Dynamic information storage or retrieval – Storage or retrieval by simultaneous application of diverse... – Magnetic field and light beam
Reexamination Certificate
2000-12-27
2004-10-19
Chen, Tianjie (Department: 2652)
Dynamic information storage or retrieval
Storage or retrieval by simultaneous application of diverse...
Magnetic field and light beam
Reexamination Certificate
active
06807131
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention pertains generally to optical and magneto-optic head devices, systems and methods for reading magneto-optical media, and more particularly to a near-field hybrid magnetic-optical system and method wherein one or more small aperture semiconductor lasers and one or more magnetic read and/or write elements are formed on a slider as a single, integrated monolithic device.
2. Description of the Background Art
The optical head of an optical read/write system can operate as a “flying head” wherein the optical head does not contact the adjacent optical medium, but is positioned close to the optical medium and separated by an air gap. The optical head includes an aerodynamically designed slider with an air bearing surface for maintaining an air cushion between the optical head and the optical medium. One or more solid state lasers are typically mounted on the slider and are positioned to read and/or write onto the optical medium. The slider is typically mounted on a read arm by a spring mechanism, with the bias of the spring mechanism and the aerodynamic shape of the slider determining the distance between the optical head and optical medium.
Conventionally, the solid state laser and slider are separate components made of different materials. The slider, for example, may comprise a metallized SiC or TiC/Al
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body which has been appropriately shaped for aerodynamic properties. A solid state laser or: lasers are mechanically attached to the slider subsequent to its fabrication. An exemplary prior art attachment process involves careful positioning of the slider on an optical flat, applying a suitable quantity of adhesive or solder to the appropriate locations on the slider, and then urging the laser or lasers along the optical flat into position using micropositioners or microtranslation apparatus. This procedure is generally carried out under an optical microscope. When the adhesive cures, the emission face of the laser should be essentially flush with the slider air-bearing surface.
In the case of magneto-optic heads, additional magnetic components must generally be attached to the slider. Magneto-optic heads typically use a laser that is external to the slider, with laser output directed to the slider via optical fiber or fibers. A reflector and objective optics are coupled to the optical head to direct the laser output towards the magneto-optical medium. A flux element or coil is attached to the slider for magnetic recording or magnetically assisted recording, and magnetoresistive or giant magnetoresistive read element may be attached as well, together with conductors for the coil and magnetic read element.
The procedures for mechanical attachment of components to a slider are difficult and time-intensive. The machining and mechanical alignment tolerances for such attachment are high, generally on the order of 15 nanometers. Improper attachment of the laser and other components cannot generally be corrected. The preparation of optical and magneto-optic heads in this manner has thus involved considerable expense.
There is accordingly a need for a magneto-optical head apparatus and method which avoids complex, difficult and expensive mechanical attachment procedures for securing optical and magnetic components to a slider. The present invention satisfies this need, as well as others, and generally overcomes the deficiencies found in the background art.
SUMMARY OF THE INVENTION
The invention is a hybrid magnetic-optical head apparatus wherein one or more solid state lasers, magnetic field biasing elements, magnetic sensing elements, and an aerodynamically shaped slider comprise a single integrated, monolithic device fabricated from the same base semiconductor material into an optical head. The monolithic optical head can be quickly and easily attached to the read arm of an optical read/write device without requiring attachment of separate laser and magnetic elements, and without micropositioning or use of optical microscopy for positioning the lasers or magnetic elements.
More specifically, the invention is a hybrid magnetic-optical head apparatus comprising a single semiconductor substrate including a first, slider region having an air bearing surface, and a second, magnetic-optical function region having a semiconductor laser and at least one magnetic element. Preferably, the magnetic-optical function region of the substrate includes a magnetic field biasing element associated with the semiconductor laser, as well as a magnetic sensing element. The slider region preferably includes an aerodynamically shaped air cavity as well as the air bearing surface, and the emission face of the laser preferably is substantially co-planar with the air bearing surface.
The magnetic-optical function region may be configured for magnetically assisted thermal recording wherein writing is carried out primarily by laser power modulation to selectively heat portions of a medium, together with assistance of an applied magnetic field to establish a preferred direction of magnetization pattern in the medium. The magnetic-optical function region may alternatively be configured for thermally assisted magnetic writing wherein writing is carried out primarily by modulation of magnetic field, together with assistance of a laser which heats the medium to reduce the medium coercivity and thereby assist in the magnetic recording.
By way of example, and not necessarily of limitation, the semiconductor substrate preferably comprises a first conductivity-type clad layer or reflective layer, a second conductivity-type clad layer or reflective layer, an active region positioned between the first conductivity-type clad layer and second conductivity-type clad layer, and a base or substrate layer of first conductivity-type semiconductor material.
By way of further example, the first conductivity-type base layer preferably comprises a layer of n-semiconductor material, while the first conductivity-type clad layer is an n-clad layer, and the second conductivity-type-clad layer is a p-clad layer. The n-clad layer or reflective layer is adjacent a first side of the active region, and the p-clad layer or reflective layer is adjacent a second side of the active layer. Preferably, one or more insulating layers are included above or on top of the p-clad layer. The semiconductor substrate is formed or grown by conventional techniques such that the n-clad layer is deposited on the n-semiconductor base layer, the active region is deposited on the n-clad layer, and the p-clad layer is deposited on the active region. The outer surface of the n-semiconductor base layer defines the n-side of the substrate, while the outer surface of insulating layer proximate to the p-clad layer defines the p-side of the substrate.
A first section or portion of the semiconductor substrate provides a slider region and includes an air bearing surface and air cavity which are aerodynamically structured and configured to define a slider for the optical head. Preferably, the air bearing surface is formed on the outermost insulating layer on the p-side of the substrate. In other embodiments of the invention, an outermost metal layer may be included on the p-side of the substrate on top of the insulating layer, with the air bearing surface defined in the metal layer.
A second portion or section of the semiconductor substrate comprises a magnetic-optical function region which preferably includes a semiconductor laser and one or more magnetic elements. A p-electrical contact adjacent to the p-clad layer and an n-electrical contact adjacent to the n-semiconductor material layer on the opposite side of the semiconductor substrate define generally a diode laser structure across the substrate. The optical mode of the laser may additionally, or alternatively be defined by oxidized or ion-implanted regions associated with the p-clad layer or n-clad layer, as is well known in the art.
The magnetic elements in the magnetic-optical function region will generally include a magnetic field biasing elem
Hesselink Lambertus
Malmhäll Roger F.
Stinson Douglas G.
Thornton Robert L.
Chen Tianjie
Do Caroline
Masaki Keiji
Research Investment Network, Inc.
Wong Steve
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