201227018 六、發明說明： 【發明所屬之技術領域】 本發明係關於一種具有剖面方形狀之纖芯部之預成形體 之製作方法、光纖之製造方法及光纖。 【先前技術】 • 作為光纖之製造方法，已知有例如專利文獻丨中記载 者。於專利文獻1中記載之光纖之製造方法中，首先，形 成大致四角複柱體狀之纖芯棒，將大致四角稜柱狀之纖芯 棒插入至成為包覆部之玻璃管並自周圍加熱使其熔化，藉 此，使玻璃管收縮而形成纖芯棒與玻璃管一體化之光纖母 材。其後，對該光纖母材進行拉絲而獲得光纖。 先前技術文獻 專利文獻 專利文獻1 :國際公開第03/075058號說明書 【發明内容】 發明所欲解決之問題 然=，於專利文獻i中記載之製造方法中，於藉由加熱 玻璃官使其純而使纖芯棒與玻㈣—體㈣，大致 棱柱狀之纖芯棒之角部容易變形。 /、骽而§，於玻璃管之 加熱時’有時熱會集中於大致四角 , 月稷杈狀之纖芯棒之緣 邛。因此，當纖芯棒溶融時，因表 之角部變圓。 &張力使纖芯棒 如此若大致四角稜柱狀之纖怒棒之角部變形， 向製造之光纖入射雷射光束時，自、 W <纖心部之端部出 159087.doc 201227018 射之光束強度低於自纖芯部之其他部分出射之光束強度之 情形。因&，於使用具有該種大致四角稜柱狀之纖怎部之 光纖進行雷射加工之情形時，有時會難以均勻地加工工件 從而降低加工精度。 本發明之目的在於提供一種可抑制剖面方形狀之纖芯材 料之角部之變形的預成形體之製作方法'光纖之製造方法 及光纖。 解決問題之技術手段 本發明之預成形體之製作方法包括下述步驟：準備别面 方形狀之纖芯材料、具有低於纖芯材料之折射率之複數根 包覆材料、及具有與包覆材料相等之折射率之套管；將纖 〜材料收今於套管内’並且於纖芯材料與套管之間填充複 數根匕覆材料，藉此形成集成體；以及熔毀（⑺Ihpw)套管 及包覆材料，而形成預成形體。 如此於本發明之預成形體之製造方法中，藉由於剖面方 形狀之纖芯材料與套管之間填充複數根包覆材料，於其後 加熱集成體㈣毀套管及包覆材料時，熱於各包覆材料中 、 可抑制熱向纖芯材料之角部集中。因此，由於 可抑制纖芯材料之角部之熔融 致纖怒材料之角部變形。 故而可防止因表面張力導 J =製作方法中，較佳為，纖芯材料之軟化點係高於 套吕匕覆材料之軟化點，於形成預成形體之步驟中，以 低；纖“才料之軟化點且高於套管及包覆材料之軟化點之 胍又”、、集成體’炼毀套管及包覆材料。於此情形時，由 I59087.doc 201227018 於防止纖芯材料之 之纖芯材料之角部之變形。而確貫地防止因表面張力導致 於上述製作方、去 包覆材料具有平”，較佳為，複數根包覆材料中一部分 材料之平坦部面接觸^於形成集成體之步驟中，以包覆 管之纖芯材料之方式，於纖芯材料與套 吕之間填充複數根包覆 部面接觸於纖芯如此稭由使包覆材料之平坦 均勾地自勺覆奸 而於炼毁套管及包覆材料時，使熱 料。又二ί傳遞至纖芯材料，故而難以軟化纖芯材 料。莽此，官^包覆材料收縮時之塵力難以施加於纖芯材 ’、9 ，進—步防止纖芯材料之角部之變形。 製作方法中’較佳為，於形成集成體之步驟中， 進而f纖心材料之側方配置調芯用波導材料。於此情形 時’猎由對預成形體進行拉絲，而可獲得於剖面方形狀之 纖芯部之側方形成有調芯用波導之光纖。因此，於將該種 光纖”光纖陣列連接之情形時，可藉由利用調芯用波導對 兩者進行調芯’而可確保所期望之調芯精度。 此時’較佳為調芯用波導材料之厚度與纖芯材料之厚度 相等。於此情形時’可使於纖芯材料之側方配置調芯用波 導材料之步驟簡單化。 本《Θ之光纖之製&方法係於實施上述預成形體之製作 方法之後，對預成形體進行減’而形成具有剖面方形狀 之纖芯部之光纖。 如此於本發明之光纖之製造方法中，可藉由實施上述預 成形體之製作方法，而如上所述防止剖面方形狀之纖芯材 159087.doc 201227018 料之角部之變形。 本發明之光纖包含剖 之側方之調芯用波導、 部。 面方形狀之纖芯部、 及覆蓋纖芯部及調芯 配置於纖芯部 用波導之包覆 藉由使用上述預成形體之製 i作方法製造该種本發明之光 所述可防止剖面方形狀之纖芯材料之角部之變 厂"又自於在纖心部之側方配置有調怒用波導，故而於 將光纖與光纖陣列連接之愔 伕乞11形時，可藉由利用調芯用波導 對兩者進行調芯，而麵所期望之調芯精度。 發明之效果 根據本發明，於預成形體夕制& π± 取小體之製作時，可抑制剖面方形狀 之纖芯材料之角部之變形。拉μ ι y藉此，例如於使用由本預成形 體製造之光纖進行雷射加工之情形捭 <馆办挎’可使自光纖照射之 光束之強度保持固定，故而可均勻地加工工件。 【實施方式】 以下，參照圖丨對本發明之預成形體之製作#法、光纖 之製造方法及光纖之較佳之實施形態進行詳細說明。 圖1係表不光纖之製造方法之一實施形態之一部分即預 成形體的製作步驟之剖面圖。本實施形態之光纖之製造方 法係製造具有剖面方形狀之纖芯部之光纖（以下，稱為 「方形纖芯光纖」）者。方形纖芯光纖為例如應用於雷射 加工用途等之光纖。 圖2係表示包含圖1所示之預成形體之製作步驟之方形纖 芯光纖之製造步驟的順序的流程圖。此處，製造具有剖面 159087.doc 201227018 正方形狀（縱&尺寸比為1:1)之纖芯部之方形纖芯光纖。亦 可製造具有縱橫尺寸比相對較小之剖面矩形狀之纖芯部的 方形纖芯光纖》 ;圖中⑹圖1⑷所示，準備剖面正方形狀之纖 芯材料卜複數根剖面圓形狀（圓柱狀）之棒狀包覆材料2、 及可收容纖芯材料1之套管3(步驟議）。作為棒狀包覆材 料2，可使用各種直徑者。 棒狀包覆材料2及套管3係於本實施形態中由相同材料形 成’但只要具有相等之折射率即可，並不限定於相同材 料纖心材料1之折射率係高於棒狀包覆材料2及套管3之 折射率。換言之，棒狀包覆材料2及套管3之折射率係低於 纖〜材料1之折射率。又，纖芯材料i之軟化點係高於棒狀 已覆材料2及套管3之軟化點。例如，纖芯材料i係由純氧 化石夕形成，棒狀包覆材料2及套管3係由添加有氟之氧化石夕 形成。 寺於以使纖芯材料1成為剖面正方形狀之方式進行 機械加工之後，使用氟酸清洗纖芯材料1，而除去存在於 纖芯材料1之表面上之微粒子之堆積物…於利用熱源 拉伸棒狀包覆材料2之後’將棒狀包覆材料2切斷為與纖芯 才料丨相同之長度，其後，使用氟酸清洗棒狀包覆材料2， 除去存在於棒狀包覆材料2之表面上之微粒子之堆積 物。又，藉由使用含有81^及(：12之混合氣體對套管3之内 側之表面進行氣相蝕刻，而自套管3之内側之表面除去雜 質或水分。 159087.doc 201227018 其次，如圖1⑷所示，將纖芯材料1插入至套管3内而收 容（步驟議）。而且’於套管3與纖站材料丨之間之空間 充複數根棒狀包覆材料2’而形成集成體4(步驟_)。' 繼而，以低於纖芯材料i之軟化點且高於棒狀包覆材❸ 及套皆3之軟化點之溫度（例如觀t以上之溫度）將集成體 4加熱60分鐘（步驟Sl04)。於一例中，將黏度”成為 1〇7·5(即lGgT1=7.5)之溫度^義為軟化點，於纖芯材m為純 氧化碎之情形時，纖芯材料丨之軟化點為17〇〇t，於棒狀 包覆材料2及套管3為添加有氣之氧切之情形時，棒狀包 覆材料2及套管3之軟化點為_左右。即，此情形時之 集成體4之加熱溫度較佳為ΐ4〇(Γ(：〜17()(Γ(：。 其次，於使套管3内之壓力降低至例如未達工心之狀態 下，熔毁套管3及棒狀包覆材料2(步驟Sl〇5)。藉此，套管 3及棒狀包覆材料2炫融而成為一體，從而形成如圖工⑻所 示之預成形體5。預成形體5包含剖面正方形狀之纖芯部 6、及覆蓋該纖芯部6之周圍之剖面圓形狀之包覆部7。此 時’較佳為以纖芯部6之黏度高於套管3及棒狀包覆材❿ 之黏度之方式設定加熱溫度。 其次，㈣種預成形體5進行拉絲而形成方形纖芯光纖 (步驟 S106)。 如上所述於本實施形態中，於將剖面正方形狀之纖芯材 料1插入至套管3内之後，於套管3與織芯材料丨之間之空間 填充熱容量較空氣小之複數根棒狀包覆材料2。因此，於 其後加熱集成體4時，熱於棒狀包覆材料2中擴散，而可抑 159087.doc 201227018 制熱向纖芯材料i之角部集中。如此藉由抑制熱之集中， 可抑制纖心材料1之角部之熔融，而可防止因表面張力導 致之纖芯材料1之角部之變形。 因此，於使用以上述方式製造之方形纖芯光纖對工件進 行雷射加工之情形_，由於自方形纖芯光纖之纖芯部照射 之光束之強度變得均勻，故而可提高工件之加工精度。 圖3係表示光纖之製造方法之其他實施形態之一部分即 預成形體的製作步驟之剖面圓。圖中，對與上述實施形態 相同之要素賦予相同符號，並省略其說明。 圖4係表示包含圖3所示之預成形體之製作步驟之方形纖 怎光纖之製造步驟的順序的流程圖。此處，製造具有縱橫 尺寸比相對較大（例如丨：5〇)之剖面矩形狀之纖芯部之方形 纖芯光纖。 於圖4中，首先，如圖3⑷所示，準備剖面矩形狀之纖怒 材料π、複數根剖面圓形狀之棒狀包覆材料2、剖面矩形 狀之纖芯加強用包覆材料12A、12B、及可收容纖芯材料 U之套f 3(步驟S111)。纖芯加強用包覆材料12A、12B使 用有2根。纖芯加強用包覆材料12A、—係由例如與棒狀 覆材料2相同之材料形成。棒狀包覆材料2、套管3及纖 〜加強用包覆材料12A、12B之折射率係低於纖芯材料u 之折射率。又，纖芯材料11之軟化點係高於棒狀包覆材料 2套管3及纖芯加強用包覆材料12A、12B之軟化點。例 如，纖芯材料11係由純氧化矽形成。 其-人，如圖3(a)所示，將纖芯材料丨丨及纖芯加強用包覆 159087.doc 201227018 材料12A、12B插入至套管3内而收容（步驟SU2)。此時， 以由2根纖芯加強用包覆材料12A於上下方向夾持纖芯材料 11並且由2根纖芯加強用包覆材料丨2 B於左右方向夾持纖芯 材料11之方式，相對於纖芯材料丨丨配置各纖芯加強用包覆 料A 12B❶藉此，纖这材料11之整個侧面與各纖站 加強用包覆材料12 A、12B面接觸。 具體而言’於將一者之纖芯加強用包覆材料12A、12B 插入至套管3内且配置於特定位置之後，旋轉套管3使該纖 心加強用包覆材料12A、12B傾斜。於此狀態下，將纖芯 材料11插入至套管3内且配置於特定位置，其後，將另一 者之纖芯加強用包覆材料12A、12B插入至套管3内且配置 於特定位置《可藉由使纖芯加強用包覆材料12A、12B傾 斜’而穩定性良好地定位纖芯材料丨i。 其次’如圖3(a)所示，於套管3與各纖芯加強用包覆材料 12A、12B之間之空間填充複數根棒狀包覆材料2，而形成 集成體13(步驟S113)。 其次，與圖1所示之步驟S104同樣地，對集成體13加熱 特定時間（步驟S114)。 繼而，與圖1所示之步驟S105同樣地，熔毀套管3、棒狀 包覆材料2、及纖芯加強用包覆材料12A、12B(步驟 S115)。藉此’形成圖3(b)所示之預成形體14。預成形體14 係包含剖面矩形狀之纖芯部1 5、及覆蓋該纖芯部15之周圍 之剖面圓形狀之包覆部16。 其次，對該種預成形體14進行拉絲而形成方形纖芯光纖 159087.doc •10· 201227018 (步驟 S116) 〇 如上所述於本實施形態中，由於以於纖芯材料11之周圍 使纖芯加強用包覆材料12八、12Β面接觸於纖芯材料丨丨之 方式而配置，故而於其後加熱集成體13時，熱均勻地自纖 芯加強用包覆材料12Α、12Β傳遞至纖芯材料η，因此， 纖芯材料11難以軟化。藉此，與於套管3與各纖芯加強用 包覆材料12Α、12Β之間填充複數根棒狀包覆材料2相結 合，可進一步防止因表面張力導致之纖芯材料丨丨之角部之 變形。 又，由於纖芯材料11與纖芯加強用包覆材料12Α、12Β 面接觸，故而於上述熔毀時，套管3、棒狀包覆材料2及纖 芯加強用包覆材料12Α、12Β收縮時之壓力難以施加於纖 芯材料11。因此，即便纖芯材料丨丨充分薄，亦可防止纖芯 材料11之變形。 進而，由於由各纖芯加強用包覆材料12A、12B夾持纖 芯材料11，故而可提高製造之方形纖芯光纖之纖芯部之同 心度、即光纖之中心與纖芯部之中心之一致度。 圖5係表示光纖之製造方法之又一實施形態之一部分即 預成形體的製作步驟的剖面圖。圖中，對與上述實施形態 相同之要素賦予相同符號，並省略其說明。 圖6係表示包含圖5所示之預成形體之製作步驟之方形纖 芯光纖之製造步驟的順序的流程圖。此處，製造於剖面矩 形狀之纖芯部之左右兩側配置有調芯用波導之方形纖芯光 纖。 159087.doc 201227018 於圖6中，首先，如圖5(a)所示，準備剖面矩形狀之纖芯 材料11、2根剖面正方形狀之調芯用波導材料2〇、複數根 剖面圓形狀之棒狀包覆材料2、2根刮面矩形狀之纖芯加強 用包覆材料12A、2根剖面矩形狀之纖芯加強用包覆材料 12B、2根剖面圓形狀之間隔物用包覆材料21、及套管^(步 驟S121)。調芯用波導材料2〇係由例如與纖芯材料u相同 之材料形成’且具有與纖芯材料11相等之折射率及軟化 點。又’調芯用波導材料2〇之剖面尺寸（各邊之長度）係與 纖心材料11之厚度（高度）相等。作為間隔物用包覆材料 2 1，亦可為具有剖面正方形狀者。 其次’將纖芯材料丨丨、調芯用波導材料2〇、纖芯加強用 包覆材料12A、12B及間隔物用包覆材料21插入至套管3内 而收容（步驟S122)。此時，於纖芯材料丨丨之左右兩側介隔 間隔物用包覆材料2丨配置調芯用波導材料2〇，於此狀態 下’由2根纖芯加強用包覆材料12A於上下方向夾持纖芯材 料11及各調芯用波導材料2〇並且由2根纖芯加強用包覆材 料12B於左右方向夾持纖芯材料11及各調芯用波導材料20 之方式’配置各纖芯加強用包覆材料12A、12B。 具體而言，於將一者之纖芯加強用包覆材料12A、12B 插入至套管3内且配置於特定位置之後，旋轉套管3使該纖 心加強用包覆材料丨2A ' i 2B傾斜。於此狀態下，將一者 之調芯用波導材料2〇、一者之間隔物用包覆材料2丨、纖芯 材料11 '另一者之間隔物用包覆材料21、及另一者之調芯 用波導材料2〇依序插入至套管3且配置於特定位置，進而 159087.doc -12· 201227018 將另一者之纖芯加強用包覆材料12A、12B插入至套管3内 且配置於特定位置。 其次’如圖5(a)所示，於套管3與各纖芯加強用包覆材料 12A、12B之間之空間填充複數根棒狀包覆材料2，而形成 集成體22(步驟S123)。 繼而’與圖1所示之步驟S104同樣地，於將該集成體22 加熱特定時間（步驟S124)之後，熔毀套管3、棒狀包覆材 料2、及纖芯加強用包覆材料12a、12B(步驟SU5)。藉 此’形成如圖5(b)所示之預成形體23。預成形體23係包含 剖面矩形狀之纖芯部15、配置於該纖芯部15之左右兩側之 1對調芯用波導24、以及覆蓋纖芯部15及各調芯用波導24 之周圍之剖面圓形狀之包覆部25。 其次，對該種預成形體23進行拉絲而形成方形纖芯光纖 (步驟 S126)。 …、:而，於方形纖芯光纖之纖芯部之厚度（高度）充分小之 情形時’有時於對方形纖芯光纖導入光時使用光纖陣列。 於此情形時，由於方形纖芯光纖之纖芯部之寬度尺寸較 大’故而於對光纖陣列與方形纖芯光纖進行調芯時，有時 無法獲得所期望之調芯精度。 一 w 一具"；々7]，纖 纖之纖芯部之左右兩側，故而可㈣料調β用波導 纖陣列與方形纖芯光纖進行調芯。具體而言，向調怒 波導入射光’此時利用㈣計測量自調芯用各波導出 光強度。藉此’可確保光纖陣列與方形狀纖芯光纖之) I59087.doc s 201227018 望之調芯精度。 再者，作為調芯用波導之尺寸，較理想的是與所連接之 光纖陣列之光纖纖芯徑為相同程度。 圖7係表示圖5所示之預成形體之製作步驟之變形例的剖 面圖。於圖7中’貞芯材料U之厚度係大於調芯用波導材 料20之剖面尺寸（各邊之長度卜於此情形時’另行準備例 如4根剖面矩形狀之間隔物用包覆材料3〇，且將該等間隔 物用包覆材料30配置於各調芯用波導材料2〇之下側及上側 即可。 本發月並不限疋於上述貫施形態。例如，於圖3 '圖$及 圖7所示之實施形態中，於集成體之形成時，使剖面矩形 狀之纖芯加強用包覆材料12A、12B面接觸於剖面矩形狀 =纖芯材料11，但作為纖芯加強用包覆材料，並不特別限 定於剖面矩形狀者’亦可使用具有平坦部之纖芯加強用包 覆材料，且使該纖芯加強用包覆材料之平坦部面接觸於剖 面矩形狀之纖芯材料丨i。 【圖式簡單說明】 圖…）、（bM系表示光纖之製造方法之_實_態之一部 刀即預成形體的製作步驟的剖面圖。 圖2係表不包含圖丨所示之預成形體之製作步驟之光纖之 製造步驟的順序的流程圖。 圖3(a)、(b)係表示光纖之製造方法之其他實施形態之一 σΡ刀即預成形體的製作步驟的剖面圖。 圖4係表示包含圖3所示之預成形體之製作步驟之光纖之 159087.doc 14 201227018 製造步驟的)嗔序的流程圖。 圖5(a)、（b)係表示光纖之製造方法之又一實施形態之一 4分即預成形體的製作步驟的剖面圖。 圖6係表示包含圖5所示之預成形體之製作步驟之光纖之 製造步驟的順序的流程圖。 圖7(a)、（b)係表示圖5所示之預成形體之製作步驟之變 形例之剖面圖。 【主要元件符號說明】 1 纖芯材料 2 棒狀包覆材料 3 套管 4 集成體 5 預成形體 6 纖芯部 7 包覆部 11 纖芯材料 12A 纖芯加強用包覆材料 12B 纖芯加強用包覆材料 13 集成體 14 預成形體 15 纖芯部 20 調芯用波導材料 22 集成體 23 預成形體 159087.doc • 15 · 201227018 24 25 調芯用 包覆部 波導 159087.doc -16-201227018 VI. [Technical Field] The present invention relates to a method for producing a preform having a core portion having a cross-sectional shape, a method for producing an optical fiber, and an optical fiber. [Prior Art] As a method of manufacturing an optical fiber, for example, those described in the patent document are known. In the method for producing an optical fiber described in Patent Document 1, first, a core rod having a substantially square-corner shape is formed, and a core rod having a substantially square prism shape is inserted into a glass tube serving as a coating portion and heated from the periphery. This melts, whereby the glass tube is shrunk to form an optical fiber preform in which the core rod and the glass tube are integrated. Thereafter, the optical fiber preform is drawn to obtain an optical fiber. PRIOR ART DOCUMENT PATENT DOCUMENT Patent Document 1: International Publication No. 03/075058 [Invention] The problem to be solved by the invention is that, in the manufacturing method described in Patent Document i, the glass is made pure by heating the glass And the core rod and the glass (four)-body (four), the corner portion of the substantially prismatic core rod is easily deformed. /, 骽 and §, when the glass tube is heated, sometimes the heat will concentrate on the roughly four corners, the edge of the moon-shaped core rod. Therefore, when the core rod is melted, the corners of the watch are rounded. & tension causes the core rod to deform like a corner of a substantially square prismatic anger stick, and when a laser beam is incident on the manufactured fiber, the end portion of the core portion is 159087.doc 201227018 The intensity of the beam is lower than the intensity of the beam emerging from other portions of the core. When &, when laser processing is performed using an optical fiber having such a substantially square prismatic fiber, it may be difficult to uniformly machine the workpiece to reduce the processing accuracy. SUMMARY OF THE INVENTION An object of the present invention is to provide a method for producing a preform, a method for producing an optical fiber, and an optical fiber, which can suppress deformation of a corner portion of a core material having a cross-sectional shape. Means for Solving the Problem The method for producing a preform according to the present invention comprises the steps of: preparing a core material having a different square shape, a plurality of coating materials having a refractive index lower than that of the core material, and having a coating a casing of equal refractive index; a fiber-material is enclosed in the casing' and a plurality of coating materials are filled between the core material and the casing, thereby forming an integrated body; and melting ((7) Ihpw) casing And coating the material to form a preform. In the method for manufacturing a preform according to the present invention, by filling a plurality of coating materials between the core material of the cross-sectional shape and the sleeve, and then heating the integrated body (4) to destroy the casing and the cladding material, The heat is concentrated in the respective cladding materials to suppress the concentration of heat toward the corners of the core material. Therefore, since the melting of the corner portion of the core material can suppress the deformation of the corner portion of the material. Therefore, it is possible to prevent the surface tension from being in the manufacturing method. Preferably, the softening point of the core material is higher than the softening point of the sheathing material, and in the step of forming the preform, the fiber is low. The softening point of the material is higher than the softening point of the casing and the cladding material, and the integrated body's refining sleeve and cladding material. In this case, I59087.doc 201227018 is used to prevent deformation of the corners of the core material of the core material. However, it is ensured that the surface of the above-mentioned fabric and the uncoated material are flat due to the surface tension. Preferably, the flat surface of a part of the plurality of coating materials is in contact with each other in the step of forming the integrated body. The method of covering the core material is to fill a plurality of roots between the core material and the sleeve to contact the core, so that the straw is covered by the flat material of the coating material. When the tube and the covering material are used, the hot material is transferred to the core material, so that it is difficult to soften the core material. Therefore, the dust force when the official coating material shrinks is difficult to apply to the core material ', 9, Further, the deformation of the corner portion of the core material is prevented. In the manufacturing method, it is preferable that in the step of forming the integrated body, the waveguide material for alignment is disposed on the side of the f-core material. By drawing the preform, the optical fiber of the core for adjusting the core can be formed on the side of the core portion of the cross-sectional shape. Therefore, when the optical fiber array is connected, the optical fiber array can be utilized. The core is tuned by a waveguide While ensuring the desired alignment accuracy. At this time, it is preferable that the thickness of the waveguide material for alignment is equal to the thickness of the core material. In this case, the step of arranging the waveguide material for aligning the core material on the side of the core material can be simplified. The "manufacturing method of the optical fiber" is an optical fiber in which the preform is subjected to a method of producing the preform, and then the preform is reduced to form a core portion having a cross-sectional shape. In the method for producing an optical fiber according to the present invention, the method of producing the preform can be used to prevent deformation of the corner portion of the core material 159087.doc 201227018 as described above. The optical fiber of the present invention includes a waveguide and a portion for alignment of the side of the cross section. The core portion of the square shape, and the coating of the core portion and the core for arranging the waveguide for the core portion are manufactured by using the method of using the preform to produce the light of the present invention. The corner of the core material of the core material is changed from the side of the core portion to the side of the core portion, so that when the fiber is connected to the fiber array, the shape can be The core is tuned by the modulating waveguide, and the desired alignment accuracy is achieved. Advantageous Effects of Invention According to the present invention, deformation of a corner portion of a core material having a cross-sectional shape can be suppressed in the production of a preform body and a π± small body. By pulling, for example, in the case of performing laser processing using an optical fiber manufactured from the present preform, the intensity of the light beam irradiated from the optical fiber can be kept constant, so that the workpiece can be uniformly processed. [Embodiment] Hereinafter, preferred embodiments of the method for producing a preform of the present invention, a method for producing an optical fiber, and an optical fiber will be described in detail with reference to the accompanying drawings. Fig. 1 is a cross-sectional view showing a step of fabricating a preform, which is one of the embodiments of the method for producing an optical fiber. The optical fiber manufacturing method of the present embodiment is an optical fiber (hereinafter referred to as "square core fiber") having a core portion having a cross-sectional shape. The square core fiber is, for example, an optical fiber used for laser processing applications and the like. Fig. 2 is a flow chart showing the procedure of the manufacturing steps of the square core fiber including the manufacturing steps of the preform shown in Fig. 1. Here, a square core fiber having a core portion having a cross-section 159087.doc 201227018 square shape (longitudinal & size ratio of 1:1) is manufactured. It is also possible to manufacture a square core fiber having a core portion having a relatively small aspect ratio and a relatively small cross-sectional dimension; and (6) as shown in Fig. 1 (4), a core material having a square shape in a cross section is prepared in a plurality of circular cross-sections (cylindrical shape). The rod-shaped covering material 2 and the sleeve 3 capable of accommodating the core material 1 (step). As the rod-shaped covering material 2, various diameters can be used. The rod-shaped covering material 2 and the sleeve 3 are formed of the same material in the present embodiment, but as long as they have equal refractive indices, the refractive index of the core material 1 of the same material is not limited to that of the rod-shaped package. The refractive index of the covering material 2 and the sleeve 3. In other words, the refractive index of the rod-shaped covering material 2 and the sleeve 3 is lower than the refractive index of the fiber-1 material 1. Further, the softening point of the core material i is higher than the softening point of the rod-shaped covering material 2 and the sleeve 3. For example, the core material i is formed of pure oxide oxide, and the rod-shaped coating material 2 and the sleeve 3 are formed of oxyfluoride to which fluorine is added. After the core material 1 is machined in a square shape, the core material 1 is washed with hydrofluoric acid, and the deposit of the fine particles existing on the surface of the core material 1 is removed... After the rod-shaped covering material 2, the rod-shaped covering material 2 is cut into the same length as the core material, and thereafter, the rod-shaped coating material 2 is washed with hydrofluoric acid, and the rod-shaped coating material is removed. A deposit of fine particles on the surface of 2. Further, the surface of the inner side of the sleeve 3 is subjected to vapor phase etching using a mixed gas containing 81 and (12) to remove impurities or moisture from the inner surface of the sleeve 3. 159087.doc 201227018 Next, as shown in the figure As shown in 1(4), the core material 1 is inserted into the sleeve 3 to be housed (step), and the space between the sleeve 3 and the material of the fiber station is filled with a plurality of rod-shaped cladding materials 2' to form an integration. Body 4 (step _). Then, the integrated body 4 is at a temperature lower than the softening point of the core material i and higher than the softening point of the rod-shaped covering material ❸ and the sleeve 3 (for example, a temperature above t) Heating for 60 minutes (step S104). In one example, the temperature at which the viscosity is 1〇7·5 (ie, lGgT1=7.5) is the softening point, and when the core material m is a pure oxidized smash, the core The softening point of the material 丨 is 17 〇〇t, and when the rod-shaped covering material 2 and the sleeve 3 are oxygen-cut by adding gas, the softening point of the rod-shaped covering material 2 and the sleeve 3 is about _. That is, in this case, the heating temperature of the integrated body 4 is preferably ΐ4〇(Γ(:~17()(Γ(:. Next, the pressure in the sleeve 3 is lowered to the example). In the state in which the work is not completed, the sleeve 3 and the rod-shaped covering material 2 are melted (step S10). Thereby, the sleeve 3 and the rod-shaped covering material 2 are spliced and integrated to form an image. The preform 5 shown in the item (8). The preform 5 includes a core portion 6 having a square shape in cross section, and a cladding portion 7 covering a circular cross section around the core portion 6. In this case, it is preferable to The heating temperature is set such that the viscosity of the core portion 6 is higher than the viscosity of the sleeve 3 and the rod-shaped covering material 。. Next, the (four) preforms 5 are drawn to form a square core fiber (step S106). In the present embodiment, after the core material 1 having a square shape in cross section is inserted into the sleeve 3, a space between the sleeve 3 and the core material is filled with a plurality of rod-shaped covering materials having a smaller heat capacity than air. 2. Therefore, when the integrated body 4 is heated, the heat is diffused in the rod-shaped covering material 2, and the heating of the core material i is concentrated by the heating of 159087.doc 201227018. Thus by suppressing the concentration of heat , can suppress the melting of the corner portion of the core material 1 and prevent the core material 1 due to surface tension The deformation of the corner portion. Therefore, in the case of performing laser processing on the workpiece using the square core fiber manufactured in the above manner, since the intensity of the light beam irradiated from the core portion of the square core fiber becomes uniform, Fig. 3 is a cross-sectional circle showing a step of forming a preform in a part of another embodiment of the method for producing an optical fiber, and the same reference numerals are given to the same elements as in the above embodiment, and the description thereof is omitted. Fig. 4 is a flow chart showing the sequence of manufacturing steps of the square fiber fiber including the manufacturing step of the preform shown in Fig. 3. Here, the manufacturing has a relatively large aspect ratio (for example, 丨: 5 〇). A square core fiber with a rectangular core section. In FIG. 4, first, as shown in FIG. 3 (4), a corrugated material π having a rectangular cross section, a rod-shaped covering material having a plurality of circular cross-sections, and a core reinforcing cladding material 12A and 12B having a rectangular cross section are prepared. And a sleeve f 3 capable of accommodating the core material U (step S111). Two core materials for reinforcing the core reinforcement 12A, 12B are used. The core reinforcing cladding material 12A is formed of, for example, the same material as the rod-shaped coating material 2. The refractive index of the rod-shaped cladding material 2, the sleeve 3, and the fiber-reinforced cladding materials 12A, 12B is lower than the refractive index of the core material u. Further, the softening point of the core material 11 is higher than the softening point of the rod-like covering material 2 sleeve 3 and the core reinforcing cladding materials 12A and 12B. For example, the core material 11 is formed of pure ruthenium oxide. As shown in Fig. 3(a), the core material 丨丨 and the core reinforcing coating 159087.doc 201227018 materials 12A and 12B are inserted into the sleeve 3 and housed (step SU2). In this case, the core material 11 is sandwiched between the two core reinforcing cladding materials 12A in the vertical direction, and the core material 11 is sandwiched between the two core reinforcing cladding materials 丨2B in the left-right direction. Each of the core reinforcing cladding materials A 12B is disposed with respect to the core material 丨丨, whereby the entire side surface of the fiber material 11 is in surface contact with the respective fiber station reinforcing cladding materials 12 A and 12B. Specifically, after one of the core reinforcing cladding materials 12A and 12B is inserted into the sleeve 3 and placed at a specific position, the rotary sleeve 3 inclines the core reinforcing covering materials 12A and 12B. In this state, the core material 11 is inserted into the sleeve 3 and placed at a specific position, and thereafter, the other core reinforcing cladding materials 12A and 12B are inserted into the sleeve 3 and disposed in a specific state. The position "the core material 丨i can be stably positioned by tilting the core reinforcing cladding materials 12A, 12B". Next, as shown in FIG. 3(a), a plurality of rod-shaped covering materials 2 are filled in the space between the sleeve 3 and each of the core reinforcing covering materials 12A and 12B to form an integrated body 13 (step S113). . Next, similarly to step S104 shown in Fig. 1, the integrated body 13 is heated for a specific time (step S114). Then, similarly to step S105 shown in Fig. 1, the sleeve 3, the rod-shaped covering material 2, and the core reinforcing cladding materials 12A and 12B are melted (step S115). Thereby, the preform 14 shown in Fig. 3(b) is formed. The preform 14 includes a core portion 15 having a rectangular cross section and a cladding portion 16 having a circular cross section covering the periphery of the core portion 15. Next, the preform 14 is drawn to form a square core fiber 159087.doc •10·201227018 (step S116). As described above, in the present embodiment, the core is made around the core material 11. The reinforcing material is disposed in such a manner that the covering material 12 and 12 are in contact with the core material, so that when the integrated body 13 is heated thereafter, the heat is uniformly transferred from the core reinforcing cladding material 12Α, 12Β to the core. The material η, therefore, is difficult to soften the core material 11. Thereby, a plurality of rod-shaped covering materials 2 are filled between the sleeve 3 and each of the core reinforcing covering materials 12A and 12A, thereby further preventing the corner portion of the core material due to surface tension. The deformation. Further, since the core material 11 is in surface contact with the core reinforcing cladding materials 12A and 12Β, the sleeve 3, the rod-shaped covering material 2, and the core reinforcing covering material 12Α, 12Β shrink during the meltdown. The pressure at that time is difficult to apply to the core material 11. Therefore, even if the core material 丨丨 is sufficiently thin, deformation of the core material 11 can be prevented. Further, since the core material 11 is sandwiched between the core reinforcing cladding materials 12A and 12B, the concentricity of the core portion of the manufactured square core fiber, that is, the center of the optical fiber and the center of the core portion can be improved. Consistency. Fig. 5 is a cross-sectional view showing a step of producing a preform, which is a part of still another embodiment of the method for producing an optical fiber. In the drawings, the same components as those in the above embodiment are denoted by the same reference numerals, and their description will be omitted. Fig. 6 is a flow chart showing the procedure of the manufacturing steps of the square core fiber including the manufacturing steps of the preform shown in Fig. 5. Here, a square core fiber in which a waveguide for alignment is disposed is disposed on the left and right sides of the core portion of the cross-sectional moment shape. 159087.doc 201227018 In Fig. 6, first, as shown in Fig. 5(a), a core material 11 having a rectangular cross section, two waveguide materials for a rectangular shape having a square cross section, and a plurality of circular cross sections are prepared. Rod-shaped coating material 2, 2 core-reinforced cladding materials 12A having a rectangular shape, two core-shaped cladding materials 12B having a rectangular cross section, and two cladding materials for spacers having a circular cross-section 21, and the casing ^ (step S121). The core-aligning waveguide material 2 is formed of, for example, the same material as the core material u and has a refractive index and a softening point equivalent to those of the core material 11. Further, the cross-sectional dimension (the length of each side) of the waveguide material 2 is the same as the thickness (height) of the core material 11. The covering material 2 1 for spacers may have a square shape in cross section. Then, the core material 丨丨, the core-aligning waveguide material 2〇, the core reinforcing cladding materials 12A and 12B, and the spacer covering material 21 are inserted into the sleeve 3 and housed (step S122). At this time, the core shielding material 2〇 is disposed on the left and right sides of the core material by the covering material 2丨, and in this state, the two core reinforcing coating materials 12A are used. In the direction of sandwiching the core material 11 and each of the alignment waveguide materials 2B, the core material 11 and the alignment waveguide material 20 are sandwiched by the two core reinforcing cladding materials 12B in the left-right direction. The core reinforcing cladding materials 12A and 12B. Specifically, after inserting one of the core reinforcing cladding materials 12A and 12B into the sleeve 3 and disposing it at a specific position, the rotary sleeve 3 makes the core reinforcing cladding material 丨2A ' i 2B tilt. In this state, one of the core-aligning waveguide materials 2, one of the spacer coating materials 2, the core material 11', the other spacer coating material 21, and the other The core-aligning waveguide material 2 is sequentially inserted into the sleeve 3 and disposed at a specific position, and further 159087.doc -12· 201227018 inserts the other core reinforcing cladding materials 12A, 12B into the sleeve 3 And configured in a specific location. Next, as shown in FIG. 5(a), a plurality of rod-shaped covering materials 2 are filled in the space between the sleeve 3 and each of the core reinforcing covering materials 12A and 12B to form an integrated body 22 (step S123). . Then, in the same manner as step S104 shown in FIG. 1, after the integrated body 22 is heated for a specific time (step S124), the sleeve 3, the rod-shaped covering material 2, and the core reinforcing cladding material 12a are melted. , 12B (step SU5). By this, a preform 23 as shown in Fig. 5(b) is formed. The preform 23 includes a core portion 15 having a rectangular cross section, a pair of alignment waveguides 24 disposed on the right and left sides of the core portion 15, and a periphery of the cover core portion 15 and each of the alignment waveguides 24. A cladding portion 25 having a circular cross section. Next, the preform 23 is drawn to form a square core fiber (step S126). ...,: When the thickness (height) of the core portion of the square core fiber is sufficiently small, the fiber array is sometimes used when introducing light into the square core fiber. In this case, since the width of the core portion of the square core fiber is large, the desired alignment accuracy may not be obtained when the fiber array and the square core fiber are aligned. One w one "; 々 7], the left and right sides of the core of the fiber, so (4) material adjustment β with the waveguide fiber array and square core fiber for core adjustment. Specifically, the incident light is incident on the oscillating waveguide. At this time, the light intensity is derived from each wave for the self-aligning core by the (four) meter. This ensures the alignment accuracy of the fiber array and the square-shaped core fiber I59087.doc s 201227018. Further, as the size of the waveguide for alignment, it is preferable that the fiber core diameter of the connected fiber array is the same. Fig. 7 is a cross-sectional view showing a modification of the manufacturing process of the preform shown in Fig. 5. In Fig. 7, the thickness of the core material U is larger than the cross-sectional dimension of the waveguide material 20 for alignment. (When the length of each side is in this case, for example, a covering material for a spacer having four rectangular cross-sections is prepared separately. The spacers 30 may be disposed on the lower side and the upper side of each of the alignment waveguide materials 2〇. The present month is not limited to the above-described embodiment. For example, in FIG. 3' In the embodiment shown in FIG. 7, in the formation of the integrated body, the core reinforcing cladding materials 12A and 12B having a rectangular cross section are in contact with the cross-sectional rectangular shape = the core material 11, but are reinforced as a core. The coating material is not particularly limited to a rectangular shape in cross section. A core reinforcing cladding material having a flat portion may be used, and the flat portion surface of the core reinforcing cladding material may be in contact with a rectangular cross section. Core material 丨i. [Simple description of the drawing] Fig....), (bM is a cross-sectional view showing a step of manufacturing a preform, which is a part of the method of manufacturing the optical fiber. Figure 制造 Manufacturing steps of the optical fiber in the fabrication step of the preform Fig. 3 (a) and (b) are cross-sectional views showing the steps of fabricating a preform of a σ Ρ 其他, which is another embodiment of the method for producing an optical fiber. Fig. 4 is a view showing the arrangement of the preform shown in Fig. 3. The flow chart of the manufacturing process of the pre-formed body of the optical fiber 159087.doc 14 201227018 manufacturing step. Fig. 5 (a) and (b) are cross-sectional views showing a step of producing a preform, which is one of the four embodiments of the method for producing an optical fiber. Fig. 6 is a flow chart showing the procedure of the manufacturing steps of the optical fiber including the manufacturing steps of the preform shown in Fig. 5. Fig. 7 (a) and (b) are cross-sectional views showing a modification of the manufacturing process of the preform shown in Fig. 5. [Main component symbol description] 1 Core material 2 Rod-shaped cladding material 3 Sleeve 4 Integrated body 5 Pre-formed body 6 Core portion 7 Covering portion 11 Core material 12A Core reinforcing cladding material 12B Core reinforcement Coating material 13 Integrated body 14 Pre-formed body 15 Core portion 20 Core material for waveguide core 22 Integrated body 23 Pre-formed body 159087.doc • 15 · 201227018 24 25 Covering waveguide for modulating core 159087.doc -16-