1234669 玖、發明說明： 【發明所屬之技術領域】 本項發明係有關一種集成光學系統、光學方法及光學系統設計裝置， 特別疋與光隔離器（optical is〇lat〇rs)有關者。 【先前技術】 光隔離器是一個1x1的單向連接器，在光學系統内它讓光在光路中只沿 著一個方向傳播，而且不允許逆向傳送。 許多光學系統通常會使用光隔離器，以消除反向傳播的電磁光波。光 隔離器可以與二極管（diGde)互相比較，二極管對從輸人端到輸出端的正 向電流具有低電阻，而對從輸出端到輸入端的反向電流具有極高電阻。同 樣的，經由光隔離器輸入埠到輸出埠的正向光波，會以低損耗的方式傳播， 而從光隔肺輸料反向輸人的光波則會大大衰減，只剩下—小部分從輸 入埠離開光隔離|§。此種光隔離II具有單向的侧特性，可⑽斷絕大部 分由輸出端返回的逆向光。 攻個傳播的「非互易原則」（_—recipr〇city principle)可應用在 此類光學裝置上，以得到所需要的_功能。非互絲則是指光訊號只會 正向傳送而不會反向傳送的特性。理想的光隔離器就狄據此種非互易原 則來製造。 法拉第旋光器（Faraday rotator)是以先前技藝所製造的光隔離器， 它採用磁光學（magnetic—optic)元件作為非互易元件。不幸的是，此種 以先刖技藝所製造的光隔離器存在許多困難，不但功能與偏振相關 (polarization dependent)，而且也很難與其他光學元件集成。 5 1234669 【發明内容】 這裡提供一個光學系統與其相關的方法，其中包含一個第一分枝，它 能夠讓光以正向與反向傳送。'第一分枝包含一個具有第一折射率 (refractive index)(ni)的第一媒質（medium)，以及一個第一端點（㈣) 和一個第二端點。此發明也包含第二分枝，只能夠讓光以正向傳送。第二 分枝包含一個具有第二折射率（ns，其中η2<ηι)的第二媒質，以及一個第 一端點和一個第二端點。第二分枝的第二端點會進一步與第一分枝結合而 形成-個角度（θ2)。使㈣，❿加·〗（_)以利用全反射（她1 reflection)原理來防止通過第一分枝的反向光進入第二分枝，其中㊀是光 從第一分枝反向進入第二分枝的入射角。 在某些具體貫例巾，第-分枝與第二分枝可以是γ形連接、_連接或X 形連接。 我們可以選擇讓第-分枝包含一個光吸收器（optical absorber)，以 吸收因為全反射而沒有傳入第二分枝的反向光。在另一種具體實例中，可 以在-分枝的某-端點放置-個光扼束器（Qptiea丨ehQker)，以提高隔離 效果。 在使用时，第为饮與第一分枝的隔離是與偏振無關的 (P〇lariZat1〇n mdependent)，我們可以選擇將一分枝某一端點的數值孔 徑（numerical aperture)調低，以提高隔離效果。也可減少一分枝的傳 送區，以提高隔離效果。而且仍射以在—分枝的某—端點放置—個扼束 器，以提高隔離效果v … 1234669 在不同的具體實财’光學純可作為光隔轉或光衰減器 ⑽_伽）。也可赠第_分枝與第二分枝具有長方形橫斷面。 第-分枝與第二分枝仍然可以作為第_個細魅的元件。也可以讓 波長選擇器（wavelength selector)與光隔離器結合，形成一個多光復用分 解器（de-multiplexer)。 再者，第二個光隔離器也可以與第_個光隔離器集成，因此而構成一 個光搞合器（optical c_er)。同時，如此形成光耗合器，也可以作為 -個加多光復職（add-multiplexer)、—個光插人器（邮㈣丨酸㈣ 或-個偏振光複合器（p〇larization beam⑽biner)。再者光^ 可包含一個Y形分離器（Y-splitter)。 在另-個具體貫例巾’第—個光隔肺與第二個光隔離器可以與第三 個光隔離器集成，而形成一個具有三個埠的光循環器（〇ptical circulator)。繼續以相同的方法，就可以建立一個具有N個埠的光循環器。 光波長選擇器也可以與光循環器結合而形成一個多光復用分解器。 再者’光糸統也可設計作為偏光H(0ptical p〇larizer)。 上述各項具體貫例，只用極簡單的結構，就可以擁有下列許多光學特 性和功能，如堅固耐用、極好的熱屬性與環境屬性'優越的穩定性與可靠 性、以及偏振無關而可達到的絕佳效能。再者，它們也容易與其他光學麥 置以及光黾子（opto-electronic)裝置集成，每一種元件都可以由一項咬 多項波導（waveguide)、光纖（optical fiber)、微光（micr〇—〇ptic)與 光子晶體（photonic crystal)的技術來製作。 1234669 【實施方式】 如圖 1 (a)、1 ， 一 、(C)、1 (d)、1 (e)、1 (f)、1 (g)和! 一…、頁了種具體貫例的光隔離器/衰減器。特別是，每-個光隔離器/ 衰、、絲個具有_對端點的光學裝置。在本項說明中，此端點可以是 圖1 (a)、:I (m w 、, 及1 (e)的光隔離器301a、3〇1(：與3〇16，各包含一 個Y形連触4 ’是由不畴射麵分枝1慎分枝I〗構成。在本項說明 中，分枝是指能夠讓光通過的媒質。 圖1 (b)、1 (d)及1 (f )的光隔離器謝b、謝d與謝各包含一 娜骑接。再者，圖丨（g)與丨（h)的光隔離器測忌與議，各包含一個 X形連接。其中那-個額外的埠（即埠21)可用來監督輸出（即璋⑻，以 及用作這些光隔離器的反饋控制。 在光隔離_la、謝e_leW形連接（或其他_賴彡連接或邮 連接），分枝15的折射率⑹大於分枝14的折射帛（n2)。可以利用全反 射原理構造-個光學單_彡連接⑽連接·彡連接）_合器。如此可 確保光只會正向傳輸。從蟑18進人的光將穿越分枝丨铜達並穿越分枝服 從輸出埠_開。在反方向，從埠19進人的光會穿越分枝15，並狀射角仏 (如圖7)達到分枝14，因為符合(η2/ηι)的條件，所以會由於全反 射現象而受阻塞。因此，光無法進入分枝14，而留在分枝15。最後光不是 從埠22離開，就是被光吸收器17消耗。下列範例是根據平面波近似（plane wave approximation)進行估算： ---------------------------------------- 1234669 範例1 (個案1) 在圖1 (a)與1 (b)中’假設折射率 ηι二1. 465，Π2=1· 460，η3=1· 455， 而02=85.30。，則計算後的插入損耗（insertion loss)大約為0.13dB，其 中 ILp=0· 129dB，ILs=0.133dB。偏振相關損耗（polarization dependent loss)(即ILs-ILp)大約為0· 004dB，隔離度大約為9dB。 (個案2) 在圖 1(c)與 1(d)中，假設折射率 ηι=ι· 465，nlc=l. 460，Π2=1. 4625， 1^=1.4575，而θ2=86·70。，則計算後的插入損耗大約為〇. 13dB， ILp=0.133dB’ ILs=0」36dB。偏振相關損耗（即iLs-ILp)大約為〇·〇〇3(1Β， 隔離度大約為9dB。 因此’隔離度是與偏振無關的（ILs大約是ILp)，但僅9dB的隔離度是 低於預期。在範例1的（個案1 )中，雖然有理想的平行入射光，在埠19的 數值孔徑NA (m，ns)仍是〇· 171，其他數值孔徑為：NA (n2，n3)=〇. 121， ΝΑ (ηι，η2)=〇·121。因為ΝΑ (in，n3)大於μ (ηι，n2)，因此一部分來自埠 19的反向光能夠進入埠18。這是因為某些反向光的入射角仏（如圖7)小於 全反射的臨界角（critical angle肌，導致隔離度降低。隔離效果取決於 反向光的全反射有效性。反向光的全反财效性練，隔離效果就愈好。 要達到較高的隔離度，可以調低輸出槔19的數值孔徑。則（i _ (」·） 各顯示出額外的光輸出埠301i與謝】。對光輸出埠301i，計算指出97%的輸 - _ — 1234669 為0(Μ(ηι，n3))。除去這3%的輸出光，就可將數值孔徑降至〇·⑵， < P曰：曰加插入知耗013dB’並且輸出光的區域會擴大。對光輸出埠 j最佳的。到基本相同的結果，但輸出區卻大於綱丨的輸出區。 雖…、輸出數值她已經概，隔離度卻並未改善，因為額外的反向光從淳 19擴大的區域而進入輸入埠μ。 我們可以使用X形連接來降低輸出物的數值孔徑（見圖丨（〕範例）。 下一範例為圖1 (g)的實體。 範例2 在01(g)中，作又0又折射率 m=l_ 5〇〇，nic=i· 4958，Π2=1· 45〇，n2C=l· 4457， Θ2=85^Θι=76〇 . 2MB , 〇 ^ 相關損耗約為〇·漏，輸出埠值孔徑降低，因此_度大幅提高至 12dB。 改善301a、301b、301c、301d、301e和301iP高離度的另-個方法，就 是減少反向光從分枝15傳送至分枝14的傳送區域。如果傳送區域減少一 半’隔離度可增加3dB，如果減少成四分之一，隔離度可增加6dB。如果所 有反向光都在分枝15與分枝14的連接處全反射，則隔離效果將非常完美。 因此，我們可以在埠18、埠19加入一個光扼束器1，如圖1 (e)、1 (f)與 1 (h)所不。光扼束器1有兩個功能：（丨）降低數值孔徑，例如從〇. ^降 至0.1或甚至0.01 ’（2)將光聚集在分枝14與15的中心部分。所獲得的光隔 離器如圖1 (e)、1 (f )和1 (h)的301e、301f和301h即擁有更好的光學 效能，而且仍然很容易串聯與集成。 1234669 光隔離器301a、301b、301c、301d、301e、301f、301g和301h也可以 作為光衰減Is。光從埠18進入而從埠i9離開時，有固定的衰減量。請看範 例3 : 範例3 在範例1的情況中，如果輸入光數值孔徑為〇· 12，且θ2=85〇，則口偏振 與s偏振的衰減大約為4. 3dB，其差異幾乎為〇 (〇. 〇〇9仙）。 因此，衰減與偏振無關。計算顯示，角度㊀2愈小，衰減愈大。衰減可隨 者入射角02的改變而變化，因此，可變的光衰減^ (縱㈣。。的㈣ attenuator)是可行的。 根據全反射原理的光隔離器301a、301b、301c、301d、301e、3〇lf、 3〇lg和301h，具有簡單的結構，並獲得許多改進：堅固耐用、極好的熱屬 性與環境屬性、優越的穩定性與可雜、以及與偏振無關，而可達到的絕 佳光學效能。再者，它們也容易與其他光學裝置以及光電子裝置集成，這 些特色使它非常適合製造其他光學裝置，例如：光搞合器、光插入器、偏 振光複合器、光循環器、加多光復用器與多光復用分解器。 為 了讓光隔離器301a、301b、301c、301d、301e、301f、3012和難 能達到最理想化，可以改變Y形連接、K形連接和义形連接的形狀。分枝巧與 分枝14具有不同的折射率ηφη2 (這可從不同的電介f取得或相同的電介質 卻因有錐削形狀而具有不同的有效折射率）。折射率無需固定不變 以是x、y和z位置的函數。在一種具體實例中，分枝（波導或光纖等等）的 橫斷面可以是方形或長方形。 1234669 總之，具體實例是根據全反射的非互㈣、縣構造，而且可以是與偏 振無關的，並非常適合於麵。_Snell的錢射雜，#舰—個光密 媒質（具有較高的折射率ηι)傳送至另—個光疏翻（具有較低的折射率n〇 時，而且入射角a超過臨界值θι。，即^ac=sin_1(n2/ni)，就會發生全反射。 其結果，所有入射光會全反射回第一個媒質，而透射光會全部被阻塞。 因為ηι大於m ’ Π2就不能大於ηι。所以，全反射是非互易的，而且只有在光 從化媒質進人祕’才會發生，但從祕質反向進人祕質咖不會發生 全反射。利用全反射，我們就可以建造光隔離器3〇la、3〇lb、3〇lc、3〇id、 301e、301f、301g和301h。合適的分枝組合可構成光傳輸通道，而且容易 與其他光電子裝置集成（如半導體裝置）。 圖2 (a)和2 (b)表示光耦合器302a*302b，藉著將一系列的光隔離 tm301e 301f與301h串聯在一起而製成（為求簡化，因此並未緣出κ形連接 與X形連接和光扼束器1的設計圖）。光從輸入埠18、2〇傳送至輸出埠19。 圖為具有隔離功能的2x1耦合器。光耦合器302a*3〇2b因為具有偏振無關的 效能，因此也可以用來作為具有隔離功能的偏振光複合器。光耦合器3〇2& 和302b也可以作為加多光復用器，從埠2〇加入一條額外的訊號通道到 從埠18已有的訊號通道（&，入2…_)而不會互相干擾，而且從埠19輸出所有 訊號（入1’2…^)。使用相同的方法可以建立Nxl的加多光復用器。再者，光 耗合器302a和302b也可以作為光纖放大器（optical fiber amplifier)中 的光插入器（並具隔離功能）；光訊號與埠18連接，雷射泵浦（pump iaser) 與槔20連接’而輸出埠19連接光纖放大器（沒有繪出）。 .......... __ _ _ _ _ 12 1234669 圖3為利用三個沒有吸收器的光隔離器3〇le、3〇lf*3〇lh所建造的光循 環器303 (為求簡化，因此也未繪邮形連接與χ形連接和光扼束器丨的設計 圖）。從埠28進入的光會沿著通道前進並從埠29離開。以類似的方法，從 埠29進入的光會從埠3〇離開，依此類推。循環器3〇3也是偏振無關的。也可 以利用相同方法建造四個或更多個蜂的光循環器。 圖4為一個2x2的光耦合器304。它包含一個2xl的光耦合器3〇2a (或 302b)，與一個γ形分離器。從埠μ與埠2〇進入的光，會傳送至輸出埠a與 槔2卜這是-個在輸入璋與輸出埠之間，具有隔離功能的2χ2光麵合器。原 則上9我們也可建立一個具有隔離功能的ΝχΜ光耦合器。 圖5疋具有一個輸入埠π、一個輸出埠19以及一個吸收器17的偏光器 305。請見範例4。 範例4 假没ηι=4· 25，mc=4· 248，Π2=1· 460，n2c=l· 455，θ2=71·04ο，且㊀广^。， 則埠21的ρ偏振光的衰減為Αρ=2·2χ1〇ΛΐΒ，而3偏振光的衰減為As=4 2dB。 因此，衰減與偏振非常相關。從埠18輸入的光強度為（p，幻，其中口是 P偏振光的強度，而s*s偏振光的強度。光線穿越分枝14到達連接處，它一 方面折射進入分枝15，並繼續以強度（p，〇 38s)從輸出埠21離開。另一 方面，它反射進入分枝13，並繼續以強度（〇，〇 62s)到達輸出埠19。埠 19疋偏振光的輸出璋。 偏光器305的插入損耗低，只有2· 07dB，但隔離效果不好。若用光隔離 器 301a、301b:则 —·-------------- 13 1234669 立一個有良好隔離效果的偏光器305。 圖6 (a)也是一個多光復用分解器306a。它包含一個沒有吸收器17的 隔離器301e (301f或301h)和一個波長選擇器61。波長選擇器61可以是帶 通濾波器或是布拉格光栅（Bragg Gratings)(用光纖或波導技術）。具 有波長（λ^λζ,λ』.··）的光訊號從輸入埠18輸入穿越輸出埠19到達波長選擇 器61 °然後，選擇的波長（如&)會反射並從輸入埠22離開。其他具有波長 (λ^λ3"·)的訊號會穿透過選擇器61傳送而沒有損耗。 同樣的，圖6 (b)也是一個多光復用分解器3〇6b。它包含一個循環器 303和一個波長選擇器61。另外可以選擇多光復用器302a和302b與多光復用 分解器306a和306b串聯在一起，以構成一個加/減多光復用器（Add/Dr〇p Multiplexer)(未顯示）。 圖7疋光隔離器301a分枝14與分枝15Y形連接的放大圖。入射光34會穿 越隔離器301a。在行經途中，按照Fresnel的公式，光在Bq反射仏與折射“， 在〇再反射a與折射^，然後再於匕、G、B2· . · ·反射與折射。為了從分枝 14入射的光線34大部分強度能到達分枝15，可滿足2htana>d，其中d*h 分別為分枝14和分枝15的寬度。透射係數為tij=2pi/(帥），反射係數為 nKpi-pO/b+pi)，其中對TM波Pi=ni/cosei表示，對TE波， 1，>1，2, 3表不媒質m，Π2，η3。在區域I的穿透率為τ=ρ3 | t丨2/ρι，其中 (n3)V，相鄰穿透光線&與⑽相位差（phasedifference) 為23=(47^嶋501)/入。，其中入。是在真空中的光波長。如果仏02==如_1 (n3/n2), 14 Ϊ234669 ⑽間平均為零。同樣的，反射率 例外。因為-叫’㈣可〒1咖是零’編 進入婼~ m 且幾乎總是會逃逸並 入媒⑽’因此並不會增加光隔_的回波反射損失。 圖8顯示—種具體實例的光扼束器_。 @具_ ’適合這套光學錢設計_程式，給以輸入參數 !异出想要的姆數。提供輸入參數，電腦程式就能夠計算與模擬光學 d ’使其達到最佳化，以讓獲得的輪出參數能夠達到想要的條件如功 。隔離度插入知耗、偏振、偏振相關損耗、回波損失等等。此外，我 們也可以將上述的不同概念與方程式結合於電腦程式，崎行運算。 雖然上面描述了不同的具體實例，但請了解這些描述僅作為範例使 ，，亚沒有限定用途。因此，較佳具體實例的廣度與範圍，並不受上述示 ^實例的限制，而是依據下财請專利範圍與其同等内容加以定義。 【圖式簡單說明】 圖 1(a)、l(b)、l(c)、1(d)、1(e)、1(f)、1(g)*1(h) 各顯示一種具體實例的光隔離器/衰減器。 圖1 (i)和1 ( j)顯示修改過的圖！（a)與1 (b)輸出埠。 圖2 (a)與2 (b)顯示一種具體實例的光耦合器/插入器/加多光復用 器/偏振光複合器。 圖3表示一種具體實例的光循環器。 圖4展示一個2x2、輸入端與輸出端之間具有隔離的光耦合器。 圖5描繪一種具體實例的偏光器。 圖i( a)皇L( —b」挺繪二種^霞 151234669 发明 Description of the invention: [Technical field to which the invention belongs] This invention relates to an integrated optical system, an optical method, and an optical system designing device, and particularly to those related to optical isolators. [Previous technology] An optical isolator is a 1x1 unidirectional connector. In the optical system, it allows light to travel in only one direction in the optical path, and does not allow reverse transmission. Many optical systems often use optical isolators to eliminate back-propagating electromagnetic light waves. Opto-isolators can be compared with diodes (diGde). Diodes have low resistance to forward current from the input to the output and extremely high resistance to reverse current from the output to the input. Similarly, the forward light waves passing from the input port to the output port of the optical isolator will propagate in a low-loss manner, while the light waves that are input from the light-transmitting lung material in the opposite direction will be greatly attenuated, leaving only a small part from Input port leaves optical isolation | §. This type of optical isolation II has a unidirectional side characteristic and can cut off most of the reverse light returned from the output. The "reciprity city principle" of the propagation can be applied to such optical devices to obtain the required functions. Non-interlacing refers to the characteristic that optical signals can only be transmitted in the forward direction and not in the reverse direction. The ideal optical isolator is manufactured according to this non-reciprocity principle. A Faraday rotator is an optical isolator manufactured by a previous technology. It uses a magnetic-optic element as a non-reciprocal element. Unfortunately, such optical isolators made by the advanced technology have many difficulties, not only the function is polarization dependent, but also difficult to integrate with other optical components. 5 1234669 [Summary of the Invention] Here is an optical system and a method related to it, including a first branch, which can transmit light in forward and reverse directions. 'The first branch contains a first medium (refractive index) (ni), a first endpoint (㈣) and a second endpoint. This invention also includes a second branch, which only allows light to travel in a forward direction. The second branch contains a second medium having a second refractive index (ns, where η2 < η), and a first endpoint and a second endpoint. The second endpoint of the second branch will be further combined with the first branch to form an angle (θ2). (1) To prevent the reverse light passing through the first branch from entering the second branch by using the principle of total reflection Angle of incidence of two branches. In some specific examples, the first branch and the second branch may be γ-shaped, _-shaped, or X-shaped. We can choose to include the first branch with an optical absorber to absorb the reverse light that has not passed into the second branch due to total reflection. In another specific example, an optical choke (Qptiea, ehQker) may be placed at an end of the -branch to improve the isolation effect. In use, the isolation between the first branch and the first branch is independent of polarization (PolariZat10m independent), we can choose to lower the numerical aperture of a certain end of a branch to increase Isolation effect. It can also reduce the transmission area of one branch to improve the isolation effect. And it still shoots with a choke placed at one end of the branch to improve the isolation effect v… 1234669 In different specific realities, the optical pure can be used as optical isolation or optical attenuator (⑽_Ga). It is also possible to give the first branch and the second branch a rectangular cross section. The -th branch and the second branch can still be used as the _th finest element. It is also possible to combine a wavelength selector with an optical isolator to form a multi-optical multiplexer (de-multiplexer). In addition, the second optical isolator can also be integrated with the first optical isolator, thus forming an optical c_er. At the same time, the optical coupler formed in this way can also be used as an add-multiplexer, an optical inserter (postal acid), or a polarizing beam combiner. Furthermore, the light ^ may include a Y-splitter. In another specific example, the first light-separating lung and the second light-isolator may be integrated with the third light-isolator, and Form an optical circulator with three ports. Continue to use the same method to build an optical circulator with N ports. The optical wavelength selector can also be combined with the optical circulator to form a multiple Optical multiplexer. In addition, the optical system can also be designed as polarized light H (0ptical p〇larizer). With the above specific examples, with a very simple structure, it can have many of the following optical characteristics and functions, such as ruggedness Durable, excellent thermal and environmental properties, 'excellent stability and reliability, and excellent performance that can be achieved regardless of polarization. Moreover, they are also easily compatible with other optical microphones and opto-electronics Device integration, One kind of element can be made by a technology of multiple wave guides (waveguide), optical fiber (optical fiber), low-light (micr0-ptic) and photonic crystal (photonic crystal) technology. 1234669 [Embodiment] Figure 1 ( a), 1, one, (C), 1 (d), 1 (e), 1 (f), 1 (g), and! one ..., page specific optical isolator / attenuator. Special Yes, each optical isolator / attenuator, and optical device with a pair of endpoints. In this description, this endpoint can be Figure 1 (a),: I (mw ,, and 1 (e ) Optical isolators 301a, 301 (: and 3〇16, each containing a Y-shaped contact 4 'is composed of non-domain projection surface branch 1 careful branch I]. In this description, branch Refers to the medium that allows light to pass through. The optical isolators shown in Figures 1 (b), 1 (d), and 1 (f) Xb, Xd, and Xie each include a Na rider. Furthermore, Figure 丨 (g) The optical isolator with 丨 (h) is not compatible, and each includes an X-shaped connection. Among them, an additional port (ie port 21) can be used to monitor the output (ie, 璋 ⑻, and the Feedback control. In optical isolation _la, thank e_leW shape connection Or other _ Lai 彡 connection or post connection), the refractive index 分 of branch 15 is greater than the refraction 帛 (n2) of branch 14. You can use the principle of total reflection to construct an optical single _ 彡 connection⑽connection · 彡 connection) _ 合This will ensure that the light will only transmit in the forward direction. The light entering from the cockroach 18 will pass through the branch and the copper reaches and passes through the branch and obey the output port. In the opposite direction, the light entering from port 19 will pass through the branch. The branch 15 and the parallel shot angle 仏 (as shown in Fig. 7) reach the branch 14 because it meets the condition of (η2 / ηι), so it will be blocked due to the total reflection phenomenon. Therefore, light cannot enter branch 14 and stay on branch 15. Finally, the light either leaves the port 22 or is consumed by the light absorber 17. The following examples are estimated based on plane wave approximation: ------------------------------------ ---- 1234669 Example 1 (case 1) In Figures 1 (a) and 1 (b), 'assuming the refractive index ηι 1.465, Π2 = 1 · 460, η3 = 1 · 455, and 02 = 85.30. , The calculated insertion loss is approximately 0.13dB, where ILp = 0.129dB and ILs = 0.133dB. The polarization dependent loss (ILs-ILp) is about 0.004dB, and the isolation is about 9dB. (Case 2) In Figures 1 (c) and 1 (d), it is assumed that the refractive index η = ι · 465, nlc = 1.460, Π2 = 1. 4625, 1 ^ = 1.4575, and θ2 = 86 · 70. , The calculated insertion loss is about 0.13dB, ILp = 0.133dB ’ILs = 0 ″ 36dB. The polarization-dependent loss (iLs-ILp) is about 〇〇〇3 (1B, the isolation is about 9dB. So 'isolation is independent of polarization (ILs is about ILp), but only 9dB of isolation is lower than It is expected that in Example 1 (case 1), although there is ideal parallel incident light, the numerical aperture NA (m, ns) at port 19 is still 0.171, and other numerical apertures are: NA (n2, n3) = 〇. 121, ΝΑ (ηι, η2) = 〇121. Because NA (in, n3) is larger than μ (ηι, n2), part of the reverse light from port 19 can enter port 18. This is because some countermeasures The incident angle 仏 (see Figure 7) to the light is smaller than the critical angle of the total reflection (critical angle muscle, resulting in reduced isolation. The isolation effect depends on the effectiveness of the total reflection of the reverse light. The total anti-financial effectiveness of the reverse light The better the isolation effect. To achieve higher isolation, you can lower the numerical aperture of the output 调 19. Then (i _ ("·) each shows an additional optical output port 301i and Xie]. For the optical output port 301i, calculations indicate that 97% of the input-1234669 is 0 (M (η, n3)). By removing this 3% of the output light, the numerical aperture can be reduced To 〇 · ⑵, < P: Add the insertion loss 013dB 'and the area of the output light will be enlarged. The best for the optical output port j. To the same result, but the output area is larger than the output area Although ..., the output value has been approximated, the isolation has not improved, because additional reverse light enters the input port μ from the enlarged area of Chun 19. We can use X-shaped connection to reduce the numerical aperture of the output (see Figure 丨 (] Example). The next example is the entity of Figure 1 (g). Example 2 In 01 (g), make 0 and the refractive index m = l_ 5〇〇, nic = i · 4958, Π2 = 1 · 45〇, n2C = l · 4457, Θ2 = 85 ^ Θι = 76〇2MB, 〇 ^ Correlation loss is about 0 · leak, output port value aperture is reduced, so the degree is greatly improved to 12dB. Improved 301a, 301b, Another method for 301c, 301d, 301e, and 301iP high-resolution is to reduce the transmission area where the reverse light is transmitted from branch 15 to branch 14. If the transmission area is reduced by half, the isolation can be increased by 3dB, if it is reduced to four One half, the isolation can be increased by 6dB. If all the reverse light is totally reflected at the junction of branch 15 and branch 14 The isolation effect will be perfect. Therefore, we can add an optical choke 1 to port 18, port 19, as shown in Figure 1 (e), 1 (f) and 1 (h). Optical choke 1 has Two functions: (丨) reduce the numerical aperture, for example, from 0.1 to 0.1 or even 0.01 '(2) focus the light in the central part of the branches 14 and 15. The obtained optical isolator is shown in Figure 1 (e ), 301e, 301f, and 301h of 1 (f) and 1 (h) have better optical performance, and they are still easy to connect and integrate. 1234669 Optical isolators 301a, 301b, 301c, 301d, 301e, 301f, 301g, and 301h can also be used as optical attenuation Is. When light enters from port 18 and exits from port i9, there is a fixed amount of attenuation. Please see Example 3: Example 3 In the case of Example 1, if the numerical aperture of the input light is 0.12 and θ2 = 85 °, the attenuation of the mouth polarization and s polarization is about 4.3 dB, and the difference is almost 0 ( 〇〇〇〇09sen). Therefore, attenuation is independent of polarization. Calculations show that the smaller the angle ㊀2, the greater the attenuation. The attenuation can be changed as the incident angle 02 changes. Therefore, a variable light attenuation ^ (longitudinal attenuator) is feasible. Optical isolators 301a, 301b, 301c, 301d, 301e, 30f, 30g, and 301h based on the principle of total reflection, have a simple structure and have obtained many improvements: rugged, excellent thermal and environmental properties, Excellent stability and heterogeneity, and independent of polarization, but the best optical performance can be achieved. Furthermore, they are also easy to integrate with other optical devices and optoelectronic devices. These features make it very suitable for manufacturing other optical devices, such as: optical couplers, optical inserters, polarized light combiners, optical circulators, and multi-optical multiplexing. Converter and multi-optical multiplexing resolver. In order to optimize the optical isolators 301a, 301b, 301c, 301d, 301e, 301f, and 3012, it is possible to change the shape of the Y-shaped connection, the K-shaped connection, and the meaning-shaped connection. The branches and branches 14 have different refractive indices ηφη2 (this can be obtained from different dielectrics f or the same dielectric but have different effective refractive indices due to the tapered shape). The refractive index need not be fixed to be a function of the x, y, and z positions. In a specific example, the cross section of the branch (waveguide or optical fiber, etc.) may be square or rectangular. 1234669 In short, the specific example is a non-mutual, county structure based on total reflection, and it can be independent of polarization and very suitable for surfaces. _Snell's money shoots, # ship—a light-tight medium (with a higher refractive index η) is transmitted to another light sparse (when it has a lower refractive index n0, and the incident angle a exceeds a critical value θι). That is, ^ ac = sin_1 (n2 / ni), total reflection will occur. As a result, all incident light will be totally reflected back to the first medium, and transmitted light will all be blocked. Because η is greater than m 'Π2 cannot be greater than η. Therefore, total reflection is non-reciprocal, and it only occurs when light enters the secret from the chemical medium. However, total reflection does not occur from the reverse of the secret into the secret. Using total reflection, we can Build optical isolators 30a, 30lb, 30lc, 30id, 301e, 301f, 301g, and 301h. Appropriate branch combinations can form optical transmission channels, and are easy to integrate with other optoelectronic devices (such as semiconductor devices) Figure 2 (a) and 2 (b) show the optical coupler 302a * 302b, which is made by connecting a series of optical isolation tm301e 301f and 301h in series (for simplicity, the κ shape Design of connection and X-shaped connection and optical choke 1). Light is transmitted from input ports 18, 20 To output port 19. The picture shows a 2x1 coupler with isolation function. The optical coupler 302a * 3〇2b can also be used as a polarized light combiner with isolation function because of its polarization-independent performance. Optical coupler 3〇 2 & and 302b can also be used as multi-optical multiplexers, adding an additional signal channel from port 20 to the existing signal channel (&, input 2 ..._) from port 18 without interfering with each other, and the slave port 19 outputs all signals (into 1'2 ... ^). Using the same method, Nxl plus multiple optical multiplexers can be established. Furthermore, the optical couplers 302a and 302b can also be used as light in optical fiber amplifiers. Inserter (with isolation function); optical signal is connected to port 18, laser pump (iaser) is connected to 槔 20 'and output port 19 is connected to fiber amplifier (not shown) ........ .. __ _ _ _ _ 12 1234669 Figure 3 is a light circulator 303 constructed using three optical isolators 30le, 30f * 30lh without absorbers (for simplicity, the post is not shown) Design of X-shaped connection and χ-shaped connection and optical choke). Light entering from port 28 Go along the channel and leave from port 29. In a similar way, the light entering from port 29 will leave from port 30, and so on. The circulator 3 is also polarization independent. You can also use the same method to build four Or more bee optical circulator. Figure 4 is a 2x2 optical coupler 304. It contains a 2xl optical coupler 302a (or 302b), and a gamma-shaped splitter. Slave port μ and port 2 〇The incoming light will be transmitted to output ports a and 槔 2. This is a 2 × 2 smooth surface coupler with isolation function between input 璋 and output port. In principle, we can also build an NXM optocoupler with isolation function. FIG. 5A is a polarizer 305 having an input port π, an output port 19 and an absorber 17. See example 4. Example 4 Assuming that η = 4.25, mc = 4.248, Π2 = 1.460, n2c = 1.455, and θ2 = 71.04. , The attenuation of the ρ-polarized light at port 21 is Δρ = 2 · 2χ1〇ΛΐΒ, and the attenuation of the 3-polarized light is As = 4 2dB. Therefore, attenuation is very much related to polarization. The light input from port 18 is (p, magic, where port is the intensity of P-polarized light, and the intensity of s * s polarized light. The light passes through branch 14 to the connection, and it refracts into branch 15 on the one hand, and Continue to leave from output port 21 with intensity (p, 038s). On the other hand, it reflects into branch 13 and continues to reach output port 19 with intensity (0, 〇62s). Port 19 (the output of polarized light). Polarizer 305 has a low insertion loss of only 2.07dB, but the isolation effect is not good. If using optical isolators 301a, 301b: then --------------- 13 1234669 Polarizer 305 with good isolation. Figure 6 (a) is also a multi-optical demultiplexer 306a. It contains an isolator 301e (301f or 301h) without an absorber 17 and a wavelength selector 61. The wavelength selector 61 can Is a band-pass filter or Bragg Gratings (using fiber or waveguide technology). An optical signal with a wavelength (λ ^ λζ, λ "..) is input from input port 18 through output port 19 to a wavelength selector 61 ° Then, the selected wavelength (such as &) will reflect and leave from input port 22. A signal with a wavelength (λ ^ λ3 " ·) will pass through the selector 61 without loss. Similarly, Fig. 6 (b) is also a multi-optical multiplexing demultiplexer 3006b. It contains a circulator 303 and a wavelength Selector 61. Alternatively, multiple optical multiplexers 302a and 302b may be selected in series with the multiple optical multiplexers 306a and 306b to form an add / drop multiple multiplexer (not shown). Figure 7: An enlarged view of the optical isolator 301a branch 14 and branch 15Y-shaped connection. The incident light 34 will pass through the isolator 301a. During the journey, according to Fresnel's formula, the light reflects and refracts at Bq. Reflect a and refraction ^, and then dagger, G, B2 · · · · Reflect and refraction. In order for most of the intensity of the light 34 incident from branch 14 to reach branch 15, 2htana > d can be satisfied, where d * h Respectively the width of branch 14 and branch 15. The transmission coefficient is tij = 2pi / (handsome), and the reflection coefficient is nKpi-pO / b + pi), which is expressed for TM wave Pi = ni / cosei, and for TE wave, 1, > 1, 2, 3 indicates the media m, Π2, η3. The transmittance in the region I is τ = ρ3 | t 丨 2 / ρι, where (n3) V The phase difference between adjacent penetrating rays & and ⑽ is 23 = (47 ^ 嶋 501) / in., Where 入 is the wavelength of light in a vacuum. If 仏 02 == such as _1 (n3 / n2 ), 14 Ϊ234669 The mean between zero is zero. Similarly, the reflectivity is exceptional. Because -called ‘㈣ 可 〒1 Coffee is zero’, it enters 婼 ~ m and almost always escapes and enters the medium ⑽ ’, so it does not increase the optical reflection loss of the echo. FIG. 8 shows a specific example of the optical choke beam_. @ 具 _ ’is suitable for this set of optical money design _ program, given the input parameters! By providing input parameters, a computer program can calculate and simulate the optical d 'to optimize it, so that the obtained wheel-out parameters can achieve the desired conditions such as work. Isolation insertion loss, polarization, polarization-dependent loss, return loss, etc. In addition, we can also combine the different concepts and equations mentioned above into computer programs to perform computations. Although different specific examples are described above, please understand that these descriptions are for example only, and Ya have no limited use. Therefore, the breadth and scope of the preferred specific examples are not limited by the examples shown above, but are defined based on the scope of patents and their equivalents. [Schematic description] Figures 1 (a), l (b), l (c), 1 (d), 1 (e), 1 (f), 1 (g) * 1 (h) each show a specific Example of optical isolator / attenuator. Figures 1 (i) and 1 (j) show the modified figures! (A) and 1 (b) output ports. Figures 2 (a) and 2 (b) show a specific example of an optical coupler / interposer / multiple optical multiplexer / polarized light combiner. Fig. 3 shows a specific example of a light circulator. Figure 4 shows a 2x2 optocoupler with isolation between the input and output. FIG. 5 depicts a polarizer of a specific example. Figure i (a) Emperor L (-b '' is a pretty picture of two types of Xia 15