飛行光學頭讀寫系統設計與表面入射型相變化光碟片之測量

Abstract

在目前商用化可擦拭光碟片中，不論是磁光碟片或是相愛化光碟片，均是採用基板入射(substrate-incidence)的記錄方式 ，其缺點在於光學讀寫頭的重量太重，以致於資料搜尋速度太慢，而且對於高數值孔徑(numerical aperture, NA)物鏡的應用也有所限制。 本文探討的飛行光學頭(flying optical head)，是在飛行滑片(slider)上嵌入高NA的物鏡，以小於１μm的高度飛行於表面入射型相變化光碟片(air-incidence phase change disk)的介電層表面上進行讀寫。利用這種近場(near-field)的記錄方式，可使光碟的記錄密度大幅提昇。 在這篇論文中，先以熱分佈和反射率的模擬結果，設計出表面入射型相變化光碟片的結構，並架設一套飛行光學頭讀寫系統，再以架設的系統量測表面入射型相變化光碟片的記錄特性。實驗的結果發現:substrate/ZnS-SiO2(5nm)/AI(80nm)/ZnS-SiO2(50nm)/GeTeSb(20nm)/ZnS-SiO2(140nm)的碟片結構有良好的記錄特性，請寫的CNR值可達38db。

Most of the commercial optical disks today use substrate-incidence recording technique. Because of the complexity of the conventional optical head, it's difficult to further reduce the mass and improve the seek time. Substrate-incidence recording technique also has some restrictions in using high numerical aperture objective lens to achieve high recording density. The flying optical head is an air-bearing slider with a high numerical aperture objective lens. The flying height between the slider and the overcoat of the air-incidence phase-change disk is less than lμm. This near-field optical technique can greatly increase the recording density of optical disk. The structure of air-incidence phase-change disk was designed by the simulation results of reflectivity and thermal distribution. We establish a dynamic testing system using a flying optical head to measure the recording characteristics of air-incidence phase-change disks. The recording media ofsubstrate/ZnS-SiO2(5nm)/AI(80nm)/ZnS-SiO2(50nm)/GeTeSb(20nm)/ZnS-SiO2(140nm) achieved read/write performance with readout CNR of 38dB.