200917600 九、發明說明： 【發明所屬之技術領域】 本發明係提供一種高效率'高穩定性之諧波產生裝置 及轉換裝置，其使從雷射共振器或其放大器所輸出之雷射 光束’朝具有形成周期性極化構造之化學計量比組成之波 長轉換用非線形結晶的周期性極化構造之周期方向射入， 於傳播方向產生與基本波不同波長之雷射光。 【先前技術】 在電子工業中，隨著DRAM、SRAM等之微細化進程 每年都在不斷地發展，內部之電路的光積體化正受到期 待。另外’亦期望能在資訊記錄領域進行高密度的記錄。 因應於該等高積體化、高密度化及微細化，在雷射加工、 表面檢查等雷射應用裝置中，期望能進行雷射光束之連續 輸出及短波長化，並亦需要能長時間保持穩定性。表示光 束之聚光性品質度的M2參數亦被要求趨近於1 (其係單一橫 向模態之値）。另外，報告有一種諧波產生裝置，其係在短 波長雷射之振盪上，利用非線形光學結晶，並於雷射光路 上設置非線形性單結晶以獲得諧波成份，再藉由對非線形 光學結晶強制性地施加電場以設置空間性之周期構造的極 化，而形成周期性極化非線形結晶，再於周期構造之周期 方向形成光的導波路，並從外部將雷射光束導入導波路， 隨著雷射光束於導波路進行傳播而將射入光束轉換爲諧 波。 該等裝置之波長轉換效率，在脈衝雷射中，因其波峰 200917600 功率高’故容易出現非線形現象，可實現高轉換效率。但 是’來自連續振盪輸出之波長轉換效率仍處於較低之狀 態。因此’在以往所提案的第2諧波產生裝置或光參變振 盪器中’係在連續雷射輸出光路上形成共振器，並以與基 本波之射入光束產生共振之方式，由壓電元件等控制共振 器之長度’以設置於共振器內之非線形光學元件來轉換波 長。但是’此構成亦伴隨有在基本波光束用以控制成共振 器內之傳播光束的相位共鳴狀態之控制系的複雜性，因 此，對穩定性之確保具有困難性。 [專利文獻1]美國專利第665 43 92號說明書 [專利文獻2]美國專利第5 800767號說明書 [專利文獻3]美國專利第5 8 3 84 8 6號說明書 [專利文獻4]日本國特開平1 1-212127號公報 [專利文獻5 ] 口本國特開2 0 0 4 - 1 9 1 9 6 3號公報 [專利文獻6 ]日本國特開2 〇 〇 3 - 1 5 1 7 6號公報 [專利文獻7]日本國特開Μ0 5 - 1 5 02 5 2號公報 【發明內容】 (發明所欲解決之課題） 所欲解決之問題點，係在雷射裝置之諧波產生裝置或 波長轉換裝置中，可達成高轉換效率、構造之簡單化及輸 (解決課題用之手段） 爲了解決上述課題’本發明採用如下之構成。 一種雷射光第2譜波產生裝置’其包含有：雷射光源’ 200917600 用以產生基本波成分之雷射光；有周期性之極化構造的非 線形光學結晶’係將該基本波成分之雷射光轉換爲第2諧 波者’其具有相互對向之第1及第2端面，而在與該第1 及第2端面垂直之軸方向具有周期方向，在與該軸方向垂 直之方向上具有極化分向；聚光光學系，係用以對該基本 波成分之雷射光進行聚光，並使之射入該非線形光學結 晶；反射光學系，係將自第2端面放射且在該非線形結晶 內產生之第2諧波成分與該基本波成分的混合光束，通過 第2端面並返回該非線形結晶內；及分光器，係在通過該 非線形結晶內之往返光路後，從第1端面輸出之該第2諧 波成分及未進行波長轉換的該基本波成分中至少取出該第 2諧波成分的雷射光束。 藉由通過該非線形結晶內之往返光路，使雷射光產生 之發熱達到均一化，並在非線形光學結晶內使溫度分布達 到均一化，所以，可在長度方向以相同條件維持波長轉換 整合條件。因此，具有可達成對諧波之轉換效率的高效率 化及穩定化、裝置小型化的效果。 另外，其特徵爲：在該雷射光源與該非線形光學結晶 之間設置光隔離器。藉由設置光隔離器’可讓通過之振盪 光束從設置於其後之光學系反射而成爲折回光線’具有不 致於發牛.進入雷射光源而對振盪光束帶來千擾的情況之效 果。 另外，其特徵爲：設置溫度調節手段’用以穩定該非 線形光學結晶之溫度。又’其特徵爲：使該非線形光學結 200917600 晶內之往返光路同軸。另外’其特徵爲：該非線形光學結 晶係摻雜了具有周期性之極化構造的Mg0或ZnO之 PPLT(periodically poled LiTa03 :被周期性極化之鉅酸鋰）、 PPSLT(periodically poled stoichiometric LiTa03:被周期 性極化之化學計量比担酸錐）、PPLN(peri〇dically poled LiNb03 :被周期性極化之鈮酸鋰）、或PPSLN(periodically ρ ο 1 e d s t 〇 i c h i 0 m e t r i c L i N b Ο 3 :被周期性極化之化學計量比 鈮酸鋰）。 另外’其k徵爲·該雷射光源係產生連續振邊光之雷 射光源。藉由雷射光源係產生連續波，即使在連續波時， 仍可產生高效率及穩定性之第2諧波。 另外’其特徵爲：該雷射光源係輸出單一波長光譜之 振盪光的光纖雷射振盪器或光纖放大器。另外，其特徵爲： 該連續振盪光之波長係7 〇 〇 n m以上、1 1 0 0 n m以下的單一波 長 ° 另外’其特徵爲：該非線形光學結晶具有導波路構造。 藉由設置導波路構造，封入導波路內之基本波光束可維持 高強度地在非線形光學結晶內傳播，以增加相互作用長 度，所以，可更進一步地達成對諧波之轉換效率的高效率 化及穩定性。 另一方面，本發明之雷射光波長轉換裝置、係將彳足雷 射光源產生之基本波成分之雷射光轉換爲第2諧波的_ 置，其包含有：有周期性之極化構造的非線形光學結晶， 係將該基本波成分之雷射光轉換爲第2諧波者，其具有牛目 200917600 互對向之第1及第2端面，而在與該第1及第2端面垂直 之軸方向具有周期方向，在與該軸方向垂直之方向上具有 極化分向；聚光光學系，係用以對該基本波成分之雷射光 進行聚光，並使之射入該非線形光學結晶；反射光學系， 係將自第2端面放射且在該非線形結晶所產生之第2諧波 成分與該基本波成分的混合光束，通過第2端面並返回該 非線形結晶；及分光器’係在通過該非線形結晶內之往返 光路後’從第1端面所輸出之該第2諧波成分及未進行波 長轉換的該基本波成分中至少取出該第2諧波成分的雷射 光束。藉由於該非線形結晶內之往返光路中通過，而使雷 射光產生之發熱達到均一化’並在非線形光學結晶內使溫 度分布達到均一化’所以’波長轉換整合條件可在長度方 向被以相同條件維持。因此，具有可達成對諧波之轉換效 率的高效率化及穩定化、裝置小型化的效果。 另外’其特徵爲：該非線形光學結晶係摻雜了具有周 期性之極化構造的MgO或ZnO之PPLT(periodicallypoled LiTa03 :被周期性極化之钽酸鋰）、PPSLT(peri〇dically poled stoichiometric LiTa03 :被周期性極化之化學計量比 鉅酸鋰）、PPLN(periodically poled LiNb03:被周期性極化 之銳酸錐）、或 PPSLN(periodically poled stoichiometric LiNbOi :被周期性極化之化學計量比鈮酸鋰）。 (發明效果） 在本發明之雷射光第2諧波產生裝置或雷射光波長轉 換裝置中’具有可達成對諧波之轉換效率的高效率化及穩 -10- 200917600 定性，並可實現裝置之小型化的效果。 【實施方式】 弟10顯不本發明之實施形態。以雷射光源1係連續 振盪雷射者爲宜。從雷射光源1輸出具有轉換爲諧波用之 基本波波長的雷射光。 在設雷射光源1爲連續振盪的情況，可使用如第2圖 所示之構成。在第2a圖中’使來自控制振盪波長之分布還 原型（DFB)雷射30的振盪輸出射入放大光纖32。在放大光 纖32上耦合有來自激勵用之雷射二極體31的激勵功率。 由此放大光纖所放大之輸出功率33係可用作爲接受波長 轉換之基本波雷射光源。 爲了使連續振盪光纖雷射之輸出偏光於明確的方向， 利用使發射雷射輸出之光纖本身具備偏光輸出及偏光保存 的功能，便可實現，在使用此構件之構成中，可採用第2 b 圖所示構造。將用作爲波長選擇之反射元件的布拉格光 柵，在放大光纖38之兩端附近35,36的至少一方之位置上 形成一個以上，並將來自激勵用之雷射二極體37的激勵功 率耦合於放大光纖3 8。以由布拉格光柵所決定之振盪波 長，連續地使輸出功率39振盪。亦可依需要另外使用放大 用光纖（未圖示），以圖謀功率之放大。此等之放大光纖32 及38，偏好於使用添加有Yb之光纖。波長可從至 1 1 0 0 n m的範圍中選出。 基本波光束之產生係可使用以具有波長可變特性之摻 鈦藍寶石結晶作爲增益媒介的雷射光源及放人器。爲了藉 -11- 200917600 由非線型光學結晶來實現高效率波長轉換，可知以光束品 質高者爲較佳’在具有單頻光譜之情況，可獲得最大之轉 換效率。振盪波長係可在700nm至l〇〇〇nrn的範圍內變化。 當然，在以脈衝模式使該等之光源動作的情況，亦可藉由 周期性極化反轉非線型結晶，獲得高波長轉換效率。 來自雷射光源1之輸出光束9係射入光隔離器2。雖 可不設光隔離器2，但爲了不致產生當通過之振盪光束從 設於其後之光學系反射而成爲回返光，並射入雷射光源1 而干擾振盪光束的情況，還是設置光隔離器2較佳。通過 光隔離器2之振盪光束10，係藉由2分之1波長板3而控 制振盪光束1 〇之直線偏光方向而成爲光束Π。2分之1波 長板3係爲了使形成在設於其後之被周期性極化的非線型 光學結晶6上的往返光路對準於規定偏光方向而被設置。 在被周期性極化的非線型光學結晶6，在垂直於紙面的方 向上形成有極化方向的情況，爲了以最大效率產生非線型 光學作用’偏光方向係如雙圓之圖示，有需要規定是垂直 於紙面的方向、亦即偏光方向與極化方向需規定爲平行。 第3圖中顯示了此種關係。非線型光學結晶6之光束的行 進方向5 1 ’係與極化之周期方向5 2平行’偏光方向6 1係 與極化方向62平行。基本波光束係通過相對於光路呈4 5 度傾斜的分光器4’並爲了形成微細之聚光點而由聚光透 鏡5進行聚光。 在非線型光學結晶6內形成有導波路的情況，聚光點 係形成於非線型光學結晶6之大致第1端面6 - 1上，而被 -1 2 - 200917600 封閉在導波路內之基本波光束’係維持高強度而於非線型 光學結晶6內進行傳播。於此導波路內進行基本波傳播之 期間，基本波成份之一部分一面轉換成第2諧波，一面朝 向非線型光學結晶6之第2端面6-2。從第2端面6-2朝空 間放射出作爲散發性光束之基本波成份及第2諧波成份。 由凹面反射鏡等之反射光學系8反射散發性光束而使其返 回非線型光學結晶6之第2端面6 - 2。反射光學系8之反射 特性’係相對於基本波及第2諧波的二個波長具有高反射 特性者。在形成有導波路之情況’在使用凹面反射鏡作爲 反射光學系8時’以設其曲率半徑爲非線型光學結晶6之 第2端面6-2的散發性光束之放射點與該凹面反射鏡之反 射面的距離的方式進行選擇，有效地進行返回非線型光學 結晶6內之導波路的反射。在使用無導波路之非線型光學 結晶的情況，以基本波在結晶之中央附近具有聚光點的方 式，配置聚光透鏡5及反射光學系8。 該非線形光學結晶係以摻雜了具有周期性之極化構造 的 MgO 或 ZnO 之 PPLT(periodically poled LiTa03 :被周期 性極化之钽酸鋰）、PPSLT(periodic ally poled stoichiometric LiTa03 :被周期性極化之化學計量比钽酸鋰）、PPLN (p e r i 〇 d i c a 11 y ρ ο 1 e d L i N b Ο 3 :被周期性極化之鈮酸鋰）、或 PPSLNiperiodically poled stoichiometric LiNb03 :被周期 性極化之化學計量比鈮酸鋰）者爲較佳。 在非線形光學結晶爲MgO : PPSLT或MgO : PPSLN的 情況’其大部分在第2諧波之波長比5 3 2 nm(綠光）等還短 200917600 的波長的情況’顯示以此光作爲媒介來吸收基本波之功率 的作用。因此，在如習知技術般以單一光路徑構成光學性 配置的情況’非線形結晶之射入端面側與射出端面側的光 束內吸收功率相異，而於結晶之光軸方向產生溫度分布。 此情況成爲被排除在溫度相位整合條件以外之原因，使得 波長轉換效率降低。非線形結晶內之溫度係使用屬習知技 術的電子冷卻（ETC)技術或加熱器，而可將溫度範圍控制在 ±0.1的程度。 f 經過往返光路而從第1端面輸出端面6-1輸出之含有 第2諧波成份及未進行波長轉換的基本波之光束1 6，再次 通過聚光鏡5而成平行光束17，並藉由以高反射率反射之 分光器4，選擇性地至少將第2諧波成份從基本波成份中 進行分離反射，而被取出至外部作爲諧波光束1 8，此光束 供給於目的之用途。基本波成份係通過分光器4，並在設 置光隔離器2的情況，以藉由光隔離器2而使雷射光源1 不會返回的方式，在內部作爲偏光方向之不同成份被排除。 ^ ' 以在此所改良之往返光束通過方法而言，沿非線型光 學結晶6之各長度方向的每一處之伴隨光吸收的發熱量係 因往返光路而被平均化，所以形成均勻之溫度分布。亦即， 在第1端面6-1之附近，射入之基本波光束強，而轉換光 束弱，fR.在返回光束中，基本波光束弱，而轉換光束變強， 另一方面，第2端面6-2之附近的發熱量，在射入方向上， 伴隨第2諧波成份之增加，其基本波成份減少，在返回光 中亦相同。依場所而由各波長成份所產生之吸收引起的發 -14- 200917600 熱’在導波路全區域中被均一化。藉此，被周期 非線型光學結晶內的溫度分布被均一化，所以， 整合條件可在長度方向被以相同條件維持，因此 周期性極化之非線型光學結晶全長，進行高效率 換。此方法與習知僅通過一個方向的方法相較， 其溫度分布之均一化極爲穩定，而且容易實現， 效率化、輸出穩疋化'裝置構成之容易度而獲得 的經濟效果等，與由習知單一光路徑所構成之構 顯現出極大之效果。利用將往返路徑設於同軸位 溫度分布亦成爲问心圓狀之分布，在光束之穩定 顯示其效果。 又，在第1圖之例中，雖採用利用凹面鏡作 學系8而於非線型光學結晶6之第2端面6-2進 返回的構成，但亦可取代此而改由凸透鏡或平 成。此情況係以使其焦點位置與（導波路）第2端面 的方式來配置用以使光束平行之凸透鏡，再設置 由凸透鏡所平行整理之光束的反射鏡。另外，即 源1不是連續振盪雷射，而是應用脈衝雷射或波 射，亦可獲得很好的效果。 [實施例] 採用MgO: PPST.T作爲非線形光學結晶，並 度（第1端面至第2端面間的長度）爲4〇 mm。採用 第2諧波產生裝置的構成，獲得單頻、單一模態 532nm之雷射輸出3.7W，其中該桌皆波產生裝 性極化之 波長轉換 ，可於被 之波長轉 明顯可知 因高轉換 之成本面 造比較， 置上，其 性方面亦 爲反射光 行反射並 面鏡所構 6-2 —致 用以反射 使雷射光 長可變雷 設結晶長 本發明之 、波長爲 置係將來 200917600 自單一模態之光纖雷射及由其放大器之構成所產生的輸出 功率爲9.4W、基本波之波長設爲1064nm的單頻的雷射光 源之雷射光，射入往返光路。對第2諧波之轉換效率，以 光功率轉換效率而言爲3 9 %。因此，在連續振盪輸出之波 長轉換效率上，可獲得高的値。 當實際使用M2測量儀並以M2値來測定上述構成之第 2諧波的光束品質時，可獲得X方向之Μ2=1·12、y方向之 M2 = 1 . 1 3。在僅通過單一光路之情況的轉換功率低的條件 下，是X方向之M2=1.23、y方向之M2=1.19的値。因此， x，y方向之M2均是在使用往返光路之本發明時，可獲得高 品質之第2諧波，而且可實現高轉換效率。 根據本發明’提供一種雷射波長轉換裝置，其將從光 纖雷射放射出之雷射光束，利用具有在摻雜有MgO或ZnO 之P P L T，P P S L T，P P L N或P P S L N等的被周期性極化之非線 型光學結晶形成往返光路，從射入端面導入基本波雷射光 束’並使被波長轉換後之諧波以相同端面作爲輸出端面的 構成’以圖謀雷射光束之轉換效率的高效率化及穩定性、 裝置之小型化，可獲得實用之諧波的連續振盪光束。 在本發明之波長轉換裝置中’在被周期性極化之非線 型光學結晶的導波路形成往返光路，可使連續振盪之雷射 光束’以高效率獲得波長轉換連續振盪輸出。與習知爲了 獲得短波長連續雷射，需要使用氪或氬之離子氣體雷射的 大電力驅動之短波長雷射振盪器比較，可大幅提高電力效 率’更可實現裝置之小型化，可廣泛地應用於使用短波長 -16- 200917600 之連續振盪輸出的雷射微細加工、微細圖案曝光、高精度 微細檢查、高密度資訊記錄等之雷射應用。 以上，說明了本發明之數個實施例。顯然本發明只要 未脫離其申請專利範圍所記載之發明的技術思想，即可以 實施變更。 (產業上之可利用性） 作爲本發明之應用例，因爲利用第2諧波之短波長且 高效率，以獲得連續振盪之基本波輸出，所以，可應用於 雷射微細加工裝置、半導體記億體之矽晶圓冗長性電路的 導電性線路之電子元件的切斷、及其他之多層構造電子元 件的層內部之除去切斷、液晶顯示面板或電漿顯示裝置的 瑕疵修正、形成於基板表面之電容、電阻、電感等的修剪、 電路基板之功能修剪、其他半導體基板之雷射精密加工、 D V D原盤製作、矽晶圓瑕疵檢查、光微影用之交叉線瑕疵 檢查等。其可以連續振盪實現高效率波長轉換，因習知利 用脈衝輸出所進行的作用’可以連續輸出來實施，所以， 因能有效利用作業效率提升、且可簡單地進行微小瑕疵檢 查等的優點’故對可實現習知需要改良之點的貢獻極大。 【圖式簡單說明】 第1圖爲本發明之諧波產生裝置的說明圖。 第2圖爲在本發明中作爲雷射光源而被使用之產生高 品質光束的光纖雷射及光纖放大裝置的例示圖。 第3圖爲具有周期性極化之非線型光學結晶的周期方 向、極化方向、偏光方向、光束行進方向的關係之示意圖。 200917600 【主要元件符號說明】 1 雷射光源 2 光隔離器 3 2分之1波長板 4 分光器 5 聚光透鏡 6 非線型光學結晶 6-1 (非線型光學結^ 6-2 第2端面 8 反射光學系 9 輸出光束 10 振盪光束 11 光束 16 含有第2諧波 成份之光束 17 平行光束 18 諧波光束 30 DFB雷射 32, 3 8 放大光纖 33, 3 9 輸出功率 35, 3 6 布拉格光柵 31， 3 7 激勵用雷射二桓 5 1 光束的行進方向 52 (極化之）周期方 6 1 偏光方向 62 極化方向 體 向 晶之）第1端面 成份及未進行波長轉換的基本波 -18-200917600 IX. Description of the Invention: [Technical Field] The present invention provides a high-efficiency 'high-stability harmonic generation device and conversion device that enables a laser beam output from a laser resonator or its amplifier' The periodic polarization structure of the nonlinear crystal for wavelength conversion having a stoichiometric composition forming a periodic polarization structure is incident in a periodic direction, and laser light having a wavelength different from the fundamental wave is generated in the propagation direction. [Prior Art] In the electronics industry, as the miniaturization process of DRAM, SRAM, etc. continues to develop every year, the integration of internal circuits is expected. In addition, it is expected to have a high-density record in the field of information recording. In order to achieve high integration, high density, and miniaturization, it is desirable to be able to perform continuous output and short wavelength of laser beams in laser applications such as laser processing and surface inspection. Maintain stability. The M2 parameter indicating the condensing quality of the beam is also required to approach 1 (which is the 横 of a single transverse mode). In addition, it is reported that there is a harmonic generating device which is based on the oscillation of a short-wavelength laser, uses non-linear optical crystallization, and provides a nonlinear single crystal on the laser beam to obtain harmonic components, and is forced by nonlinear optical crystallization. The electric field is applied to set the polarization of the periodic structure of the space, and the periodically polarized non-linear crystal is formed, and the waveguide of the light is formed in the periodic direction of the periodic structure, and the laser beam is externally guided into the waveguide. The laser beam propagates through the waveguide to convert the incident beam into a harmonic. The wavelength conversion efficiency of these devices is prone to non-linear phenomena in pulsed lasers due to their high peak power of 200917600, which enables high conversion efficiency. However, the wavelength conversion efficiency from the continuous oscillation output is still low. Therefore, 'in the second harmonic generating device or the optical parametric oscillator proposed in the past, a resonator is formed on the continuous laser output optical path, and the piezoelectric wave is resonated with the incident light beam of the fundamental wave. The element or the like controls the length of the resonator to convert the wavelength with a non-linear optical element disposed in the resonator. However, this configuration is accompanied by the complexity of the control system for controlling the phase resonance state of the propagating beam in the resonator in the fundamental wave beam, and therefore, it is difficult to secure stability. [Patent Document 1] US Patent No. 665 43 92 [Patent Document 2] US Patent No. 5 800767 Specification [Patent Document 3] US Patent No. 5 8 3 84 8 6 Specification [Patent Document 4] Japanese Special Kaiping Japanese Unexamined Patent Publication No. Hei No. Hei No. Hei 2 - No. 2 - No. 2 - 1 1 1 1 1 [Patent Document 7] Japanese Patent Laid-Open Publication No. Hei 0-5 - 1 5 02 5 2 [Summary of the Invention] (Problems to be Solved by the Invention) The problem to be solved is a harmonic generation device or wavelength conversion of a laser device In the device, high conversion efficiency, simplification of structure, and transmission (method for solving problems) can be achieved. In order to solve the above problems, the present invention adopts the following configuration. A laser light second spectrum generating device includes: a laser source '200917600 for generating a fundamental wave component; a nonlinear optical crystal having a periodic polarization structure' is a laser beam of the fundamental wave component The second harmonic is converted to have first and second end faces facing each other, and has a periodic direction in an axial direction perpendicular to the first and second end faces, and a pole in a direction perpendicular to the axial direction. a concentrating optical system for concentrating the laser light of the fundamental wave component and causing it to be incident into the nonlinear optical crystal; the reflective optical system radiating from the second end face and in the nonlinear crystal a mixed light beam of the second harmonic component generated in the ground and the fundamental wave component is returned to the nonlinear crystal through the second end surface; and the spectroscope is outputted from the first end surface after passing through the round-trip optical path in the nonlinear crystal At least the laser beam of the second harmonic component is extracted from the second harmonic component and the fundamental wave component not subjected to wavelength conversion. By passing the round-trip optical path in the nonlinear crystal, the heat generated by the laser light is made uniform, and the temperature distribution is made uniform in the nonlinear optical crystal. Therefore, the wavelength conversion integration condition can be maintained under the same conditions in the longitudinal direction. Therefore, it is possible to achieve high efficiency and stabilization of harmonic conversion efficiency and miniaturization of the device. Further, it is characterized in that an optical isolator is disposed between the laser light source and the non-linear optical crystal. By providing the optical isolator, the oscillating light beam passing through it can be reflected as a folded light from the optical system disposed behind, and has the effect of not causing a rush to enter the laser light source and causing disturbance to the oscillating light beam. Further, it is characterized in that a temperature adjusting means is provided for stabilizing the temperature of the nonlinear optical crystal. Further, it is characterized in that the non-linear optical junction 200917600 is coaxial with the round-trip optical path. In addition, the non-linear optical crystal system is doped with PPLT (periodically poled LiTa03: periodically polarized lithium acid) having a periodic polarization structure, and PPSLT (periodically poled stoichiometric LiTa03: a stoichiometric ratio of periodically polarized acid cones, PPLN (peridically poled LiNb03: periodically poled lithium niobate), or PPSLN (periodically ρ ο 1 edst 〇ichi 0 metric L i N b Ο 3: stoichiometrically stoichiometric ratio lithium niobate). Further, the k-signal is a laser light source that generates continuous vibration light. By generating a continuous wave by a laser light source, even in the case of a continuous wave, a second harmonic with high efficiency and stability can be produced. Further, the laser light source is a fiber laser oscillator or an optical fiber amplifier that outputs oscillating light of a single wavelength spectrum. Further, the continuous oscillation light has a wavelength of 7 〇 〇 n m or more and a single wavelength of 1 1 0 0 n m or less. Further, the nonlinear optical crystal has a waveguide structure. By providing the waveguide structure, the fundamental wave beam enclosed in the waveguide can be propagated in the nonlinear optical crystal with high intensity to increase the interaction length, so that the efficiency of conversion of harmonics can be further improved. And stability. On the other hand, the laser light wavelength conversion device of the present invention converts the laser light of the fundamental wave component generated by the laser light source into the second harmonic, which includes a periodic polarization structure. a non-linear optical crystal which converts the laser light of the fundamental wave component into a second harmonic, and has the first and second end faces of the bulls 200917600 facing each other, and the axis perpendicular to the first and second end faces The direction has a periodic direction, and has a polarization direction in a direction perpendicular to the axis direction; the concentrating optical system is configured to condense the laser light of the fundamental wave component and inject the nonlinear light into the nonlinear optical crystal; In the reflective optical system, the mixed light beam emitted from the second end surface and the second harmonic component generated by the nonlinear crystal and the fundamental wave component passes through the second end surface and returns to the nonlinear crystal; and the spectroscope is passed through After the round-trip optical path in the nonlinear crystal, the second harmonic component output from the first end face and the fundamental wave component not subjected to wavelength conversion are at least the laser beam of the second harmonic component. By the passage of the round-trip optical path in the nonlinear crystal, the heat generated by the laser light is uniformized and the temperature distribution is uniformed in the nonlinear optical crystal. Therefore, the wavelength conversion integration condition can be the same in the length direction. maintain. Therefore, it is possible to achieve an effect of increasing the efficiency and stability of the conversion efficiency of harmonics and miniaturizing the device. In addition, it is characterized in that the non-linear optical crystal system is doped with PPOT (periodically polled LiTa03: periodically poled lithium niobate) having a periodic polarization structure, and PPSLT (peri〇dically poled stoichiometric LiTa03) : stoichiometrically stoichiometric ratio lithium acid), PPLN (periodically poled LiNb03: periodically polarized sharp acid cone), or PPSLN (periodically poled stoichiometric LiNbOi: stoichiometric ratio by periodic polarization Lithium acid). (Effect of the Invention) In the laser light second harmonic generating device or the laser light wavelength converting device of the present invention, "the efficiency of converting the harmonics can be achieved, and the stability is stabilized, and the device can be realized. Miniaturized effect. [Embodiment] The younger brother 10 does not show an embodiment of the present invention. It is advisable to use a laser source 1 to continuously oscillate a laser. Laser light having a fundamental wavelength converted to harmonics is output from the laser light source 1. In the case where the laser light source 1 is continuously oscillated, the configuration as shown in Fig. 2 can be used. In Fig. 2a, the oscillating output from the distribution reductive (DFB) laser 30 controlling the oscillation wavelength is incident on the amplifying fiber 32. The excitation power from the excitation laser diode 31 is coupled to the amplification fiber 32. The amplified output power 33 of the amplifying fiber is thus used as a basic wave laser source that accepts wavelength conversion. In order to polarize the output of the continuously oscillating fiber laser in a clear direction, the optical fiber itself that emits the laser output has the functions of polarized output and polarization preservation, and the second b b can be used in the construction of the member. The structure shown in the figure. A Bragg grating serving as a wavelength selective reflection element is formed at least one position near the both ends 35, 36 of the amplifying fiber 38, and the excitation power from the excitation laser diode 37 is coupled to Amplify the fiber 3 8 . The output power 39 is continuously oscillated by the oscillation wavelength determined by the Bragg grating. Amplifying fiber (not shown) can also be used as needed to enlarge the power. These amplifying fibers 32 and 38 prefer to use Yb-added fibers. The wavelength can be selected from the range of up to 1 1 0 0 n m. The generation of the fundamental wave beam can use a laser light source and a discharge device using a titanium-doped sapphire crystal having a wavelength-variable characteristic as a gain medium. In order to achieve high-efficiency wavelength conversion by non-linear optical crystallization by -11-200917600, it is known that the highest beam quality is preferable. In the case of having a single-frequency spectrum, the maximum conversion efficiency can be obtained. The oscillation wavelength can vary from 700 nm to 10 nm. Of course, in the case where the light sources are operated in the pulse mode, the nonlinear crystallization can be reversed by periodic polarization to obtain high wavelength conversion efficiency. The output beam 9 from the laser source 1 is incident on the optical isolator 2. Although the optical isolator 2 may not be provided, in order to prevent the oscillating light beam from being reflected by the optical system disposed behind and returning to the laser light source 1 to interfere with the oscillating light beam, or to provide an optical isolator 2 is preferred. The oscillating beam 10 passing through the optical isolator 2 is controlled by the one-half of the wavelength plate 3 to control the linearly polarized direction of the oscillating beam 1 而 to become the beam Π. One-half of the long-wavelength plate 3 is provided in order to align the round-trip optical path formed on the periodically-polarized nonlinear optical crystal 6 disposed in the predetermined polarization direction. In the case where the nonlinear optical crystal 6 which is periodically polarized is formed with a polarization direction in a direction perpendicular to the plane of the paper, in order to generate a nonlinear optical effect with maximum efficiency, a polarization direction such as a double circle is required. The regulation is that the direction perpendicular to the paper surface, that is, the polarization direction and the polarization direction are defined to be parallel. This relationship is shown in Figure 3. The traveling direction 5 1 ' of the light beam of the nonlinear optical crystal 6 is parallel to the periodic direction 5 2 of the polarization. The polarizing direction 6 1 is parallel to the polarization direction 62. The fundamental wave beam is condensed by the condensing lens 5 through a beam splitter 4' which is inclined at 45 degrees with respect to the optical path and in order to form a fine condensed spot. When a waveguide is formed in the nonlinear optical crystal 6, the light-converging point is formed on the substantially first end face 6-1 of the nonlinear optical crystal 6, and the fundamental wave enclosed in the waveguide by -1 2 - 200917600 The beam 'transmits in the nonlinear optical crystal 6 while maintaining high intensity. While the fundamental wave propagates in the waveguide, one of the fundamental wave components is converted into the second harmonic, and faces the second end face 6-2 of the nonlinear optical crystal 6. The fundamental wave component and the second harmonic component which are the emitted light beams are emitted from the second end face 6-2 toward the space. The diffused light beam is reflected by the reflective optical system 8 such as a concave mirror to return to the second end face 6-2 of the nonlinear optical crystal 6. The reflection characteristic of the reflection optical system 8 is a high reflection characteristic with respect to two wavelengths of the fundamental wave and the second harmonic. In the case where a waveguide is formed, 'when a concave mirror is used as the reflection optical system 8', a radiation beam having a radius of curvature of the second end face 6-2 of the nonlinear optical crystal 6 is formed and the concave mirror is formed. The distance of the reflecting surface is selected so that the reflection of the waveguide in the nonlinear optical crystal 6 is efficiently returned. In the case of using a nonlinear optical crystal having no waveguide, the condensing lens 5 and the reflection optical system 8 are disposed in such a manner that the fundamental wave has a condensed spot near the center of the crystal. The non-linear optical crystal is PPLT (periodically poled LiTa03: periodically poled lithium niobate) doped with a periodic polarization structure, and PPSLT (periodic ally poled stoichiometric LiTa03: periodic pole Stoichiometric ratio lithium niobate), PPLN (peri 〇dica 11 y ρ ο 1 ed L i N b Ο 3 : periodically poled lithium niobate), or PPSLNiperiodically poled stoichiometric LiNb03 : periodically polarized The stoichiometric ratio of lithium niobate is preferred. In the case where the nonlinear optical crystal is MgO : PPSLT or MgO : PPSLN, most of the cases where the wavelength of the second harmonic is shorter than the wavelength of 5 3 2 nm (green light) and the like is shorter than 200917600 'displays the light as a medium. The effect of absorbing the power of the fundamental wave. Therefore, in the case where the optical arrangement is constituted by a single light path as in the prior art, the absorption power in the beam on the side of the incident end face of the non-linear crystal and the side of the exit end face is different, and a temperature distribution occurs in the direction of the optical axis of the crystal. This situation is excluded from the temperature phase integration conditions, resulting in a decrease in wavelength conversion efficiency. The temperature in the non-linear crystals is controlled by an electronic cooling (ETC) technique or a heater of the prior art, and the temperature range can be controlled to the extent of ±0.1. f The light beam 16 including the second harmonic component and the fundamental wave not subjected to wavelength conversion output from the first end face output end 6-1 via the round-trip optical path is again passed through the condensing mirror 5 to form the parallel beam 17 and is made high by The reflectance reflecting spectroscope 4 selectively separates and reflects at least the second harmonic component from the fundamental wave component, and extracts it to the outside as a harmonic beam 18. The beam is supplied for the purpose. The fundamental wave component passes through the spectroscope 4, and in the case where the optical isolator 2 is provided, the laser light source 1 does not return by the optical isolator 2, and the different components inside the polarization direction are excluded. ^ ' With the round-trip beam passing method improved here, the amount of heat generated by light absorption along each of the longitudinal directions of the nonlinear optical crystal 6 is averaged by the round-trip optical path, so that a uniform temperature is formed. distributed. That is, in the vicinity of the first end face 6-1, the fundamental wave beam incident is strong, and the converted beam is weak, fR. In the return beam, the fundamental wave beam is weak, and the converted beam becomes strong, on the other hand, the second The amount of heat generated in the vicinity of the end face 6-2 decreases in the incident direction with the increase of the second harmonic component, and is also the same in the returning light. The radiation caused by the absorption of each wavelength component depending on the location is uniform in the entire region of the waveguide. Thereby, the temperature distribution in the periodic nonlinear optical crystal is uniformized. Therefore, the integration condition can be maintained under the same conditions in the longitudinal direction. Therefore, the full length of the nonlinear optical crystal which is periodically polarized is highly efficiently exchanged. Compared with the conventional method of only one direction, the uniformity of the temperature distribution is extremely stable, and it is easy to realize, the efficiency is improved, the output is stabilized, and the economic effect obtained by the ease of the device configuration is Knowing the structure of a single light path shows great results. By setting the round-trip path to the coaxial position, the temperature distribution also becomes a circular distribution, and the effect is shown by the stability of the beam. Further, in the example of Fig. 1, the second end face 6-2 of the non-linear optical crystal 6 is returned by the concave mirror system 8, but instead of the convex lens or the flat. In this case, a convex lens in which the light beams are parallel is arranged such that the focus position thereof and the second end surface of the (guide path) are arranged, and a mirror in which the light beams are collimated in parallel by the convex lenses is disposed. In addition, source 1 is not a continuous oscillating laser, but a pulsed laser or a wave is applied, and a good effect can be obtained. [Examples] MgO: PPST.T was used as the nonlinear optical crystal, and the degree (the length between the first end face and the second end face) was 4 mm. Using the configuration of the second harmonic generating device, a single-frequency, single-mode 532 nm laser output of 3.7 W is obtained, wherein the table wave generates wavelength conversion of the mounted polarization, which can be clearly converted by the wavelength. The cost aspect is compared, and the aspect is also reflected by the reflection of the reflected mirror. 6-2 is used to reflect the laser light and the variable length is set to be long. The wavelength of the invention is set. 200917600 Laser light from a single-mode fiber laser and a single-frequency laser source with an output power of 9.4W and a fundamental wave wavelength of 1064 nm, is injected into the round-trip optical path. The conversion efficiency of the second harmonic is 39% in terms of optical power conversion efficiency. Therefore, a high defect can be obtained in the wavelength conversion efficiency of the continuous oscillation output. When the M2 measuring instrument is actually used and the beam quality of the second harmonic of the above configuration is measured by M2, the Μ2 = 1·12 in the X direction and M2 = 1.13 in the y direction can be obtained. In the case where the conversion power is low only in the case of a single optical path, it is 値 in the X direction of M2 = 1.23 and the y direction of M2 = 1.19. Therefore, in the present invention using the round-trip optical path, M2 in the x and y directions can obtain a high-quality second harmonic and can achieve high conversion efficiency. According to the present invention, there is provided a laser wavelength conversion device which emits a laser beam radiated from a fiber laser by periodically polarizing a PPLT, PPSLT, PPLN or PPSLN doped with MgO or ZnO. The non-linear optical crystal forms a round-trip optical path, and a basic wave laser beam is introduced from the incident end surface, and the wavelength-converted harmonics are configured to have the same end surface as an output end surface to optimize the conversion efficiency of the laser beam. The stability and the miniaturization of the device enable a continuous oscillating beam of practical harmonics. In the wavelength conversion device of the present invention, the round-trip optical path is formed in the waveguide of the nonlinear optical crystal which is periodically polarized, so that the continuously oscillating laser beam ′ can obtain the wavelength-converted continuous oscillation output with high efficiency. In order to obtain a short-wavelength continuous laser, it is necessary to use a large-power-driven short-wavelength laser oscillator using a krypton or argon ion gas laser to greatly improve the power efficiency, and the device can be miniaturized. It is used in laser applications such as laser micromachining, fine pattern exposure, high-precision micro-inspection, and high-density information recording using continuous oscillation output of short wavelength-16-200917600. Hereinabove, several embodiments of the present invention have been described. It is apparent that the present invention can be modified as long as it does not depart from the technical idea of the invention described in the scope of the patent application. (Industrial Applicability) As an application example of the present invention, since the short-wavelength of the second harmonic is used and high efficiency is obtained to obtain a fundamental wave output of continuous oscillation, it can be applied to a laser micro-machining device and a semiconductor chip. Cutting of electronic components of the conductive line of the wafer redundancy circuit, and removal of the inside of the layer of the other multilayer electronic component, correction of the liquid crystal display panel or the plasma display device, formation on the substrate Trimming of capacitors, resistors, inductors, etc. on the surface, functional trimming of circuit boards, laser precision machining of other semiconductor substrates, DVD mastering, wafer inspection, and cross-cut inspection of photolithography. It is possible to achieve high-efficiency wavelength conversion by continuous oscillation, and it is known that the action by the pulse output can be implemented by continuous output. Therefore, it is possible to effectively utilize the work efficiency improvement, and it is possible to easily perform a small defect inspection. The contribution that can be achieved by the need for improvement is enormous. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is an explanatory view of a harmonic generating device of the present invention. Fig. 2 is a view showing an example of a fiber laser and a fiber amplifying device which are used as a laser light source to generate a high-quality light beam in the present invention. Fig. 3 is a view showing the relationship between the periodic direction, the polarization direction, the polarization direction, and the traveling direction of the light beam of the nonlinear optical crystal having periodic polarization. 200917600 [Description of main components] 1 Laser source 2 Optical isolator 3 1/1 wavelength plate 4 Beam splitter 5 Concentrating lens 6 Non-linear optical crystal 6-1 (Non-linear optical junction ^ 6-2 2nd end 8 Reflective optics 9 Output beam 10 Oscillation beam 11 Beam 16 Beam containing the second harmonic component 17 Parallel beam 18 Harmonic beam 30 DFB Laser 32, 3 8 Amplified fiber 33, 3 9 Output power 35, 3 6 Bragg grating 31 , 3 7 excitation laser diode 5 1 beam travel direction 52 (polarization) period side 6 1 polarization direction 62 polarization direction body direction crystal) first end face component and basic wave 18 without wavelength conversion -