1358869 九、發明說明： 【發明所屬之技術領威】 本發明係關於一種Q_切換雷射，尤指一種提高增益光 纖和飽和吸收光纖的核心直徑（核心面積）比值之全光纖型 被動式Q-切換雷射。 【先前技術】1358869 IX. Description of the Invention: [Technical Leadership of the Invention] The present invention relates to a Q_switching laser, and more particularly to an all-fiber passive Q- which increases the ratio of the core diameter (core area) of a gain fiber and a saturated absorption fiber. Switch the laser. [Prior Art]
所謂Q-切換雷射即是高功率脈衝雷射，而Q-切換則是 產生高功率脈衝光的技術。Q-切換的技術又分主動式和被 動式。被動式Q-切換技術是使用一可飽和吸收的材料，放 置於雷射共振腔内，雷射一經激發即可自動產生高功率脈 衝光’因此被動式Q-切換雷射又稱飽和吸收切換雷射。 相較於主動式Q-切換雷射’飽和吸收（3_切換雷射結構巧 單、體積小、成本低。缺點是飽和吸收Q-切換的材料 取得。 ’易The so-called Q-switched laser is a high-power pulsed laser, while the Q-switching is a technique that produces high-power pulsed light. The Q-switching technology is divided into active and passive. Passive Q-switching technology uses a saturable absorption material placed in the laser cavity to automatically generate high-power pulse upon excitation. Therefore, passive Q-switched lasers are also called saturated absorption switching lasers. Compared with the active Q-switched laser 'saturated absorption (3_switching laser structure is simple, small in size, low in cost. The disadvantage is that the saturated absorption Q-switched material is obtained.
由於光纖的諸多優點，光纖型雷射是一新興熱門的 究主題。目前市面上最常見的Q_切換光纖雷射，大多數 是採用光纖外部（3_切換裝置，即雷射光需要先離開光 經過主動或被動Q-切換處理之後，再將光耦合進入、 由於-般單模光纖的核心只有約1〇 易 如 =作會造成能量損失高、Q_切換效率低、以= 發表並經實驗證實的主動式j 動設備，外加於光纖某區段上，二 5 1358869 些驅動設備必須是可快速切換電性，一般來說是相當昂貴 且笨重。另外，在一些已發表的全光纖被動式Q切換雷射 的相關文獻中，多是假設使用一些過渡金屬掺雜的特殊光 纖當作飽和吸收Q-切換，再經由模擬驗證雷射脈衝的產 生，事實上這些過渡金屬掺雜的特殊光纖是很難以製作並 且取得的。 美國公告第5652756號及美國公開第20060007965號 之技術内容皆非全光纖型之結構，光必須先離開光纖，處 理後再耦合回去光纖；而美國公告第713〇319號之主要技 術雖是全光纖型，但必須使用主動式Q切換元件。 故1知Q-切換光纖雷射技術仍存有許多缺失，而有待 改進，且發明一全光纖型被動式q_切換雷射，實為刻不容 緩之課題。 【發明内容】 本發明之目的在於提供一種全光纖型被動式切換雷 射，使容易產生全光纖型飽和吸收Q_切換脈衝雷射，利用 此雷射架構提高原光纖型飽和吸收Q-切換脈衝雷射的 切換效率，產生更咼功率的脈衝光；其原理是藉由提高增 益光纖和飽和吸收光纖的核心直徑（核心面積）比值，以降低 兩者核心的光強度密度比值，因而達到強化Q切換速率之 目的，且本發明結構簡單和成本低，可被廣泛應用在醫療、 醫學研究、物理基礎研究和工業精密加工上，而具有極大 的學術和商業價值，。 ^ 本發明之另一目的在於提供一種飽和吸收光纖，該飽 6 1358869 和吸收光纖可以吸收雷射波長，並且到達餘和後即不再吸 收，而該飽和吸收光纖的核心直徑（或面積）比增益光纖的核 心直徑（或面積）小，使得該飽和吸收光纖内的光強度密度大 於增益光纖内的光強度密度，因此可加速飽和吸收光纖達 到飽和狀態’進而產生Q-切換雷射脈衝。 本發明之又一目的在於提供一種全光纖型共振腔（An all-fiber resonator) ’該全光纖型共振腔包含光纖和光纖型元 件，而該全光纖型共振腔可為駐波共振腔型式 (standing-wave resonators)，或為環型共振腔型式（ring resonators) ’該兩種共振腔體内的結構設計必須避免飽和吸 收光纖吸收激發光源。 其中’飽和吸收Q-切換的材料原必需滿足一個先決條 件，即是飽和吸收材料的absorption cross section，必 需大於雷射增益材質的 stimulated emission cross seeticm σ 而且兩者比值愈大，飽和吸收Q_切換的效率愈 好。本發明即是藉由提高增益光纖内核心面積&和飽和吸 收光纖内核心面積的比值，調整此一先決條件為：Due to the many advantages of fiber optics, fiber-optic lasers are an emerging topic of research. At present, the most common Q_switched fiber lasers on the market are mostly externally used (3_switching device, ie laser light needs to leave the light after active or passive Q-switching processing, then couple the light into, due to - The core of a single-mode fiber is only about 1 〇 如 = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = 1358869 Some drive devices must be able to switch quickly, which is generally quite expensive and cumbersome. In addition, in some published literatures on all-fiber passive Q-switched lasers, it is assumed that some transition metal doping is used. The special fiber is used as a saturated absorption Q-switch, and the laser pulse is verified by simulation. In fact, these transition metal doped special fibers are difficult to manufacture and obtain. US Bulletin No. 5652756 and US Publication No. 20060007965 The technical content is not all-fiber type structure, the light must leave the fiber first, and then be coupled back to the fiber after processing; and the main technology of US Bulletin No. 713〇319 Although it is all-fiber type, it must use active Q switching components. Therefore, there are still many defects in Q-switched fiber laser technology, and it needs to be improved, and an all-fiber passive q_switching laser is invented. SUMMARY OF THE INVENTION The object of the present invention is to provide an all-fiber passive switching laser, which is easy to generate an all-fiber type saturated absorption Q_switched pulse laser, and utilizes the laser architecture to improve the saturation absorption of the original fiber type. The switching efficiency of the Q-switched pulsed laser produces pulsed light with higher power; the principle is to reduce the ratio of the core intensity (core area) of the gain fiber and the saturated absorption fiber to reduce the ratio of the light intensity density of the core. Therefore, the purpose of enhancing the Q switching rate is achieved, and the invention has the advantages of simple structure and low cost, and can be widely applied to medical, medical research, physical basic research and industrial precision processing, and has great academic and commercial value. Another object is to provide a saturated absorption fiber that absorbs laser wavelengths and absorbs laser wavelengths, and After the arrival of the sum, the absorption is not absorbed, and the core diameter (or area) of the saturated absorption fiber is smaller than the core diameter (or area) of the gain fiber, so that the light intensity density in the saturated absorption fiber is greater than the light intensity in the gain fiber. The density, thus accelerating the saturated absorption fiber to reach saturation state, and thereby generating a Q-switched laser pulse. Another object of the present invention is to provide an all-fiber resonator (the all-fiber type resonator) Fiber-optic and fiber-optic components, and the all-fiber resonators can be standing-wave resonators or ring resonators. The structural design of the two resonators must be Avoid saturated absorption fibers that absorb the excitation source. The 'saturated absorption Q-switched material must meet a prerequisite condition, that is, the absorption cross section of the saturated absorption material, which must be larger than the seismic emission cross seeticm σ of the laser gain material, and the larger the ratio, the saturated absorption Q_switching The better the efficiency. The present invention adjusts this ratio by increasing the ratio of the core area within the gain fiber to the core area of the saturated absorption fiber:
由於雷射光被侷限在光纖内的光纖核心（Fiber C〇re) 中傳輸。藉由提高’可降低光束在增益光纖核心内的強 度雄·度。反之’藉由降低可提向光束在飽和吸收光纖 核心内的強度密度。因此可加速飽和吸收光纖達到飽和狀 態’進而產生Q-切換雷射脈衝。所以（一）、若飽和吸收材 料的小於雷射增益材質的crse，本發明可藉由提高辦益光 7 纖内核二面積4和飽和吸收光纖内核心面積的比值’ 使此材料可Q_切換雷射。因此，本發明使得飽和吸收Q切 換材料的選擇性大幅增加。（二）、若飽和吸收材料的略 大於雷射增益材質的本發明可藉由提高&和Ζα的比 值’使得Q-切換效率大幅提升，產生更高功率的脈衝光雷 射。 為達到上述目的之全光纖型被動式Q-切換雷射，包含 一經由一激發光源放射出的激發光波；一第一光纖光柵， 設於該激發光源之輸出側；一增益光纖’設於該第一光纖 光柵之輸出側；一飽和吸收光纖，設於該增益光纖之輸出 側，以及一第二光纖光栖，設於該飽和吸收光纖之輪出側； 其中該飽和吸收光纖之核心面積或直徑比該增益光纖之核 心面積或直徑小，使得經過該飽和吸收光纖核心的光強度 密度大於經過該增益光纖核心的光強度密度。 該飽和吸收光纖的材質可吸收該雷射波長。 該飽和吸收光纖為掺铒光纖或其他等效之光纖。 該增益光纖為掺铒光纖或其他等效之光纖。 該第一光纖光柵可全反射雷射波長，而該第二光纖光 栖則提供一疋比例反射雷射波長，剩餘比例則為雷射輸出β 【實施方式】 雖然本發明將參閱含有本發明較佳實施例之所附圖式 予以充分描述’但在此描述之前應瞭解熟悉本行之人士可 修改本文中所描述之發明’同時獲致本發明之功效。因此， 須暸解以下之描述對熟悉本行技藝之人士而言為一廣泛之 1358869 揭示，且其内容不在於限制本發明。 請參閱第一圖，係顯示本發明全光纖型被動式Q-切換 雷射1第一實施例之結構示意圖。本發明第一實施例之全 光纖型被動式Q-切換雷射1包含一經由一激發光源2放射 出的激發光波；一第一光纖光柵3，設於該激發光源2之輸 出側；一增益光纖4，設於該第一光纖光柵3之輸出侧；一 飽和吸收光纖5，設於該增益光纖4之輸出側；以及一第二 光纖光柵6，設於該飽和吸收光纖5之輸出側。 其中，當激發光波2激發該增益光纖4時會產生一自 體輻射光波和一雷射增益，經該第一光纖光柵3可全反射 該雷射光波之波長至該第二光纖光柵6,而於該第一光纖光 柵3與該第二光纖光柵6間共振。該共振的雷射光波經該 第二光纖光柵6 —部分輸出，一部份反射繼續共振。雷射 光波的形成是從自體輻射光波的放大開始。該自體輻射光 波經過該增益光纖4會被放大，而經過飽和吸收光纖5會 因被吸收而變小，使得自體輻射光波一開始被抑制而無法 被放大成雷射。但當飽和吸收光纖5到達吸收飽和狀態後 即不再吸收，此時自體輻射光波會在來回共振中被增益光 纖4快速放大，而形成一雷射脈衝。該飽和吸收光纖5之 核心面積或直徑比該增益光纖4之核心面積或直徑小，使 得經過該飽和吸收光纖5核心的光強度密度大於經過該增 益光纖4核心的光強度密度。如此結構設計可使飽和吸收 光纖5快速到達吸收飽和狀態’進而產生Q-切換雷射脈衝。 而第一圖是最簡單的全光纖型被動式Q-切換雷射1， 為駐波共振腔結構，其中該飽和吸收光纖5的材質不會吸 9 1358869 收該激發光源2 ’該第一光纖光柵3是駐波共振腔的反射 鏡，可以全反射該雷射光波之波長，而該第二光纖光柵6 則提供一定比例的該雷射光波之波長反射，而剩餘比例為 雷射輸出7。 請參閱第二圖’係顯示本發明全光纖型被動式Q-切換 雷射11第二實施例之結構示意圖。本發明第二實施例之全 光纖型被動式Q-切換雷射11包含一經由一激發光源12放 射出的激發光波；一分波多工器13，設於該激發光源12之 輸出側；一飽和吸收光纖18，設於該分波多工器13之第一 侧19; 一增益光纖14,設於該分波多工器π之第二側15 ; 一第一光纖光栅16，設於該增益光纖14之第一側17 ;以 及一第二光纖光柵20，設於該飽和吸收光纖18之輸出側。 其中，該分波多工器13先導入該激發光源12所發射 之激發光波，且激發增益光纖14並避免該激發光源12被 該飽和吸收光纖18吸收。該增益光纖14接收來自於該分 波多工器13之激發光源會產生一自體輻射光波和一雷射增 益，並由該第一光纖光柵16全反射來自於該增益光纖14 之雷射光波之波長，而於該第一光纖光栅16與該第二光纖 光柵20間共振。該共振的雷射光波經該第二光纖光柵2〇 一部分輸出’ 一部份反射繼續共振。雷射光波的形成是從 自體輻射光波的放大開始。該自體輻射光波經過該增益光 纖14會，故Ί經過飽和吸收光纖18會因被吸枚而變 小使，自體轄射光波—開始被抑制而無法被放大成雷 射。但=飽和吸枚光纖18到達吸收飽和狀態後即不再吸 收此、自體輕射光波會在來回共振中被增益光纖^快速 1358869 放大’而成為一雷射脈衝。該飽和吸收光纖18之核心面積 或直徑比該增益光纖14之核心面積或直徑小，使得經過該 飽和吸收光纖18核心的光強度密度大於經過該增益光纖14 核心的光強度密度。如此結構設計可使飽和吸收光纖18快 速到達吸收飽和狀態，進而產生Q-切換雷射脈衝。 第二圖是第一圖的變型化，本發明第一實施例及第二 實施例同為駐波共振腔結構。其中該飽和吸收光纖18的材 質可以吸收該激發光源12。而該第一光纖光柵16是駐波共 振腔的反射鏡’可以全反射該雷射光波之波長，而該第二 光纖光柵20則提供一定比例的該雷射光波之波長反射，而 剩餘比例為雷射輸出21。 第三圖為本發明全光纖型被動式Q·切換雷射31之第三 實施例之結構示意圖。本發明第三實施例之全光纖型被動 式Q-切換雷射31包含一經由激發光源32發射出的激發光 波；一分波多工器33，係導入激發光波，且激發該增益光 纖38 ; —飽和吸收光纖34，設於該分波多工器33之第一 侧35 ; —光循環器36，設置於該飽和吸收光纖34的輸出 侧；一光纖光柵37，設置於該光循環器36之輸出侧；一增 益光纖38，設於該分波多工器33之第二侧39，並介於該 分波多工器33及光循環器36之間。 其中’該分波多工器33先導入該激發光源32所發射 之激發光波，且激發該增益光纖38，該增益光纖38接收來 自於該分波多工器33之激發光源產生一自體輻射光波和一 雷射增益。該自體轄射光波經過該增益光纖38會被放大， 而經過分波多工器33到達飽和吸收光纖34會因被吸收而 11 1358869 變小。經該飽和吸收光纖34吸收後穿透的光波至該光循環 器36’而該光波先從該光循環器36之端點a至端點b再到 該光纖光柵37 ’該光纖光柵37可配合該光循環器36將光 波反射回去(從該光循環器36之端點b至端點c)而使該光波 經過該增益光纖38被放大’再依序循環共振。當飽和吸收 光纖34到達吸收飽和狀態時後即不再吸收，此時自體輻射 光波會在共振中被增益光纖38快速放大，而成為一雷射脈 衝。 由於該光循環器36本身可排除該激發光源32之雷射 光波之波長，因此不需考慮該飽和吸收光纖34可否吸收了 該激發光源32的雷射波長。該光循環器36配合該光纖光 柵37使得光波在環型共振腔只能有單一行進共振方向。而 該光纖光柵37把一定比例的雷射光波反射回去環型共振腔 内’而剩餘比例為雷射輸出40。該飽和吸收光纖34之核心 面積或直徑比該增益光纖38之核心面積或直徑小，使得經 過該飽和吸收光纖34核心的光強度密度大於經過該增益光 纖38核心的光強度密度。如此結構設計可使飽和吸收光纖 34快速到達吸收飽和狀態，進而產生Q-切換雷射脈衝。 第四圖為本發明全光纖型被動式q_切換雷射41之第四 實知例之結構示意圖。本發明第四實施例之全光纖型被動 $ Q-切換雷射41包含一經由一激發光源42放射出的激發 光波；一分波多工器43，係導入激發光波，且激發增益光 =48 ;—光循環器44 ’設置於該分波多工器43的第一侧 飽和吸收光纖46，設於該光循環器44之輸出侧；一 '纖光％| 47 ’設置於該飽和吸收光纖46之輸出側；以及一 12 增益光纖48 ’設於該分波多工器43之第二側49，並介於 該分波多工器43及光循環器44之間。 其中，該分波多工器43先導入該激發光源42所發射 之激發光波’且激發該增益光纖48,該增益光纖48接收來 自於該分波多工器43之激發光源產生一自體輻射光波和一 雷射増益。該自體輻射光波經過該增益光纖48會被放大。 波經過該分波多工器43至該光循環器44。先從該光循環 器44之端點a至端點b，並且經過該飽和吸收光纖46而到 該光纖光柵47，該光纖光柵47可配合該光循環器44將雷 射光波反射回去，再經過該飽和吸收光纖46。光波兩次經 ，該飽和吸收光纖46會因被吸收而變小。光波(從該光循環 益44之端點b至端點c)，到達該增益光纖48被放大，再 依序循環共振。當飽和吸收光纖34到達吸收飽和狀態時後 即不再吸收，此時自體輻射光波會在共振中被增益光纖38 快速放大’而成為一雷射脈衝。 第四圖是第三圖的改良型，本發明第三實施例及第四 實施例同為環型共振腔結構。由於該光循環器44本身可排 除該激發光源42之雷射波長，因此不需考慮該飽和吸收光 纖46可否吸收了該激發光源42的雷射波長。該光循環器 44配合該光纖光栅47使得光波在環型共振腔只能有單一行 進共振方向。而該光纖光柵47把一定比例的雷射光波反射 回去環型共振腔内，而剩餘比例為雷射輸出50。該飽和吸 收光纖46之核心面積或直徑比該增益光纖48之核心面積 或直徑小，使得經過該飽和吸收光纖46核心的光強度密度 大於經過該增益光纖48核心的光強度密度。如此結構設計 13 1358869 可使飽和吸故光纖34快速到達吸收飽和狀態，進而產 切換雷射脈衝。 請參閱第五圖，係顯示本發明全光纖型被動式Q切 雷射11第二實施例之數據圖，並配合第二圖。該増益光纖 14和該飽和吸收光纖18為同樣材質的掺餌光纖，丄二增益 光纖14和該飽和吸收光纖18核心面積比值為8，共“2 期長度為1公尺。該飽和吸收光纖18的小訊號損耗 (small-signal l〇ss)取為3dB，該第一光纖光柵μ和該第二 光纖光柵20之反射頻譜的中心波長為155〇nm、^寬^ 0.8nm、中心波長的反射率各為1〇〇%和7〇%。該分波多工 器13可以把980mn波長的激發光源12耦合進入共振腔並 激發該增益光纖14。模擬結果顯示此雷射設計可產生連續 脈衝，脈衝之間隔約為13ms。每一個脈衝能量約為丨丄6 μ·Γ’脈衝寬度25.5ns。若假設輸出模態直徑為20 μιη，則功 率密度可達約145MW/cm2。 請參閱下列表一，係顯示本發明全光纖型被動式9_切 換雷射1、11、31、41等四個實施例所產生的脈衝輸出，而 全光纖型被動式Q-切換雷射1、H、31、41均使用相同的 模擬假設如下：增益光纖和飽和吸收光纖的核心面積比值 GV4)為8，比值(σ/σα)為卜共振腔週期長度為1公尺， 餘和吸收光纖的小訊號損耗(small_signal l〇ss)為3dB。輸出 端的光纖光柵中心波長為1550nm、中心波長的反射率為 70%。非飽和吸收性損耗為0.5dB。Because the laser light is confined to the fiber core (Fiber C〇re) in the fiber. By increasing ', the intensity of the beam within the core of the gain fiber can be reduced. Conversely, by reducing the intensity density of the beam that can be lifted into the core of the saturated absorption fiber. Therefore, the saturated absorption fiber can be accelerated to a saturation state, thereby generating a Q-switched laser pulse. Therefore, (1) if the saturated absorbing material is smaller than the laser gain material, the present invention can make the material Q_switchable by increasing the ratio of the core area of the core 7 and the core area of the saturated absorbing fiber. Laser. Therefore, the present invention greatly increases the selectivity of the saturated absorption Q-switching material. (b) If the saturated absorbing material is slightly larger than the laser gain material, the invention can greatly increase the Q-switching efficiency by increasing the ratio of & Ζα, resulting in a higher power pulsed light laser. The all-fiber passive Q-switching laser for achieving the above purpose comprises: an excitation light wave emitted through an excitation light source; a first fiber grating disposed on an output side of the excitation light source; and a gain fiber disposed in the first An output side of a fiber grating; a saturated absorption fiber disposed on an output side of the gain fiber, and a second fiber optic, disposed on a wheel-out side of the saturated absorption fiber; wherein a core area or diameter of the saturated absorption fiber The core area or diameter of the gain fiber is smaller than the intensity of the light intensity through the core of the saturated fiber. The material of the saturated absorption fiber absorbs the laser wavelength. The saturated absorption fiber is an erbium doped fiber or other equivalent fiber. The gain fiber is an erbium doped fiber or other equivalent fiber. The first fiber grating can totally reflect the laser wavelength, and the second fiber fiber provides a 疋-ratio reflected laser wavelength, and the remaining ratio is the laser output β. [Embodiment] Although the present invention will be described with reference to the present invention, The drawings of the embodiments are fully described 'but it should be understood that those skilled in the art can modify the invention described herein while achieving the effects of the invention. Therefore, it is to be understood that the following description is a broad disclosure of 1358869 to those skilled in the art and is not intended to limit the invention. Referring to the first figure, there is shown a schematic structural view of a first embodiment of the all-fiber type passive Q-switched laser 1 of the present invention. The all-fiber passive Q-switching laser 1 of the first embodiment of the present invention comprises an excitation light wave emitted through an excitation light source 2; a first fiber grating 3 disposed on the output side of the excitation light source 2; a gain fiber 4. An output side of the first fiber grating 3; a saturated absorption fiber 5 disposed on an output side of the gain fiber 4; and a second fiber grating 6 disposed on an output side of the saturation absorption fiber 5. Wherein, when the excitation light wave 2 excites the gain fiber 4, an auto-radiation light wave and a laser gain are generated, and the wavelength of the laser light wave can be totally reflected by the first fiber grating 3 to the second fiber grating 6, and Resonating between the first fiber grating 3 and the second fiber grating 6. The resonant laser light is partially output through the second fiber grating 6, and a portion of the reflection continues to resonate. The formation of a laser light wave begins with the amplification of the self-radiating light wave. The self-radiating light wave is amplified by the gain fiber 4, and becomes smaller by being absorbed by the saturated absorption fiber 5, so that the self-radiation light wave is initially suppressed and cannot be amplified into a laser. However, when the saturated absorption fiber 5 reaches the absorption saturation state, it is no longer absorbed, and at this time, the self-radiation light wave is rapidly amplified by the gain fiber 4 in the back and forth resonance to form a laser pulse. The core area or diameter of the saturated absorption fiber 5 is smaller than the core area or diameter of the gain fiber 4, so that the light intensity density passing through the core of the saturated absorption fiber 5 is greater than the light intensity density passing through the core of the gain fiber 4. Such a structural design allows the saturated absorption fiber 5 to quickly reach the absorption saturation state and thereby generate a Q-switched laser pulse. The first picture is the simplest all-fiber passive Q-switched laser 1 , which is a standing wave resonant cavity structure, wherein the material of the saturated absorption fiber 5 does not absorb 9 1358869 to receive the excitation light source 2 'the first fiber grating 3 is a mirror of the standing wave resonator, which can totally reflect the wavelength of the laser light wave, and the second fiber grating 6 provides a certain proportion of the wavelength reflection of the laser light wave, and the remaining ratio is the laser output 7. Referring to the second figure, a schematic structural view of a second embodiment of the all-fiber type passive Q-switching laser 11 of the present invention is shown. The all-fiber passive Q-switching laser 11 of the second embodiment of the present invention comprises an excitation light wave emitted through an excitation light source 12; a wavelength division multiplexer 13 is disposed on the output side of the excitation light source 12; An optical fiber 18 is disposed on the first side 19 of the splitter multiplexer 13; a gain fiber 14 is disposed on the second side 15 of the splitter multiplexer π; a first fiber grating 16 is disposed on the gain fiber 14 The first side 17; and a second fiber grating 20 are disposed on the output side of the saturated absorption fiber 18. The splitter multiplexer 13 first introduces the excitation light wave emitted by the excitation light source 12, and excites the gain fiber 14 and prevents the excitation light source 12 from being absorbed by the saturated absorption fiber 18. The gain fiber 14 receives an excitation light source from the split multiplexer 13 to generate an autoradiation light wave and a laser gain, and the first fiber grating 16 totally reflects the laser light from the gain fiber 14. The wavelength resonates between the first fiber grating 16 and the second fiber grating 20. The resonant laser light propagates through a portion of the output of the second fiber grating 2' to continue to resonate. The formation of a laser light wave begins with the amplification of the self-radiating light wave. The self-radiating light wave passes through the gain fiber 14, so that the saturated absorption fiber 18 is reduced by being sucked, and the self-regulating light wave is initially suppressed and cannot be amplified into a laser. However, if the saturated absorbing fiber 18 reaches the absorption saturation state, it will no longer absorb this, and the self-lighting light wave will be amplified by the gain fiber ^1,869,869 in the back and forth resonance to become a laser pulse. The core area or diameter of the saturable absorbing fiber 18 is smaller than the core area or diameter of the gain fiber 14 such that the intensity of the light intensity through the core of the saturated absorbing fiber 18 is greater than the intensity of the light passing through the core of the gain fiber 14. Such a structural design allows the saturated absorption fiber 18 to quickly reach the absorption saturation state, thereby generating a Q-switched laser pulse. The second figure is a modification of the first figure, and the first embodiment and the second embodiment of the present invention are the same as the standing wave resonator structure. The material of the saturated absorption fiber 18 can absorb the excitation light source 12. The first fiber grating 16 is a mirror of the standing wave resonator, which can totally reflect the wavelength of the laser light wave, and the second fiber grating 20 provides a certain proportion of the wavelength reflection of the laser light wave, and the remaining ratio is Laser output 21. The third figure is a schematic structural view of a third embodiment of the all-fiber type passive Q·switching laser 31 of the present invention. The all-fiber passive Q-switching laser 31 of the third embodiment of the present invention comprises an excitation light wave emitted by the excitation light source 32; a wavelength division multiplexer 33 is introduced to the excitation light wave and excites the gain fiber 38; The absorption fiber 34 is disposed on the first side 35 of the split multiplexer 33; the optical circulator 36 is disposed on the output side of the saturated absorption fiber 34; and a fiber grating 37 is disposed on the output side of the optical circulator 36. A gain fiber 38 is disposed on the second side 39 of the split multiplexer 33 and interposed between the split multiplexer 33 and the optical circulator 36. Wherein the splitter multiplexer 33 first introduces the excitation light wave emitted by the excitation light source 32, and excites the gain fiber 38, and the gain fiber 38 receives the excitation light source from the splitter multiplexer 33 to generate an autoradiation light wave and A laser gain. The self-regulating light wave is amplified by the gain fiber 38, and the wavelength of the saturated absorbing fiber 34 passing through the split multiplexer 33 is reduced by 11 1358869. The light wave that is absorbed by the saturated absorption fiber 34 is transmitted to the optical circulator 36', and the light wave first passes from the end point a to the end point b of the optical circulator 36 to the fiber grating 37'. The optical circulator 36 reflects the light waves back (from the end b of the optical circulator 36 to the end point c) such that the light waves are amplified by the gain fiber 38 'repetitively cyclically resonating. When the saturated absorption fiber 34 reaches the absorption saturation state, it is no longer absorbed, and at this time, the self-radiation light wave is rapidly amplified by the gain fiber 38 in resonance to become a laser pulse. Since the optical circulator 36 itself can exclude the wavelength of the laser light of the excitation light source 32, it is not necessary to consider whether the saturated absorption fiber 34 can absorb the laser wavelength of the excitation light source 32. The optical circulator 36 cooperates with the fiber grating 37 so that the light wave can only have a single traveling resonance direction in the ring type resonant cavity. The fiber grating 37 reflects a certain proportion of the laser light waves back into the toroidal resonator cavity and the remaining ratio is the laser output 40. The saturated absorption fiber 34 has a core area or diameter that is smaller than the core area or diameter of the gain fiber 38 such that the intensity of the light intensity through the core of the saturated absorption fiber 34 is greater than the intensity of the light passing through the core of the gain fiber 38. Such a structural design allows the saturated absorption fiber 34 to quickly reach the absorption saturation state, thereby generating a Q-switched laser pulse. The fourth figure is a schematic structural view of a fourth practical example of the all-fiber passive q_switching laser 41 of the present invention. The all-fiber passive $Q-switching laser 41 of the fourth embodiment of the present invention comprises an excitation light wave emitted through an excitation light source 42; a wavelength division multiplexer 43 is introduced into the excitation light wave, and the excitation gain light is 48; The optical circulator 44' is disposed on the first side saturated absorbing fiber 46 of the multiplexer 43 and disposed on the output side of the optical circulator 44. A 'fibrous %| 47 ' is disposed on the saturated absorbing fiber 46. An output side; and a 12 gain fiber 48' are disposed on the second side 49 of the split multiplexer 43 and interposed between the split multiplexer 43 and the optical circulator 44. The splitter multiplexer 43 first introduces the excitation light wave emitted by the excitation light source 42 and excites the gain fiber 48. The gain fiber 48 receives an excitation light source from the splitter multiplexer 43 to generate an autoradiation light wave. A laser benefit. The autoradiation light wave is amplified by the gain fiber 48. The wave passes through the split multiplexer 43 to the optical circulator 44. From the end point a to the end point b of the optical circulator 44, and through the saturated absorption fiber 46 to the fiber grating 47, the fiber grating 47 can cooperate with the optical circulator 44 to reflect the laser light back, and then pass through The saturated absorption fiber 46. When the light wave passes twice, the saturated absorption fiber 46 becomes smaller due to being absorbed. The light wave (from the end b of the light cycle 44 to the end point c) reaches the gain fiber 48 and is amplified, and then sequentially resonates. When the saturated absorption fiber 34 reaches the absorption saturation state, it is no longer absorbed, and at this time, the self-radiation light wave is rapidly amplified by the gain fiber 38 in resonance to become a laser pulse. The fourth figure is a modified version of the third figure, and the third embodiment and the fourth embodiment of the present invention are both ring-shaped resonator structures. Since the optical circulator 44 itself can exclude the laser wavelength of the excitation source 42, it is not necessary to consider whether the saturated absorption fiber 46 can absorb the laser wavelength of the excitation source 42. The optical circulator 44 cooperates with the fiber grating 47 so that the light wave can only have a single direction of resonance in the ring type resonant cavity. The fiber grating 47 reflects a certain proportion of the laser light back into the ring-shaped resonator, and the remaining ratio is the laser output 50. The core area or diameter of the saturated absorbing fiber 46 is smaller than the core area or diameter of the gain fiber 48 such that the intensity of the light intensity through the core of the saturated absorbing fiber 46 is greater than the intensity of the light passing through the core of the gain fiber 48. Such a structural design 13 1358869 allows the saturated suction fiber 34 to quickly reach the absorption saturation state, thereby producing a switching laser pulse. Referring to the fifth drawing, the data diagram of the second embodiment of the all-fiber type passive Q-cut laser 11 of the present invention is shown, and is accompanied by the second figure. The benefit fiber 14 and the saturated absorption fiber 18 are doped fiber of the same material, and the core area ratio of the second gain fiber 14 and the saturated absorption fiber 18 is 8, and the total length of the phase 2 is 1 meter. The saturated absorption fiber 18 The small signal loss (small-signal l〇ss) is taken as 3 dB, and the center wavelength of the reflection spectrum of the first fiber grating μ and the second fiber grating 20 is 155 〇 nm, ^ width ^ 0.8 nm, and reflection at the center wavelength The rates are each 1% and 7%. The splitter multiplexer 13 can couple the 980 nm wavelength excitation source 12 into the cavity and excite the gain fiber 14. The simulation results show that the laser design can produce continuous pulses, pulses. The interval is about 13ms. Each pulse energy is about μ6 μ·Γ' pulse width is 25.5 ns. If the output mode diameter is 20 μηη, the power density can reach about 145 MW/cm2. See Table 1 below. The pulse output generated by the four embodiments of the all-fiber passive 9_switching lasers 1, 11, 31, 41, etc. of the present invention is shown, and the all-fiber passive Q-switching lasers 1, H, 31, 41 are used. The same simulation assumptions are as follows: gain fiber and The core area ratio GV4) of the absorption fiber is 8, the ratio (σ/σα) is 1 meter length of the cavity, and the small signal loss (small_signal l〇ss) of the absorption fiber is 3dB. The center wavelength is 1550 nm, the reflectance at the center wavelength is 70%, and the unsaturated absorption loss is 0.5 dB.
在本發明第四實施例全光纖型被動式Q-切換雷射中， 該飽和吸收光纖係置於該光纖光柵之前，可使得該飽和吸 收光纖内有一上一下來回的光傳遞方向，藉此增加該飽和 °及故光纖内的光強度密度，因而更強化了 Q_切換效率。本 發明之共振腔體内的結構設計原則是避免飽和吸收光纖吸 收數發光源》 本發明之優點在於： 1·光纖輕便易操作。 2·能量損失低。 3. Q-切換效率高。 4. 封裝容易。 5. 製作成本低β 雖然本發明已以較佳實施例揭露如上，然其並非用以 限定本發明，任何熟悉此技藝者，在不脫離本發明之精神 和範圍内，當可作各種之更動與潤飾，因此，本發明之保 護範圍，當視後附之申請專利範圍所界定者為準。 15 1358869 【圖式簡單說明】 第一圖為本發明全光纖型被動式Q-切換雷射之第一 實施例之結構示意圖。 第二圖為本發明全光纖型被動式Q-切換雷射之第二 實施例之結構示意圖。 第三圖為本發明全光纖型被動式Q-切換雷射之第三 實施例之結構示意圖。 第四圖為本發明全光纖型被動式Q-切換雷射之第四 實施例之結構示意圖。 第五圖為本發明全光纖型被動式Q-切換雷射第二實 施例之數據圖。 【主要元件符號說明】 1、 11、31、41…全光纖型被動式Q-切換雷射 2、 12、32、42…激發光源 3、 16---第一光纖光撕 4、 14、38、48---增益光纖 5、 18、34、46…飽和吸收光纖 6、 20第二光纖光柵 7、 21、40、50---雷射輸出 13…分波多工器 15、39、49---第二側 17、19、35、45---第一側 33、43…分波多工器 36、44…光循環器 16 1358869 37、47…光纖光柵In the all-fiber passive Q-switching laser of the fourth embodiment of the present invention, the saturated absorption fiber is placed in front of the fiber grating, so that the saturated absorption fiber has a light-back direction of the upper and lower back and forth, thereby increasing the Saturated ° and the light intensity density in the fiber, thus further enhancing the Q_ switching efficiency. The structural design principle in the resonant cavity of the present invention is to avoid the saturation absorption fiber absorption number of light source. The advantages of the present invention are as follows: 1. The optical fiber is light and easy to operate. 2. Low energy loss. 3. Q-switching efficiency is high. 4. Packaging is easy. 5. The production cost is low. Although the present invention has been disclosed in the above preferred embodiments, it is not intended to limit the invention. Any one skilled in the art can make various changes without departing from the spirit and scope of the invention. And the scope of the present invention, therefore, is defined by the scope of the appended claims. 15 1358869 [Simple description of the drawings] The first figure is a schematic structural view of the first embodiment of the all-fiber passive Q-switching laser of the present invention. The second figure is a schematic structural view of a second embodiment of the all-fiber passive Q-switched laser of the present invention. The third figure is a schematic structural view of a third embodiment of the all-fiber passive Q-switched laser of the present invention. The fourth figure is a schematic structural view of a fourth embodiment of the all-fiber passive Q-switched laser of the present invention. Figure 5 is a data diagram of a second embodiment of an all-fiber passive Q-switched laser of the present invention. [Main component symbol description] 1, 11, 31, 41... all-fiber passive Q-switching laser 2, 12, 32, 42... excitation light source 3, 16---first fiber light tearing 4, 14, 38, 48---Gain fiber 5, 18, 34, 46... Saturated absorption fiber 6, 20 Second fiber grating 7, 21, 40, 50---Laser output 13... Split-wave multiplexer 15, 39, 49-- - second side 17, 19, 35, 45 - first side 33, 43 ... splitter multiplexer 36, 44 ... optical circulator 16 1358869 37, 47... fiber grating