1289220 玖、發明說明： C 明屬々貝】 發明領域 本發明係有關於非線性光學裝置，更特定言之，係有 5關於二極體雷射結構式光線之頻率轉換用的一種裝置。 c先前技術】 發明背景 半導體雷射在光纖傳輸系統、信號放大系統、波分複 用傳輸系統、波分轉換系統、波長交叉連接系統以及類似 10系統扮演重要的角色。此外，半導體雷射在光學測量領域 中係為有用的。 半導體雷射（最先於1959年提出）係根據非平衡載體之 電流注入一半導體主動介質中，導致居量反轉及充分的模 態增益用以獲得雷射作用。 15 現參考該等圖式，基本上目前在雷射市場具支配地位 的有二類型半導體雷射，如第la-b圖中所示。第la圖係圖示 一垂直共振腔面射型雷射(VCSEL)，其中光子係於垂直方 向（於第la圖中為向上)上，在一高精度腔中循環。於此類雷 射中，該腔室為短的並且每一循環的增益係為極低的。因 20此，在每一反射時確保極低損失係極為重要的，否則，無 法達到雷射作用或將需過大電流密度，對於連續波作業而 言係不適合。由於最早係於1962年提出，所以垂直共振腔 面射型雷射（VCSEL)已極為普及。垂直共振腔面射型雷射 (VCSEL)能夠製成為小的，能夠在低定限電流下作動，並 1289220 係在一極為易於製造的平面技術下製成。 另一類型的半導體雷射係為一邊射型雷射，如第lb圖 中所示。於此類雷射中，一主動介質（例如，一薄層）係配置 在其之折射率係大於周圍包覆層的一波導中，用以確保約 5 束於波導中的雷射光。所產生的光線在典型之30度-60度的 大角度下，在元件之刻面出口處折射。邊射型雷射的優點 在於其之小型輸出孔徑，同時地具有高光線輸出功率。邊 射型雷射超越垂直共振腔面射型雷射(VCSEL)的缺點在於 像散現象，通常在使用環形輸出孔徑時發生。此外，與垂 10 直共振腔面射型雷射(VCSEL)相對地，於邊射型雷射中， 溫度增加導致因半導體隨著溫度增加之帶間隙窄化 (bandgap narrowing)所致使的顯著波長變換。 所有半導體雷射的其中之一缺點在於，發射光線之波 長（或頻率）係受限制在半導體材料之能量間隙（energy 15 bandgap)值所提供之數值上。此外，由於藉由所熟知量子 井、量子線或量子點異質結構之不同結構所造成的載體之 局部化，所以有效的波長可變換至一較大數值(所謂的紅移 (red shift))。半導體雷射技術已針對羾_又化合物半導體充 分成長，並涵蓋超越600奈米之波長。目前所熟知低於6〇〇 20奈米波長的半導體雷射(例如，位在紫外光至綠光頻譜範圍） 係極不成熟。 半導體雷射的一附加缺點在於不良的光束品質、寬光 譜及波長之不良的溫度穩定性。 已有提出複數種方法用以產生波長低於6〇〇奈米的光 1289220 線，基本上使用非線性光學技術，將自半導體雷射輸出之 光線波長轉換。該等技術能夠產生極度寬廣光譜範圍之光 線，例如自中紅外光(mid-IR)至可見光。頻率轉換技術之實 例包括和頻產生(SFG)、倍頻（其係為SFG之一特別狀況）、 5 差頻產生(DFG)及光參量產生。 近年來，頻率轉換製程已可商業化用於製造諸如取代 多瓦氬離子(multi-Watt Ar+ ion)之倍頻綠光源雷射，以及在 用於國防應用的增強功率位準下產生中紅外光(mid-IR)輻 射的光參量振盪器等產品。 10 例如，於此併入本文以為參考資料的美國專利第 5，175,741號中揭露一種使用非線性光學(NL〇)單晶體的波 長轉換方法。一固態雷射係藉由一半導體雷射所激發，並 藉由該固態雷射攝盪而產生一雷射光束。該非線性光學 (NLO)晶體接著將一雷射光束之波長及一激發雷射光束之 15波長轉換成一光波之波長，其之頻率係為雷射光束之頻率 的總和。 大體上因複數種論證引起對在頻率轉換製程中固態雷 射的茜求。首先，一固態雷射提供一具相當低光束發散及 低像散的高品質雷射光束。再者，雷射光束之頻譜寬度係 2〇夠小，容許非線性光學(NL〇)晶體之最大波長轉換效率。例 如，針對一鈮酸鉀(KNb〇3)晶體而言，轉換效率的尖峰值之 t峰全幅值，典型地約為〇.5奈米。因此，縣寬度低於〇1 奈米的固態雷射係極適於藉由鈮酸鉀(KNb〇3)的頻率轉換。 然而，上述技術承受以下無效率的限制。由一半導體 1289220 二極體雷射光線轉換至一固態雷射的最大功率轉換效率， 並不高於30%。一方面，固態雷射利用一非線性光學(nl〇) 晶體轉換至第二諧波的頻率轉換效率，能夠高達7〇%。因 此’製程之無效率性係源自於將二極體雷射（或燈）光轉換成 5 固態雷射光線的步驟。 例如，於美國專利第5,991，317號及6,241，720號中揭露 建議用於改良效率之技術，該等揭露内容於此併入本文以 為參考資料。於該等技術中，使用腔内轉換的概念。例如， 美國專利第5,991，317號揭露一種藉由二或更多的共振鏡所 10 界定的共振腔。一雷射晶體及複數之非線性光學(NLO)晶體 係配置在該共振腔中。一二極體激發源供給一激發光束至 一雷射晶體，並產生一具複數之軸向模態照射非線性光學 (NL0)晶體的雷射光束，以及產生一倍頻（或三倍）輸出光 束0 15 然而’該等技術之轉換效率仍然相當低。可確認的是， 低轉換效率需使用高功率二極體雷射，不可避免地必需受 冷卻。因此’該無效率問題，由於加熱造成能量損失而加 劇’其損失至少為總能量的90%。 此外’針對轉換效率，非線性光學(NL〇)晶體的最佳波 20長係視溫度而定（例如，就鈮酸鉀(KNb03)而言，最佳波長 為0.28奈米/°K)。如此係與固態雷射相矛盾，其中該波長係 為穩定的。就一有效率的作業而言，非線性光學(NL〇)晶體 的溫度，係藉由將系統添加成分而精確地加以控制，從而 增加設計的複雜性。 1289220 另一缺點在於，固態雷射具有 制了取得一任音相本 嚴軺疋我的波長，限 “率轉換波長的可能性。 於上述技術中 _ 接地使用固態雷射執ΐ極體雷射係用於激發仙，同時間 的-可”解決村仃頻率轉換1於改請率轉換效率 接頻率轉換。係使用邊射型二極體雷射用於一直 性光學射’雷射波長與最佳非線 生光線的寬廣配:係極其困難，首先由於所產 八9 一― 人係因為雷射波長為溫度相依。 10 另-缺點在於，二極體雷射之極高的光束發散。此發 政致使雷射光束相關於所需的結晶方向強烈地偏向，並附 加地毀壞元件之性能。。 光束發散之修正典型地需要包含一些透鏡的一複雜設 置’該等透鏡如此配置用以將激發輻射聚焦在非線性光學 (NLO)晶體之表面上〔為此，例如，見义臟^.等人“使用 15單模二極體雷射激發源在中的差頻產生 (Difference-Frequency Generation in AgGaS2 by Use of Single-Mode Diode-Laser Pump Sources)，，，Optics 1^批1^，18，；^〇.13:1062-1064，1993及美國專利第5,912,910、 6,229,828、及6,304,585號〕。然而，用於將雷射輸出轉換成 2〇 一平行光束的附加透鏡，係為所熟知用以致使光束直徑顯 著地變寬，因而降低功率密度，其係針對有效波長轉換的 一主要需求。由於該等問題，邊射型二極體雷射並未在商 業上用於直接頻率轉換，通常係用作為固態雷射的激發源。 美國專利第6,097,540號中揭露另一使用半導體二極體 1289220 雷射用於直接頻率轉換的系統。於此系統，藉由數種雷射 所產生的光束，藉由一透鏡及反射鏡之系統結合成一單光 束，並經導引在一非線性光學（NLO)晶體之一表面上。然 而，此解決方案並未提供超越上述技術的顯著優點，所提 5 出的系統係極為複雜且價昂，包含大量的雷射，僅提供一 腔外轉換且非為波長穩定的。 因此，對於沒有上述限制的頻率轉換的一裝置，具有 廣泛認定的需求’並係為南度有利的。 【發明内容】 10 發明概要 根據本發明之一觀點，提供一種用於光線之頻率轉換 的裝置，該裝置包括：（a)—發光元件用於發射具有一第一 頻率的一光線，該發光元件係為一具有一選定之延伸波導 的邊射型半導體發光二極體，致使延伸波導的一基本橫向 15 模態其特徵在於一低光束發散；（b)—光反射器，其經建構 及設計因此光線通過界定在發光元件與光反射器之間的一 外部腔室數次，並提供一回饋用於產生具有第一頻率的一 雷射光；以及(c)一非線性光學晶體，配置在外部腔室中並 經選定，因此當具有第一頻率的雷射光通過非線性光學晶 20 體數次時，該第一頻率經轉換成與其不同的一第二頻率。 根據以下所說明本發明之較佳具體實施例的進一步特 性，該裝置進一步包括至少一附加的發光元件。 根據所說明之較佳具體實施例的進一步特性，該至少 一附加的發光元件係為一具有延伸波導的邊射型半導體發 10 1289220 光二極體。 根據所說明之較佳具體實施例的進一步特性，該裝置 進一步包括配置一光譜選擇性濾光鏡，俾便防止具第二頻 率之光線照射該發光元件。 5 根據所說明之較佳具體實施例的進一步特性，該裝置 進一步包括一透鏡，配置在介於發光元件與非線性光學晶 體之間的外部腔室中。 根據本發明之另一觀點，提供一種轉換光線之頻率的 方法，該方法包括：（a)利用一發光元件發射具有一第一頻 10 率的一光線，選定具有一延伸波導的一邊射型半導體發光 二極體的發光元件，致使一延伸波導的基本橫向模態其特 徵在於一低光束發散；（b)使用一光反射器，用於容許光線 通過界定在發光元件與光反射器之間的一外部腔室數次， 俾便提供一回饋用於產生具有第一頻率的一雷射光；以及 15 (c)使用一非線性光學晶體，配置在外部腔室中用以將雷射 光的第一頻率轉換成第二頻率，其中該第二頻率與第一頻 率不同。 根據以下所說明本發明之較佳具體實施例的進一步特 性，該方法進一步包括藉由將延伸波導暴露至一注入電流 20 而發光。 根據所說明之較佳具體實施例的進一步特性，該方法 進一步包括利用一透鏡將一微弱發散光束轉換成一平行光 束。 根據本發明之一附加觀點，提供一種製造用於光線之 11 1289220 頻率轉換的一裝置的方法，該方法包括：（a)提供一發光元 件用於發射具有一第一頻率的一光線，該發光元件係為一 具有一選定之延伸波導的邊射型半導體發光二極體，致使 延伸波導的一基本橫向模態其特徵在於一低光束發散；（b) 5提供一光反射器並將該光反射器配置與該發光元件相對， 该光反射器經建構及設計因此光線通過界定在發光元件與 光反射器之間的一外部腔室數次，並提供一回饋用於產生 具有第一頻率的一雷射光；以及(c)提供一非線性光學晶 體’其係配置在外部腔室中並經選定，因此當具有第一頻 10率的雷射光通過非線性光學晶體數次，該第一頻率經轉換 成與其不同的一第二頻率。 根據以下所說明本發明之較佳具體實施例的進一步特 性，該方法進一步包括提供至少一附加的發光元件。 根據所說明之較佳具體實施例的進一步特性，該延伸 15波導在暴露至一注入電流時，能夠發射光線。 根據所說明之較佳具體實施例的進一步特性，選定發 光元件之一帶條長度及注入電流，因此藉由注入電流僅產 生一非同調光線’並且該雷射光係藉結合注入電流與回饋 而產生。 根據所說明之較佳具體實施例的進一步特性，該外部 腔室經設計致使大體上在基本橫向模態下產生雷射光。 根據所說明之較佳具體實施例的進一步特性，選定光 反射器俾便反射頻率與第二頻率不同的光線，並用以傳輸 具第二頻率的光線。 12 1289220 根據所說明之較佳具體實施例的進一步特性，該發光 元件係由複數層所構成。 根據所說明之較佳具體實施例的進一步特性，該發光 元件包括一與自一第一側邊的延伸波導相鄰的η-發射器 5 (n-emitter)，以及一與自一第二側邊的延伸波導相鄰的ρ-發 射器（p-emitter)。 根據所說明之較佳具體實施例的進一步特性，該延伸 波導包括一主動區域，其係構成在掺雜一η-雜質的一第一 延伸波導區域與摻雜一ρ-雜質的一第二延伸波導區域之 10 間，該第一及第二延伸波導區域係為光線可透射的。 根據所說明之較佳具體實施例的進一步特性，該主動 區域包括至少一層。 根據所說明之較佳具體實施例的進一步特性，該主動 區域包括一系統，其係由一量子井系統、一量子線系統、 15 一量子點系統以及該等系統之結合所組成之群組中選定。 根據所說明之較佳具體實施例的進一步特性，該η-發 射器之厚度係大於10微米。 根據所說明之較佳具體實施例的進一步特性，該發光 元件之一前刻面係以一抗反射塗層塗佈。 20 根據所說明之較佳具體實施例的進一步特性，該發光 元件之一後刻面係以一高度反射塗層塗佈。 根據所說明之較佳具體實施例的進一步特性，該高度 反射塗層包括複數層。 根據所說明之較佳具體實施例的進一步特性，該高度 13 1289220 反射塗層特徵在於一預定阻帶(stopband)係夠窄，俾便提供 南反射性的基本橫向模態以及一低反射性的南階橫向模 態。 根據所說明之較佳具體實施例的進一步特性，該光反 5 射益包括複數層。 根據所說明之較佳具體實施例的進一步特性，該光反 射器特徵在於一預定阻帶(stopband)係夠窄，俾便提供一高 反射性的基本橫向模態以及一低反射性的高階橫向模態。 根據所說明之較佳具體實施例的進一步特性該高度反 10射塗層及光反射器其個別的特徵在於一預定阻帶(stopband) 係夠窄’俾便提供一高反射性的基本橫向模態以及一低反 射性的兩階彳頁向模態。 根據所說明之較佳具體實施例的進_步特性，該非線 性光學晶體的特徵在於一頻率轉換效率，進一步其中該高 15度反射塗層之阻帶的溫度相依性，係相當於頻率轉換效率 之溫度相依性。 根據所說明之較佳具體實施例的進一步特性，該非線 性光學晶體的特徵在於一頻率轉換效率，進一步其中該光 反射器之阻f的溫度相依性，係相當於頻率轉換效率之溫 20 度相依性。 根據所說明之較佳具體實施例的進—步特性，該高度 反射塗層之阻帶的溫度相依性，係相當於頻率轉換效率之 溫度相依性。 根據所說明之較佳具體實施例的進一步特性，該方法 14 1289220 進一步包括一具光譜選擇性濾光鏡並將該渡光鏡定位，俾 便防止具第二頻率的光線照射發光元件。 根據所說明之較佳具體實施例的進一步特性，該具光 譜選擇性濾光鏡係構成位在面向該發光元件之一側邊上的 5 非線性光學晶體上。 根據所說明之較佳具體實施例的進一步特性，該延伸 波導包括至少二部分，每一部分具有不同的折射率，致使 該延伸波導的特徵在於一可變化的折射率。 根據所說明之較佳具體實施例的進一步特性，該延伸 10 波導的至少二部分包括具有一中級折射率的一第一部分， 以及具有一高折射率的一第二部分，經設計並建構該第一 及第二部分致使基本的橫向模態係於該第一部分中產生， 洩漏進入該第二部分並在一預定角度下退出通過發光元件 之一前刻面。 15 根據所說明之較佳具體實施例的進一步特性，該延伸 波導的至少一部分包括一光子帶溝晶體(Photonic bandgap crystal) 〇 根據所說明之較佳具體實施例的進一步特性，該光子 帶溝晶體包括一具有一週期調制折射率的結構，於該處結 20 構包括複數層。 根據所說明之較佳具體實施例的進一步特性，該發光 元件包括至少一吸收層，能夠吸收位在該光子帶溝晶體之 一層中的光線。 根據所說明之較佳具體實施例的進一步特性，該發光 15 1289220 元件包括複數之吸收層致使該每一複數之吸收層係位在光 子帶溝晶體之一不同層中。 根據所說明之較佳具體實施例的進一步特性，該延伸 波導的至少一部分包括一缺陷，與光子帶溝晶體之一第— 5側邊相鄰，選定該缺陷及光子帶溝晶體致使該基本橫向模 態係局部化在該缺陷處，並且所有其他的模態係延伸涵蓋 該光子帶溝晶體。 根據所說明之較佳具體實施例的進一步特性，該缺陷 包括一具有一 η側邊及一 p側邊的主動區域，當暴露至_注 10入電流時該主動區域能夠發射光線。 根據所說明之較佳具體實施例的進一步特性，選定光 子帶溝晶體及缺陷之總厚度，俾便容許低光束發散。 根據所說明之較佳具體實施例的進一步特性，該發光 元件包括一與光子帶溝晶體之一第二側邊相鄰的發射 15器，以及一ρ-發射器係以缺陷和光子帶溝晶體隔開並與缺 陷相鄰。 根據所說明之較佳具體實施例的進一步特性，該發光 元件包括一具有一可變化折射率的摻雜層化結構，該卜 摻雜層化結構係介於ρ-發射器與缺陷之間。 20 根據所說明之較佳具體實施例的進一步特性，該〜發 射器係構成在基板之一第一側邊上，該基板係為-瓜々半 導體。 根據所說明之較佳具體實施例的進一步特性，該瓜 半導體係由GaAs、lnAs、ΙηΡ及GaSb所組成之群組中選定。 16 1289220 根據所說明之較佳具體實施例的進一步特性，該主動 區域的特徵在於一能量帶間隙係較基板之能量帶間隙為 窄。 根據所說明之較佳具體實施例的進一步特性，該發光 5 元件包括一η-接點與基板接觸，以及一p-接點與p-發射器接 觸。 根據所說明之較佳具體實施例的進一步特性，選定可 變化的折射率用以防止基本橫向模態延伸至該η-接點及/或 ρ-接點。 10 根據所說明之較佳具體實施例的進一步特性，該Ρ-發 射器包括至少一與該延伸波導接觸的ρ摻雜層，以及至少一 與該Ρ-接點接觸的Ρ+-摻雜層。 根據所說明之較佳具體實施例的進一步特性，該缺陷 進一步包括一配置在主動區域之η-側邊並夾合在一第一對 15 附加層之間，供電子所用的第一薄通道阻障層，以及一配 置在主動區域之ρ-側邊並夾合在一第二對附加層之間，供 孔所用的第二薄通道阻障層。 根據所說明之較佳具體實施例的進一步特性，該第一 薄通道阻障層係由一微弱摻雜η-層及一未摻雜層所組成之 20 群組中選定的材料所構成。 根據所說明之較佳具體實施例的進一步特性，該第二 薄通道阻障層係由一微弱摻雜ρ -層及一未摻雜層所組成之 群組中選定的材料所構成。 根據所說明之較佳具體實施例的進一步特性，該缺陷 17 1289220 進一步包括一厚η-摻雜層與遠離主動區域的第一對附加層 的其中之一層連續；以及一厚卜摻雜層與遠離主動區域的 第二對附加層連續。 根據所說明之較佳具體實施例的進一步特性，該第一 5對附加層的至少其中之一層係由一微弱摻雜η-層及一未摻 雜層所組成之群組中選定的材料所構成。 根據所說明之較佳具體實施例的進一步特性，該第二 對附加層的至少其中之一層係由一微弱摻雜^層及一未摻 雜層所組成之群組中選定的材料所構成。 10 根據所說明之較佳具體實施例的進一步特性，該方法 進一步包括配置一透鏡並將該透鏡定位在介於發光元件與 非線性光學晶體間的外部腔室中。 根據所說明之較佳具體實施例的進一步特性，設計並 建構该透鏡用以將一微弱發散光束變換成一平行光束。 15 根據所說明之較佳具體實施例的進一步特性，該光反 射器係為一平坦式光反射器，能夠反射該平行光束。 本發明藉由提供一遠超越先前技術，用於頻率轉換的 裝置’克服目前所熟知的概念與形式之該等缺點。 除非另有定義，否則本發明所屬於此所用的所有技術 20及科學名詞，與熟知此技藝之人士通常所瞭解者具相同的 意義。儘管與於此所說明相似或等效的方法及材料能夠於 本發明之實務或測試中使用，但以下係說明適合的方法及 材料。若有抵觸，則由包括定義的專利說明書主導。此外， 材料、方法及實例僅具說明性並不意欲受到限定。 18 1289220 圖式簡單說明 於此相關於伴隨圖式，僅藉由實例說明本發明。現詳 細具體地相關於該等圖式’所強調的是，所示之細節係經 由實例並僅係為了說明本發明之較佳具體實施例的說明性 5 論述，並為了提供咸信係為本發明之原理及概念性觀點之 最為有用且能夠立即瞭解的說明。就這一點而言，並不試 圖針對本發明之一基本瞭解更為詳細地顯示本發明之結構 細節，相關於圖式所作的說明，熟知此技藝之人士對於實 務上本發明如何具體化為數種形式將為顯而易見的。 10 圖式中： 第la圖係為一先前技術之垂直共振腔面射型雷射 (VCSEL)的概略視圖； 第lb圖係為一先前技術之邊射型雷射的概略視圖； 第2圖係為一先前技術之垂直共振腔面射型雷射 15 (VCSEL)式頻率轉換裝置的概略視圖； 第3圖係為本發明之一用於光線頻率轉換的裝置之概 略視圖； 第4圖係為本發明之一用於頻率轉換的裝置之概略視 圖，包括一抗反射塗層及一高度反射塗層構成在一發光元 20 件的不同刻面上； 第5圖係為本發明之一用於頻率轉換的裝置之概略視 圖，其中發光元件包括一光子帶溝晶體； 第6圖係為本發明之一用於頻率轉換的裝置之概略視 圖，其中一洩漏雷射係用於產生主要光線； 19 1289220 第圖係為本發明之一用於頻率轉換的裝置之相兄略視 圖，其包括-用於提供一平行光束的透鏡以及一平坦式光 反射器； 第8圖係為本發明之一用於頻率轉換的裝置之概略視 5圖八在毛光元件及光反射器上包括附加的多層式塗層； 第9圖係為本發明之轉換光線頻率的一方法的一流程 圖；以及 第10圖係為本發明之製造用於頻率轉換之裝置的一方 法的一流程圖。 10 【實施方式】 較佳實施例之詳細說明 本發明係為能夠用於轉換一雷射頻率的一頻率轉換裝 置及方法。具體地，本發明能夠用於提供一雷射光，其之 頻率位在一寬光譜範圍中。更特定言之，例如，本發明能 15夠於光儲存應用中使用，其中需要短波長用以藉由減小特 有的特徵尺寸而增加儲存資料的密度，或應用在投影顯示 器’其中綠及藍光雷射係為全彩應用所需。本發明係為一 種製造該裝置的進一步方法。 為了對本發明有較佳的瞭解，如第3-8圖中所示，首先 20參考於第2圖中所示的一傳統式（亦即，先前技術)頻率轉換 裝置的結構及操作。 第2圖係圖示一先前技術之頻率轉換裝置，其係基於一 垂直共振腔面射型雷射(VCSEL)。 因此’該先前技術裝置包括一 VCSEL型結構101，其係 20 1289220 製成為一多層結構，在一基板102上磊晶地成長。VCSEL 型結構101包括一底部分布式布拉袼反射鏡(DBR)l〇3,以及 一主動區域106係位在一半導體腔室104中。於此裝置中， VCSEL型結構101並未包括一頂部分布式布拉格反射鏡 5 (DBR)。亦為於業界中所熟知的相似裝置，其中包括一相關 於分布式布拉格反射鏡(DBR)103具有一相對低品質的頂部 分布式布拉格反射鏡(DBR)。 於使用中，該VCSEL型結構101係為藉由一外部雷射光 束109而光激發，並產生一光線其係藉由一外部鏡114反射 10 回至該VCSEL型結構101。選定該VCSEL型結構1〇1及雷射 光束109之功率，致使該VCSEL型結構101並未自由鏡114 所反射光線產生不具一附加功率的雷射光。鏡114及VCSEL 型結構101界定一有效腔室，其包括半導體腔室104及一外 部腔室112。該有效腔室限制一增強的光線回饋，其足以產 生一雷射光111。一位在外部腔室112中的NLO晶體113，係 用於將雷射光111之頻率轉換成一具不同頻率（典型地高於 光線111之頻率）的雷射光115，其係自外部鏡114穿過而出。 VCSEL型結構所熟知地具有一寬的主光束之孔徑，典 型地大小為100微米。寬孔徑之優點在於低雷射光束發散， 20 並且在將光線聚焦回至VCSEL型結構而無顯著損失且無困 難性。使用外部鏡容許在腔室内部聚集光功率，係與在使 用傳統式腔外直接二極體激發狀況下的低效率單通道放大 成對比。 然而’當VCSEL型結構之光輸出孔徑係等於熱散逸所 21 1289220 用表面時，由該等結構獲得一高功率密度係極其困難。 再者，VCSEL型結構之光激發需求顯著地降低裝置的 總轉換效率，其已受VCSEL之低功率密度限制。熟知此技 藝之人士應察知的是，由於頂部接觸層之高阻力，所以 5 VCSEL無法藉由注入電流均勻地激發。因此，於上述及相 似的先前技術裝置中，因使用光激發之VCSEL而損及該轉 換效率。 上述限制的一解決之道在於，以邊射型半導體雷射（見 上述先前技術部分中的第1 b圖）取代該V C S E L。邊射型雷射 10 超越VCSEL的優點有兩部分：⑴邊射型雷射的實體尺寸係 足以有效地散熱，有助於一高功率密度；以及㈤)能夠使用 一直接電激發而產生邊射型雷射，係與實務上僅能使用光 激發的VCSEL成對比。 然而，目前所熟知的邊射型雷射具有一特別窄的波 15導，典型地係位在次微米範圍中。由於波導的窄化，所以 難以將藉由鏡反射回波導的光線聚焦而無顯著的功率損 失。此外，邊射型雷射的特徵在於一高光束發散，妨礙雷 射光相關於NLO晶體之最佳結晶方向的精確定向。 藉由提供一種具有一改良的邊射型雷射，於此亦視為 2〇邊射型半導體發光二極體，的頻率轉換裝置，本發明成 功地提供一針對上述問題的解決方案。 因此，根據本發明之-觀點，提供一用於光線之頻率 轉換的裝置，於此大體上視為裝置1〇。 在詳細說明本發明之至少一具體實施例之前，應瞭解 22 1289220 的是’本發明並不限定應用在以下所說明或是於圖式中圖 不的結構細節及元件配置上。本發明可為其他的具體實施 例，或以不同的方式實踐或完成。同時，應瞭解的是，於 此所用的措辭及術語係針對說明之目的，不應視為具限制 5 性0 現再次參考該等圖式，第3圖係為裝置1〇之概略圖式， 其包括一發光元件201用於發射一具有一第一頻率的光 線。發光元件201係為一具有一延伸波導2〇4的邊射型半導 體發光二極體，經選定致使波導2〇4之一基本橫向模態的特 10徵在於一低光束發散。裝置1〇進一步包括一光反射器214及 一NLO晶體213，配置在界定於發光元件與光反射器之間的 一外部腔室212中。NLO晶體可為任一熟知的NLO晶體，其 之特徵在於預定的頻率轉換效率，諸如，但不限定在錕酸 鉀(KNb03)或鈮酸鋰(LiNb03)。 15 根據本發明之一較佳具體實施例，當暴露至一注入電 流時，例如使用一順向偏壓218，波導204能夠發射光線通 過一前刻面210。較佳地，選定發光元件201之帶條長度及 注入電流，因此注入電流並未提供雷射發光所用的最小狀 況，而產生一非同調主光線。 2〇 外部腔室212與波導204構成一界定在光反射器214與 波導204之一後刻面269之間·的有效腔室。在裝置10之操作 模態下，此有效腔室對主發射光線提供一附加回饋，因而 產生一雷射光211。 根據本發明之一較佳具體實施例，藉由一足夠窄之阻 23 1289220 f光反射裔214之一決定部分(jucJici〇us secti〇n)，提供來自 光反射器214之雷射光211的基本橫向模態的一高反射性， 如之後進一步詳細地相關於第8圖，該部分較佳地係構成為 一多層結構。熟知此技藝之人士應察知的是，光反射器 5之一預定的窄阻帶亦用於藉由提供其之高階橫向模態之一 低反射性，濾除雷射光211之非所需模態。 因此’雷射光211通過NLO晶體213複數次，將雷射光 211轉換成具有一與第一頻率不同之第二頻率的雷射光 215。較佳地，選定光反射器214，俾便反射具有第二頻率 10外之一頻率的光線(例如，光線211)，並傳輸具有第二頻率 的光線(光線215)。此外，為了達到裝置1〇之最佳轉換效率， 光反射器214之阻帶較佳地具有如NL〇晶體213之頻率轉換 效率的相同（或相似的）溫度相依性。因此，視Nl〇晶體213 之型式、定向、幾何形狀及尺寸而定，裝置1〇提供一高品 15質雷射光，其能夠具有一實質低波長，如之後進一步說明。 在提供裝置10之一進一步詳細說明之前，如上文中所 描述並根據本發明，將注意力放在所提供的優點上。 因此，本發明之較佳具體實施例的一特別優點，係為 發光元件201之設計，因此延伸波導2〇4提供一單模態雷射 20光211。使用一延伸波導典型地導致產生複數之光學模態的 雷射光。因而，基本光學模態沿著波導之方向傳播並顯示 一窄遠場圖（far-field diagram)，其係位在與發光元件2〇1之 前刻面210垂直的一方向上的中心處。高階橫向光學模態之 傳播可說明為，相關於此方向在一些角度下發生。 24 1289220 典型地’高階模態的遠場圖形係顯著地較基本模態之 运％圖形為I，並且通常包含側波瓣(side i〇bes)。當藉由 光反射器214反射回至前刻面21〇時，位在一高階光學模態 下的光線係經部分折射離開該腔室，與光反射器214之形式 5最佳化的基本模態之光線相對。因此，該等折射損失對於 咼階模悲而§係為顯著的，並且對於基本模態而言係微不 足道地小。易言之，光反射器214所提供的回饋對於基本模 態而言係為強烈的，並且對於高階模態而言係為微弱的。 如此容許在注入電流下實現該等狀況，雷射帶之長度、外 10部鏡之形狀及位置致使雷射作用僅在基本橫向模態下發 生。 熟知此技藝之人士應察知的是，以上所述係為一般的 優點，與所使用的發光元件數目無關。更特定言之，根據 本發明之一較佳具體實施例，可使用一個以上的發光元 15 件，其中藉由附加的發光元件所產生的光線能夠經由一特 別的光學系統而受引導至NL0晶體213上。因此，倘若與發 光元件201相似地製造並操作至少其中之一發光元件，則能 夠為一和頻產生或為一差頻產生或是任何其他的頻率結 合0 根據本發明之一較佳具體實施例，發光元件2〇1係成長 在一基板202上，其較佳地由任一 M-V半導體材料或是π-V半導體合金所構成，例如，坤化銦(InAs)、碟化銦(inp)、 或銻化鎵(GaSb)、或為其他合金。更佳的基板2〇2係以砷化 鎵(Ga As)製成。 25 1289220 5亥t置10之一特徵在於該延伸波導204，如所提及，提 供一光線其中基本橫向模態具有一低光束發散。根據本發 明之一較佳具體實施例，波導204係構成在一 n_發射器2〇3 與一 P-發射器220之間，其中該n_發射器203較佳地係直接成 5長在基板202上，並係自一側邊與波導2〇4相鄰，同時發 射器係自另一側邊與波導204相鄰。 延伸波導204較佳地包括一主動區域2〇6，其係構成在 以一η-雜質摻雜的一第一波導區域205，與以一p-雜質摻雜 的一第二波導區域207之間。該第一波導區域205及第二波 10 導區域207二者係為光可透射的。 該第一波導區域205及第二波導區域207較佳地為與基 板202晶格匹配（lattice-matched)或幾乎晶格匹配的該等材 料所構成的層或是多重層結構。 導入該第一波導區域2〇5中的雜質係為施體雜質（d〇nor 15 impurities)，諸如，但非限定在硫(S)、硒(Se)及碲(Te)。可 交替地，該第一波導區域205可以兩性雜質摻雜，諸如，但 非限定在矽（Si)、鍺(Ge)及錫（Sn)，可在該等技術狀況下導 入，其主要地與陽離子次晶格結合，因此使用作為施體雜 質。因此，該第一波導區域205，例如，可為藉由分子束磊 20 晶並掺雜濃度約為2 X 1017 cm·3的矽(Si)雜質而成長的砷化 鎵(GaAs)或砷鋁化鎵(GaAlAs)層。 於此所使用的用語“約為”係為±50%。 可導入第二波導區域207的雜質係為受體(acceptor)雜 質，諸如，但非限定在鈹(Be)、鎂(Mg)、鋅(Zn)、鎘(Cd)、 26 1289220 鉛(Pb)及錳(Μη)。可交替地，第二波導區域207可以兩性雜 質摻雜，諸如，但非限定在矽(Si)、鍺(Ge)及錫(Sn)，可在 該等技術狀況下導入，其主要地與陰離子次晶格結合並使 用作為受體雜質。因此，該第二波導區域207，例如，可為 5藉由分子束磊晶並摻雜濃度約為2 X 1〇17 cm·3的鈹(Be)雜質 而成長的砷化鎵(GaAs)或砷鋁化鎵(GaAlAs)層。 主動區域206較佳地係藉由任一具有能量帶間隙的插 入所構成’其之能量帶間隙係窄於基板202之能量帶間隙。 根據本發明之一較佳具體實施例，該主動區域206，例如， 10可為一量子井、量子線、量子點或任何該等結合之系統。 該主動區域206可構成為一單層系統或是一多層系統。於較 佳具體實施例中，該基板202係以砷化鎵(GaAs)製成，主動 區域206，例如，可為InAs、Ini xGaxAs、InxGai x yAlyAs、1289220 玖 发明 发明 发明 发明 发明 发明 发明 发明 发明 发明 发明 发明 发明 发明 发明 发明 发明 发明 发明 发明 发明 发明 发明 发明 发明 发明 发明 发明 发明 发明 发明 发明 发明 发明 发明 发明 发明 发明 发明 发明 发明 发明 发明 发明 发明 发明 发明 发明 发明c Prior Art Background of the Invention Semiconductor lasers play an important role in optical fiber transmission systems, signal amplification systems, wavelength division multiplexing transmission systems, wavelength division conversion systems, wavelength cross-connect systems, and the like. In addition, semiconductor lasers are useful in the field of optical measurement. Semiconductor lasers (first proposed in 1959) are injected into a semiconductor active medium based on the current of the unbalanced carrier, resulting in a reversal of the population and sufficient modal gain to achieve a laser effect. 15 Referring now to these figures, there are basically two types of semiconductor lasers that are currently dominant in the laser market, as shown in Figure la-b. The first diagram illustrates a vertical cavity surface-emitting laser (VCSEL) in which photons are circulated in a high-precision cavity in a vertical direction (upward in FIG. la). In such lasers, the chamber is short and the gain per cycle is extremely low. Because of this, it is extremely important to ensure extremely low loss during each reflection. Otherwise, it is impossible to achieve laser action or excessive current density, which is not suitable for continuous wave operation. Since the earliest system was proposed in 1962, vertical cavity surface-emitting lasers (VCSELs) have become extremely popular. Vertical cavity surface-emitting lasers (VCSELs) can be made small, capable of operating at low-limit currents, and the 1289220 is fabricated in an extremely easy-to-manufacture planar technology. Another type of semiconductor laser is a side-emitting laser, as shown in Figure lb. In such lasers, an active medium (e.g., a thin layer) is disposed in a waveguide having a refractive index greater than the surrounding cladding to ensure about 5 beams of laser light in the waveguide. The resulting light is refracted at the exit of the facet of the component at a large angle of typically 30 degrees to 60 degrees. The advantage of edge-emitting lasers is their small output aperture and high light output power. A disadvantage of edge-emitting lasers over vertical cavity surface-emitting lasers (VCSELs) is the astigmatism that typically occurs when a ring-shaped output aperture is used. In addition, in contrast to a vertical-cavity surface-emitting laser (VCSEL), in edge-emitting lasers, an increase in temperature results in a significant wavelength due to bandgap narrowing of the semiconductor with increasing temperature. Transform. One of the disadvantages of all semiconductor lasers is that the wavelength (or frequency) of the emitted light is limited by the value provided by the energy 15 bandgap value of the semiconductor material. In addition, the effective wavelength can be converted to a larger value (so-called red shift) due to localization of the carrier by known structures of quantum wells, quantum wires or quantum dot heterostructures. Semiconductor laser technology has been fully developed for 羾_ compound semiconductors and covers wavelengths exceeding 600 nm. Semiconductor lasers known to have wavelengths below 6 〇〇 20 nm (eg, in the ultraviolet to green spectrum range) are extremely immature. An additional disadvantage of semiconductor lasers is poor beam quality, wide optical spectrum, and poor temperature stability of wavelengths. A number of methods have been proposed for generating light 1289220 lines having wavelengths below 6 nanometers, essentially using nonlinear optical techniques to convert the wavelength of light from the semiconductor laser output. These techniques are capable of producing extremely broad spectral ranges of light, such as from mid-IR to visible light. Examples of frequency conversion techniques include sum frequency generation (SFG), frequency multiplication (which is a special condition of SFG), 5 difference frequency generation (DFG), and optical parametric generation. In recent years, frequency conversion processes have been commercially available for fabricating multiplier green light source lasers such as multi-Watt Ar+ ions, as well as generating mid-infrared light at enhanced power levels for defense applications. (mid-IR) products such as optical parametric oscillators. For example, a wavelength conversion method using a nonlinear optical (NL〇) single crystal is disclosed in U.S. Patent No. 5,175,741, which is incorporated herein by reference. A solid state laser is excited by a semiconductor laser and a laser beam is generated by the solid state laser. The nonlinear optical (NLO) crystal then converts the wavelength of a laser beam and the 15 wavelength of an excited laser beam into a wavelength of light, the frequency of which is the sum of the frequencies of the laser beams. In general, the pleading of solid-state lasers in the frequency conversion process is caused by a plurality of arguments. First, a solid-state laser provides a high-quality laser beam with a fairly low beam divergence and low astigmatism. Furthermore, the spectral width of the laser beam is small enough to allow for maximum wavelength conversion efficiency of nonlinear optical (NL〇) crystals. For example, for a potassium citrate (KNb〇3) crystal, the full amplitude of the t peak of the peak of the conversion efficiency is typically about 〇. 5 nm. Therefore, a solid-state laser system with a county width of less than 〇1 nm is highly suitable for frequency conversion by potassium citrate (KNb〇3). However, the above techniques suffer from the following inefficiencies. The maximum power conversion efficiency from a semiconductor 1289220 diode laser to a solid state laser is no more than 30%. On the one hand, solid-state lasers can convert up to 7〇% using a nonlinear optical (nl〇) crystal to convert the frequency to the second harmonic. Therefore, the inefficiency of the process is derived from the step of converting diode laser (or lamp) light into 5 solid laser light. Techniques for improving efficiency are disclosed, for example, in U.S. Patent Nos. 5,991,317 and 6,241,720, the disclosures of each of which are hereby incorporated by reference. In these techniques, the concept of intracavity conversion is used. For example, U.S. Patent No. 5,991,317 discloses a resonant cavity defined by two or more resonant mirrors. A laser crystal and a plurality of nonlinear optical (NLO) crystal systems are disposed in the resonant cavity. A diode excitation source supplies an excitation beam to a laser crystal and produces a complex laser beam that illuminates a nonlinear optical (NL0) crystal with an axial mode and produces a multiple (or triple) output. Beam 0 15 However, the conversion efficiency of these techniques is still quite low. It can be confirmed that low conversion efficiency requires the use of high power diode lasers, which inevitably require cooling. Therefore, the inefficiency problem is exacerbated by the energy loss caused by heating, which is at least 90% of the total energy. In addition, for the conversion efficiency, the optimum wavelength of the nonlinear optical (NL〇) crystal is determined by the temperature (for example, in the case of potassium citrate (KNb03), the optimum wavelength is 0. 28 nm / ° K). This is inconsistent with solid-state lasers where the wavelength is stable. For an efficient operation, the temperature of a nonlinear optical (NL〇) crystal is precisely controlled by adding components to the system, thereby increasing the complexity of the design. Another disadvantage of 1289220 is that solid-state lasers have the potential to achieve a wavelength that is strictly limited to my wavelength, which is limited to the possibility of "rate conversion wavelength." In the above technique, _ grounding uses solid-state lasers for the polar body laser system. In order to stimulate the fairy, at the same time - can solve the village frequency conversion 1 in the conversion rate conversion efficiency and frequency conversion. The use of edge-emitting diode lasers for the continuous optical projection 'the wavelength of the laser and the wide distribution of the best non-line light: extremely difficult, first because of the production of the eight 9-- human system because the laser wavelength is The temperature is dependent. 10 Another - the disadvantage is that the extremely high beam of the diode laser diverges. This aging causes the laser beam to be strongly biased in relation to the desired crystallographic direction and additionally destroys the performance of the component. . Correction of beam divergence typically requires a complex arrangement of lenses that are configured to focus the excitation radiation onto the surface of a nonlinear optical (NLO) crystal [for this purpose, for example, seeing dirty ^. Etc. "Difference-Frequency Generation in AgGaS2 by Use of Single-Mode Diode-Laser Pump Sources,", Optics 1^ Batch 1^, 18 ,;^〇. 13:1062-1064, 1993 and U.S. Patent Nos. 5,912,910, 6,229,828, and 6,304,585. However, additional lenses for converting laser output into 2 〇 a parallel beam are well known to cause the beam diameter to be significantly broadened, thereby reducing power density, which is a major requirement for efficient wavelength conversion. Due to these problems, edge-emitting diode lasers are not commercially used for direct frequency conversion and are typically used as excitation sources for solid-state lasers. Another system for using a semiconductor diode 1289220 laser for direct frequency conversion is disclosed in U.S. Patent No. 6,097,540. In this system, a beam of light produced by several lasers is combined into a single beam by a system of lenses and mirrors and guided onto a surface of a nonlinear optical (NLO) crystal. However, this solution does not offer significant advantages over the above techniques, and the resulting system is extremely complex and expensive, contains a large number of lasers, provides only one out-of-cavity conversion and is not wavelength stable. Therefore, for a device that does not have the above-mentioned limited frequency conversion, it has a widely recognized demand and is advantageous in the south. SUMMARY OF THE INVENTION 10 SUMMARY OF THE INVENTION According to one aspect of the present invention, an apparatus for frequency conversion of light is provided, the apparatus comprising: (a) a light emitting element for emitting a light having a first frequency, the light emitting element An edge-emitting semiconductor light-emitting diode having a selected extended waveguide, such that a substantially transverse 15 mode of the extended waveguide is characterized by a low beam divergence; (b) a light reflector constructed and designed Thus the light passes through an external chamber defined between the light-emitting element and the light reflector several times and provides a feedback for generating a laser light having a first frequency; and (c) a nonlinear optical crystal disposed externally The chamber is selected and thus, when the laser light having the first frequency passes through the nonlinear optical crystal 20 times, the first frequency is converted to a second frequency different therefrom. According to further features of the preferred embodiments of the invention described below, the apparatus further includes at least one additional illuminating element. According to still further features in the described preferred embodiments, the at least one additional illuminating element is a side-emitting semiconductor 126 1289220 photodiode having an extended waveguide. In accordance with further features of the illustrated preferred embodiment, the apparatus further includes configuring a spectrally selective filter to prevent light having a second frequency from illuminating the illuminating element. In accordance with further features of the illustrated preferred embodiment, the apparatus further includes a lens disposed in the outer chamber between the light emitting element and the nonlinear optical crystal. According to another aspect of the present invention, a method of converting a frequency of light rays is provided, the method comprising: (a) emitting a light having a first frequency rate by using a light emitting element, and selecting a side-emitting semiconductor having an extended waveguide a light-emitting element of a light-emitting diode such that a substantially transverse mode of an extended waveguide is characterized by a low beam divergence; (b) a light reflector is used for allowing light to pass between the light-emitting element and the light reflector. An external chamber is provided several times, a sputum provides a feedback for generating a laser light having a first frequency; and 15 (c) a nonlinear optical crystal is used, which is disposed in the external chamber for the first of the laser light The frequency is converted to a second frequency, wherein the second frequency is different from the first frequency. According to still further features in the preferred embodiments of the invention described below, the method further comprises illuminating by exposing the extended waveguide to an injection current 20. According to still further features in the described preferred embodiments, the method further includes converting a weakly divergent beam into a parallel beam using a lens. According to an additional aspect of the present invention, there is provided a method of fabricating a device for frequency conversion of 11 1289220 for light, the method comprising: (a) providing a light emitting element for emitting a light having a first frequency, the illumination The component is an edge-emitting semiconductor light-emitting diode having a selected extended waveguide such that a substantially transverse mode of the extended waveguide is characterized by a low beam divergence; (b) 5 provides a light reflector and the light a reflector arrangement opposite the light-emitting element, the light reflector being constructed and designed such that light passes through an outer chamber defined between the light-emitting element and the light reflector a number of times and provides a feedback for generating the first frequency a laser light; and (c) providing a nonlinear optical crystal configured to be disposed in the outer chamber and selected such that when the laser light having the first frequency 10 passes through the nonlinear optical crystal several times, the first frequency Converted to a second frequency different from it. According to further features of the preferred embodiments of the invention described below, the method further includes providing at least one additional illuminating element. According to still further features in the described preferred embodiments, the extension 15 waveguide is capable of emitting light upon exposure to an injection current. According to a further feature of the preferred embodiment illustrated, one of the strip elements is selected to have a strip length and an injection current, so that only a non-coherent ray ' is generated by the injection current and the laser light is generated by combining the injection current with the feedback. In accordance with further features of the illustrated preferred embodiment, the outer chamber is designed to produce laser light substantially in a substantially transverse mode. In accordance with a further feature of the illustrated preferred embodiment, the selected light reflector sputum reflects light of a different frequency than the second frequency and is used to transmit light having a second frequency. 12 1289220 According to further features of the preferred embodiment illustrated, the illuminating element is constructed of a plurality of layers. According to still further features in the described preferred embodiments, the illuminating element includes an n-emitter 5 adjacent to the extended waveguide from a first side, and a second side The edge extends the adjacent p-emitter of the waveguide. According to still further features in the described preferred embodiments, the extended waveguide includes an active region that is formed in a first extended waveguide region doped with an n- impurity and a second extension doped with a p- impurity Between 10 of the waveguide regions, the first and second extended waveguide regions are light transmissive. According to still further features in the described preferred embodiments, the active region comprises at least one layer. According to still further features in the described preferred embodiments, the active region comprises a system consisting of a quantum well system, a quantum wire system, a 15-quantum dot system, and a combination of such systems. Selected. According to still further features of the preferred embodiment illustrated, the thickness of the η-emitter is greater than 10 microns. According to a further feature of the preferred embodiment illustrated, one of the front facets of the illuminating element is coated with an anti-reflective coating. According to a further feature of the preferred embodiment illustrated, one of the rear facets of the illuminating element is coated with a highly reflective coating. According to still further features in the described preferred embodiments, the highly reflective coating comprises a plurality of layers. In accordance with further features of the illustrated preferred embodiment, the height 13 1289220 reflective coating is characterized by a predetermined stopband that is narrow enough to provide a substantially reflective substantially transverse mode and a low reflectivity. Southern order transverse mode. In accordance with further features of the described preferred embodiments, the optical reflex includes a plurality of layers. According to still further features in the described preferred embodiments, the light reflector is characterized in that a predetermined stopband is narrow enough to provide a highly reflective substantially transverse mode and a low reflectivity high order lateral direction. Modal. According to further features of the preferred embodiment illustrated, the highly reflective coating and the light reflector are individually characterized in that a predetermined stopband is narrowed to provide a highly reflective substantially transverse mode. State and a low-reflectivity two-order page-directed mode. According to the advanced embodiment of the preferred embodiment, the nonlinear optical crystal is characterized by a frequency conversion efficiency, and further wherein the temperature dependence of the stop band of the high 15 degree reflective coating is equivalent to the frequency conversion efficiency. Temperature dependence. According to still further features of the described preferred embodiments, the nonlinear optical crystal is characterized by a frequency conversion efficiency, and further wherein the temperature dependence of the resistance f of the photoreflector is equivalent to a temperature dependence of the frequency conversion efficiency of 20 degrees. Sex. According to the advanced characteristics of the preferred embodiment described, the temperature dependence of the stop band of the highly reflective coating corresponds to the temperature dependence of the frequency conversion efficiency. In accordance with further features of the illustrated preferred embodiment, the method 14 1289220 further includes a spectrally selective filter and positioning the directional mirror to prevent illumination having a second frequency from illuminating the illuminating element. According to a further feature of the preferred embodiment illustrated, the spectrally selective filter is formed on a 5 nonlinear optical crystal facing one side of the light-emitting element. According to still further features in the described preferred embodiments, the extended waveguide includes at least two portions each having a different index of refraction such that the extended waveguide is characterized by a variable index of refraction. According to still further features in the described preferred embodiments, at least two portions of the extended 10 waveguide include a first portion having a median index of refraction and a second portion having a high index of refraction, designed and constructed The first and second portions cause the substantially transverse mode to be created in the first portion, leaking into the second portion and exiting through a front facet of one of the light-emitting elements at a predetermined angle. In accordance with a further feature of the illustrated preferred embodiment, at least a portion of the extended waveguide includes a photonic bandgap crystal, which is further characterized according to the preferred embodiment illustrated. A structure having a periodic modulation index of refraction is included, where the junction 20 structure comprises a plurality of layers. According to still further features in the described preferred embodiments, the illuminating element comprises at least one absorbing layer capable of absorbing light rays in a layer of the photonic grooved crystal. According to still further features in the described preferred embodiments, the illuminating 15 1289220 element includes a plurality of absorbing layers such that each of the plurality of absorbing layers is in a different layer of the photonic grooved crystal. According to still further features in the described preferred embodiments, at least a portion of the extended waveguide includes a defect adjacent to a side of the 1-5th of the photonic grooved crystal, the defect and the photonic grooved crystal being selected to cause the substantially lateral The modality is localized at the defect, and all other modal extensions cover the photonic grooved crystal. According to still further features in the described preferred embodiments, the defect includes an active region having a side of η and a side of a p which is capable of emitting light when exposed to a current. In accordance with further features of the illustrated preferred embodiment, the total thickness of the photonic grooved crystal and the defect is selected to permit low beam divergence. According to still further features in the described preferred embodiments, the illuminating element comprises an emitter 15 adjacent to a second side of the photonic grooved crystal, and a ρ-emitter is a defect and a photonic grooved crystal Separated and adjacent to the defect. According to still further features in the described preferred embodiments, the illuminating element comprises a doped stratification structure having a variable index of refraction between the p-emitter and the defect. In accordance with a further feature of the preferred embodiment illustrated, the ~-emitter is formed on a first side of the substrate, which is a melon semiconductor. According to still further features of the preferred embodiment illustrated, the melon semiconductor is selected from the group consisting of GaAs, lnAs, ΙηΡ, and GaSb. 16 1289220 According to still further features in the described preferred embodiments, the active region is characterized by an energy band gap that is narrower than an energy band gap of the substrate. According to still further features in the described preferred embodiments, the luminescence 5 component includes an n-contact in contact with the substrate and a p-contact in contact with the p-emitter. In accordance with further features of the illustrated preferred embodiment, the variable index of refraction is selected to prevent the substantially transverse mode from extending to the n-contact and/or p-contact. According to still further features in the described preferred embodiments, the Ρ-emitter includes at least one p-doped layer in contact with the extended waveguide, and at least one Ρ+-doped layer in contact with the Ρ-contact . According to still further features in the described preferred embodiments, the defect further includes a first thin channel resistance for the electron to be disposed between the η-side of the active region and sandwiched between a first pair of 15 additional layers a barrier layer, and a second thin channel barrier layer disposed on the side of the active region and sandwiched between a second pair of additional layers for the aperture. According to still further features in the described preferred embodiments, the first thin channel barrier layer is comprised of a selected one of the group consisting of a weakly doped n-layer and an undoped layer. According to still further features in the described preferred embodiments, the second thin channel barrier layer is comprised of a selected material selected from the group consisting of a weakly doped p-layer and an undoped layer. According to further features of the illustrated preferred embodiment, the defect 17 1289220 further includes a thick η-doped layer continuous with one of the first pair of additional layers remote from the active region; and a thick doped layer and The second pair of additional layers away from the active area are continuous. According to still further features in the described preferred embodiments, at least one of the first five pairs of additional layers is selected from the group consisting of a weakly doped n-layer and an undoped layer. Composition. According to still further features in the described preferred embodiments, at least one of the layers of the second pair of additional layers is comprised of a selected material selected from the group consisting of a weakly doped layer and an undoped layer. In accordance with further features of the illustrated preferred embodiment, the method further includes configuring a lens and positioning the lens in an external chamber between the light emitting element and the nonlinear optical crystal. In accordance with further features of the described preferred embodiments, the lens is designed and constructed to convert a weakly divergent beam into a parallel beam. According to a further feature of the preferred embodiment illustrated, the light reflector is a flat light reflector capable of reflecting the parallel beam. The present invention overcomes these shortcomings of the presently known concepts and forms by providing a device for frequency conversion that goes far beyond the prior art. All of the techniques 20 and scientific terms used herein, unless otherwise defined, have the same meaning as commonly understood by those skilled in the art. Although methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present invention, the following are illustrative of suitable methods and materials. In case of conflict, it is dominated by a patent specification including definitions. In addition, the materials, methods, and examples are illustrative only and are not intended to be limiting. 18 1289220 BRIEF DESCRIPTION OF THE DRAWINGS The present invention will be described by way of example only with respect to the accompanying drawings. The details of the present invention are to be considered as being in the nature of the description The most useful and immediately understandable description of the principles and conceptual aspects of the invention. In this regard, the details of the structure of the present invention are not intended to be more particularly understood in the light of the understanding of the invention. The form will be obvious. In the drawings: Figure la is a schematic view of a prior art vertical cavity surface-emitting laser (VCSEL); Figure lb is a schematic view of a prior art edge-emitting laser; A schematic view of a prior art vertical cavity surface-emitting laser 15 (VCSEL) type frequency conversion device; FIG. 3 is a schematic view of a device for light frequency conversion of the present invention; A schematic view of a device for frequency conversion of the present invention, comprising an anti-reflective coating and a highly reflective coating formed on different facets of a luminescent element 20; Figure 5 is used for one of the inventions A schematic view of a device for frequency conversion, wherein the light-emitting element comprises a photonic grooved crystal; and FIG. 6 is a schematic view of a device for frequency conversion of the present invention, wherein a leaky laser system is used to generate primary light; 19 1289220 is a schematic view of a phase of a device for frequency conversion of the present invention, comprising: a lens for providing a parallel beam and a flat light reflector; FIG. 8 is one of the inventions For frequency conversion Figure 5 shows an additional multilayer coating on the bristle element and the light reflector; Figure 9 is a flow chart of a method for converting the light frequency of the present invention; and Figure 10 is a A flow chart of a method of manufacturing an apparatus for frequency conversion of the invention. [Embodiment] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention is a frequency conversion apparatus and method that can be used to convert a laser frequency. In particular, the invention can be used to provide a laser light having a frequency in a wide spectral range. More specifically, for example, the present invention can be used in optical storage applications where short wavelengths are required to increase the density of stored data by reducing the characteristic feature size, or to be used in projection displays 'where green and blue light The laser system is required for full color applications. The present invention is a further method of making the device. For a better understanding of the present invention, as shown in Figures 3-8, reference is first made to the construction and operation of a conventional (i.e., prior art) frequency conversion device shown in Figure 2. Figure 2 is a diagram showing a prior art frequency conversion device based on a vertical cavity surface-emitting laser (VCSEL). Thus, the prior art device includes a VCSEL type structure 101 which is fabricated as a multilayer structure and epitaxially grown on a substrate 102. The VCSEL type structure 101 includes a bottom distributed Brass mirror (DBR) 103, and an active region 106 is tied in a semiconductor chamber 104. In this arrangement, the VCSEL type structure 101 does not include a top distributed Bragg reflector 5 (DBR). Also similar to those well known in the industry, including a distributed Bragg mirror (DBR) 103 having a relatively low quality top distributed Bragg mirror (DBR). In use, the VCSEL-type structure 101 is photoexcited by an external laser beam 109 and produces a ray that is reflected back to the VCSEL-type structure 101 by an external mirror 114. The power of the VCSEL type structure 1〇1 and the laser beam 109 is selected such that the VCSEL-type structure 101 does not emit light from the free mirror 114 to produce laser light without an additional power. Mirror 114 and VCSEL-type structure 101 define an active chamber that includes a semiconductor chamber 104 and an outer chamber 112. The active chamber limits an enhanced ray feedback that is sufficient to produce a laser light 111. A NLO crystal 113 in the outer chamber 112 is used to convert the frequency of the laser light 111 into a laser light 115 of a different frequency (typically higher than the frequency of the light ray 111) that passes through the outer mirror 114. And out. The VCSEL type structure is well known to have a wide main beam aperture, typically 100 microns in size. The advantage of the wide aperture is that the low laser beam diverges, 20 and there is no significant loss and difficulty in focusing the light back to the VCSEL type structure. The use of an external mirror allows for the accumulation of optical power inside the chamber in contrast to the low efficiency single channel amplification using conventional external cavity direct diode excitation conditions. However, when the light output aperture of the VCSEL type structure is equal to the surface used for the heat dissipation 21 1289220, it is extremely difficult to obtain a high power density system from such structures. Moreover, the photoexcitation requirements of VCSEL-type structures significantly reduce the overall conversion efficiency of the device, which has been limited by the low power density of VCSELs. Those skilled in the art will recognize that the 5 VCSEL cannot be uniformly excited by the injection current due to the high resistance of the top contact layer. Therefore, in the above and similar prior art devices, the conversion efficiency is impaired by the use of photoexcited VCSELs. A solution to the above limitation is to replace the V C S E L with a side-emitting semiconductor laser (see Figure 1 b in the prior art section above). Edge-emitting laser 10 The advantages of the over-the-VCSEL are twofold: (1) the physical size of the edge-emitting laser is sufficient to dissipate heat efficiently, contributing to a high power density; and (5)) the ability to generate a side shot using a direct electrical excitation. Lasers are in contrast to VCSELs that can only be photo-excited. However, the currently known edge-emitting lasers have a particularly narrow wave of conductance, typically in the submicron range. Due to the narrowing of the waveguide, it is difficult to focus the light reflected back to the waveguide by the mirror without significant power loss. In addition, edge-emitting lasers are characterized by a high beam divergence that prevents the precise orientation of the laser light associated with the optimal crystallographic orientation of the NLO crystal. The present invention successfully provides a solution to the above problems by providing a frequency conversion device having a modified edge-emitting type laser which is also considered to be a 2-sided edge-emitting semiconductor light-emitting diode. Thus, in accordance with the present invention, a device for frequency conversion of light is provided, generally referred to herein as a device. Before describing at least one embodiment of the present invention, it is understood that the description of the invention is not limited to the details of the application and the arrangement of the elements. The invention may be embodied in other specific embodiments or in various ways. At the same time, it should be understood that the phraseology and terminology used herein are for the purpose of description and should not be construed as limiting. FIG. 3 is a schematic diagram of the device again. It includes a light emitting element 201 for emitting light having a first frequency. The light-emitting element 201 is an edge-emitting semiconductor light-emitting diode having an extended waveguide 2〇4, which is selected such that a substantially transverse mode of the waveguide 2〇4 is characterized by a low beam divergence. The device 1 further includes a photo reflector 214 and an NLO crystal 213 disposed in an outer chamber 212 defined between the light emitting element and the light reflector. The NLO crystal can be any well known NLO crystal characterized by a predetermined frequency conversion efficiency such as, but not limited to, potassium citrate (KNb03) or lithium niobate (LiNb03). In accordance with a preferred embodiment of the present invention, waveguide 204 is capable of emitting light through a front facet 210 when exposed to an injection current, such as a forward bias 218. Preferably, the length of the strip of light-emitting element 201 and the injected current are selected such that the injected current does not provide the minimum condition for laser illumination, resulting in a non-coherent chief ray. 2〇 The outer chamber 212 and the waveguide 204 form an effective chamber defined between the light reflector 214 and one of the rear facets 269 of the waveguide 204. In the operational mode of device 10, the active chamber provides an additional feedback to the primary emitted light, thereby producing a laser beam 211. According to a preferred embodiment of the present invention, the basic portion of the laser light 211 from the light reflector 214 is provided by a sufficiently narrow resistance 23 1289220 f one of the light reflecting elements 214 (jucJici〇us secti〇n) A high reflectivity of the transverse mode, as will be described in more detail later in connection with Fig. 8, the portion is preferably constructed as a multilayer structure. It will be appreciated by those skilled in the art that a predetermined narrow stop band of the light reflector 5 is also used to filter out the undesired modes of the laser light 211 by providing one of its high order transverse modes with low reflectivity. . Thus, the laser light 211 is passed through the NLO crystal 213 a plurality of times to convert the laser light 211 into laser light 215 having a second frequency different from the first frequency. Preferably, the light reflector 214 is selected to reflect light having a frequency other than the second frequency 10 (e.g., light 211) and to transmit light having a second frequency (light 215). Moreover, in order to achieve optimum conversion efficiency of the device, the stop band of the photo reflector 214 preferably has the same (or similar) temperature dependence as the frequency conversion efficiency of the NL 〇 crystal 213. Thus, depending on the type, orientation, geometry and size of the Nl〇 crystal 213, the device 1 provides a high quality laser light that can have a substantially low wavelength, as further explained below. Prior to further detailed description of one of the devices 10, as described above and in accordance with the present invention, attention is directed to the advantages provided. Thus, a particular advantage of a preferred embodiment of the present invention is the design of the illuminating element 201 such that the extended waveguide 2 〇 4 provides a single mode laser 20 211. The use of an extended waveguide typically results in the generation of a plurality of optical modes of laser light. Thus, the basic optical mode propagates in the direction of the waveguide and exhibits a narrow far-field diagram that is centered at the center in the direction perpendicular to the front facet 210 of the light-emitting element 2〇1. The propagation of high-order transverse optical modes can be explained by the fact that this direction occurs at some angles. 24 1289220 Typically, the far-field graphics of the higher-order modes are significantly more I-like than the basic modes, and typically contain side lobes. When reflected back to the front facet 21 by the light reflector 214, the light in a higher order optical mode is partially refracted away from the chamber, and the basic mode optimized with the form 5 of the light reflector 214 The light of the state is opposite. Therefore, the refractive loss is significant for the first order mode and is not significant for the basic mode. In other words, the feedback provided by the light reflector 214 is strong for the fundamental mode and weak for the higher order modes. This allows for such conditions to be achieved at the injection current, the length of the laser strip, the shape and position of the outer 10 mirrors causing the laser to occur only in the substantially transverse mode. It will be appreciated by those skilled in the art that the above is a general advantage regardless of the number of light-emitting elements used. More specifically, in accordance with a preferred embodiment of the present invention, more than one illuminating element 15 can be used, wherein light generated by the additional illuminating element can be directed to the NL0 crystal via a special optical system. 213. Therefore, if at least one of the light-emitting elements is manufactured and operated similarly to the light-emitting element 201, it can be combined for one-frequency generation or for a difference frequency generation or any other frequency. 0. According to a preferred embodiment of the present invention The light-emitting element 2〇1 is grown on a substrate 202, which is preferably composed of any MV semiconductor material or π-V semiconductor alloy, for example, indium (InAs), indium (inp), Or gallium antimonide (GaSb), or other alloys. A more preferred substrate 2〇2 is made of gallium arsenide (Ga As). One of the features of the 25 1289220 5 is that the extended waveguide 204, as mentioned, provides a ray in which the substantially transverse mode has a low beam divergence. According to a preferred embodiment of the present invention, the waveguide 204 is formed between an n_transmitter 2〇3 and a P-transmitter 220, wherein the n_transmitter 203 is preferably directly grown at 5 The substrate 202 is adjacent to the waveguide 2〇4 from one side while the emitter is adjacent to the waveguide 204 from the other side. The extension waveguide 204 preferably includes an active region 2〇6 formed between a first waveguide region 205 doped with an n- impurity and a second waveguide region 207 doped with a p-impurity. . Both the first waveguide region 205 and the second waveguide region 207 are optically transmissive. The first waveguide region 205 and the second waveguide region 207 are preferably a layer formed of a lattice-matched or nearly lattice-matched material of the substrate 202 or a multi-layer structure. The impurity introduced into the first waveguide region 2〇5 is a dopant impurity such as, but not limited to, sulfur (S), selenium (Se), and tellurium (Te). Alternatively, the first waveguide region 205 may be doped with an amphiphilic impurity, such as, but not limited to, germanium (Si), germanium (Ge), and tin (Sn), which may be introduced under such technical conditions, which are mainly The cationic sublattice is combined and thus used as a donor impurity. Therefore, the first waveguide region 205 may be, for example, gallium arsenide (GaAs) or arsenic aluminum grown by molecular beam epitaxy and doped with cerium (Si) impurities having a concentration of about 2×10 17 cm·3. Gallium (GaAlAs) layer. The term "about" as used herein is ±50%. The impurity that can be introduced into the second waveguide region 207 is an acceptor impurity such as, but not limited to, beryllium (Be), magnesium (Mg), zinc (Zn), cadmium (Cd), 26 1289220 lead (Pb). And manganese (Μη). Alternatively, the second waveguide region 207 may be doped with an amphoteric impurity such as, but not limited to, germanium (Si), germanium (Ge), and tin (Sn), which may be introduced under such technical conditions, mainly with anions The secondary lattice is combined and used as an acceptor impurity. Therefore, the second waveguide region 207 may be, for example, gallium arsenide (GaAs) grown by molecular beam epitaxy and doped with bismuth (Be) impurities having a concentration of about 2×1〇17 cm·3 or A gallium arsenide (GaAlAs) layer. The active region 206 is preferably formed by any insertion with an energy band gap whose energy band gap is narrower than the energy band gap of the substrate 202. In accordance with a preferred embodiment of the present invention, the active region 206, for example, 10, can be a quantum well, quantum wire, quantum dot, or any such combined system. The active area 206 can be constructed as a single layer system or as a multi-layer system. In a preferred embodiment, the substrate 202 is made of gallium arsenide (GaAs), and the active region 206 can be, for example, InAs, Ini xGaxAs, InxGai x yAlyAs,
InxGa^xAsiyNy或相似材料之插入的系統，其中x及y係標明 15 —合金成分。 η-發射器203較佳地係以與基板202晶格匹配或是幾乎 晶格匹配的材料製成，例如，合金材料Gai_xAlxAs。此外， η-發射器203較佳地係為所產生光線可穿透的並摻雜施體 雜質，如同先前進一步詳述，與該第一波導區域205之摻雜 20 作業相似。 根據本發明之一較佳具體實施例，ρ-發射器220包括至 少一 Ρ-摻雜層208以及至少一 ρ+掺雜層209，其中ρ-摻雜層 208係配置在波導204與ρ+摻雜層209之間。ρ-摻雜層208與 摻雜層209較佳地係為光可透射的，並係以基板202晶格匹 27 1289220 配或是幾乎晶格匹配的一材料製成。層208及209係摻雜受 體雜質，與第二波導區域207之摻雜作業相似。層2〇8與2〇9 之間在摻雜程度上有所差異。較佳地，然而第二波導區域 207及p-摻雜層208之摻雜程度係為相似的，p+摻雜層209之 5摻雜程度係較高的。例如，於具體實施例中，第二波導區 域207的摻雜程度係約為2 X 1〇17 cnT3，p+摻雜層209可為一 藉由刀子束蠢晶所成長的GaAlAs層，並以一濃度約為2 X 1019 cnT3的Be雜質摻雜。 元件201之一較佳厚度係為1〇微米或更高，較佳的帶寬 1〇係約自7微米至約10微米或更高，以及元件2〇1之一較佳長 度係約為1〇〇微米或更高。 如所提及，發光元件201經設計及建構，因此波導204 提供一單模態雷射光211。例如，如此能夠藉由選定n-發射 态203及p-摻雜層208之折射率低於波導2〇4之折射率。該形 15式確保雷射輻射之基本橫向模態係受限在波導204的範圍 内’並係在η-發射器203及p-摻雜層208中衰變(decays)。 順向偏壓218較佳地係經由一η-接點216，與基板202接 觸，而與發光元件2〇1連接，以及一ρ-接點217其係與ρ-發射 器22〇(或ρ+摻雜層209)接觸。接點216及2Π係可製成為任一 20所熟知的結構，諸如，但不限定在多層金屬結構。例如， η-接點216可構成為一 Ni-Au-Ge之三層結構，以及ρ-接點217 可構成為一Ti-Pt-Au之三層結構。 根據本發明之一較佳具體實施例，裝置1〇進一步包括 配置一具光譜選擇性濾光鏡260，俾便防止光線215照射發 1289220 光元件201。於一具體實施例中，濾光鏡260可構成在NLO 晶體213上，與發光元件201相對。於此具體實施例中，例 如，濾光鏡260可由一介電沉積物構成，諸如，但不限定在 Si〇2、MgF2、或 ZnS 〇 5 相關於第4圖，根據本發明之一較佳具體實施例，發光 元件201之前刻面210及後刻面269，分別地以一抗反射塗層 320及一高度反射塗層319塗佈。 該高度反射塗層319係用於將經由該後刻面269的損失 降至最低。如此能夠，例如，藉由構成一在反射性上具有 10 一阻帶的塗層而達成。該塗層319之阻帶能夠設計得夠窄， 俾便一高反射性的基本橫向模態以及一低反射性的高階橫 向模態。根據本發明之一較佳具體實施例，塗層319係以一 多層介電結構所構成，其經設計用以提供在一窄頻譜區域 中的高反射性。如於本具體實施例中之後進一步的詳細說 15 明（見第8圖），對於基本橫向光學模態而言，反射性越高且 損失越低，同時對於高階模態而言，損失將顯著地較高。 因此，此具體實施例容許一附加選定的模態，並有助於獲 得單模態雷射作用。 如上述進一步的詳細說明，抗反射塗層320確保僅以附 加回饋，並僅針對基本橫向光學模態發生雷射作用。 根據本發明之一較佳具體實施例，塗層319及320之阻 W具有與NL0晶體213之頻率轉換效率相同（或相似）的溫度 相依性。該每一塗層319及320較佳地包括以業界所熟知的 任一適合材料所構成的複數層，例如，該材料為介電沉積 29 1289220 物，諸如，但不限定在Si02、MgF2、或ZnS。 現參考第5圖，其係為一較佳具體實施例之裝置的一 概略圖式，其中係使用光子帶隙晶體雷射之概念。為更適 當地識別本發明之目前的較佳具體實施例，於之後將進一 5 步詳加說明，於第5圖中分別地以代表符號401及440代表發 光元件及波導。 因此，於此具體實施例中，延伸波導440之至少一部分 包括一光子帶隙晶體(PBC)430之η週期431。光子帶隙晶體 (PBC)430之每一週期431，較佳地係由一為低折射率以及一 10 為高折射率的二η-摻雜層所構成。 根據本發明之一較佳具體實施例，發光元件401包括一 缺陷432，其係配置在光子帶隙晶體(PBC)430與ρ-摻雜層 208之間。缺陷432較佳地包括一具有一η-侧邊433及一p-側 邊435的主動區域434，當暴露至注入電流時，例如使用偏 15 壓218，用於發射光線。如之後進一步說明，使用用於光線 初步產生的光子帶隙晶體(PBC)430，提供具一極寬波導的 一高效率低臨限電流密度輻射源。 光子帶隙晶體（PBC)雷射之概念，首先係由 Ledentsov，N.N.及Shchukin，V·A·於文章中採用，文章標題為 20 “使用GaAs量子點的長波長雷射（Long Wavelength Lasers Using GaAs-Based Quantum Dots)”，出版於Photonics and Quantum Technologies for Aerospace Applications IV， proceedings of SPIE，Donkor，E.et al.，editor，4732:15 -26, 2002。大體上而言，光子帶隙晶體(PBC)係為一多維結構， 30 1289220 其特徵在於週期性折射率調制。為簡化起見，考量一結構 僅在一方向上，例如Z方向，具有折射率之週期性調制。於 一無限、完全週期性光子帶隙晶體(PBC)中，電磁波或光子 特徵在於一定義明確的波向量，於X方向上的]^，以及於y 5 方向上的ky，致使電場E或是磁場Η在X及y空間座標上的每 一分量之空間相依性，係說明為一平面波， E，H 〜exp(ikxx)exp(ikyy)， (EQ.1) 然而，根據Bloch’s原理，在z座標上的相依性並非說明 為一平面波而係為一平面波與一週期函數，u(z)，之乘積， 10 具有與折射率之調制相同之週期。因此，場之總空間相依 性係為： E，H 〜exp(ikxx)exp(ikyy)exp(ikzz)u(z)， (EQ.2) 電磁波或是光子能量之頻率的特徵頻帶，包括週期電 磁波傳播整個晶體的容許能帶（allowed bands)，以及電磁波 15 無法傳播的禁帶隙(forbidden bandgaps )。 光子帶隙晶體(PBC)之一理想週期性，能夠因終止該等 層（插入)之連續或是違反折射率之週期性量變曲線的任一 缺陷之類型而被蓄意地中斷。該一缺陷能夠將電磁波局部 化，或是使電磁波局不定域化。就局部化效應而言，能夠 20 有二型式之電磁波：⑴波局部化在缺陷處並衰變離開該缺 陷以及(ii)波延伸涵蓋整個光子帶隙晶體(PBC)，其中延伸 波之空間量變曲線可因一缺陷而受擾動。 於一更為傳統形式之基於層之週期連續性的雷射，光 線在與折射率調制軸，例如z軸，平行的方向上傳播，然而 31 1289220 波向量之X及y分量符合kx=0&ky=0。此情況典型地係針對 一VCSEL。於此型式之雷射中，層之週期連續性經設計， 在某些臨界波長下提供高反射性頻譜範圍（阻帶）。“缺陷，， 層經設計用以在此阻帶内提供一約束模態。 5 如由Ledenstov等人所提出之PBC雷射的一極佳優點在 於’此雷射得益於PBC特性，其未與特定波長之反射相關。 於此方法中，PBC經設計致使在z方向上發生折射率之週期 調制，光線之主要傳播係發生在X方向上。中斷週期性致使 於橫向基本模態下的光線係在缺陷處局部化在z方向上，並 10 於z方向上衰變離開該缺陷。於此狀況下，對於在反射性上 阻帶之特別頻譜位置，或是對於已知波長的外部腔室厚度 並無存在一般的需求。當PBC之週期性並未直接地與傳播 光線之波長相關時，裝置10可同時地使用於寬的波長範 圍，例如，1微米、0·9微米及0.8微米。應察知的是，裝置 15 之此特性，在設計及製造上提供極高的容限，該容限對 於直接頻率轉換係特別有利的。 缺陷432用以將雷射輻射之模態局部化的能力，係由二 參數所控制。該第一參數係為缺陷432與PBC之參考層的折 射率之間的差異，Δη。該第二參數係為缺陷之容積。就一 20維pBC而言，其中僅在一方向上調制折射率，該第二參數 係為缺陷432之厚度。大體上，當Δη數值增加時，在一固定 缺陷厚度下，亦增加藉由缺陷而受局部化之模態數。當缺 陷之厚度增加時，在一固定的Δη下，亦增加藉由缺陷而受 局部化之模態數。選定該等二參數，An及缺陷之厚度，因 32 1289220 此一並僅有一雷射輻射模態係藉由缺陷432局部化。其他模 態係延伸涵蓋PBC。 因此’根據本發明之一較佳具體實施例，選定缺陷432 及光子帶隙晶體(PBC)430，致使基本光學模態，其係在與 5折射率調制軸垂直的方向上傳播，係局部化在缺陷432處並 衰變離開缺陷432，然而所有其他（高階）光學模態係延伸涵 蓋整個光子帶隙晶體。增益區域因而能夠直接地安置在光 子帶隙晶體之缺陷處或與其接近。 遍及整個結構的所需之折射率量變曲線係如下地計算 10而得。導入一模型結構。基本TE模態及高階TE模態，係自 對波動方程式之特徵向量問題的解法而得。當經計算而得 基本模態時，該遠場圖形係藉使用以下方法計算而得，例 如’ H.C.Casey，Jr·及Μ·Β· Panish之半導體雷射 (Semiconductor Lasers)，Part A，Academic Press，N.Y”1978, 15 ChaPter 2。由於在最低光束發散、在主動區域中基本模態 之最大振幅、與在主動區域該較高模態之振幅和基本模態 之振幅的最低比值之間提供較佳的相互影響之最佳化，而 得所需的結構。 如所提及，主動區域434較佳地係配置在缺陷432中， 20於該處雷射輻射之基本模態係局部化。基本模態之所需局 部化長度，係藉由二傾向之相互影響而確定。一方面，該 局部化長度需夠大，用以提供一低遠場光束發散。另一方 面’局部化長度應足夠地短於PBC之長度。在pbc之總厚度 的比例下，提供基本模態的有效局部化，因而與其他模態 33 1289220 相較，在基本模態下顯著地增強電場強度。例如，於一具 體實施例中，PBC雷射達到一4度的光束發散，同時在一具 有〇·8微米GaAs腔室及Ga^xAlxAs包覆層，其中χ=〇·3，的一 標準雙異質結構雷射中約束係數為0.11。 5 應察知的是，此設計促進自延伸波導440的一單橫向模 態雷射作用，導致裝置10之更為有效的光線頻率轉換。 根據本發明之一較佳具體實施例，選定製成接點層216 及217的材料，因此僅有延伸高階模態係由層216及217散 射’而基本模,％隙藉由缺陷432充分局部化，並未及接點區 10 域因此並未散射。接點層216及217的適當材料包括，例如， 合金金屬。 此外，發光元件401可進一步包括一或更多的吸收層 420，位在光子帶隙晶體430的其中之一第一層431中，離開 該缺陷432 ,致使吸收該所有延伸高階模態，同時該局部化 基本模態仍不受影響。吸收層420亦可位在光子帶隙晶體 430的該等不同層431内。 光子帶隙晶體(PBC)較佳地係由與基板202晶格匹配或 幾乎晶格匹配的一材料所構成並為發射光線可穿透的。於 上述位在一GaAs基板上的一元件之實例中，較佳具體實施 2〇 例係為具一調制銘成分，X，的合金Ga^xAlxAs。較佳地選 定週期數，η，每一層之厚度，以及每一層中合金成分，用 以提供雷射輻射之一且僅有一模態的局部化。 視裝置10之製程以及裝置10之應用而定，可變化發光 元件401中層的數目及主動區域的位置。因此，一具體實施 34 1289220 例包括與第5圖之具體實施例相似導入吸收層的該等結 構，但是主動區域係位在缺陷外部。另一具體實施例包括 主動區域係位在缺陷外部的該等結構，在具低折射率的每 一層與具一高折射率的一相鄰層乏間導入漸近式折射率 5 層。一附加具體實施例，其中主動區域係位在缺陷外部， 包括載體用之薄通道阻障層，環繞該主動區域。本發明之 其他具體實施例中，主動區域係位在缺陷外部，包括一些 或所有元件，例如，吸收層、漸近式折射率層及環繞載體 用的薄通道阻障層。本發明之其他具體實施例包括該等結 10 構，其中缺陷係位在主動區域之η-側邊或p-側邊上。 元件401之一較佳厚度係約為1〇微米或更厚，光子帶隙 晶體(PBC)430之較佳的週期431數係約自5至10或更多，較 佳的帶寬係約自7微米至1〇微米或更高，以及元件4〇1之較 佳長度係約為100微米或更高。 15 裝置10之效率可進一步藉由發光元件401之一適當洩 漏設計而加強，其中所有的延伸高階模態係為舰並貫穿 進入基板202或接點層216及217，與基本模態相反，如所提 及，其並未及基板202或接點層216及217並且未受任何洩漏 損失。 ^ 20 現參考第6圖，於一較佳具體實施例中，裝置10中使用 一沒漏雷射用於產生主要光線。 因此，於此具體實施例中皮導204較佳地包括二部 分，一具有一中級折射率的第一部分539以及較佳地_具有 -局折射率的第二部分54〇。主動區域施係夹合在層如及 35 1289220 207之間，該每-層的特徵在於一中級折射率。在主動區域 206中產生自第-部分539(具有中級折射率他漏而出至第 一部分540(具有鬲折射率）的光線，係沿著一路徑541傳播， 並由蝻刻面210退出在外部腔室512内沿著路徑511傳播。光 5線511係於腔室中傳播，大體上係於一相關於與前刻面21〇 之垂直方向傾斜的方向上傳播。在一特定角度下傳播，造 成一回饋係僅針對一單橫向洩漏模態選擇性地存在。成為 一單模態光線，一旦光線511進入NLO晶體213，發生有致 率的頻率轉換，以及產生一經轉換光線515。如上述進一步 10的詳細說明，光線515經由光反射器214出現。 弟^一。卩刀540 ’發生基本模怨'/¾漏進入該部分，較佳地 係以與基板202晶格匹配或幾乎晶格匹配的一材料所構 成’發射光線可穿透的，η-摻雜，並具有一高折射率。摻 雜雜質之型式及摻雜程度較佳地與如上述進一步詳細說明 15的層相同。於上述位在一GaAs基板上的一元件之實例 中’較佳材料係為Ga^AlxAs，其中根據折射率的需求選定 调制紹成分，X。 可任擇地並為較佳地，可製造用於產生主要光線的洩 漏雷射，致使波導204僅包括第一部分539，而不具第二部 20 分540。於此具體實施例中，所產生的光線直接地洩漏進入 基板202。 相關於第7圖，根據本發明之一較佳具體實施例，裝置 10可進一步包括一透鏡650，用於將一微弱發散光束611轉 換成一平行光束651。於此具體實施例中，使用一平坦光反 36 1289220 射器614取代一聚焦光反射器。此具體實施例之一特別的優 點在於’平坦光反射器之所需設計大體上較一聚焦光反射 器之設計簡單。透鏡650能夠以任一業界所熟知的材料製 成’諸如’但不限定在玻璃或是石英玻璃。 5 第8圖圖示另一較佳具體實施例中的裝置10，其中包括 複數之塗層。因此，如上述之說明，發光元件201可包括位 在前刻面210上的抗反射塗層32〇，以及位在後刻面269上的 一可以多層介電結構所構成的高度反射塗層719。於具體實 施例中’使用一附加高度反射塗層714作為一光反射器。可 10交替地，塗層714可構成在光反射器214或614上。較佳地設 計塗層714之厚度、形狀及層數，有助於塗層714之選擇性 反射、吸收及/或傳輸特性。具體地，塗層714較佳地提供 基本橫向模態（211、511或651)的高反射性及低損失，以及 針對轉換光線215的高傳輸係數及低損失，及針對高階非所 15 需模態的高損失。 應瞭解的是，本發明之範疇係意欲包括所有上述塗層 之結合。例如，於一些具體實施例中，一或更多塗層可獨 立地成為一單層或是一多層塗層。此外，於其他具體實施 例中，塗層714可包括塗層320及/或塗層319。 20 對於塗層使用多層結構容許選擇該等組成材料，以與 NLO晶體之光學頻率轉換之最大效率的頻譜位置的相同方 式下，根據溫度變化移動窄阻帶之頻譜位置。如此容許達 到裝置10之頻率轉換效率的一極高溫度穩定性。 塗層714及719可以任一所熟知的材料構成，用以具有 37 1289220 4寸疋反射、吸收及/或傳輸特性’諸如，但不限定在可交替 的介電材料沉積物，例如，Si〇2、MgF2、或ZnS。 現蒼考第9圖’根據本發明之另一觀點，提供一種轉換 光線頻率的方法。該方法包括以下的方法步驟，如第9圖中 5 的流程圖所示。 因此，於一第一步驟中，以方塊8〇2代表，自一發光元 件發射一具有一第一頻率的光線，該發光元件，例如，可 為發光元件201或是發光元件401，如上述進一步之詳細說 明。於一第二步驟中，以方塊804代表，使用一光反射器用 10於容許光線在一外步腔室内通過多次並通過一 NL〇晶體， 其中外部腔室，例如，可設計成外部腔室212或外部腔室 512，以及該NLO晶體可為具有適合光轉換特性的任一所熟 知之NLO晶體，例如，如上述進一步之詳細說明的具有或 不具塗層260之NLO晶體213。使光線在外步腔室内通過多 15次，提供一回饋係足以產生具有一第一頻率的雷射光。於 一第三步驟中，以方塊806代表，具有第一頻率的雷射光通 過非線性光學晶體數次。該非線性光學晶體將雷射光之第 一頻率轉換成第二頻率，該第二頻率係與第一頻率不同。 根據本發明之一較佳的具體實施例，該光反射器可為 20光反射器214、614、714或是與其相似的任一光反射器。附 加並為較佳地，該光反射器可塗佈一單層塗層或是一多芦 塗層，如上述的進一步詳細說明。可任擇地，該方法可進 一步包括一附加步驟，以方塊808代表，其中使用一透鏡， 例如，透鏡650，將一微弱發散光束變換成一平行光束。 38 1289220 根據本發明之一附加觀點，提供一種製造用於光線之 頻率轉換之裴置的方法。 第10圖係為該方法之方法步驟的一流程圖，其中於一 第一步驟中，以方塊902代表，提供一發光元件，例如，發 5 光元件201或發光元件401。於一第二步驟中，以方塊904代 表，提供並配置一光反射器與該發光元件相對，以及於一 第三步驟中，以方塊906代表，在界定介於發光元件與光反 射器之間的一外部腔室中提供並配置一NLO晶體。根據本 發明之一較佳的具體實施例，建構及設計該發光元件、光 10反射器及非線性光學晶體，因此光線通過NLO晶體數次並 k供一回饋用於產生具有經轉換頻率的一雷射光，如上述 進一步的詳細說明。 應察知的是’為了清楚起見，於個別具體實施例中之 上下文中說明的本發明之特性，亦可以於一單一具體實施 15例中以結合方式提供。相反地，為了簡潔起見，於一單一 -體實；Μ狀上下文巾制的本發明之不同特性，亦可以 分別地或是以任-適合的次結合方式提供。 儘官本發明已結合其之特定具體實施例加以說明，但 明顯可知的是，複數種可交替方式、修改形式及變化形式 〇對^知此技藝之人士而言係為顯而易見的。因此，本發 ，。人所有4等可交替方式、修改形式及變化形式， 2蓋於附加之中請專利範圍的精神與廣泛之_内。於本 曰中所提及的所有公開案、專利及專射請案，於此 王文引用方式併人說明書中以為參考資料，該引用的程 39 1289220 度就如同已個別地及特定地將各個個別公開案、專利或專 利申請案以引用的方式併入内容一般。此外，於本申請案 中任一參考文獻的引用或確認，不應視為許玎該適用於先 前技術之參考文獻適用於本發明。 5 【圈式簡單說明】 第la圖係為一先前技術之垂直共振胜面射型雷射 (VCSEL)的概略視圖； 第lb圖係為一先前技術之邊射型雷射的概略視圖； 第2圖係為一先前技術之垂直共振腔面射型雷射 10 (VCSEL)式頻率轉換裝置的概略視圖； 第3圖係為本發明之一用於光線頻率轉換的裝置之概 略視圖； 第4圖係為本發明之一用於頻率轉換的裝置之概略視 圖，包括一抗反射塗層及一高度反射塗層構成在一發光元 15 件的不同刻面上； 第5圖係為本發明之一用於頻率轉換的裝置之概略視 圖，其中發光元件包括一光子帶溝晶體； 第6圖係為本發明之一用於頻率轉換的裝置之概略祝 圖，其中一洩漏雷射係用於產生主要光線； 20 第7圖係為本發明之一用於頻率轉換的裝置之概略祝 圖，其包括一用於提供一平行光束的透鏡以及一平坦式光 反射器； 第8圖係為本發明之一用於頻率轉換的裝置之概略祝 圖，其在發光元件及光反射器上包括附加的多層式塗層； 40 1289220 第9圖係為本發明之轉換光線頻率的一方法的一流程 圖；以及 第10圖係為本發明之製造用於頻率轉換之裝置的一方 法的一流程圖。 5 【圖式之主要元件代表符號表】 10…裝置 210…前刻面 101"_VCSEL 型結構 214、614…光反射器 102、202…基板 216 ···!!-接點 103…分布式布拉格反射鏡 217…ρ-接點 104…半導體腔室 218…順向偏壓 106···主動區域 220…ρ-發射器 109···外部雷射光束 260…渡光鏡 111、115、211、215…雷射光 269…後刻面 112、212、512…外部腔室 319…高度反射塗層 113、213 …NLO 晶體 320…抗反射塗層 114…外部鏡 420…吸收層 201、401…發光元件 430…光子帶隙晶體 203、230···η-發射器 431…週期/第一層 204…延伸波導 432…缺陷 205…第一波導區域 433…η-側邊 206、434···主動區域 435…ρ-側邊 207…第二波導區域 440…波導 208 "·ρ-摻雜層 511、541…路徑 209···ρ+摻雜層 515…經轉換光線 41 1289220 539···第一部分 540···第二部分 611···微弱發散光束 650…透鏡 651···平行光束 714、719…高度反射塗層InxGa^xAsiyNy or a system of similar material insertion, where x and y are labeled as 15 alloy compositions. The η-emitter 203 is preferably made of a material that is lattice-matched or nearly lattice-matched to the substrate 202, for example, the alloy material Gai_xAlxAs. In addition, η-emitter 203 is preferably permeable to the generated light and doped with donor impurities, as described in detail above, similar to the doping 20 operation of the first waveguide region 205. In accordance with a preferred embodiment of the present invention, the p-emitter 220 includes at least one germanium-doped layer 208 and at least one p+ doped layer 209, wherein the p-doped layer 208 is disposed in the waveguide 204 and ρ+ Between the doped layers 209. The p-doped layer 208 and the doped layer 209 are preferably light transmissive and are made of a material of the substrate 202 lattice 27 1289220 or almost lattice matched. Layers 208 and 209 are doped with dopant impurities similar to the doping operation of second waveguide region 207. The degree of doping differs between layers 2〇8 and 2〇9. Preferably, however, the degree of doping of the second waveguide region 207 and the p-doped layer 208 are similar, and the degree of doping of the p+ doped layer 209 is higher. For example, in a specific embodiment, the doping degree of the second waveguide region 207 is about 2×1〇17 cnT3, and the p+ doping layer 209 can be a GaAlAs layer grown by a knife beam, and Be impurity doping at a concentration of approximately 2 X 1019 cnT3. Preferably, one of the elements 201 has a thickness of 1 〇 micron or higher, a preferred bandwidth of 1 〇 is from about 7 microns to about 10 microns or more, and a preferred length of one of the elements 2 〇 1 is about 1 〇. 〇 microns or higher. As mentioned, the light-emitting element 201 is designed and constructed such that the waveguide 204 provides a single-mode laser light 211. For example, the refractive index of the selected n-emission state 203 and p-doped layer 208 can be made lower than the refractive index of the waveguide 2〇4. This shape ensures that the fundamental transverse mode of the laser radiation is limited to within the range of the waveguide 204 and is decayed in the η-emitter 203 and the p-doped layer 208. The forward bias 218 is preferably in contact with the substrate 202 via an n-contact 216, and is coupled to the light emitting element 2〇1, and a p-contact 217 is coupled to the p-emitter 22〇 (or ρ + Doped layer 209) is in contact. Contacts 216 and 2 can be fabricated into any of the 20 well known structures such as, but not limited to, a multilayer metal structure. For example, the η-contact 216 may be formed as a three-layer structure of Ni-Au-Ge, and the ρ-contact 217 may be constructed as a three-layer structure of Ti-Pt-Au. In accordance with a preferred embodiment of the present invention, apparatus 1 further includes a spectrally selective filter 260 that prevents light 215 from illuminating light member 201. In one embodiment, the filter 260 can be formed on the NLO crystal 213 opposite the light emitting element 201. In this embodiment, for example, the filter 260 may be composed of a dielectric deposit such as, but not limited to, Si 〇 2, MgF 2 , or ZnS 〇 5 in relation to FIG. 4, preferably in accordance with one of the present inventions. In a specific embodiment, the front facet 210 and the rear facet 269 of the light-emitting element 201 are respectively coated with an anti-reflective coating 320 and a highly reflective coating 319. The highly reflective coating 319 is used to minimize losses through the back facet 269. This can be achieved, for example, by constructing a coating having a resistive band of 10 in the reflective property. The stop band of the coating 319 can be designed to be narrow, a high-reflective basic transverse mode and a low-reflective high-order transverse mode. In accordance with a preferred embodiment of the present invention, coating 319 is constructed of a multilayer dielectric structure designed to provide high reflectivity in a narrow spectral region. As further detailed later in this embodiment (see Figure 8), the higher the reflectivity and the lower the loss for a substantially transverse optical mode, while the loss will be significant for higher order modes. Higher ground. Thus, this embodiment allows for an additional selected mode and contributes to single mode laser action. As further detailed above, the anti-reflective coating 320 ensures that only the additive feedback is applied and the laser action occurs only for the substantially transverse optical modes. In accordance with a preferred embodiment of the present invention, the barriers W of the coatings 319 and 320 have the same (or similar) temperature dependence as the frequency conversion efficiency of the NL0 crystal 213. Each of the coatings 319 and 320 preferably includes a plurality of layers of any suitable material well known in the art, for example, the material is dielectric deposited 29 1289220, such as, but not limited to, SiO 2 , Mg F 2 , or ZnS. Referring now to Figure 5, which is a schematic illustration of a preferred embodiment of the apparatus, the concept of a photonic band gap crystal laser is used. In order to more appropriately identify the presently preferred embodiment of the present invention, a further step will be described hereinafter, and the light-emitting elements and waveguides are represented by representative symbols 401 and 440, respectively, in FIG. Thus, in this particular embodiment, at least a portion of the extended waveguide 440 includes an n-cycle 431 of a photonic bandgap crystal (PBC) 430. Each period 431 of the photonic band gap crystal (PBC) 430 is preferably composed of a two η-doped layer which is a low refractive index and a 10 is a high refractive index. In accordance with a preferred embodiment of the present invention, light-emitting element 401 includes a defect 432 disposed between photonic bandgap crystal (PBC) 430 and p-doped layer 208. Defect 432 preferably includes an active region 434 having an n-side 433 and a p-side 435 for emitting light when exposed to an injection current, for example using a bias voltage 218. As further explained later, a photonic bandgap crystal (PBC) 430 for the initial generation of light is used to provide a high efficiency, low threshold current density radiation source having an extremely wide waveguide. The concept of photonic bandgap crystal (PBC) lasers was first adopted by Ledentsov, NN and Shchukin, V.A., and the article titled "Long Wavelength Lasers Using GaAs Using GaAs Quantum Dots" -Based Quantum Dots)", published in Photonics and Quantum Technologies for Aerospace Applications IV, proceedings of SPIE, Donkor, E. et al., editor, 4732: 15-26, 2002. In general, a photonic band gap crystal (PBC) is a multi-dimensional structure, and 30 1289220 is characterized by periodic refractive index modulation. For the sake of simplicity, consider a structure that has a periodic modulation of the refractive index in only one direction, such as the Z direction. In an infinite, fully periodic photonic bandgap crystal (PBC), the electromagnetic wave or photon is characterized by a well-defined wave vector, ^ in the X direction, and ky in the y 5 direction, resulting in an electric field E or The spatial dependence of each component of the magnetic field X on the X and y space coordinates is described as a plane wave, E, H ~ exp(ikxx)exp(ikyy), (EQ.1) However, according to Bloch's principle, in z The dependence on the coordinates is not a plane wave and is a product of a plane wave and a periodic function, u(z), and 10 has the same period as the modulation of the refractive index. Therefore, the total spatial dependence of the field is: E, H ~ exp(ikxx)exp(ikyy)exp(ikzz)u(z), (EQ.2) The characteristic frequency band of the electromagnetic wave or the frequency of the photon energy, including the period Electromagnetic waves propagate the allowable bands of the entire crystal and forbidden bandgaps that electromagnetic waves 15 cannot propagate. One of the photonic bandgap crystals (PBC), ideally periodic, can be intentionally interrupted by the type of any defect that terminates the continuity of the layer (insertion) or violates the refractive index. This defect can localize the electromagnetic wave or delocalize the electromagnetic wave. In terms of localization effects, there are 20 types of electromagnetic waves: (1) wave localization at the defect and decay away from the defect and (ii) wave extension covering the entire photonic bandgap crystal (PBC), where the spatial variation curve of the extended wave Can be disturbed by a defect. In a more conventional form of layer-based periodic continuity of laser light, the light propagates in a direction parallel to the refractive index modulation axis, such as the z-axis, whereas the X and y components of the 31 1289220 wave vector conform to kx=0& Ky=0. This situation is typically for a VCSEL. In this type of laser, the periodic continuity of the layer is designed to provide a highly reflective spectral range (stopband) at certain critical wavelengths. "Defects, the layer is designed to provide a constrained mode within this stopband. 5 A great advantage of the PBC laser as proposed by Ledenstov et al. is that 'this laser benefits from PBC characteristics, which is not Correlated with the reflection of a specific wavelength. In this method, the PBC is designed to cause periodic modulation of the refractive index in the z direction, and the main propagation of light occurs in the X direction. Interruption periodically causes light in the transverse fundamental mode. Is localized in the z-direction at the defect and decays away from the defect in the z-direction. In this case, for a particular spectral position of the resistive stop band, or for an external chamber thickness of known wavelength There is no general need. When the periodicity of the PBC is not directly related to the wavelength of the propagating light, the device 10 can be used simultaneously over a wide range of wavelengths, for example, 1 micron, 0. 9 micron, and 0.8 micron. It is appreciated that this feature of the device 15 provides an extremely high tolerance in design and manufacture that is particularly advantageous for direct frequency conversion systems. The ability of defect 432 to localize the mode of laser radiation, Controlled by two parameters, the first parameter is the difference between the refractive index of the reference layer of the defect 432 and the PBC, Δη. The second parameter is the volume of the defect. In the case of a 20-dimensional pBC, only The refractive index is modulated in one direction, and the second parameter is the thickness of the defect 432. In general, when the value of Δη is increased, the number of modes localized by the defect is also increased at a fixed defect thickness. When the thickness is increased, the number of modes localized by the defect is also increased at a fixed Δη. The thickness of the two parameters, An and the defect are selected, and there is only one laser radiation mode due to 32 1289220. It is localized by defect 432. Other modal extensions encompass PBC. Thus, in accordance with a preferred embodiment of the present invention, defect 432 and photonic bandgap crystal (PBC) 430 are selected to cause a basic optical mode, Propagating in a direction perpendicular to the 5 refractive index modulation axis is localized at defect 432 and decays away from defect 432, whereas all other (higher order) optical mode extensions encompass the entire photonic bandgap crystal. The gain region can thus Directly placed at or close to the defect of the photonic bandgap crystal. The required refractive index variation curve throughout the structure is calculated as follows. A model structure is introduced. The basic TE mode and the high-order TE mode, It is derived from the solution of the eigenvector problem of the wave equation. When the basic modal is calculated, the far field graph is calculated by the following method, for example, 'HCCasey, Jr· and Μ·Β· Panish Semiconductor Lasers, Part A, Academic Press, NY" 1978, 15 ChaPter 2. Optimizing for better interaction between the lowest beam divergence, the maximum amplitude of the fundamental mode in the active region, and the lowest ratio of the amplitude of the higher mode and the amplitude of the fundamental mode in the active region, And get the structure you need. As mentioned, the active region 434 is preferably disposed in the defect 432 where the fundamental mode of the laser radiation is localized. The required localized length of the basic mode is determined by the mutual influence of the two tendencies. In one aspect, the localized length needs to be large enough to provide a low far field beam divergence. The other side 'localized length should be sufficiently shorter than the length of the PBC. At the ratio of the total thickness of pbc, effective localization of the fundamental mode is provided, thus significantly enhancing the electric field strength in the fundamental mode compared to the other modes 33 1289220. For example, in one embodiment, the PBC laser reaches a beam divergence of 4 degrees while a standard double with a GaAs8 μm GaAs chamber and a Ga^xAlxAs cladding layer, where χ=〇·3, The constraint coefficient in a heterostructure laser is 0.11. 5 It will be appreciated that this design facilitates a single transverse mode laser action from the extended waveguide 440, resulting in a more efficient light frequency conversion of the device 10. In accordance with a preferred embodiment of the present invention, the materials from which the contact layers 216 and 217 are formed are selected such that only the extended higher order modes are scattered by layers 216 and 217 and the fundamental mode is sufficiently localized by defect 432. It does not scatter with the 10 domain of the contact zone. Suitable materials for the contact layers 216 and 217 include, for example, alloy metal. In addition, the light-emitting element 401 may further include one or more absorption layers 420 located in one of the first layers 431 of the photonic band gap crystal 430, away from the defect 432, so as to absorb all of the extended higher-order modes while The localized basic mode is still unaffected. The absorbing layer 420 can also be located within the different layers 431 of the photonic bandgap crystal 430. The photonic band gap crystal (PBC) is preferably formed of a material that is lattice matched or nearly lattice matched to the substrate 202 and is permeable to the emitted light. In the above example of a component on a GaAs substrate, a preferred embodiment is an alloy Ga^xAlxAs having a modulation composition, X. The number of cycles, η, the thickness of each layer, and the alloy composition in each layer are preferably selected to provide one of the laser radiations and only one mode localization. Depending on the process of device 10 and the application of device 10, the number of layers in the illuminating element 401 and the location of the active area can be varied. Thus, a specific implementation 34 1289220 includes such structures that are introduced into the absorbent layer similarly to the embodiment of Figure 5, but with the active region tied outside of the defect. Another embodiment includes such structures in which the active region is tied outside the defect, and an asymptotic refractive index 5 layer is introduced between each layer having a low refractive index and an adjacent layer having a high refractive index. In an additional embodiment, wherein the active region is tied outside the defect, including a thin channel barrier layer for the carrier, surrounding the active region. In other embodiments of the invention, the active region is located outside of the defect and includes some or all of the components, such as an absorbing layer, an asymptotic refractive index layer, and a thin channel barrier layer surrounding the carrier. Other embodiments of the invention include such a structure in which the defect is on the η-side or p-side of the active region. Preferably, one of the elements 401 has a thickness of about 1 〇 micron or more, and the preferred period 431 of the photonic bandgap crystal (PBC) 430 is about 5 to 10 or more, and the preferred bandwidth is about 7 Micron to 1 〇 micron or higher, and the preferred length of the element 〇1 is about 100 microns or higher. 15 The efficiency of device 10 can be further enhanced by a suitable leakage design of one of light-emitting elements 401, wherein all of the extended higher-order modes are ships and penetrate into substrate 202 or contact layers 216 and 217, as opposed to the basic mode, such as As mentioned, it does not have substrate 202 or contact layers 216 and 217 and is not subject to any leakage losses. ^ 20 Referring now to Figure 6, in a preferred embodiment, a leak-free laser is used in device 10 for generating primary light. Thus, in this particular embodiment the skin guide 204 preferably includes two portions, a first portion 539 having a median index of refraction, and preferably a second portion 54A having a refractive index. The active region is sandwiched between layers such as 35 1289220 207, which is characterized by a median index of refraction. Light from the first portion 539 (having a medium refractive index leaking out to the first portion 540 (having an annulus refractive index) is generated in the active region 206, propagates along a path 541, and exits externally by the engraved face 210 The chamber 512 propagates along the path 511. The light 5 line 511 propagates in the chamber and is generally propagated in a direction that is oblique to the vertical direction of the front facet 21〇. Propagating at a specific angle, The feedback system is selectively present only for a single lateral leakage mode. As a single mode light, once the light 511 enters the NLO crystal 213, a frequency conversion occurs, and a converted light 515 is generated. In detail, the ray 515 appears via the light reflector 214. The shovel 540 'generates the spurt'/3⁄4 leak into the portion, preferably in a lattice match or almost lattice match with the substrate 202. A material constituting 'emission light permeable, η-doped, and having a high refractive index. The type of dopant impurity and the degree of doping are preferably the same as those of the layer 15 as described in further detail above. in In the example of a component on a GaAs substrate, the preferred material is Ga^AlxAs, wherein the composition is selected according to the requirements of the refractive index, X. Optionally, and preferably, it can be fabricated for generating primary light. Leaking the laser causes the waveguide 204 to include only the first portion 539 without the second portion 20 minutes 540. In this particular embodiment, the generated light directly leaks into the substrate 202. In relation to Figure 7, in accordance with the present invention In a preferred embodiment, apparatus 10 can further include a lens 650 for converting a weakly diverging beam 611 into a parallel beam 651. In this embodiment, a flat light counter 36 1289220 614 is used instead of a focus. Light reflectors. A particular advantage of this particular embodiment is that the desired design of a flat light reflector is generally simpler than that of a focused light reflector. The lens 650 can be made of any material well known in the art. 'But not limited to glass or quartz glass. 5 Figure 8 illustrates a device 10 in another preferred embodiment, including a plurality of coatings. Thus, as explained above, The light-emitting element 201 can include an anti-reflective coating 32A on the front facet 210 and a highly reflective coating 719 on the back facet 269 that can be formed of a multi-layer dielectric structure. In a particular embodiment An additional highly reflective coating 714 acts as a light reflector. Alternatively, the coating 714 can be formed on the light reflector 214 or 614. The thickness, shape and number of layers of the coating 714 are preferably designed to aid The selective reflection, absorption and/or transmission characteristics of the coating 714. In particular, the coating 714 preferably provides high reflectivity and low loss of the substantially transverse mode (211, 511 or 651), as well as for the converted light 215. High transmission coefficient and low loss, and high loss for high-order non-15 required modes. It will be appreciated that the scope of the invention is intended to include all combinations of the above coatings. For example, in some embodiments, one or more coatings can be independently a single layer or a multilayer coating. Moreover, in other embodiments, the coating 714 can include a coating 320 and/or a coating 319. 20 The use of a multilayer structure for the coating allows the selection of the constituent materials to move the spectral position of the narrow stop band in response to temperature changes in the same manner as the spectral position of the maximum efficiency of the optical frequency conversion of the NLO crystal. This allows for an extremely high temperature stability of the frequency conversion efficiency of the device 10. Coatings 714 and 719 can be constructed of any of the well-known materials to have 37 1289220 4 inch 疋 reflection, absorption and/or transmission characteristics such as, but not limited to, alternating dielectric material deposits, for example, Si〇. 2. MgF2, or ZnS. According to another aspect of the present invention, a method of converting the frequency of light is provided. The method includes the following method steps, as shown in the flow chart of Figure 5 in Figure 9. Therefore, in a first step, represented by a block 8 〇 2, a light having a first frequency is emitted from a light-emitting element, and the light-emitting element may be, for example, the light-emitting element 201 or the light-emitting element 401, as described above. Detailed description. In a second step, represented by block 804, a light reflector is used 10 to allow light to pass through the NL〇 crystal multiple times in an outer chamber, wherein the outer chamber, for example, can be designed as an external chamber 212 or external chamber 512, and the NLO crystal can be any well-known NLO crystal having suitable light-converting characteristics, such as NLO crystal 213 with or without coating 260 as further detailed above. The light is passed through the outer chamber for 15 more times, providing a feedback system sufficient to produce laser light having a first frequency. In a third step, represented by block 806, the laser light having the first frequency passes through the nonlinear optical crystal several times. The nonlinear optical crystal converts the first frequency of the laser light into a second frequency that is different from the first frequency. In accordance with a preferred embodiment of the present invention, the light reflector can be a 20-light reflector 214, 614, 714 or any light reflector similar thereto. Additionally and preferably, the photoreflector can be coated with a single layer coating or a multiple coating, as described in further detail above. Optionally, the method can further include an additional step, represented by block 808, wherein a lens, such as lens 650, is used to transform a weakly divergent beam into a parallel beam. 38 1289220 In accordance with an additional aspect of the present invention, a method of fabricating a device for frequency conversion of light is provided. Figure 10 is a flow diagram of the method steps of the method, wherein in a first step, represented by block 902, a light-emitting element, such as a light-emitting element 201 or a light-emitting element 401, is provided. In a second step, represented by block 904, a light reflector is provided and disposed opposite the light emitting element, and in a third step, represented by block 906, between the light emitting element and the light reflector. An NLO crystal is provided and configured in an external chamber. According to a preferred embodiment of the present invention, the light-emitting element, the light 10 reflector and the nonlinear optical crystal are constructed and designed, so that the light passes through the NLO crystal several times and is fed back for generating a one having a converted frequency. Laser light, as further detailed above. It is to be understood that the features of the invention, which are described in the context of a particular embodiment, may also be provided in combination in a single embodiment. Conversely, for the sake of brevity, the various features of the present invention in a single-body, sinuous context can also be provided separately or in any suitable sub-combination. The present invention has been described in connection with the specific embodiments thereof, and it is apparent that a plurality of alternatives, modifications, and variations are obvious to those skilled in the art. Therefore, this issue, . All 4 alternatives, modifications, and variations of the person, 2 are included in the spirit of the patent scope and the scope of the patent. All the publications, patents and special shots mentioned in this article are cited in the Wang Wen cited method and the reference manual. The referenced 39 3989220 degrees is as if individually and specifically Individual publications, patents, or patent applications are incorporated by reference in their entirety. In addition, the citation or confirmation of any of the references in this application should not be construed as a reference to the prior art. 5 [Simple description of the loop] The first diagram is a schematic view of a prior art vertical resonance surface-emitting laser (VCSEL); the lb diagram is a schematic view of a prior art edge-emitting laser; 2 is a schematic view of a prior art vertical cavity surface-emitting laser 10 (VCSEL) type frequency conversion device; FIG. 3 is a schematic view of a device for light frequency conversion of the present invention; Figure 1 is a schematic view of a device for frequency conversion of the present invention, comprising an anti-reflective coating and a highly reflective coating formed on different facets of a luminescent element 15; Figure 5 is a A schematic view of a device for frequency conversion, wherein the light-emitting element comprises a photonic grooved crystal; and FIG. 6 is a schematic diagram of a device for frequency conversion of the present invention, wherein a leaky laser system is used for generating Main light; 20 Figure 7 is a schematic diagram of a device for frequency conversion of the present invention, comprising a lens for providing a parallel beam and a flat light reflector; Figure 8 is the invention One for frequency transfer A schematic diagram of an apparatus comprising an additional multilayer coating on a light-emitting element and a light reflector; 40 1289220 Figure 9 is a flow diagram of a method of converting light frequencies of the present invention; and Figure 10 A flow chart of a method of fabricating a device for frequency conversion of the present invention. 5 [Main component representative symbol table of the drawing] 10...device 210...front facet 101"_VCSEL type structure 214, 614...light reflector 102, 202...substrate 216 ···!!-contact 103...distributed Prague Mirrors 217...p-contacts 104...semiconductor chambers 218... forward biases 106··active regions 220...ρ-emitters 109··external laser beams 260...the directional mirrors 111, 115, 211, 215...Laser light 269...Back facets 112,212,512...External chamber 319...Highly reflective coating 113,213...NLO Crystal 320...Anti-reflective coating 114...External mirror 420...Absorption layer 201, 401...Light-emitting element 430 ...photonic bandgap crystals 203, 230 ... η - emitter 431 ... period / first layer 204 ... extended waveguide 432 ... defect 205 ... first waveguide region 433 ... η - side 206 , 434 · active region 435 ... ρ - side 207 ... second waveguide region 440 ... waveguide 208 " ρ - doped layer 511 , 541 ... path 209 · · · ρ + doped layer 515 ... converted light 41 1289220 539 · · · first part 540···Second part 611···Weak divergent beam 650...Lens 651···Parallel light Highly reflective coating 714, 719 ...
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