超寬頻掺鉻釔鋁石榴石自發放大輻射光源應用於光學低同調掃描之研究

光學低同調掃描建立在白光干涉術的基礎架構上，不僅容易實現，還有潛力提供高達微米等級的影像解析度，因此近年來逐漸成為眾人矚目的焦點，尤其是在光纖元件檢測、積體光路以及薄膜結構量測等應用上更是發展迅速。在成本的考量下，目前的低同調掃描系統大都使用超亮度二極體作為系統光源，其解析度約可達10至15微米，然而對於生物檢體掃描以及醫療診斷的用途而言，卻需要更高的解析度才能區分出更細緻微小的差異。我們使用波長為1064 nm的掺鐿光纖雷射來激發本實驗室所生長出來的雙層纖衣掺四價鉻釔鋁石榴石晶體光纖後，可得到中心波長位於1.38微米且頻寬為265 nm之自發放大輻射。在本研究中，我們將此全新的寬頻光源應用於光學低同調掃描之研究上，並藉由檢測鍍金之反射鏡得到本系統之點擴散函數，且進一步證實在真空中的縱向解析度可達5.1微米。為了釐清光源的頻譜形狀與點擴散函數之相對應關係，在本論文中也利用Matlab程式作了模擬並深入探討。最後經由掃描一片厚度為3微米的TiO2膜層檢體，我們成功地區分出兩個相鄰的介面也因此證實了本系統的空間解析力。

關鍵字

掺鉻釔鋁石榴石；自發放大輻射；光學低同調掃描；光源

並列摘要

Based on white-light interferometry, optical low coherence reflectometry (OLCR) has emerged as a promising technique for obtaining high-axial-resolution measurements for fiber optic, integrated optic, and thin film structures. Recent OLCR modules incorporating superluminescent diodes have achieved high resolution of 10-15 um. However, for applications to biological and medical diagnostics, higher imaging resolution is required. We have successfully developed a novel broadband light source, on the basis of a double-clad Cr+4:YAG crystal fiber, generating broadband ASE centered at 1.38 um with a bandwidth of 265 nm by an 1064-nm Yb fiber pump laser. In the research, the light source of the OLCR system was implemented with the Cr:YAG fiber. The point spread function (PSF) of the system was obtained by placing a gold-plated mirror as a sample, and a 5.1-um axial resolution in free space was experimentally demonstrated. Simulation was performed to analyze the relationship between the lineshape of the light source to the corresponding PSF. Finally we prepared a 3-um thick TiO2 coated sample for depth scanning, and successfully distinguished the adjacent refractive index interfaces.

並列關鍵字

Cr:YAG ； ASE ； OLCR ； light source

參考文獻

[22] J. Haggerty, “Production of fibers by a floating zone fiber drawing technique,” NASA Contract Rep., NASA-CR-120948 (1972).

[1] P. Flournoy, R. McClure, and G. Wyntjes, “White-light interferometric thickness gauge,” Appl. Opt., 11, 1907 (1972).

[2] K. Takada, I. Yokohama, K. Chida, and J. Noda, “New measurement system for fault location in optical waveguide devices based on an interferometric technique,” Appl. Opt., 26, 1603 (1987).

[3] B. Danielson and C. Whittenberg, “Guided-wave with micrometer resolution,” Appl. Opt., 26, 2836 (1987).

[4] D. Engin, “Complex optical low coherence reflectometry with tunable source,” IEEE Photon. Technol. Lett., 16, 1346 (2004).

國際替代計量

超寬頻掺鉻釔鋁石榴石自發放大輻射光源應用於光學低同調掃描之研究

全文下載

主題瀏覽