- 學位論文
半導體雷射之抗反射鍍膜技術研究
The Technology of Antireflection Coatings on Semiconductor Laser
摘要
此篇論文主要是研究在非對稱多重量子井(Nonidentical Multiple Quantum Wells)雷射二極體一端鏡面上鍍抗反射膜(Antireflection Coatings)，而此抗反射膜是具有寬光譜特性，能使雷射二極體降低Fabry-Perot共振效應。從鍍上抗反射膜之端面量測雷射二極體光強度-電流(L-I)特性曲線，並觀察曲線是無起振點(Threshold)，這顯示出雷射二極體振盪現象很小，及量測光譜(Spectrum)特性曲線，測得光強度之半功率全寬FWHP(Full Width at Half Power)達到218nm(1359.45nm ~1577.45nm)波長寬。 再將抗反射膜分別鍍在1550nm波長及1300nm波長雷射二極體上，所測得發光光譜寬分別為75nm(1500nm ~1575nm)波長及88nm(1250nm~1338nm)波長寬。並運算估計此抗反射膜之反射率分別為0.00022及0.00021。 文中也敘述抗反射膜層是使用光學薄膜特徵矩陣(Characteristic Matrix) 理論設計與模擬，經選定適當光學鍍膜材料後，使用熱蒸鍍方法蒸鍍薄膜，以磷化銦(InP)晶片輔助測試膜層效果，使用熱處理解決光學鍍膜材料熱應力問題，及驗證鍍在InP晶片上之抗反射膜層，在不同溫度環境下之附著性測試，經證實仍然具有良好之附著性。 由於非對稱多重量子井雷射二極體，具有雙光域雷射光，所以必須設計一最佳抗反射膜層，以涵蓋此雙光域雷射光。經由詳實設計與實驗，採用雙層薄膜各自使用非1/4波長膜相，其光學抗反射膜是具有寬光譜範圍特徵，使得此雷射二極體在鍍膜端面之發射光，達成高穿透率效果。
並列摘要
This essay mainly investigates antireflection (AR) coatings on one facets of laser diodes with nonidentical multiple quantum wells. The AR coating has broadband characteristics to reduce the Fabry-Perot resonance. The light-current curve of the laser diode is measured. With AR coating, the laser diode has no threshold, indicating no oscillation. The spectrum is also measured. It shows that the AR coating could make the device exhibit FWHP (Full Width at Half Power) of 218nm spectral width (1359.45nm ~1577.45nm). Laser diodes at the lasing wavelength around 1550 nm and 1300 nm, respectively are also AR-coated. After AR coating, their emission spectra have the spectral width of 75nm (1500nm ~1575nm) and 88nm (1250nm~1338nm) , respectively. The AR-coated reflectivity is estimated to be 0.00022 and 0.00021. The theory of Thin-Film Optical Characteristic Matrix is used to design and simulation the antireflection coatings. InP wafers are used for testing the coating conditions using thermal evaporation. Some suitable optical coating materials are experimented. Also, the problem of heat stress with the optical coating materials is investigated. With proper heating situation, the antireflection coatings on InP wafer has good adhesion under some environment test. The laser diodes with the nonidentical multiple quantum wells oscillate at dual spectral band. Therefore, the AR coatings need special design to simultaneously suppress the lasing at dual bands. The coating conditions also need careful experiment to prove their functions. After design and experiment, using dual-layer Thin-Film with each layer different from 1/4 wave length, broadband AR coating can be achieved for laser diodes in the optical communication.