201121183 六、發明說明： 【發明所屬之技術領域】 本發明係有關於升頻雷射系統’特別係有關於使用脈 衝式激發方法的藍綠光升頻雷射系統。 【先前技術】 由於細胞組織、某些合金與半導體材料對藍綠光具有 極佳的吸收率，因此藍綠光波段（藍光：430-490nm ;綠 光:490-580nm)的雷射能夠應用於多種產業，例如生醫感測 器、不銹鋼(鐵鎳合金)與半導體(Si或GaAs)的加工。然而， 習知的半導體雷射卻很難產生藍綠光波段的雷射，例如 InGaN或AlInGaP產生雷射的波段分別是可見光波段 (360-600nm)與紅外光波段（i，〇〇〇-i,7〇〇nm)。此外，習知的 倍頻雷射（non-linear conversion laser)利用倍頻晶體將紅外 光波段的雷射轉換綠光波段的雷射；然而，因為習知的倍 頻雷射在轉換頻率時需要使用許多面鏡，所以無法被積體 化；此外，習知的倍頻雷射也有倍頻晶體水解的現象。 升頻雷射（upconversion laser)利用不同的機制產生藍 綠光波段的雷射。具體而言，升頻雷射藉著在二氧化矽 (Silica)光纖中摻雜稀土族元素離子（Rare Earth Ions， RE3+)(其後簡寫為Si02:RE3+雷射光纖），並利用re3+的電子 在不同能階間的躍遷產生藍綠光波段(546nm)的雷射，這一 類的稀土族元素離子包括Er3+(铒離子）、Tm3+(鍤離子）或 Pr3+(镨離子），Er3+、Tm3+和Pr3+產生藍綠光波段的雷射分 別 546nm、450nm 和 492nm。 201121183 第1圖為Er3+能階圖，用以說明升頻雷射的激發原理 (pumping principle)與升頻雷射產生的習知方法。如第1圖 所示，Er3+包括能階E!、E2、E3、E4、E5和e6，其分別表 示電子能量由低至高的六種能階，其光譜學符號(spectrum term)分別為 4I〗5/2、4I!3/2、4I〗i/2、％/2 (或 4F9/2)、4S3/2，以 及4F7/2。值得注意的是，E]、E3和E5這三個能階與發出藍 綠光波段的雷射有關，為了簡化說明，特別將能階E〗、E3 和E5稱為基態能階E!、中間態能階E3和上能階E5。具體 φ 而言，首先，通常使用具有第一波長的第一雷射將基態能 階E/hw)的電子激發至中間態能階E3(4IU/2)，然後，再 使用具有第二波長的第二雷射將中間態能階E/l!!/2)的電 子激發至能階E/F^2)，能階E6的電子會以非輻射形式 (nonradiative form)衰減至上能階EX%/2)，最後因為上能 階Ε5的電子存活時間（約為ns數量級)遠小於基態能階 E〗的電子存活時間τΚ可視為無限大），所以由上能階&向 下躍遷至基態能階Ei並產生藍綠光波段的雷射（54611111)， 鲁其中非輕射形式的能篁通常轉變成晶格振動的能量（即聲 子，phonon)’且聲子最終會變成熱能散逸。A 有時候會將使用第二波長的第二雷射=態方:階 E/In;2)的電子激發至能階，且能階£6的電子以非 輻射形式（ncmradiative form)衰減至上能階E5(4S3/2)的過 程’直接稱為將中間態能階E3的電子激發至上能階e5。除 了由能階A至上能階E5所釋放出來的能量會以非輻射的 形式變成聲子外’由中間態能階Eg至基態能階E!所釋放 出來的能量也會以非輻射的形式變成聲子，其中由能階 201121183 至基態能階E〗的向下躍遷會產生波長為iwonm的雷射。 對於Si〇2:Er3+雷射光纖而言，形成藍綠光波段之雷射 的條件為：在上能階Es與激態能階El間形成居量反轉 (population inversion) ’換句話說，即在能階&的電子數必 須大於在能階E!的電子數，以數學式表示如下： 令=-(i?13 + ri2 h + (為】+ % )«2 + 〇431 + i?31) w4 + (名 + % )„5 (式 1) dm —=fVl5n, + R25n2 + i?36«3 -(Wl5 + W52 + A,,)n5 (式 2) dns dri n (式 3) 其中叫代表能階Ei的電子數，（di^/dt)和（dn5/dt)分別代 表基態能階E!和上能階E5的電子數時間變化率，Rjk表示 來自激發源的貢獻，用以將能階Ej的電子激發至能階Ek ; Anm表示由能階En至Em的自發輻射係數（spontaneous emission coefficient); Wnm表示由能階En至Em的受激輻射 係數(stimulated emission coefficient);且正負號分別代表增 加和減少。值得注意的是，（式1)-(式3)僅適用於Er3+，不 同種類的離子有不同的（式1)-(式3)。 習知的第一雷射和第二雷射均使用連續波雷射 (continuous waves(CW) laser)，CW雷射的輸出對時間而言 為常數。對Si02:Er3+雷射光纖而言，使用CW雷射將基態 能階Ei的電子至中間態能階E3時，中間態能階E3中已激 發的電子也不斷地以非輻射（聲子）的形式向下躍遷至能階 E〗（亦稱聲子效應），這使得中間態能階E3的電子數(n3)無法 充分累積以供應中間能階E3至能階E6的激發，最終造成 上能階E5的電子數(n5)始終無法大幅超過基態能階E】的電 201121183 子數(η!)。 參考（式1)，當基態能階El的電子被激發至中間態能 階Eg時，來自於第一雷射的貢獻（即使得基態能階& 的電子數(η!)持續地減少，以數學型式說明即為：由於第一 雷射的激發，（式1)等號右邊第一項中的（_Ri3)對基態能階 的電子數時間變化率（dni/dt)作反向貢獻。理論上，由於 (-Rn)對（dni/dt)的反向貢獻，應該能使（式3)非常容易被滿 足。但是實際上，基態能階Ει被激發的電子並未全部停留 於中間態能階E3，如前所述，因為中間態能階&中已激發 的電子也不斷地以非輻射（聲子）的形式向下躍遷至基態能 尸白’使付（式3)實際上並不是非常容易被滿足；以數學 型式說明即為Κ υ中（_Ri3)所減少的數值並未全部使 (dni/dt)降低，而是又部分地轉移至（+A21)，使得（dni/dt) =減乂不如預期，其中A。代表由能階向下躍遷至基態 月匕^ E〗的自發輕射係數。由上述可知，.在激發Si02:Er3+ 田射光，時’習知的CW雷射激發效率不佳。類似地，因 為稀土私兀素具有類似的能階圖，所以在激發Si02:RE3+ 雷射，纖時1知的cw雷射激發效率亦不佳。 亟需—種脈衝式升頻雷㈣統與其脈衝式激發 藉著抑$ Si〇2:Re3+雷射光纖的聲子效應，從而改善 升頻雷射的效率。 【發明内容】 &供種監綠光脈衝式升頻雷射系統，包括： 201121183 增益介質和脈衝式激發源。增益介質，具有基態能階、中 間態能階以及上能階。脈衝式激發源，用以激發增益介質 作升頻轉換，其中脈衝式激發源輸出複數脈衝組，每一脈 衝組包括第一脈衝與第二脈衝，第一脈衝用以將基態能階 的電子激發至中間態能階，且第二脈衝用以將中間態能階 的電子激發至上能階，當上能階的電子向下躍遷至基態能 階即產生藍綠光脈衝式升頻雷射。 本發明亦提供一種脈衝式激發方法，用以產生藍綠光 脈衝式升頻雷射，包括：提供增益介質，其中增益介質具 有基態能階、中間態能階以及上能階；以及從脈衝式激發 源輸出複數脈衝組至增益介質，每一脈衝組包括第一脈衝 與第二脈衝，第一脈衝用以將基態能階的電子激發至中間 態能階，且第二脈衝用以將中間態能階的電子激發至上能 階，當上能階的電子向下躍遷至基態能階即產生藍綠光脈 衝式升頻雷射。 本發明提供一種脈衝式激發方法，用以產生藍綠光升 頻雷射，包括：提供增益介質，其中該增益介質具有基態 能階以及上能階；以及從脈衝式激發源輸出複數脈衝組至 增益介質，且脈衝組間的時間間距小於該上能階的電子存 活時間，每一脈衝組包括第一脈衝，第一脈衝用以將基態 能階的電子直接激發至上能階，當該上能階的電子向下躍 遷至該基態能階即產生藍綠光脈衝式升頻雷射。 【實施方式】 201121183 (第一實施例） 第2圖為本發明脈衝式升頻雷射系統2〇〇的圖示。脈 衝式升頻雷射系統200包括增益介質’以及脈衝式激發源 206。 在本實施例中，增益介質係為Er3+，但並非以此為限， 其他種類的RE3+，例如Tm3+或pr3+亦能作為增益介質。增 益介質包括基態能階Ε!、中間態能階e3以及上能階e5。 此外，脈衝式升頻雷射系統2〇〇更包括载有增益介質的光 • 纖202和光學共振腔，光纖包括二氧化矽(si〇2)光纖和 /或 ZBLAN(ZrF4-BaF2_LaF3-AlF3-NaF)光纖，並具有第一端 202a、第二端202b和饋入端202c。光學共振腔具有全反射 鏡204a和半反射鏡204b。 脈衝式激發源206包括輸出端206a耦接於光纖202的 饋入端202c，脈衝式激發源2〇6用以輸出複數脈衝組 PG1-PGN，脈衝組之每一者具有第一脈衝ρι與第二脈衝 P2 ’舉例而言，第一脈衝組PG1包括第一脈衝？1和第二脈 •衝且在第一週期t]内依序被發出，並且為了抑制聲子效 應，所以第一週期q小於中間態能階&的電子存活時間， 其中複數脈衝組PG1-PGN之每一者彼此間的時間間隔為 脈衝組距h。第一脈衝！^的光波長為第一波長心，用以將 基態能階Ε!的電子激發至中間態能階&，且第二脈衝h 的光波長為Μ，用以將中間態能階&的電子激發至上能階 Ε5 ’接著上能階Es的電子向下躍遷至基態能階艮並產生藍 綠光波段的雷射並且第一脈衝Ρι的波長（第一波長和第 二脈衝Ρ2的波長（第二波長λ2)大於藍綠光升頻雷射的波 201121183 長。 光學共振腔包括一全反射鏡204a與一半反射鏡 2〇4b，分別耦接於光纖202的第一端202a與第二端202b。 在本實施例中，全反射鏡204a的鍍膜對光波長為546、975 和l，550nm的反射率（R)分別為100%、100%和〇%，半反 射鏡204b對光波長為546、975和l，550nm的反射率分別 為30%、100%和0%。全反射鏡204a和半反射鏡204b對 光波長為975nm的反射率均為100%，使得脈衝式激發源 206產生的第一脈衝P!和第二脈衝p2能夠在全反射鏡204a 和半反射鏡204b間重複激發增益介質。全反射鏡204a和 半反射鏡204b對光波長為546nm的反射率分別為100%和 30% ’使得增益介質產生的升頻雷射能夠在全反射鏡204a 被反射回載有增益介質的光纖202，用以再度加強上能階 Es至基態能階El的受激輻射，並等到升頻雷射的強度足夠 大時’便能夠在半反射鏡204b穿透出去。全反射鏡204a 和半反射鏡204b對光波長為l,550nm的反射率均為0%， 其用以抑制能階E2至基態能階E,的受激輻射（其相應的光 波長為l，550nm)，這是因為光波長為l，550nm的受激輻射 分別會穿透出全反射鏡204a和半反射鏡204b。藉由全反 射鏡204a和半反射鏡204b所形成的光學共振腔，使得產 生的升頻雷射在第一端202a和第二端202b間來回經過載 有增益介質的光纖202多次以得到足夠的放大。 (第二實施例） 第3A圖為RE3+能階圖和本發明產生升頻雷射的脈衝 201121183 式激發方法。類似地’ re3+包括能階El、e2、e3、e4、e5 和E6 ’其分別表示電子能量由低至高的六種能階。 首先，提供增益介質，其中增益介質包括基態能階Ει、 中間態能階E3以及上能階Es。在本實施例中，增益介質係 為Er ，但並非以此為限，其他種類的rE3+，例如Tm3+ 或Pr亦能作為增益介質。接著，從脈衝式激發源2〇6輸 出複數脈衝組PG1-PGN至增益介質，複數脈衝組pG1_PGN 之每一者包括第一脈衝Pi與第二脈衝p2。舉例而言，第一 •脈衝組PG1包括第一脈衝Pi和第二脈衝P2且在第一週期 t】内依序被發出，並且為了抑制聲子效應，所以第一週期 t!小於中間態能階&的電子存活時間，且複數脈衝組 PG1-PGN之每一者彼此間的時間間隔為脈衝組距h，第一 脈，h用以將基態能階E】的電子激發至中間態能階&， 且第一脈衝p2用以將中間態能階&的電子激發至上能階 E5,藉由κ上能階&至基態能階&的電子躍遷產生藍綠光 脈衝式升頻雷射，其中第一波長^等於第二波長λ]，並且 第脈衝Pi的波長（第一波長和第二脈衝的波長（第 二波長λ2)大於升頻雷射的波長。要注意的是，在本實施例 中，第一脈衝Pl與第二脈衝ρ2重疊。 ”產生升頻田射之習知方法不同的是，藉由使用脈衝 1激，源2G6 ’使知本發明能夠抑制習知的雷射激發 %•的聲Α應這是因為第—脈衝I和第二脈衝？！間在小 能階E3之電子存活時間的第-週期tl内被依序地 :完畢，所以能抑制中間態能階E3至能階&的聲子效 具體衝Pi將基聽料的電子激發至 [ 11 201121183 中間態能階e3時，第-邮淑ρ+丄 尚未以非向 能 ㈣E3的電子 维碴主月匕階h刖發出，用以將尚未 Γ么=躍遷至能階E2的電子再激發上能階 Ϊ二;間態能階&至能階匕的非賴射躍遷。參 考（式）並以數學型式說明：由於第一脈衝^的激發 為第1#! p反向續。但是與習知方法不同的是，因 間態能階^的電子尚未以非輻射型 ==2前發出，所以(式”中(如)所減少 降低乂 士夕至(+A21)的貢獻’而是全部用於使（dn]/dt) 產生雷施例的方式’能夠增加叫#雷射光纖 為第中’第—脈衝Pl和第二脈衝P2的波長分別 ρ 第二波長λ2 ’且第-脈衝Pl和第二脈衝 強度11和第二強度i2,其中第-波長 1寺於第一波長λ2(=975ϋΓη、，b资-,. τ，廿m)且弟一強度I】等於第二強度 ^㈣脈衝A和第二脈衝P2並未重疊。要注意的是， !::1乂脈衝組心2和脈衝間的時間㈣ 白&的存活時間而定。舉例而言，因為Er3+中 二子的存活時間約為毫秒㈣數量級，所以第 出，且第^口 ^ 一脈衝I在第一週期tl(<5mS)内依序地被發 衝租距睛組Μ1與第二脈衝組PG2 間距（脈 大於2咖’且脈衝間的時間間距大於2ms，其中 =週=(<5ms)係電子被第—脈衝6激發至中間態能階 3且尚未向下躍遷至基態能階E,的時間。在某师施例 12 201121183 ^第脈衝P!和第二脈衝h的半高寬㈣ 10ms。在某些實例中，势 ’ 、 第一脈衝Ρ丨和第二脈衝ρ2的時間 ^ =義為第—脈衝的強度衰減為Μ至第二脈衝 =上升至12/2的時間。此外’習知技藝者應能理解，可 依據不同的實驗條件選擇脈衝的強度關係，例如第一強产 匕於第二強度12，+或是第-強度I]的強度小於第二強； ^於不_RE3+，其+間態能階&電子的存活時 有所不同，故亦可根據不同的㈣+選擇相應的第一 (第三實施例） 第3B圖為re3+能階圖知士& nn A L , 式激發太、表/ 士每 產生升頻雷射的脈衝 土方法。在本實施例中，帛一脈衝&和第二脈 的波長分別為第-波長λι和第二波長&，且第__ 2 和第二脈衝?2的強度分別為第一強度 ！ 中第一波長λΐ等於第二波長λ2(=975ηιη)，f201121183 VI. Description of the Invention: TECHNICAL FIELD OF THE INVENTION The present invention relates to an up-converting laser system', particularly to a blue-green optical up-converting laser system using a pulsed excitation method. [Prior Art] Since cell tissue, certain alloys and semiconductor materials have excellent absorption rates for blue-green light, lasers in the blue-green light band (blue light: 430-490 nm; green light: 490-580 nm) can be applied. A variety of industries, such as biomedical sensors, stainless steel (iron-nickel alloy) and semiconductor (Si or GaAs) processing. However, conventional semiconductor lasers are difficult to produce lasers in the blue-green band. For example, the wavelength bands in which InGaN or AlInGaP generate lasers are visible light (360-600 nm) and infrared light (i, 〇〇〇-i, respectively). , 7〇〇nm). In addition, conventional non-linear conversion lasers use a frequency doubling crystal to convert lasers in the infrared band into lasers in the green band; however, because conventional frequency doubling lasers require conversion frequencies Many mirrors are used, so they cannot be integrated; in addition, conventional frequency-doubled lasers also have the phenomenon of frequency-doubling crystal hydrolysis. Upconversion lasers use different mechanisms to produce lasers in the blue-green band. Specifically, the up-converted laser is doped with rare earth element ions (Rare Earth Ions, RE3+) (hereinafter abbreviated as SiO 2 : RE 3 + laser fiber) by using Silica fibers, and using re3+ electrons. Transitions between different energy levels produce lasers in the blue-green band (546 nm). Such rare earth elements include Er3+ (铒 ions), Tm3+ (锸 ions) or Pr3+ (镨 ions), Er3+, Tm3+, and Pr3+. The lasers that produce the blue-green band are 546 nm, 450 nm, and 492 nm, respectively. 201121183 Figure 1 is an Er3+ energy level diagram illustrating the pumping principle of the upconverted laser and the known method of raising the frequency of the laser. As shown in Figure 1, Er3+ includes energy levels E!, E2, E3, E4, E5, and e6, which represent the six energy levels of electron energy from low to high, respectively, and the spectrum term is 4I. 5/2, 4I!3/2, 4I〗i/2, %/2 (or 4F9/2), 4S3/2, and 4F7/2. It is worth noting that the three energy levels E, E3 and E5 are related to the laser emitting blue-green light band. In order to simplify the description, the energy levels E, E3 and E5 are especially called the ground state energy level E! State energy level E3 and upper energy level E5. Specifically, in particular, first, a first laser having a first wavelength is used to excite electrons of a ground state energy level E/hw) to an intermediate energy level E3 (4 IU/2), and then, a second wavelength is used. The second laser excites the electrons of the intermediate state energy level E/l!!/2) to the energy level E/F^2), and the electrons of the energy level E6 are attenuated to the upper energy level EX% in a nonradiative form. /2), finally, because the electron survival time of the upper level Ε5 (about ns order of magnitude) is much smaller than the electron survival time τΚ of the ground state energy level E, it can be regarded as infinite), so the upper energy level & The energy level Ei and the blue-green band laser (54611111), the energy of the non-light-emitting form is usually converted into the energy of the lattice vibration (ie, phonon) and the phonon will eventually become heat dissipation. A will sometimes use the second laser of the second wavelength = state E / In; 2) the electrons are excited to the energy level, and the electrons of the order of 6 are attenuated to the upper energy in the ncmradiative form. The process of the order E5 (4S3/2) is directly referred to as exciting the electron of the intermediate state energy level E3 to the upper energy level e5. Except that the energy released from energy level A to upper energy level E5 will become phonon in non-radiative form, the energy released from the intermediate state energy level Eg to the ground state energy level E! will also become non-radiative. Phonons, in which the downward transition from the energy level 201121183 to the ground state energy level E, produces a laser with a wavelength of iwonm. For the Si〇2:Er3+ laser fiber, the condition for forming a laser in the blue-green band is: forming a population inversion between the upper energy level Es and the excitatory energy level E. In other words, That is, the number of electrons in the energy level & must be greater than the number of electrons in the energy level E!, expressed as follows: Let =-(i?13 + ri2 h + (for) + %) «2 + 〇431 + i ?31) w4 + (name + %) „5 (Formula 1) dm —=fVl5n, + R25n2 + i?36«3 -(Wl5 + W52 + A,,)n5 (Formula 2) dns dri n (Formula 3 Where is the electron number representing the energy level Ei, (di^/dt) and (dn5/dt) represent the time-varying rate of the electron number of the ground state energy level E! and the upper energy level E5, respectively, and Rjk represents the contribution from the excitation source, The electrons of the energy level Ej are excited to the energy level Ek; Anm represents the spontaneous emission coefficient of the energy levels En to Em; Wnm represents the stimulated emission coefficient of the energy levels En to Em. And the sign indicates the increase and decrease, respectively. It is worth noting that (Equation 1)-(Formula 3) is only applicable to Er3+, and different kinds of ions have different (Equation 1)-(Formula 3). a laser and a second mine The continuous wave (CW) laser is used, and the output of the CW laser is constant for time. For the Si02:Er3+ laser fiber, the CW laser is used to connect the electron of the ground state Ei to the middle. At the energy level E3, the excited electrons in the intermediate energy level E3 also continuously transition to the energy level E (also known as the phonon effect) in the form of non-radiation (phonon), which makes the intermediate energy level The electron number (n3) of E3 cannot be fully accumulated to supply the excitation of the intermediate energy level E3 to the energy level E6, and finally the electron number (n5) of the upper energy level E5 cannot always exceed the electric energy 201121183 subnumber of the ground state energy level E] ( η!). Referring to (Equation 1), when the electron of the ground state energy level E1 is excited to the intermediate state energy level Eg, the contribution from the first laser (ie, the number of electrons (η!) of the ground state energy level & Continuously reduced, mathematically stated: due to the excitation of the first laser, (_Ri3) in the first term on the right side of the equation (1) is the time-dependent rate of change (dni/dt) of the electron number of the ground state energy level. Reverse contribution. In theory, due to the inverse contribution of (-Rn) to (dni/dt), it should be possible to make (Equation 3) very easy to be In fact, the electrons excited by the ground state energy level Ει do not all stay in the intermediate energy level E3, as described above, because the excited electrons in the intermediate energy level & are constantly non-radiative (sound) The form of the sub) jumps down to the ground state can be corpse white 'Make pay (Formula 3) is actually not very easy to be satisfied; in mathematical form, the value reduced by _ υ (_Ri3) is not all made (dni /dt) is lowered, but is partially transferred to (+A21), such that (dni/dt) = minus is less than expected, where A. Represents the spontaneous light-weight coefficient from the energy level down to the ground state. From the above, it can be seen that the conventional CW laser excitation efficiency is poor when the SiO 2 :Er 3 + field light is excited. Similarly, since the rare earth quercetin has a similar energy level diagram, the excitation efficiency of the cw laser is also poor when the SiO 2 :RE 3 + laser is excited. There is an urgent need for a pulsed up-conversion ray (four) system and its pulsed excitation to improve the efficiency of the up-converting laser by suppressing the phonon effect of the $Si〇2:Re3+ laser fiber. SUMMARY OF THE INVENTION & for the green light pulse type up-conversion laser system, including: 201121183 gain medium and pulse excitation source. The gain medium has a ground state energy level, an intermediate state energy level, and an upper energy level. a pulsed excitation source for exciting a gain medium for up-conversion, wherein the pulse excitation source outputs a complex pulse group, each pulse group includes a first pulse and a second pulse, and the first pulse is used to excite the ground state energy level To the intermediate state energy level, and the second pulse is used to excite the electrons of the intermediate state energy level to the upper energy level, and the blue-green light pulse type up-conversion laser is generated when the upper level electrons are shifted downward to the ground state energy level. The present invention also provides a pulsed excitation method for generating a blue-green pulse-type up-conversion laser, comprising: providing a gain medium, wherein the gain medium has a ground state energy level, an intermediate state energy level, and an upper energy level; and a pulse type The excitation source outputs a complex pulse group to the gain medium, each pulse group includes a first pulse and a second pulse, the first pulse is used to excite electrons of the ground state energy level to an intermediate state energy level, and the second pulse is used to be an intermediate state The electrons of the energy level are excited to the upper energy level, and when the upper order electrons are shifted down to the ground state energy level, a blue-green light pulse type up-conversion laser is generated. The present invention provides a pulsed excitation method for generating a blue-green light ascending laser, comprising: providing a gain medium, wherein the gain medium has a ground state energy level and an upper energy level; and outputting a complex pulse group from the pulsed excitation source to Gain medium, and the time interval between the pulse groups is smaller than the electron survival time of the upper energy level, each pulse group includes a first pulse, and the first pulse is used to directly excite the electrons of the ground state energy level to the upper energy level, when the upper energy The electrons of the order are shifted downward to the ground state level to produce a blue-green pulse-type up-conversion laser. [Embodiment] 201121183 (First Embodiment) Fig. 2 is a view showing a pulse type up-converting laser system 2 of the present invention. The pulsed up-converting laser system 200 includes a gain medium' and a pulsed excitation source 206. In the present embodiment, the gain medium is Er3+, but not limited thereto, and other types of RE3+, such as Tm3+ or pr3+, can also be used as gain media. The gain medium includes the ground state energy level Ε!, the intermediate state energy level e3, and the upper energy level e5. In addition, the pulsed up-conversion laser system 2 includes an optical fiber 202 carrying an optical medium and an optical resonant cavity, and the optical fiber includes a ceria (si〇2) fiber and/or a ZBLAN (ZrF4-BaF2_LaF3-AlF3- The NaF) fiber has a first end 202a, a second end 202b, and a feed end 202c. The optical resonant cavity has a total reflection mirror 204a and a half mirror 204b. The pulse excitation source 206 includes an output end 206a coupled to the feed end 202c of the optical fiber 202, and a pulse excitation source 2〇6 for outputting the complex pulse group PG1-PGN, each of the pulse groups having the first pulse ρι and the first Two pulses P2 ' For example, the first pulse group PG1 includes the first pulse? 1 and the second pulse are rushed and sequentially emitted in the first period t], and in order to suppress the phonon effect, the first period q is smaller than the electron survival time of the intermediate state energy level &amp; The time interval between each of the PGNs is the pulse group distance h. The first pulse! The wavelength of the light is the first wavelength center, and the electron of the ground state energy level 激发! is excited to the intermediate state energy level & and the wavelength of the second pulse h is Μ, which is used for the intermediate state energy level & The electron is excited to the upper level Ε5' and then the electron of the upper level Es is shifted down to the ground state level 艮 and produces a blue-green band of laser light and the wavelength of the first pulse (ι (the first wavelength and the wavelength of the second pulse Ρ2 ( The second wavelength λ2) is longer than the wave of the blue-green light up-conversion laser 201121183. The optical cavity includes a total reflection mirror 204a and a half mirror 2〇4b coupled to the first end 202a and the second end of the optical fiber 202, respectively. 202b. In the present embodiment, the total reflection mirror 204a has a reflectance (R) of 100%, 100%, and 〇% for light wavelengths of 546, 975, and 1,550 nm, respectively, and the half mirror 204b has a wavelength of light. The reflectances of 546, 975 and 1,550 nm are 30%, 100% and 0%, respectively. The total reflectance of the total reflection mirror 204a and the half mirror 204b to the light wavelength of 975 nm is 100%, so that the pulse excitation source 206 is generated. The first pulse P! and the second pulse p2 can repeatedly increase the excitation between the total reflection mirror 204a and the half mirror 204b. The total reflection mirror 204a and the half mirror 204b have a reflectance of 100% and 30% for a wavelength of 546 nm, respectively, so that the up-converting laser generated by the gain medium can be reflected back to the full-mirror 204a to carry the gain medium. The optical fiber 202 is used to reinforce the stimulated radiation of the upper level Es to the ground level E1, and wait until the intensity of the up-converted laser is sufficiently large to be able to penetrate through the half mirror 204b. The total reflection mirror 204a and the half The mirror 204b has a reflectance of 0% at 550 nm, and is used to suppress the stimulated radiation of the energy level E2 to the ground state energy level E (the corresponding wavelength of the light is 1,550 nm) because The stimulated radiation having a wavelength of 1, 550 nm penetrates the total reflection mirror 204a and the half mirror 204b, respectively. The optical resonance cavity formed by the total reflection mirror 204a and the half mirror 204b causes the generated up-conversion laser to be generated. The optical fiber 202 carrying the gain medium is passed back and forth between the first end 202a and the second end 202b a plurality of times to obtain sufficient amplification. (Second Embodiment) FIG. 3A is a RE3+ energy level diagram and the present invention generates an up-converted laser. Pulse 201121183-style excitation method. Similarly 're3+ includes energy El, e2, e3, e4, e5, and E6' respectively represent six energy levels from low to high electron energy. First, a gain medium is provided, wherein the gain medium includes a ground state energy level Ει, an intermediate state energy level E3, and an upper energy level. Es. In the present embodiment, the gain medium is Er, but not limited thereto, and other types of rE3+, such as Tm3+ or Pr, can also be used as the gain medium. Then, the complex pulse group is output from the pulse excitation source 2〇6. PG1-PGN to gain medium, each of the complex pulse groups pG1_PGN includes a first pulse Pi and a second pulse p2. For example, the first pulse group PG1 includes the first pulse Pi and the second pulse P2 and is sequentially emitted in the first period t], and in order to suppress the phonon effect, the first period t! is smaller than the intermediate state energy The electron survival time of the order & and the time interval between each of the complex pulse groups PG1-PGN is the pulse group distance h, the first pulse, h is used to excite the electron of the ground state energy level E] to the intermediate state energy The order &, and the first pulse p2 is used to excite the electrons of the intermediate state energy level & to the upper energy level E5, and generate a blue-green light pulse type liter by the electronic transition of the upper energy level & to the ground state energy level & Frequency laser, wherein the first wavelength ^ is equal to the second wavelength λ], and the wavelength of the first pulse Pi (the first wavelength and the second pulse wavelength (second wavelength λ2) are greater than the wavelength of the up-converted laser. In the present embodiment, the first pulse P1 overlaps with the second pulse ρ2. The conventional method of generating an up-frequency field is different in that the source 2G6' can suppress the conventional method by using the pulse 1 excitation. The laser emits %• the sonar should be because of the first pulse I and the second pulse?! The first period tl of the electron survival time of the small energy level E3 is sequentially: completed, so that the phonon effect of the intermediate state energy level E3 to the energy level & amp can be suppressed, and the electrons of the base hearing material are excited to [ 11 201121183 In the intermediate state energy level e3, the first-mail ρ+ 丄+ has not been issued by the non-directional energy (4) E3 electron 碴 碴 , , , , , , , , , , , , , , = = = = = = = = = = = = = = = = The upper energy level ;2; the non-relational transition of the energy level & to the energy level 。. Refer to (formula) and explain in mathematical form: because the excitation of the first pulse ^ is the first #! p reverse continuation. Different from the conventional method, since the electron of the inter-level energy level ^ has not been emitted before the non-radiation type ==2, the decrease in the (in the formula) reduces the contribution of the gentleman to (+A21). It is all used to make (dn]/dt) a way to generate a thunderbolt. 'It is possible to increase the wavelength of the laser beam to the middle 'the first pulse' P1 and the second pulse P2 respectively ρ second wavelength λ2 ' and - a pulse P1 and a second pulse intensity 11 and a second intensity i2, wherein the first wavelength 1 is at the first wavelength λ2 (= 975 ϋΓ η, b b -, . τ, 廿 m) and the first intensity I Equal to the second intensity ^ (four) pulse A and the second pulse P2 do not overlap. It should be noted that the ratio of !::1 乂 pulse group 2 and the time between pulses (4) white & Since the survival time of the two sub-segments in Er3+ is on the order of milliseconds (fourth), the first one, and the first pulse I is sequentially sent to the rented eye group Μ1 and the second in the first period tl (<5mS). Pulse group PG2 spacing (pulse greater than 2 coffee' and the time interval between pulses is greater than 2ms, where = week = (<5ms) is the electron excited by the first pulse 6 to the intermediate energy level 3 and has not yet jumped down to the ground state energy Level E, the time. In a division of the case 12 201121183 ^ the first pulse P! and the second pulse h half-height (four) 10ms. In some instances, the time of the potential ', the first pulse Ρ丨, and the second pulse ρ2 is = the time at which the intensity of the first pulse decays to 第二 to the second pulse = rises to 12/2. In addition, the 'skilled artisan should understand that the intensity relationship of the pulse can be selected according to different experimental conditions, for example, the intensity of the first strong enthalpy at the second intensity 12, + or the first intensity I] is less than the second strong; In the absence of _RE3+, the +-internal energy level & electronic survival time is different, so the corresponding first (third embodiment) can also be selected according to different (four) + 3B picture is re3 + energy level diagram & nn AL , the method of pulsing soil for each type of excitation and excitation. In this embodiment, the wavelengths of the first pulse & and the second pulse are the first wavelength λι and the second wavelength & respectively, and the intensities of the first __ 2 and the second pulse ? 2 are respectively the first intensity! The first wavelength λ ΐ is equal to the second wavelength λ 2 (= 975 η ηη), f
Hit強度12:但纽意的是，第-心第=上 2且類似於第一貫施例，本實施例之第一週期t、舰 ^距t2和脈衝間的時間間距係根據電子在中間態能階 的存活時間而定，在此不再贅述。但要注意的是，竇 施例中，複數脈衝組PG1_pGN之每一 貫 脈衝，以及-較短時間的脈衝，並且較長 間的Hit intensity 12: but the intention is that the first-heart is the upper 2 and is similar to the first embodiment. The first period t, the ship's distance t2 and the time interval between the pulses in this embodiment are based on electrons in the middle. The survival time of the energy level is determined and will not be described here. However, it should be noted that in the sinus case, each pulse of the complex pulse group PG1_pGN, and the pulse of the shorter time, and the longer
短時間的脈衝重疊。舉例而言，第一脈’曰筮R衝與較 ^ , 矛脈衡ρι和第二脈衝P 的半高寬(FWHM)分別為5ms * -，並且第一脈= 第二脈衝Ρ:重疊（如第3Β圖所示 ]與 /、甲弟一脈衝Ρι和第 201121183 —脈衝p2的半高寬係根據電 間而定。料，習知技㈣的存活時 條件選擇脈衝的強度關係’例如;解二據不同的實驗 I2, m τ 弟—強度11大於第二強度 2 +H-強度^的強度小於第二強度ΐ2;由於不同的 可Μ 態能階Ε3電子的存活時間时所不同，故亦 選擇相應的第-週期t]，例如大於= (第四實施例） 式激圖ίΓ:能階圖和本發明產生升頻咖 法。在本實施例中，第—脈衝P1和第二脈衝P2 =長=第一波以和第二波長λ2，且第一脈衝P1 第的強度分別為第一強度11和第二強度k且 中第-度12 ’但要注意的是，在此實施例 衝p並夫：最不4於弟二波長λ2，且第一脈衝Pl和第二脈 t = /。類似於第二實施例，本實施例之第一週期 脈衝間的時間間距係根據電子在中間態 二心不再贅述。此外，f知技藝 倍Γ二^可依據不同的實驗條件選擇脈衝的強度關 強产二於筮-強度11大於第二強度12 ’或是第-強度11的 雷強度12，由於不同的RE3+，其中間態能階E3 f存相亦有所不同，故亦可根據不同的re3+選擇 目應的第週期t] ’例如大於5ms的第—週期ti。 (第五實施例） 201121183 第3D圖為R£能階圖和本發明產生升頻雷射的脈衝 式激發方法。在本實施例中，第一脈衝Pi和第二脈衝h 的，長分別為第一波長λ丨和第二波長λ2，且第一脈衝Pi 和第二脈衝P2的強度分別為第一強度I!和第二強度12，且 第:強度I】等於第二強度h，但要注意的是，在此實施例 中第一 ^長λ!不等於第二波長M，且第一脈衝Pi和第二脈 衝P2重疊。類似於第二實施例，本實施例之第一週期q、 脈衝組距t2和脈衝間的時間間距係根據 參的存活時間而定’在此不再資述。但要注意的 貫施例中，複數脈衝、组PG1_PGN之每一者亦包括一較長時 間的脈衝’以及一較短時間的脈衝，並且較長時間的脈衝 與較短時間的脈衝重疊。舉例而言，第一脈衝^和第二脈 衝P2的半高寬(FWHM)分別為5ms和_，並且第一脈衝 P!與第二脈衝p2重疊（如第3D圖所示），其中第一脈衝Pi 和第二脈衝P 2的半高寬係根據電子在中間態能階£ 3的存 活時間而定。此外，習知技藝者應能理解，可依據不同的 •實驗條件選擇脈衝的強度關係，例如第一強度^大於第二 強度12, *是第一強度h的強度小於第二強度l2;由於^ 同的，，其中間態能階&電子的存活時間亦有所不同， 故亦可根據不同的故+選擇相應的第—週期q，例如大於 5ms的第一週期t!。 (第六實施例） 第3E圖為RE”能階圖和本發明產生升頻雷射的脈衝 式激發方法。為了簡化說明，相同於第—至第五實施例的 15 201121183 類似之處不再贅述，對於Si〇2:RE3+雷射光纖而言，本實施 例與第一至五實施例的不同之處在於僅藉由單一脈衝Pi而 將基態能階E〗的電子直接激發至上能階e5，然後上能階 Es的激發電子再向下躍遷產生升頻雷射，其中脈衝的時間 間距小於上能階Es的電子存活時間，使得居量反轉得以在 上能階E5被產生。因為基態能階El的電子是直接被激發 到上月b 1¾ Es ’所以可以忽略中間態能階丑3和能階e2間以 及能階E2和基態能階E]間的聲子效應，進而改善升頻雷 射的效率。具體而言，脈衝式激發源206用以輸出複數脈 衝組PG1-PGN，脈衝組之每一者僅具有一第一脈衝匕，複 數脈衝組PG1-PGN之每一者彼此間的時，間間隔為脈衝組 距t：2 ’脈衝組距t2小於上能階Es的電子存活時間。第一脈 衝用以將基態能階E】的電子激發至上能階e5，接著上 能階Es的電子向下躍遷至基態能階E】並產生藍綠光脈衝 式升頻雷射。 對於Si〇2:RE3+雷射光纖而言，本發明提供脈衝式激發 源’並藉由脈衝式激發源輸出的第一脈衝Ρι和第二脈衝 P2，使得本發明能夠抑制習知的CW雷射激發時的聲子效 應。這是因為第一脈衝P〗和第二脈衝P2間的時間間距小於 中間態能階Es的電子存活時間，所以能抑制中間態能階 至基態能階E1的聲子效應。本發明也提供脈衝式激發 源，並藉由脈衝式激發源輸出之單一的脈衝ρι而將基熊能 階h的電子直接激發至上能階I，使得聲子效應可以被忽 略。 雖然本發明以較佳實施例揭露如上，但並非用以限制 201121183 本發明。此外，習知技藝者應能知悉本發明申請專利範圍 應被寬廣地認定以涵括本發明所有實施例及其變型。Short time pulse overlap. For example, the first pulse '曰筮R rush and the ^, the spear ρι and the second pulse P have a full width at half maximum (FWHM) of 5 ms * -, respectively, and the first pulse = the second pulse Ρ: overlap ( As shown in Fig. 3, and /, A brother-pulse 和ι and 201121183 - the half-height of the pulse p2 is determined according to the electricity. The material, the survival time of the conventional technique (4) selects the intensity relationship of the pulse 'for example; According to different experiments I2, m τ — - intensity 11 is greater than the second intensity 2 + H-strength ^ is less than the second intensity ΐ 2; due to different Μ state energy level Ε 3 electron survival time is different, so The corresponding first period t] is also selected, for example, greater than = (fourth embodiment). The energy level diagram and the present invention generate an up-converter method. In the present embodiment, the first pulse P1 and the second pulse P2 = length = first wave and second wavelength λ2, and the first intensity of the first pulse P1 is the first intensity 11 and the second intensity k, respectively, and the middle degree 12', but it is noted that in this embodiment Punctual p: the least two is the second wavelength λ2, and the first pulse P1 and the second pulse t = /. Similar to the second embodiment, the first cycle of the embodiment The time interval between pulses is not described in detail according to the electrons in the intermediate state. In addition, the skill of the technique can be selected according to different experimental conditions. The intensity of the pulse is selected to be strong. The intensity is greater than the second intensity. 'Or the intensity-intensity 11 of the lightning intensity 12, due to different RE3+, the intermediate state energy level E3 f is also different in phase, so it is also possible to select the corresponding period t] 'for more than 5ms according to different re3+ The first period ti. (Fifth Embodiment) 201121183 The 3D diagram is a R £ energy diagram and a pulse excitation method for generating an up-converted laser according to the present invention. In this embodiment, the first pulse Pi and the second pulse The lengths of h are respectively the first wavelength λ 丨 and the second wavelength λ 2 , and the intensities of the first pulse Pi and the second pulse P 2 are the first intensity I! and the second intensity 12, respectively, and the first: the intensity I] is equal to the first The second intensity h, but it should be noted that in this embodiment, the first length λ! is not equal to the second wavelength M, and the first pulse Pi and the second pulse P2 overlap. Similar to the second embodiment, the embodiment The first period q, the pulse group distance t2, and the time interval between pulses are based on the survival time of the reference However, in this case, the complex pulse, each of the groups PG1_PGN also includes a longer-time pulse and a shorter time pulse, and a longer time The pulse overlaps with the pulse of a shorter time. For example, the full width at half maximum (FWHM) of the first pulse ^ and the second pulse P2 are 5 ms and _, respectively, and the first pulse P! overlaps with the second pulse p2 (eg, In the 3D diagram, wherein the full width at half of the first pulse Pi and the second pulse P 2 is determined by the survival time of the electron at the intermediate state energy level of £3. Furthermore, those skilled in the art should understand that • Experimental conditions select the intensity relationship of the pulse, for example, the first intensity ^ is greater than the second intensity 12, * is the intensity of the first intensity h is less than the second intensity l2; due to the same, the intermediate state energy level & The survival time is also different, so the corresponding first period q can be selected according to different reasons, for example, the first period t! greater than 5 ms. (Sixth embodiment) Fig. 3E is a RE" energy level diagram and a pulse excitation method for generating an up-converted laser of the present invention. For the sake of simplicity, the similarities to the 15th to the fifth embodiment are no longer the same. It is to be noted that, for the Si〇2:RE3+ laser fiber, the present embodiment is different from the first to fifth embodiments in that the electron of the ground state level E is directly excited to the upper level e5 by only a single pulse Pi. Then, the excitation electrons of the upper level Es are further shifted to generate an up-converted laser, wherein the time interval of the pulse is smaller than the electron survival time of the upper energy level Es, so that the population reversal is generated at the upper energy level E5. The electrons of the energy level El are directly excited to the last month b 13⁄4 Es ' so the phonon effect between the intermediate state energy level ugly 3 and the energy level e2 and between the energy level E2 and the ground state energy level E] can be ignored, thereby improving the up frequency The efficiency of the laser. Specifically, the pulse excitation source 206 is configured to output a complex pulse group PG1-PGN, each of the pulse groups having only a first pulse 匕, each of the complex pulse groups PG1-PGN Time interval, pulse group distance t: 2 'pulse The distance t2 is smaller than the electron survival time of the upper energy level Es. The first pulse is used to excite the electron of the ground state energy level E] to the upper energy level e5, and then the electron of the upper energy level Es is shifted down to the ground state energy level E] and generates blue Green light pulse type up-conversion laser. For Si〇2: RE3+ laser fiber, the present invention provides a pulsed excitation source' and outputs a first pulse 和 and a second pulse P2 by a pulse excitation source. The invention can suppress the phonon effect in the conventional CW laser excitation. This is because the time interval between the first pulse P and the second pulse P2 is smaller than the electron survival time of the intermediate energy level Es, so that the intermediate state energy can be suppressed. The phonon effect of the order to the ground state energy level E1. The present invention also provides a pulsed excitation source, and directly excites electrons of the base bear level h to the upper energy level I by a single pulse ρι output from the pulse excitation source, so that the phonon The present invention is not to be construed as limiting the present invention in its preferred embodiments. Further, it should be understood by those skilled in the art that the scope of the present invention should be broadly recognized to encompass the present invention. Example embodiments and variations all.
17 201121183 【圖式簡單說明】 本發明能夠以實施例伴隨所附圖式而被理解，所附圖 式亦為實施例之一部分。為了簡化說明，在所附圖式中， 能階係根據能量的大小由高至低排列，能階的間距並未按 照實際的能量差而繪製，並且脈衝組的第一週期、脈衝組 距、脈衝間的時間間距，以及脈衝的半寬高（FWHM)並未按 照比例繪製，但習知技藝者應能知悉本發明申請專利範圍 應被寬廣地認定以涵括本發明之實施例及其變型。 第1圖為Er3+能階圖和產生升頻雷射的習知(CW)激發 鲁 方法； 第2圖為本發明脈衝式升頻雷射系統之一實施例的圖 示（第一實施例）； 第3A圖為RE3+能階圖和本發明產生升頻雷射之脈衝 式激發方法的一實施例（第二實施例）； 第3B圖為RE3+能階圖和本發明產生升頻雷射之脈衝 式激發方法的一實施例（第三實施例）； 第3C圖為RE3+能階圖和本發明產生升頻雷射之脈衝 _ 式激發方法的一實施例（第四實施例）； 第3D圖為RE3+能階圖和本發明產生升頻雷射之脈衝 式激發方法的一實施例（第五實施例）； 第3E圖為RE3+能階圖和本發明產生升頻雷射之脈衝 式激發方法的一實施例（第六實施例）。 【主要元件符號說明】 18 201121183 200〜脈衝式升頻雷射系統； 202〜光纖； 202a〜第一端； 202b〜第二端； 202c〜饋入端； 204a〜全反射鏡； 204b〜半反射鏡； 206〜脈衝式激發源； 206a~|li·出端； Ει-Εβ〜能階； h〜第一週期； t2〜脈衝組距， PG1、PG2、...、PGN〜脈衝組；BRIEF DESCRIPTION OF THE DRAWINGS The present invention can be understood by the accompanying drawings, which are also a part of the embodiments. In order to simplify the description, in the figure, the energy level is arranged according to the magnitude of the energy from high to low, the energy level spacing is not drawn according to the actual energy difference, and the first period of the pulse group, the pulse group distance, The time interval between pulses, and the half width and height of the pulse (FWHM) are not drawn to scale, but it will be appreciated by those skilled in the art that the scope of the invention should be broadly recognized to encompass embodiments of the invention and variations thereof. . 1 is an Er3+ energy level diagram and a conventional (CW) excitation method for generating an up-converted laser; FIG. 2 is an illustration of an embodiment of a pulsed up-conversion laser system of the present invention (first embodiment) FIG. 3A is an embodiment of a RE3+ energy level diagram and a pulsed excitation method for generating an up-converted laser of the present invention (second embodiment); FIG. 3B is a RE3+ energy level diagram and the present invention generating an up-conversion laser An embodiment of the pulsed excitation method (third embodiment); FIG. 3C is an embodiment of the RE3+ energy level diagram and the pulse generation method of the present invention for generating an up-conversion laser (fourth embodiment); The figure shows an embodiment of the RE3+ energy level diagram and the pulsed excitation method for generating an up-converted laser according to the present invention (fifth embodiment); the third embodiment shows the RE3+ energy level diagram and the pulse excitation of the up-converted laser of the present invention. An embodiment of the method (sixth embodiment). [Major component symbol description] 18 201121183 200~pulse up-conversion laser system; 202~ fiber; 202a~ first end; 202b~ second end; 202c~feeding end; 204a~ total reflection mirror; 204b~ semi-reflection Mirror; 206~pulse excitation source; 206a~|li·out; Ει-Εβ~ energy level; h~first period; t2~pulse group distance, PG1, PG2, ..., PGN~pulse group;
Pi〜第一脈衝； P2〜第二脈衝； λι〜第一波長； 入2〜第二波長。 19Pi~first pulse; P2~second pulse; λι~first wavelength; into 2~second wavelength. 19