The refractive-index distribution normal to the polished surface of fused quartz measured by ellipsometry

Abstract

One of the dominant factors influencing the frequency aging of a crystal oscillator is the amount of surface irregularity left by polishing upon its crystal resonator. This paper deals with the refractive-index distribution of fused quartz as a measure of polished layer depth. It is found that the refractive-index distribution can be expressed by a combination of an exponential function and a linear function. The refractive index decreases exponentially from a surface value of 1.736 to a certain value at a depth of 50±10 Å and from it decreases linearly to the bulk value of 1.460 at a depth of 2000±200 Å.

The quality factor of deeply etched quartz resonators : theory and experiments

“…24 Quartz resonators plates are generally prepared by mechanical processes such as lapping and polishing [1]. Mechanical lapping results in the formation of a disturbed surface layer [2][3][4][5][6][7][8] which can markedly affect the performance of the resonator [4][5][6][7][8][9]. Hence in the past few years some measurements [7][8][9] have been made to evaluate the influence of this disturbed surface layer on the quality factor, Q, of quartz resonators.…”

Values of the refractive index of bulk quartz

“…Based on results of ellipsometric measurements, it was found in [21] that the refractive index on the surface of fused quartz is 1.736, decreases exponentially down to depths of 50 ± 10 Å, and then decreases linearly to a depth of 2000 ± 20 Å, approaching a bulk value of n b = 1.46, which is characteristic of fused quartz. The authors of [22] showed that quartz of KU grade (which contains more than 99.99% of SiO 2 ) has a higher optical homogeneity of the surface and, consequently, stoichiometry of the surface layer at final stages of polishing.…”

“…It is no accident that great attention has been paid for a long time to the investigation of quartz and to the determination of the refractive indices of the surface layer and bulk material [20][21][22][23][24]. The refractive index of the surface layer of quartz differs from its bulk refractive index (n b ), which leads to radiation loss [20].…”

“…Grinding and polishing the surface of any substrate, including quartz, gives rise to the formation of a disturbed layer, the refractive index of which differs significantly from n b [20][21][22][23][24]. Based on results of ellipsometric measurements, it was found in [21] that the refractive index on the surface of fused quartz is 1.736, decreases exponentially down to depths of 50 ± 10 Å, and then decreases linearly to a depth of 2000 ± 20 Å, approaching a bulk value of n b = 1.46, which is characteristic of fused quartz.…”

Исследование Поверхностного Слоя, Образующегося При Обработке Кварцевого Стекла С Помощью Механохимического И Ионного Полирования

“…В настоящее время для этих задач широко используется весь арсенал современных технических средств контроля атомарного и молекулярного состава дефектов поверхностного слоя [11][12][13][14][15][16][17]. Свойства поверхностного слоя кварцевого стекла, модифицированного в результате механoхимической полировки (МХП) [18][19][20][21][22][23][24][25][26], могут быть улучшены с помощью последующей полировки/бомбардировки ионным пучком (БИП) [27][28][29][30][31][32][33][34][35]. В результате повышается УФ светопропускание, отражение в ИК области и заметно возрастает лучевая прочность [36][37][38].…”