling systems.
The Migration of Bound and Leaky Solutions to the Waveguide Dispersion Relation
Authors: Smith R. E. , Houde-Walter S. N.
Published: February 2023

The eigenmodes of open planar waveguides, like that in Fig. 1, are often determined by finding the solutions to a equation formed by setting a complex function, the open dispersion function, equal to zero.
The Development of Magneto-Optical Disk Memory with Semiconductor Lasers
Authors: Imamura Nobutake
Published: February 2023

Magneto-optical disk memory (MODM) is one of the optical disk memories. Since it uses thin magnetic films as the recording medium, it is possible to erase and re-record. Therefore, the magneto-optical disk memory combines the two advantages--a high density which is a characteristic of optical memories and the rewriting capabibility which is caracteristic of magnetic memories.
The Resistance to Oxidation of Te-Se Optical Recording Films
Authors: Terao Motoyasu , Horigome Shinkichi , Shigematsu Kazuo , Miyauchi Yasushi , Nakazawa Masatoshi
Published: February 2023

It has already been reported that recording thin films for optical disk which are mainly composed of Te have high performance1),2),3). It is also known that the resistance to oxidation is greatly improved by addition of Se2). This paper reports details of the tests on resistance to oxidation of Te-Se thin films, the relation of substrate surface materials and oxidation rates, and effects of additional metallic elements such as Pb, Bi, Sb, Sn, Pb and As on microcrystal growth.
High-Power Diode Lasers for Optical Recording
Authors: Botez D.
Published: February 2023

Semiconductor diode lasers suitable for optical recording must satisfy a variety of stringent requirements: reliable operation in a fundamental spatial mode at 30 to 60 mW peak power and 50% duty cycle; beam direction independent of drive level and/or duty cycle; and a virtually stigmatic beam. We present and discuss here the major types of single-mode diode lasers suitable for optical recording.
Low noise characteristics of VSIS lasers in single-longitudinal mode
Authors: Matsui S. , Takiguchi H. , Taneya M. , Yamamoto O. , Hayashi H. , Yamamoto S. , Yano S. , Hijikata T.
Published: February 2023

Low noise characteristics of semiconductor lasers are reguired for optical disk systems. In generally, single longitudinal mode lasers originate large mode competition noise as the gain envelope shifts with tempurature. Still more, feedback-induced noise of a single-mode laser occur, when a little portion of the laser output reflected by an external mirror is fed back into the laser cavity1). To improve this noise characteristics, it is important to stabilize the longitudinal mode in index guided laser2). This stabilization would be atained with gain suppression of nonlasing modes caused by nonlinear optical interactions with the lasing mode3)4).
Optical Recording in Amorphous Hydrogenated Tellurium
Authors: Schiavone L.M. , Bösch M.A. , Haller H.R. , Hubbard W.E. , Good E. , Shay J.L.
Published: February 2023

The optical writing characteristics of sputtered tellurium films are presented. We compare thin films sputtered in argon to those sputtered in an argon-hydrogen mixture. Preliminary stress tests are described.
An Improved Organic Dye Binder Optical Disk Recording Medium
Authors: Gupta Mool C.
Published: February 2023

Optical disks using organic dye binder recording media yield high performance,1,2 good environmental stability, and high recording sensitivity. Carrier-to-noise ratios > 65 dB (30 kHz bandwidth) have been attained. Their digital recording characteristics are highly linear. Bit error rates3 of 10−5 or less have been reported. Digital or video information is recorded by formation of pits in the recording medium. The basic recording mechanism4 in this medium is by ablation; owing to low thermal diffusivity of the medium, the recording process is essentially adiabatic.
Digitai Magneto-Optical Disk Drive
Authors: Deguchi T. , Katayama H. , Takahashi A. , Ohta K. , Kobayashi S. , Okamoto T.
Published: February 2023

Magneto-optical (M-O) disk with an amorphous magnetic film of rare earth-transition metal (RE-TM) alloy has an advantage of easy recording and erasing with a low power laser such as a semiconductor laser diode. The M-O disk memory is useful for reversible optical mass memory systems. Recently, many studies of the M-O disk have been carried out in both fields of media and systems from the practical point of view.(1,2,3,4)
Analysis of Optical Recording on Photochromic Media
Authors: Tomlinson W. J.
Published: February 2023

While most of the research on materials for reversible optical recording has been on materials using amorphous ←→ crystalline transitions or magneto-optic effects, there have been some proposals for the use of photochromic materials[1]. In this paper we present the results of a preliminary analysis of the intrinsic characteristics of photochromic materials, and the consequences of those characteristics on a bit-oriented optical memory.
Optical Digital Data Storage Using the Photovoltaic Method
Authors: Marchant David D.
Published: February 2023

An alternative method to optically store digital data using the photovoltaic properties of several materials has been studied by Battelle, Pacific Northwest Laboratories. Writing consists of using a scanning laser beam to create miniature photosensitive areas that produce electrical power. Reading consists of activating the photosensitive areas using a scanning laser beam, thereby producing electrical signals that can then be electronically recognized and processed.
Progress in Frequency Domain Optical Storage
Authors: Bjorklund G. C. , Moerner W. E. , Levenson M. D. , Schellenberg F. M. , Bernays D. J.
Published: February 2023

The phenomenon of persistent spectral hole burning allows the frequency of a tunable laser source to be utilized as an additional dimension for the organization of an optical data storage system.1 Potential gains of greater than a factor of 1000 in achievable storage densities over conventional optical storage are possible. In addition, extremely fast random access times can be achieved in the frequency dimension.
Code Design for Optical Storage - a Comparison to Magnetic Storage
Authors: Siegel Paul H.
Published: February 2023

Magnetic recording on disks and tapes has been successfully used for digital data storage for over 25 years. Binary digits (bits) are stored as the presence or absence of magnetization reversals along a track. During readback, the sequence of magnetization transitions induces a corresponding pulse train, from which the recorded bit string is recovered by detection of peak positions relative to time intervals generated by a synchronized clock.
Simulation of Radial Tracking Error Signals on Optical Disk Drives
Authors: DeVore Scott L.
Published: February 2023

Optical disk drives require a radial tracking error signal to control a radial actuator. This actuator is used to follow track runout introduced by respindling the media platter and nonrepeatable spindle runout. The error signal can be optically derived by a variety of methods.1 This paper represents a method of simulating the radial error signal resulting from several different optical tracking methods as an aid to design evaluation and tolerance analysis.
A New Tracking Servo Technology
Authors: Arai S. , Hamada K. , Ogawa K.
Published: February 2023

In the near future, optical disk will find a big market in a field of office automation because of its large capacity and inter changeability, as a replacement for the widely used magnetic tapes and floppy disks.
Magneto-Optic Erasable Disc Memory with Two Optical Heads
Authors: Taira Kozo , Murakami Teruo , Ichihara Katsutarou , Mori Masafumi
Published: February 2023

In recent years, several magneto-optic (MO) erasable disc memories have been reported. However, they have not yet been put to practical use, because the recording media, composed of Fe as the main component, has a short lifetime. Information cannot be overwritten, in contrast with magnetic memories.
Recent Trends of Magneto-optical Disk Memory
Authors: Imamura Nobutake
Published: February 2023

The development of the magneto-optical disk memory has been pursued with extreme rapidity over the last few years. Since initially the CN ratio was low, it was felt that a long lead time would be required to bring the development to the stage of practical application. As will be described below, the characteristics have been constantly improved year after year so that the practical use of the magneto-optica1 disk memory is now only a question of time.
A Magneto-optic Polarization Readout Model
Authors: Campbell David K. , Towner David K.
Published: February 2023

Information stored on magneto-optic disks is typically read using a linearly polarized laser beam whose state of polarization is altered by the Faraday and/or polar Kerr effects upon reflection from the recording medium. Polarization sensitive optics are used to convert these media induced polarization changes into irradiance variations at photodetectors. Because the magneto-optic polarization effects are small (typically less than one degree of polarization rotation in the reflected beam) it is essential that the optical system introduce little additional polarization change if the recorded signal is to be recovered faithfully. This paper describes a polarization model that is used to predict the effects that real optical elements will have on the readout signals, noise, and ultimately, the signal to noise ratio of a magneto-optic recording system.
Highly Reliable TbCo Film for Erasable Optical Disk Memory
Authors: Ichihara K. , Taira K. , Terashima Y. , Shimanuki S. , Yasuda N.
Published: February 2023

Amorphous rare earth-transition metal alloy (RE-TM) films are the most promising candidates for an erasable optical memory media. For plactical use, long-term preservation for recording, large figure of merit value for readout and high sensitivity for writing and erasing must be thoroughly accomplished. However, RE-TM films containing Fe as a chief element are mostly weakly resistant against atmospheric conditions, so it is considered very difficult to achieve practical reliability by an easy protection method.
Voltage-tunable optical data storage using persistent spectral hole burning
Authors: Bogner U. , Beck K. , Schätz P. , Maier Max
Published: February 2023

The use of persistent spectral hole burning in optical data storage allows an increase of the storage density up to a factor of 1000 compared to the common spatial matrix of optical bits.1 The information is stored by burning at low temperature a sequence of narrow spectral holes in the inhomogeneously broadened optical transition of optical centers, e.g. dye molecules embedded in an amorphous polymer, with a tunable narrow-bandwidth laser. One bit of information is encoded by the presence or absence of a hole at a given location in frequency space. The information is read by observing the absorption or the fluorescence of the storage material using a laser with tunable frequency. One of the problems of spectral hole burning data storage arises from the fact that for addressing the memory locations the laser frequency has to be changed over a large frequency range with high accuracy and speed.
Frequency Domain Optical Storage: The Importance of Photon-Gated Materials
Authors: Moerner W. E. , Macfarlane R. M. , Lenth W.
Published: February 2023

Persistent spectral hole-burning (PHB, also called photochemical hole-burning) permits use of the optical frequency for encoding digital information through the presence and absence of spectral holes that are burned in inhomogeneously broadened absorption lines at low (liquid helium) temperatures. The optical frequency or wavelength at which a given hole is burned acts as an additional dimension for data storage, hence this optical recording scheme has been called Frequency Domain Optical Storage (FDOS). The combination of spectral and spatial data-recording can make storage densities in excess of 1010 bits/cm2 possible; furthermore, since rotation of the recording medium is not necessary, shorter random access times will result. The future success of the FDOS concept will rely on progress in several technological and engineering areas as well as on advances in several critical materials areas1.
Erasable Bilayer Dye-Polymer Optical Recording Medium
Authors: Hartman John S. , Lind Michael A.
Published: February 2023

An erasable bilayer organic dye-polymer optical recording medium has been developed which provides high CNR performance and the prospect for long archival data integrity. Media operation utilizes separate lasers for the write (λ=840nm) and the erase (λ=780nm) processes. This paper will include a description of media operation and a summary of preliminary test results.
Conductive Polymers as Active Optical Storage Media
Authors: Gambogi William , Traynor Lee , Buhks Ephraim
Published: February 2023

Conjugated polymers have been intensively studied in recent years due to their intrinsic conductivity and the wide range over which conductivity can be varied.1 Polypyrrole and polythiophene have received particular attention because these materials are stable in air with conductivity in the range of 102 S/cm.2 While conductivity and weight loss have been determined as a function of temperature,3 analysis of the resultant pyrolized products has not been attempted. Of particular interest is the photothermal and/or photochemical processes which would be initiated by a focused laser beam.
New Magneto-Optic Head with a Built-in Generator for a Bias Magnetic Field
Authors: Kobori Hiromichi , Murakami Teruo , Mori Masafumi
Published: February 2023

The necessity for an excess permanent magnet or electromagnet is a major drawback for a magneto-optic (MO) erasable disc memory from the cost, size and access speed viewpoints. However, generating an appropriate bias magnetic field is essential, related to the recording principle.
Design to minimize aberrations of focusing grating coupler under wavelength shift
Authors: Cronkite Patrick , Lawrence George
Published: February 2023

An optical disk write/read head using integrated optics has been demonstrated by S. Ura et al.1 Figure 1 is a schematic drawing of a typical device.2 The light is emitted from a laser diode at one end of the slab (Point R1). The light is trapped in an optical film on the slab and travels in the form of a guided wave in one dimension. The light is diffracted by a grating which consists of modulation in the depth of the film or variation in the index. One order of the diffracted light comes to a focus at Point R2.
Mueller Matrix Tools in Magneto Optic Data Storage Systems
Authors: Bell Bernard W.
Published: February 2023

The operation of a Photo Elastic Modulator (PEM) type ellipsometer is described in Mueller matrix terms. The phase shift (δ) between orthogonal polarization components and the relative amplitude ratio (tan) is contained in the Mueller matrix elements and can be obtained via combinations of measured matrix elements using no mechanical motion. A phase shift measurement accuracy of ±0.2° has been obtained without calibration. The short term repeatibility of both δ and is ± 0.01°. A computer controlled implementation is described along with simple algorithms to extract the ellipsometric constants. The Mueller matrix of a magneto optic film system has been used along with one for a "leaky" beamsplitter to form the optical readout system matrix for an ideal system. One of the Stokes parameters is porportional to the differential detection signal often used in MO data detection schemes.
A Performance Model for Optical Recording Read Channels
Authors: Lynch R. T.
Published: February 2023

A model of the readback, equalization and data detection processes in optical recording has been used to analyze the soft error rate performance that could be expected as a function of these parameters and the noise present in the channel. The model is based on one developed originally by P. H. Siegel(1), and extended by R. G. Hirko and T. D. Howel(2). This original model was designed to analyze inductive magnetic storage channels. The optical channel model uses much of the methodology and several of the components from the earlier work. Significant modifications and additions were required to allow analysis of codes of interest in optical storage, and to account for the different channel transfer function encountered in an optical channel.
Drive Issues for High Performance Magneto-optic Recording
Authors: Campbell David K.
Published: February 2023

In recent years much research has been directed towards developing magneto-optic recording technology, and in assessing its competitiveness in the computer data storage market. High areal density, removable media, reliability, and projected manufacturing costs make magneto-optic drives a very interesting mass storage alternative. However many drive designs have focused on only the above attributes, ignoring performance, thereby developing "slow" magneto-optic drives. Magneto-optic drives will certainly be more competitive if they are designed with equal or greater performance than comparably priced, comparable capacity, Winchester drives. This paper will examine the tradeoffs necessary to develop high performance magneto-optic drives. Design procedures for the read/write optics, media, modulation codes, formats, servo optics, and servo/seek mechanism and control, will be examined.
Effects of Incident Angle on Readout in Magneto-Optic Storage Media
Authors: Deeter Merritt N. , Sarid Dror
Published: February 2023

Presently, the technology of magnetooptics seems to hold the most promise in the area of erasable optical data storage. As noted by several authors1,2, the performance of a magnetooptical disk in terms of the readout signal-to-noise ratio (SNR) depends critically on the multilayer film structure of the disk. However, in optimizing this structure to give the highest SNR, calculations of relevant optical parameters have usually only been made for the case of normally incident plane-waves. This is clearly only an approximation since, in low f-number systems, rays strike the disk surface at angles of incidence of up to 40 or 50 degrees3. In this paper, we investigate the role of angle of incidence in structural optimization.
New Material Developments for Write-Once and Erasable Phase-Change Optical Recording
Authors: Gravesteijn D.J.
Published: February 2023

Recently, there has been a resurgence of interest in the use of laser-induced phase changes as the recording mechanism1-5 in optical storage. This approach is applicable both for write-once5 and for erasable recording1-4. In the latter case there are stringent demands on the crystallization properties of the optical medium. First, heating by a pulsed laser should allow for the creation of amorphous domains in a polycrystalline layer. Secondly, a stability of the amorphous phase of at least, say, 10 years is required at temperatures as high as 70°C, whereas at elevated temperatures recrystallization should be feasible within one passage of a. preferably circular, light spot (typically < 1 µs). This paper illustrates that suitable materials for erasable recording can be found using the results of classical crystallization theory6,7.
Luminescent Recording Media with Photochemical Recording for Optical Memory
Authors: Alfimov M.V. , Nazarov V.B.
Published: February 2023

Luminescent recording media is a thin polymer film incorporated light-sensitive compound which as the result of photochemical reaction under recording beam irreversibly transforms into another compound with luminescence. With information reading light induces luminescence registered by a photoelectronic receiver. Analogous principle is considered in (1,2).
Optical Servo Crosstalk
Authors: Prikryl I.
Published: February 2023

One of the parameters affecting the focus and tracking servo performance is servo crosstalk. Servo crosstalk consists of mechanical, electrical and optical crosstalks. In this paper only the optical crosstalk for systems utilizing the push-pull tracking error signal is investigated. Optical crosstalk we define as a redistribution of radiant intensity over active areas of a servo detector, causing a tracking error signal variation due to a defocusing (focus error) and a focus signal variation due to a tracking error.
Optimizing the Noise Performance of a Magneto-Optic Read Channel
Authors: Dewey Anthony G.
Published: February 2023

One of the problems in the design a magneto-optic read-write head is determining the light level needed at the data detectors. Figure 1 is a schematic of a typical M-O head in which PBS1 and PBS2 are actually leaky beam-splitters that divert from the main optical path (laser to disk and back) some fraction of the p-polarized (unrotated) light. On the outward path this diverted light reduces the efficiency of the head and, especially from the point of view of writing on the disk, the goal would be to minimize this loss. On the return path the light diverted by PBS 1 goes to the servo detectors to provide focus and track-error signals, and that by PBS2 goes to the data detectors.
Edge Shift of Written Domain in Magnetic Field Moduiation Method for Magneto-Optic Disk
Authors: Watanabe Hitoshi , Nakao Takeshi , Maeda Takeshi , Saito Atsushi , Nagai Nobuyuki
Published: February 2023

Magnetic field modulation method is one of the most promising type of high speed overwriting in the magneto-optic disk.l) In this method, a focused laser beam continuously irradiates an information track through the disk substrate and a magnetic field applied by a magnetic head is modulated with the information to be recorded. Information is stored at domain position, or at both side edges of one domain, called domain-edge recording. It has been found that written domain edge in magnetic field modulation method shifts from the position of laser beam irradiated when magnetic field is reversed.
Read Channel Optical Modeling for a Bump Forming Dye-Polymer Medium
Authors: Hartman John S. , Mansuripur Masud
Published: February 2023

Read channel optical modeling has been conducted for a bump forming dye-polymer medium developed by Optical Data, Inc. (ODI). The medium configuration options and operating principles have been reported previously (1,2,3). This paper will present a simple model for written marks on the media and the results of preliminary read channel optical modeling to determine the effects of media and drive variables on the read signal.
Real-time Holographic Optical Storage
Authors: Xu Kebin , Yuan Yang , Xu Haiying , Hong Jing , Xu Yuhuan
Published: February 2023

This letter presents the holographic storage properties in LiNbO3:Pr and LiNbO3:Ce:Fe crystals and demonstrates real-time parallel optical associative memory system implemented with LiNbO3:Ce:Fe as recording medium and a LiNbO3:Fe amplifier used to provide feedback, thresholding and gain. In our experiment, the retrieval of complete image when only a partial image addresses the system is demonstrated.
Progress of Phase Change Single Beam Overwrite Technology
Authors: Terao Motoyasu
Published: February 2023

In the first report on phase change single beam overwrite1), 2), it was determined that information rewriting is possible by only the laser power modulation between a crystallizing power level and an amorphizing power level. However, there was a large residual signal, which was mainly caused by insufficient crystallization speed. The erase ratio (decrease of an old signal) was approximately 12dB at that time.
Million Cycle Overwritable Phase Change Optical Disk Media
Authors: Ohta Takeo , Uchida Masami , Yoshioka Kazumi , Furukawa Shigeaki , Kotera Koichi
Published: February 2023

GeTe-Sb2Te3-Sb pseudo ternary components alloy shows laser induced fast crystallization speed. Increasing the Sb concentration leads to higher crystallization temperature around 180°C. Thin film disk structure of 20nm active layer produce stable bit error rate characteristics of more than million cycle over-write.
Detection of Magneto-optic Signals Using An External Cavity Laser Diode
Authors: Fukushima Nobuhiro , Sawaki Ippei
Published: February 2023

A small optical head is necessary to improve the data transfer rate, access time, and recording capacity of optical disk memory. Recently, using an external cavity laser diode to make a small optical head has been proposed[1]. However, since this method is based on switching between spontaneous emission and laser oscillation due to the reflectance change of the medium, it cannot be used for magneto-optic media.
Multi-Beam Magneto-Optical Disk Drive for Parallel Read/Write Operation
Authors: Katayama R. , Yoshihara K. , Yamanaka Y. , Tsunekane M. , Kubota K. , Yoshida K.
Published: February 2023

Optical disk systems, using a laser beam for data recording and reading, are expected for use as high density information storage systems. Recently, erasable magneto-optical disk systems have come up in the commercial market. On the other hand, there are many requirements for higher data transfer rate systems, such as digital video image applications. A multi-beam optical disk drive1),2) can meet these requirements by following reasons.
Ge-Te-Ti Thin Films for High Performance Phase Change Optical Recording
Authors: Raychaudhuri Pranab K.
Published: February 2023

It has been known for some time now that thin GeTe films are readily prepared in the amorphous state by a variety of deposition techniques. The films are stable at room temperature but convert to the crystalline state upon thermal treatment. The amorphous-to-crystalline transition occurs at 150° C with significant changes in optical constants.1 The GeTe thin film as a phase change optical recording layer was considered in 19722 but has not been seriously looked at until recently. The recent study3 on the laser-induced phase transformation kinetics reveals that the crystallization rate of GeTe film is slow (250 ns crystallization time) and a deviation in either direction from the stoichiometric composition seriously retards the crystallization kinetics. On the basis of these observations it may be assumed that any of the GeTe phase change media is unable to support the high data transfer rate sought in optical recording.
Clock Generation Circuit of a Sampled Servo Optical Disk Drive
Authors: Ozawa Y. , Hamaguchi S. , Moritsugu M. , Futamata A.
Published: February 2023

There are two ISO standards for 5.25 in. servo format. One is the continuous servo format, and the other is the sampled servo format. The two formats have a different clock generation system and tracking servo error detection system. In the sampled servo system, the clock is always generated by the clock generation circuit even during accessing. This system uses embedded clock pits which are prerecorded on the disk as shown in Fig. 1. In the case of 1800 rpm disk rotation, an 11 MHz clock is generated from a 40kHz clock pit signal. Fig. 2 shows a block diagram of the clock generation circuit. The circuit is divided into two parts: Clock pit detection and the PLL(Phase Locked Loop). PLL is simpler than continuous servo system, and the design theory is already well known. Clock pit detection detects and extracts the clock pit signal from the read out signal by counting the unique distance against the generated clock. Thus, pit detection and clock generation are mutually dependent. Before the first clock pit is detected(when the disk begins to rotate), the clock must be generated with better than 2.7% accuracy. So, the PLL pull-in circuit is necessary for start up. We developed a new clock generation circuit which is linked to the spindle motor control circuit, and which has fast pull-in characteristics.
Compatibility test for Phase Change Erasable and WORM media in a Multi-function drive
Authors: Ohara Shunji , Inokuchi Chikashi , Furutani Tadashige , Ishida Takashi , Ishibashi Kenzo , Kurahashi Akira , Yoshida Tornio
Published: February 2023

Optical media based on amorphous and crystal phase change have been studied in several laboratories[1][2]. A WORM (Write Once Read Many times) drive is commercially available today[3]. Regarding PCE (Phase Change Erasable) media, recent works have made advanced progress [4][5]. The optical data memory using PCE media has two big features. One is that it has one pass direct overwriting function. It is expected to improve the performance of the current rewritable optical memory. The another is that it has a high performance of handling both PCE and WORM media intrinsically, so-called a multi-function drive. In this paper, we will discuss how to have realized a multi -function drive and report compatibility test results among PCE and WORM media measured by the drive.
10ms direct seeking of 90mm magneto-optical disk with flying optical head
Authors: Yasukawa K. , Iguchi D. , Yamaguchi S. , Murakami A. , Nomiyama T. , Takahashi K. , Ueyanagi K.
Published: February 2023

We have developed a flying optical head to attain high speed accessing which is the important issue in applying optical disks for computer file memories1)2). This time, we studied direct seeking technology with the flying optical head and successfully applied the technology for 90mm magneto-optical disks.
A Shot-Noise-Limited High-power Green Laser for Higher Density Optical Disk Systems
Authors: Kubota Shigeo , Oka Michio
Published: February 2023

Various kinds of laser diode based frequency doubling devices have been developed to provide a compact, efficient and visible coherent light source. A diode pumped, intra-cavity doubled solid state laser has advantages in its good spatial and temporal coherence, very low noise and scalability by parallel pumping.1 These advantages derive from the intrinsic characteristics of a solid state laser. We have reported stabilized second harmonic generation (SHG) by polarization-mode decoupling with a KTiOPO4 (KTP) doubler and a quarter wave plate (QWP) inside a Nd:YAG laser cavity.2 Since spatial coherence of the pump source is not necessary, a broad area laser diode (LD) can be used for pumping to generate the several mW green output required for readout of optical disks. A 1W LD allows a several tens of green output, sufficient for recording optical disks.3 A 1W green output was reported using a multimode optical fiber bundle for parallel pumping.4
A New Approach to High-density Recording on an Magneto-optical Disk
Authors: Fujita Goro , Urakawa Yoshiyuki , Yamagami Tamotsu , Watanabe Tetsu
Published: February 2023

We investigated the influence of pit shape upon write/read MTF in MO recording, which differs depending on the recording method used. Furthermore, we investigated three channel codings to determine their suitability for the high-density recording using simulation and measurement.
Performances of pregrooved phase change rewritable media in 680 nm laser diode system
Authors: Ohta Takeo , Yoshioka Kazuya , Akiyama Tetuya , Heil Stephen F. , Takagi Yuuji , Yoshida Tomio
Published: February 2023

High density recording has been studied by using phase change rewritable(PCR) media, 680 nm laser diode and high numerical aperture focus lens of 0.55. The pregrooved disks having narrow track pitch have been prepared. The tracking parameter at narrow track pitch and the write/read characteristics have been measured and the attainable recording density by PPM recording method has been estimated. The relationship between the overwrite erase ratio and the jitter of play back signal has been studied.
Stability of phase-change optical disks produced by a pass-through type sputtering system
Authors: Suzuki M. , Morishita N. , Tajima S. , Nakao M. , Nishimura K. , Ohta M.
Published: February 2023

Many types of rewritable optical disks have been proposed and studied. Some of them are currently used for computer data storage and audio/video signal recording. Of these types, a phase-change rewritable (PCR) type shows great promise as a future optical recording media. It can be easily overwritten, and the carrier-to-noise ratio (CNR) is high over wide range of wavelengths, from 400nm to 900nm.1) A phase-change media shows high performance characteristics, but it has not been shown that a high performance phase-change media can be mass-produced, as MO media is.
Multilayer Volumetric Storage
Authors: Rubin K. , Rosen H. , Strand T. , Imaino W. , Tang W.
Published: February 2023

We describe a new method of increasing the density of information stored on optical storage disks. This technology is based on the use of distinct data layers which are partially transmissive and separated by a spacer layer1. It takes advantage of the narrow depth of focus provided by the objective lens to allow selective access to data on each layer by moving the focal position of the objective lens. This technology is extendible to more than two layers, can be used with other methods of increasing storage capacity, and can be implemented with only modest changes to existing media and drive manufacturing lines.
Advance of Magneto-Optical Super Resolution for Very High Density MO Recording
Authors: Owa Hideo
Published: February 2023

Large capacity is strongly required for the next generation magneto-optical disks in order to manage huge data such as digital images. We reported that a super resolution is realized by using an exchange-coupled multi-layer disk in 1991. This novel technology is called Magnetically Induced Super Resolution(MSR) and it more than doubles the readout resolution limit of the conventional optical disk system without shortening the laser wavelength or increasing the numerical aperture(NA) of the optical lens 1)2).
Minimum Magnetic Domain Width of TbFeCo by Magnetic Field Modulation Recording
Authors: Komatsu Masao , Tanaka Asato , Yoshida Hidemi , Kobayashi Yoshimitsu
Published: February 2023

Higher density recording is necessary for MO to be recognized as useful storage media. We can raise capacity over 8 times by means of green laser and magnetic super resolution . Minimum mark size will be 0.2 μm in this case. There should be two problems when we use green laser. One is smaller Kerr rotation of TbFeCo. The other is stability of magnetic domain of 0.2 μm.
Signal and Noise Patterns in the Collection Aperture of Optical Data Storage Devices
Authors: Milster Tom D. , Chen Zhiyong
Published: February 2023

The data pattern on the recording surface can be thought of as collections of cosinusoidal gratings, no matter what the technique used for modulating the reflected light. Reflected light from a focused beam contains a zero order and ± 1st diffracted orders, as shown in Figure 1. The separation angle between the diffracted orders depends on the spatial frequency of the grating. High spatial frequencies yield large separation of the diffracted orders. Light collected by the objective lens contains the zero order and portions of the diffracted orders. The signal amplitude received from the detectors depends on the modulation of the interference between the diffracted orders and the zero order. The amount of modulation depends on the overlap area. At low frequencies, the overlap area is most of the collection aperture. At high frequencies the overlap area reduces, so the signal amplitude decreases.
Measurement of Crystallization Speed in Phase-Change Media
Authors: Narayan Raghuram , Mansuripur Masud
Published: February 2023

Phase-change media [1] in DVD-RAM systems has been a hot bed of research in the past several years. In phase-change optical recording a high power "write" beam irradiates the disk and forms an amorphous mark. The amorphous mark is written in a crystalline background. The difference in the optical constants between the amorphous and crystalline areas enables the amorphous mark to be read back by a "read" beam of substantially lower power compared to the "write" beam. An "erase" beam with a power level less than the write beam can be used to erase the amorphous mark. The erase beam raises the temperature of the phase-change layer to a value that is conducive for rapid crystallization.
Time Resolving Analysis of Amorphous Mark Forming in Phase Change Optical Disks
Authors: Kando Hidehiko , Maeda Takeshi , Terao Motoyasu , Miyamoto Makoto , Hirotsune Akemi , Ohnuki Hideo
Published: February 2023

Phase change mark simulator is investigated. Nucleation, crystal growth, and re-crystallization at amorphous/crystal boundary are taken into consideration. Crystallization is evaluated with 3-dimensional thermal analysis. Mark shapes of experiments and simulation are in good agreement. Amorphous mark forming process was analyzed with the simulator.
Vector Diffraction and Surface-wave Excitation in an Optical Disk System
Authors: Yeh Wei-Hung , Li Lifeng , Mansuripur M.
Published: February 2023

The period of the current pre-grooved optical disks is on the order of one optical wavelength. The understanding of the interaction of focused beams with this type of high frequency periodic structure using the conventional scalar diffraction theory, with which most optical engineers are familiar, is no longer adequate; a vector theory must be used. Furthermore, the use of multilayer dielectric and metallic coatings and high numerical aperture beams in modern optical disk technology inevitably entails excitation of surface waves (surface plasmon and waveguide modes). A good understanding of the vector diffraction and the possible influence of the surface waves on the various extracted signals is important in the design and analysis of new generations of optical disks.
Data Channel Simulation of a Scanner Based Optical Tape System
Authors: Pillai Usha , Kumar B.V.K. Vijaya
Published: February 2023

Large-capacity optical tape systems are attractive for archival storage of large databases [1,2] maintained by the government, insurance companies, etc. The recent increase in demand for storage space, created by the popularity of the world wide web, is expected to provide tape systems a significant share in the commercial market as well. Innovations in tape readback mechanisms [2-6] have resulted in increased data rates. One such technique employs an optical head mounted on a scanner which is moving rapidly over the tape in a zig-zag manner, thus multiplexing the readback from several tracks. The non-uniform speed of the scanner gives rise to a rapidly varying channel response, which makes the scanner head readback different from one having a constant speed or whose speed varies relatively slowly. It is to be expected that the equalization and data detection techniques that are known to work well in systems using the latter heads may need to be either modified or entirely substituted by novel methods when a scanner head is used. Our research aims to identify these implications by means of a software simulator that emulates a scanner based optical tape data channel.
Digital Holographic Storage of Multiple High Capacity Data Pages in Thick Photopolymer Systems
Authors: Dhar Lisa , Boyd Carol , Campbell Scott , Curtis Kevin , Harris Alex , Hill Adrian , Levinos Nicholas , Schilling Marcia , Tackitt Michael , Wilson William
Published: February 2023

In this letter we report on the holographic storage and recovery of multiple high capacity (800 x 600, 480 kbit) data pages in thick (250 μm and 500 μm) photopolymer media. The lack of adequate storage materials has been one of the primary obstacles in the technical development of holographic data storage. Recent advances in photopolymer systems have focused attention on the viability of these materials for write-once-read-many-times holographic data storage1. Among the many challenges in using photopolymer materials, two of the most pressing are fabricating a medium that allows high capacity data pages to be pixel-matched through the material and designing a system that is dimensionally stable enough to allow the recording and high fidelity recovery of multiplexed digital data pages.
Exchange coupling in magneto-optical CAD-MSR disks
Authors: Peng Chubing , Mansuripur M.
Published: February 2023

In magneto-optical data storage, magnetically-induced super resolution (MSR) is one of promising technologies for realizing high-density recording. There are various detection schemes to detect data marks in the disks. Among them, center aperture detection (CAD) requires no initializing or bias field for readout. The CAD-MSR film usually consists of two or three magnetic layers. The magnetization of readout layer is in-plane at room temperature but becomes perpendicular at high temperature [1,2]. In the three-layer structure, an intermediate layer is used to mediate the exchange coupling between readout and writing layers so that abrupt transition of polar Kerr rotation can be obtained [3]. In the studies of CAD-MSR, magneto-optical Kerr effect measurements are usually conducted in a electromagnet equipped with a heating stage. Here we present some experimental results on CAD-MSR sample using static tester.
A Simple Nonlinear Channel Model for Phase Change Optical Recording Media
Authors: Yuan Yifei , Kumar B.V.K. Vijaya
Published: February 2023

In optical recording, phase change media has such advantages as direct overwriting, no need for magnetic head and large signal amplitude using simple optics [1]. It is important to develop an appropriate channel model for phase-change media optical recording as it may help us find good equalization and detection schemes. Conventional channel models consider marks as one-dimensional (along the track) and assumes linear superposition in readout [2]. However, as the recording density is increased, mark shapes for different lengths become different and the linear model tends to be less valid. In this paper, we present a more realistic channel model which considers both write and read processes as two-dimensional. An adiabatic thermal model is applied to write marks and geometrical optics is assumed in readout. The resulting channel model consists of two linear filters with a nonlinearity sandwiched in between.
A rewritable optical disk system with over 10 GB of capacity
Authors: Osato Kiyoshi , Yamamoto Kenji , Ichimura Isao , Maeda Fumisada , Kasami Yutaka
Published: February 2023

Recently, the capacity of an optical disk was increased up to 4.7 GB such as DVD with a demand of playing back a digital video. In order to record a digital video data more than 3 hours, the capacity of a rewritable disk is expected to exceed 10 GB.
Reading Optical ROM with Near Field of SIL Theory and Experiment
Authors: Ootaki K. , Ooki H. , Tokoyoda Y. , Irita T. , Saito J.
Published: February 2023

From the viewpoint of super high density recording in optical storage, near field recording (NFR) by using a solid immersion lens (SIL) is getting payed attention. The SIL is a hemi- or super-hemi-spherical lens which is located very close to the recording surface. In other words, the gap or distance between the SIL surface and the recording surface should be so small that the evanescent wave from the SIL surface could reach to the recording surface. There are a few primitive reports about SIL readouting of optical ROM memories[1], [2], [3]. In this report, we will analyze the SIL readout signal from optical ROM, by using the vector diffraction theory. We will report the gap height sensitivity of the readout signal and the polarization dependence of the readout signal.
Deciphering the vibronic lasing performances in an electron-phonon-photon coupling system
Authors: Miao Rulin , Fu Yu , Lu Dazhi , Liang Fei , Yu Haohai , Zhang Huaijin , Wu Yicheng
Published: February 2023

Coupling between electronic motions and the lattice vibrations, phonons could broaden the spectral bandwidth of the fluorescence spectroscopy by the energy transferring, which was recognized from the beginning of last century and successfully applied in many vibronic lasers. However, the laser performances under electron-phonon coupling were mainly prejudged by the experimental spectroscopy. The multiphonon participated lasing mechanism is still elusive and should be in-depth investigated. Here, a direct quantitative relationship between the laser performance and phonon participating dynamic process was derived in theory. With a transition metal doped alexandrite (Cr3+:BeAl2O4) crystal, the multiphonon coupled laser performance was manifested in experiments. Associated with the Huang-Rhys factor calculations and hypothesis, the multiphonon participated lasing mechanism with phonon numbers from 2 to 5 was discovered and identified. This work provides not only a credible model for understanding the multiphonon participated lasing, but should also boost the study of laser physics in the electron-phonon-photon coupled systems.
Spherical vector radiative transfer model for satellite ocean color remote sensing
Authors: Xu Fei , He Xianqiang , Jin Xuchen , Cai Wencai , Bai Yan , Wang Difeng , Gong Fang , Zhu Qiankun
Published: February 2023

Atmospheric correction is the key step for satellite ocean color remote sensing. However, most of the existing atmospheric correction algorithms do not consider the effects of Earth curvature. In fact, Earth curvature has a significant impact on satellite observation signals under large solar zenith angles or large viewing zenith angles. In this study, based on the Monte Carlo method, a vector radiative transfer model with spherical shell atmosphere geometry (hereafter our SSA-MC model) considering the influence of Earth curvature was established, which can be applied to conditions with high solar zenith angles or high viewing zenith angles. Our SSA-MC model was first compared with the Adams&Kattawar model, and the results show that the mean relative differences are 1.72%, 1.36% and 1.28% for solar zenith angles of 0∘, 70.47∘ and 84.26∘, respectively. Moreover, our SSA-MC model was further validated by more recently benchmarks from Korkin’s scalar and vector models, and the results show that the relative differences are mostly less than 0.5% even at extremely high solar zenith angles (84.26∘). Then, our SSA-MC model was verified with the Rayleigh scattering radiance calculated by the look-up tables (LUTs) in SeaDAS under low-to-moderate solar or viewing zenith angles, and the results show that the relative differences are less than 1.42% when solar zenith angles are less than 70∘ and viewing zenith angles are less than 60∘. Our SSA-MC model was also compared with the Polarized Coupled Ocean-Atmosphere Radiative Transfer model based on the pseudo-spherical assumption (PCOART-SA), and the results show that the relative differences are mostly less than 2%. At last, based on our SSA-MC model, the effects of Earth curvature on Rayleigh scattering radiance were analyzed for both high solar zenith angles and high viewing zenith angles. The result shows that the mean relative error between the plane-parallel (PP) geometry and spherical shell atmosphere (SSA) geometry is 0.90% when the solar zenith angle is 60∘ and the viewing zenith angle is 60.15∘. However, the mean relative error increases with increasing solar zenith angle or viewing zenith angle. When the solar zenith angle is 84∘ and the viewing zenith angle is 84.02∘, the mean relative error is 4.63%. Thus, Earth curvature should be considered in atmospheric corrections at large solar or viewing zenith angles.