JP5831046B2

JP5831046B2 - Optical module

Info

Publication number: JP5831046B2
Application number: JP2011185280A
Authority: JP
Inventors: 昭生白崎
Original assignee: Mitsubishi Electric Corp
Current assignee: Mitsubishi Electric Corp
Priority date: 2011-08-26
Filing date: 2011-08-26
Publication date: 2015-12-09
Anticipated expiration: 2031-08-26
Also published as: JP2013045092A

Description

本発明は、例えば光通信システムに用いられる光モジュールに関する。 The present invention relates to an optical module used in, for example, an optical communication system.

特許文献１には、双方向光通信用の光モジュールが開示されている。この光モジュールの筐体には、発光素子、受光素子、及び光ファイバが取り付けられている。 Patent Document 1 discloses an optical module for bidirectional optical communication. A light emitting element, a light receiving element, and an optical fiber are attached to the casing of the optical module.

特開２００８−２０９２６６号公報JP 2008-209266 A

特許文献１に開示される光モジュールでは小型化が不十分であった。 The optical module disclosed in Patent Document 1 has been insufficiently miniaturized.

本発明は、上述のような課題を解決するためになされたもので、小型化に好適な光モジュールを提供することを目的とする。 SUMMARY An advantage of some aspects of the invention is that it provides an optical module suitable for miniaturization.

本発明に係る光モジュールは、第１側面と第２側面が対向し、第３側面と第４側面が該第１側面と該第２側面をつなぎつつ対向するように形成された筐体と、第１集光レンズと第１発光素子を有し、該第１集光レンズが該筐体の内部に位置することで、該第１側面から該筐体の内部に進入するように設けられた第１発光装置と、受光用集光レンズと受光素子を有し、該第２側面に設けられた受光装置と、該第３側面に設けられた、光信号を双方向に伝送する光ファイバと、第２集光レンズと第２発光素子を有し、該第４側面であって該第１側面と該第２側面の中間位置より該第２側面側に設けられた第２発光装置と、該第１発光素子から出射した第１送信光を反射して該光ファイバの端面に入射させ、該第２発光素子から出射した第２送信光を透過して該光ファイバの端面に入射させるように該筐体内に設けられた第１光フィルタと、該筐体内の該第１光フィルタと該光ファイバの間に設けられ、該第１送信光と該第２送信光を透過して該光ファイバの端面に入射させ、該光ファイバからの受信光を反射して該受光素子に入射させる第２光フィルタと、該筐体内の、該第１光フィルタと該第２光フィルタの間に設けられ、該第１送信光と該第２送信光のうち、該第１発光素子と該第２発光素子に戻る成分を遮断する光アイソレータと、を備え、該第１発光装置の該筐体内への進入量は、該受光装置の該筐体内への進入量より大きく、該第２発光素子と該光ファイバを結ぶ線は、該筐体の長手方向に対して傾き、該第１側面から該第１光フィルタまでの距離は、該第１側面から該第２光フィルタまでの距離より大きいことを特徴とする。
An optical module according to the present invention includes a housing formed such that the first side surface and the second side surface face each other, and the third side surface and the fourth side surface face each other while connecting the first side surface and the second side surface, The first condensing lens and the first light emitting element are provided, and the first condensing lens is provided inside the housing so that the first condensing lens enters the housing from the first side surface. A first light-emitting device, a light-receiving condensing lens and a light-receiving element, a light-receiving device provided on the second side surface, and an optical fiber provided on the third side surface for transmitting optical signals bidirectionally A second light emitting device having a second condensing lens and a second light emitting element, the fourth light emitting device being provided on the second side surface of the fourth side surface from an intermediate position between the first side surface and the second side surface; Second transmission light reflected from the first light-emitting element and incident on the end face of the optical fiber after being reflected from the first light-emitting element. A first optical filter provided in the casing so as to be transmitted and incident on the end face of the optical fiber; and provided between the first optical filter and the optical fiber in the casing; And a second optical filter that transmits the second transmission light and enters the end face of the optical fiber, reflects the reception light from the optical fiber and enters the light receiving element, and the first optical filter in the housing. An optical isolator that is provided between the optical filter and the second optical filter, and that blocks the component that returns to the first light emitting element and the second light emitting element of the first transmission light and the second transmission light. An amount of the first light emitting device entering the housing is larger than an amount of the light receiving device entering the housing, and a line connecting the second light emitting element and the optical fiber is a length of the housing. The distance from the first side surface to the first optical filter is inclined with respect to the direction, and the distance from the first side surface to the second optical filter is Wherein the larger distance to the filter.

本発明によれば、発光装置を筐体内に進入させるように光軸を調整するので、小型化に好適な光モジュールを提供できる。 According to the present invention, since the optical axis is adjusted so that the light emitting device enters the housing, an optical module suitable for downsizing can be provided.

本発明の実施の形態１に係る光モジュールを含むシステム全体を示す図である。It is a figure which shows the whole system containing the optical module which concerns on Embodiment 1 of this invention. 本発明の実施の形態１に係る光モジュールを示す図である。It is a figure which shows the optical module which concerns on Embodiment 1 of this invention. 本発明の実施の形態１に係る光モジュールの動作を示す図である。It is a figure which shows operation | movement of the optical module which concerns on Embodiment 1 of this invention. 比較例の光モジュールを示す図である。It is a figure which shows the optical module of a comparative example. 本発明の実施の形態２に係る光モジュールを示す図である。It is a figure which shows the optical module which concerns on Embodiment 2 of this invention. 本発明の実施の形態３に係る光モジュールを示す図である。It is a figure which shows the optical module which concerns on Embodiment 3 of this invention.

実施の形態１．
図１は、本発明の実施の形態１に係る光モジュールを含むシステム全体を示す図である。光モジュール１０は、１０Ｇ−ＥＰＯＮ（１０Ｇｉｇａｂｉｔ−ＥｔｈｅｒｎｅｔＰａｓｓｉｖｅＯｐｔｉｃａｌＮｅｔｗｏｒｋ）システムの一部である。１０Ｇ−ＥＰＯＮシステムは、局舎に設置される局側光回路終端装置（ＯＬＴ：ＯｐｔｉｃａｌＬｉｎｅＴｅｒｍｉｎａｌ）と、ＯＬＴと各加入者宅をつなぐ光分岐線路と、加入者宅に設置される加入者側光回路終端装置（ＯＮＵ：ＯｐｔｉｃａｌＮｅｔｗｏｒｋＵｎｉｔ）を備えている。 Embodiment 1 FIG.
FIG. 1 is a diagram showing an entire system including an optical module according to Embodiment 1 of the present invention. The optical module 10 is a part of a 10 G-EPON (10 Gigabit-Ethernet Passive Optical Network) system. The 10G-EPON system consists of a station-side optical circuit terminator (OLT) installed in a station building, an optical branch line connecting the OLT and each subscriber house, and a subscriber side installed in the subscriber house. An optical circuit unit (ONU) is provided.

１０Ｇ−ＥＰＯＮシステムは、１Ｇｂｐｓ及び１０Ｇｂｐｓの伝送レートのデータを上り（ＯＮＵからＯＬＴ）及び下り（ＯＬＴからＯＮＵ）の双方向に伝送する。この双方向通信は、一芯の光ファイバで、伝送レート、伝送方向ごとに設定された計４波長の信号を波長多重して行われる。 The 10G-EPON system transmits data at transmission rates of 1 Gbps and 10 Gbps in both directions (ONU to OLT) and downlink (OLT to ONU). This bidirectional communication is performed by wavelength multiplexing a total of four wavelengths of signals set for each transmission rate and transmission direction using a single optical fiber.

ＯＬＴは、前述の双方向通信を実現するために光モジュール１０（トリプレクサ）を備えている。光モジュール１０はＸＦＰ（１０ＧｉｇａｂｉｔＳｍａｌｌＦｏｒｍ−ａｃｔｏｒＰｌｕｇｇａｂｌｅ）等の仕様に従うトランシーバに搭載されている。 The OLT includes an optical module 10 (triplexer) to realize the above-described bidirectional communication. The optical module 10 is mounted on a transceiver conforming to a specification such as XFP (10 Gigabit Small Form-actor Pluggable).

図２は、本発明の実施の形態１に係る光モジュールを示す図である。光モジュール１０は、１Ｇｂｐｓの下り信号を送信する発光素子と、１０Ｇｂｐｓの下り信号を送信する発光素子と、１Ｇｂｐｓと１０Ｇｂｐｓのどちらの信号も受信可能な受光素子とを１芯の光ファイバに結合させたものである。以下、光モジュール１０について詳細に説明する。 FIG. 2 is a diagram showing the optical module according to Embodiment 1 of the present invention. The optical module 10 combines a light emitting element for transmitting a 1 Gbps downstream signal, a light emitting element for transmitting a 10 Gbps downstream signal, and a light receiving element capable of receiving both 1 Gbps and 10 Gbps signals into a single optical fiber. It is a thing. Hereinafter, the optical module 10 will be described in detail.

光モジュール１０は、筐体１２を備えている。図１において筐体１２は輪郭だけが示されている。筐体１２は、第１側面１２ａ、第２側面１２ｂ、第３側面１２ｃ、及び第４側面１２ｄを備えている。第１側面１２ａと第２側面１２ｂは対向している。第３側面１２ｃと第４側面１２ｄは、第１側面１２ａと第２側面１２ｂをつなぎつつ対向している。 The optical module 10 includes a housing 12. In FIG. 1, only the outline of the housing 12 is shown. The housing 12 includes a first side surface 12a, a second side surface 12b, a third side surface 12c, and a fourth side surface 12d. The first side surface 12a and the second side surface 12b are opposed to each other. The third side surface 12c and the fourth side surface 12d face each other while connecting the first side surface 12a and the second side surface 12b.

第１側面１２ａには第１発光装置１４が設けられている。第１発光装置１４は、第１集光レンズ１４ａと、レーザダイオードで形成された第１発光素子１４ｂを有している。第１集光レンズ１４ａは筐体１２の内部に位置している。これにより第１発光装置１４は第１側面１２ａから筐体１２の内部に距離Ｌだけ進入している。 A first light emitting device 14 is provided on the first side surface 12a. The first light emitting device 14 includes a first condenser lens 14a and a first light emitting element 14b formed of a laser diode. The first condenser lens 14 a is located inside the housing 12. Accordingly, the first light emitting device 14 enters the inside of the housing 12 by the distance L from the first side surface 12a.

第２側面１２ｂには受光装置１６が設けられている。受光装置１６は、受光用集光レンズ１６ａと、フォトダイオードで形成された受光素子１６ｂを有している。受光用集光レンズ１６ａは、第２側面１２ｂに沿うように設けられている。 A light receiving device 16 is provided on the second side surface 12b. The light receiving device 16 includes a light receiving condensing lens 16a and a light receiving element 16b formed of a photodiode. The light receiving condensing lens 16a is provided along the second side surface 12b.

第３側面１２ｃには光ファイバ１５が設けられている。光ファイバ１５の端面は、ファイバコア(ファイバ内部で光が閉じ込められている領域)内の光伝搬方向に対して６〜８度程度傾くように斜め研磨されている。ところで、光ファイバの端面がファイバコア内の光伝搬方向に対し垂直な場合、加入者側から伝送された光がその端面で反射され、再び加入者側に戻ってしまい反射減衰量の規格(ＯＬＴはＯＮＵに対して一定以上の光を反射してはならない規格)を満足できなくなってしまう。これを防止するために、光ファイバ１５の端面は斜め研磨されている。光ファイバ１５の端面を６〜８度斜め研磨する場合、スネルの法則から、光ファイバ１５と最適に結合する光軸はファイバコアの光伝搬方向に対し３〜４度傾く。 An optical fiber 15 is provided on the third side surface 12c. The end face of the optical fiber 15 is obliquely polished so as to be inclined by about 6 to 8 degrees with respect to the light propagation direction in the fiber core (region where light is confined inside the fiber). By the way, when the end face of the optical fiber is perpendicular to the light propagation direction in the fiber core, the light transmitted from the subscriber side is reflected by the end face and returns to the subscriber side again, and the standard of return loss (OLT) Will not be able to satisfy the standard (which must not reflect a certain amount of light) on the ONU. In order to prevent this, the end face of the optical fiber 15 is obliquely polished. When the end surface of the optical fiber 15 is obliquely polished by 6 to 8 degrees, the optical axis optimally coupled to the optical fiber 15 is inclined by 3 to 4 degrees with respect to the light propagation direction of the fiber core from Snell's law.

第４側面１２ｄには第２発光装置１８が設けられている。第２発光装置１８は、第２集光レンズ１８ａと、レーザダイオードで形成された第２発光素子１８ｂを有している。第２発光装置１８は、第４側面１２ｄの第２側面１２ｂ側に設けられている。つまり、第２発光装置１８は、第４側面１２ｄであって第１側面１２ａと第２側面１２ｂの中間位置より第２側面１２ｂ側に設けられている。第２発光装置１８を第２側面１２ｂ側に設けるのは、光ファイバ１５と第２発光素子１８ｂを最適に結合する光軸を第２側面１２ｂの方向に傾けるためである。 A second light emitting device 18 is provided on the fourth side surface 12d. The second light emitting device 18 includes a second condenser lens 18a and a second light emitting element 18b formed of a laser diode. The second light emitting device 18 is provided on the second side surface 12b side of the fourth side surface 12d. That is, the second light emitting device 18 is provided on the second side surface 12b side from the intermediate position between the first side surface 12a and the second side surface 12b on the fourth side surface 12d. The reason why the second light emitting device 18 is provided on the second side surface 12b side is to tilt the optical axis for optimally coupling the optical fiber 15 and the second light emitting element 18b toward the second side surface 12b.

第１発光素子１４ｂ、受光素子１６ｂ、第２発光素子１８ｂのそれぞれは、１枚の集光レンズを介することで収束光学系を成して、光ファイバ１５と結合している。なお、図２に示す通り、第１側面１２ａ及び第２側面１２ｂと平行方向を「長手方向」と称する。そしてこの長手方向と垂直で、第３側面１２ｃ及び第４側面１２ｄと平行な方向を「短手方向」と称する。 Each of the first light-emitting element 14b, the light-receiving element 16b, and the second light-emitting element 18b forms a converging optical system via one condenser lens and is coupled to the optical fiber 15. As shown in FIG. 2, the direction parallel to the first side surface 12a and the second side surface 12b is referred to as a “longitudinal direction”. A direction perpendicular to the longitudinal direction and parallel to the third side surface 12c and the fourth side surface 12d is referred to as a “short direction”.

筐体１２の内部には、第１光フィルタ２２、光アイソレータ２４、及び第２光フィルタ２６が設けられている。第２光フィルタ２６は、第１光フィルタ２２と光ファイバ１５の間に設けられている。光アイソレータ２４は、第１光フィルタ２２と第２光フィルタ２６の間に設けられている。 Inside the housing 12, a first optical filter 22, an optical isolator 24, and a second optical filter 26 are provided. The second optical filter 26 is provided between the first optical filter 22 and the optical fiber 15. The optical isolator 24 is provided between the first optical filter 22 and the second optical filter 26.

第１光フィルタ２２と第２光フィルタ２６は、第１発光素子１４ｂ又は第２発光素子１８ｂから出射した光を光ファイバ１５に結合させるように導くものである。また、第２光フィルタ２６は受信光を受光素子１６ｂに導くものである。光アイソレータ２４は、第１発光素子１４ｂと第２発光素子１８ｂから出射した光がこれらに戻らないように設けられるものである。 The first optical filter 22 and the second optical filter 26 guide the light emitted from the first light emitting element 14 b or the second light emitting element 18 b so as to be coupled to the optical fiber 15. The second optical filter 26 guides received light to the light receiving element 16b. The optical isolator 24 is provided so that the light emitted from the first light emitting element 14b and the second light emitting element 18b does not return to these.

光アイソレータ２４の最適入力波長は、光モジュール１０の動作温度範囲の最大値と最小値の中間の温度に最適化され、第１発光素子１４ｂの発光波長と第２発光素子１８ｂの発光波長の中間の値に設定されている。本発明の実施の形態１に係る光モジュール１０の動作温度範囲は０℃〜８０℃である。そのため、光アイソレータ２４の最適入力波長は、４０℃に最適化され、第１発光素子１４ｂの発光波長と第２発光素子１８ｂの発光波長の中間の値に設定されている。 The optimum input wavelength of the optical isolator 24 is optimized to an intermediate temperature between the maximum value and the minimum value of the operating temperature range of the optical module 10, and is intermediate between the emission wavelength of the first light emitting element 14b and the emission wavelength of the second light emitting element 18b. Is set to the value of The operating temperature range of the optical module 10 according to Embodiment 1 of the present invention is 0 ° C. to 80 ° C. Therefore, the optimum input wavelength of the optical isolator 24 is optimized to 40 ° C., and is set to an intermediate value between the emission wavelength of the first light emitting element 14b and the emission wavelength of the second light emitting element 18b.

図３は、本発明の実施の形態１に係る光モジュールの動作を示す図である。第１光フィルタ２２は、第１発光素子１４ｂから出射した第１送信光を反射して光ファイバ１５の端面に入射させ、第２発光素子１８ｂから出射した第２送信光を透過して光ファイバ１５の端面に入射させる。第２光フィルタ２６は、第１送信光と第２送信光を透過して光ファイバ１５の端面に入射させ、光ファイバ１５からの受信光を反射して受光素子１６ｂに入射させる。光アイソレータ２４は、第１送信光と第２送信光のうち、第１発光素子１４ｂと第２発光素子１８ｂに戻る成分（戻り光という）を遮断する。 FIG. 3 is a diagram illustrating the operation of the optical module according to Embodiment 1 of the present invention. The first optical filter 22 reflects the first transmission light emitted from the first light emitting element 14b to enter the end face of the optical fiber 15, and transmits the second transmission light emitted from the second light emitting element 18b to transmit the optical fiber. 15 is incident on the end face. The second optical filter 26 transmits the first transmission light and the second transmission light to be incident on the end face of the optical fiber 15, and reflects the reception light from the optical fiber 15 to be incident on the light receiving element 16b. The optical isolator 24 blocks a component (referred to as return light) that returns to the first light emitting element 14b and the second light emitting element 18b from the first transmission light and the second transmission light.

上記のような構成により、第１発光素子１４ｂから出射した第１送信光は集光レンズ１４ａに集光された後、第１光フィルタ２２で反射され、光アイソレータ２４と第２光フィルタ２６を透過し光ファイバ１５の端面に入射する。第２発光素子１８ｂから出射した第２送信光は集光レンズ１８ａに集光された後、第１光フィルタ２２、光アイソレータ２４、及び第２光フィルタ２６を透過し光ファイバ１５の端面に入射する。光ファイバ１５からの受信光は第２光フィルタ２６で反射し集光レンズ１８ａによって集光されて受光素子１６ｂの受光面に入射する。 With the configuration as described above, the first transmission light emitted from the first light emitting element 14b is collected by the condenser lens 14a, then reflected by the first optical filter 22, and passed through the optical isolator 24 and the second optical filter 26. The light passes through and enters the end face of the optical fiber 15. The second transmission light emitted from the second light emitting element 18 b is collected by the condenser lens 18 a, and then passes through the first optical filter 22, the optical isolator 24, and the second optical filter 26 and enters the end face of the optical fiber 15. To do. The received light from the optical fiber 15 is reflected by the second optical filter 26, collected by the condenser lens 18a, and incident on the light receiving surface of the light receiving element 16b.

ところで、光ファイバ１５は斜め研磨されて、光ファイバ１５と第２発光素子１８ｂを最適に結合する光軸を第２側面１２ｂの方向に傾かせている。図３には、この傾きを分かりやすくするために、第２側面１２ｂと平行な破線が描かれている。 By the way, the optical fiber 15 is obliquely polished, and the optical axis that optimally couples the optical fiber 15 and the second light emitting element 18b is inclined in the direction of the second side face 12b. In FIG. 3, a broken line parallel to the second side surface 12b is drawn to make this inclination easy to understand.

本発明の実施の形態１に係る光モジュールの特徴の説明に先立ち、その意義を明確にするめに比較例について説明する。図４は、比較例の光モジュールを示す図である。比較例の光モジュール１００は、光ファイバ１０４を備えている。光ファイバ１０４の端面はファイバコア内の光伝搬方向に対し垂直に形成されている。光ファイバ１０４と第２発光素子１８ｂを最適に結合する光軸は、第２側面１２ｂと平行方向に伸びている。 Prior to the description of the characteristics of the optical module according to Embodiment 1 of the present invention, a comparative example will be described in order to clarify its significance. FIG. 4 is a diagram illustrating an optical module of a comparative example. The optical module 100 of the comparative example includes an optical fiber 104. The end face of the optical fiber 104 is formed perpendicular to the light propagation direction in the fiber core. The optical axis that optimally couples the optical fiber 104 and the second light emitting element 18b extends in a direction parallel to the second side surface 12b.

比較例の光モジュール１００は、第１集光レンズ１４ａの直近に光アイソレータ１０６を備えている。また、第２集光レンズ１８ａの直近に光アイソレータ１０８を備えている。これにより、第１送信光は第１光フィルタ２２に入射する前に光アイソレータ１０６を透過する。第２送信光は第１光フィルタ２２に入射する前に光アイソレータ１０８を透過する。 The optical module 100 of the comparative example includes an optical isolator 106 in the immediate vicinity of the first condenser lens 14a. An optical isolator 108 is provided in the immediate vicinity of the second condenser lens 18a. Thereby, the first transmission light passes through the optical isolator 106 before entering the first optical filter 22. The second transmitted light passes through the optical isolator 108 before entering the first optical filter 22.

比較例の光モジュール１００では、光ファイバ１０４と第２発光素子１８ｂを最適に結合する光軸が第２側面１２ｂと平行方向に伸びるため、第１光フィルタ２２と第２光フィルタ２６は筐体の短手方向の中央に配置される。また、光アイソレータが２つ必要である。これらの要因により比較例の光モジュール１００は小型化が困難である。特に、光モジュールをＸＦＰサイズのトランシーバに搭載する場合には光モジュールの短手方向の寸法制約を満たすのが困難となる。 In the optical module 100 of the comparative example, since the optical axis that optimally couples the optical fiber 104 and the second light emitting element 18b extends in a direction parallel to the second side surface 12b, the first optical filter 22 and the second optical filter 26 are a casing. It is arranged in the center in the short direction. In addition, two optical isolators are required. Due to these factors, it is difficult to downsize the optical module 100 of the comparative example. In particular, when the optical module is mounted on an XFP-sized transceiver, it is difficult to satisfy the dimensional constraints in the short direction of the optical module.

ところが、本発明の実施の形態１に係る光モジュール１０は、光ファイバ１５と第２発光素子１８ｂを最適に結合する光軸が第２側面１２ｂの方向に傾けられているため、この光軸上に設けられる第１光フィルタ２２、光アイソレータ２４、及び第２光フィルタを第２側面１２ｂ側に寄せて配置できる。第１光フィルタ２２、光アイソレータ２４、及び第２光フィルタ２６を第２側面１２ｂ側に寄せて配置すると、第１発光装置１４の最適配置位置（光ファイバ１５との結合が最適となる位置）も第２側面１２ｂ側に寄る。これにより第１発光装置１４を筐体１２の内部に距離Ｌだけ進入させることができるので光モジュール１０の短手方向の寸法を短くできる。 However, in the optical module 10 according to Embodiment 1 of the present invention, the optical axis that optimally couples the optical fiber 15 and the second light emitting element 18b is inclined in the direction of the second side surface 12b. The first optical filter 22, the optical isolator 24, and the second optical filter that are provided on the second side surface 12b can be disposed close to the second side surface 12b. When the first optical filter 22, the optical isolator 24, and the second optical filter 26 are arranged close to the second side surface 12b, the optimal arrangement position of the first light emitting device 14 (the position where the coupling with the optical fiber 15 is optimal). Also approaches the second side surface 12b side. Accordingly, the first light emitting device 14 can be made to enter the inside of the housing 12 by the distance L, so that the size of the optical module 10 in the short direction can be shortened.

第１発光素子と受光素子を１つの側面に並べると、これらの相互干渉を抑制するために、第１発光素子と受光素子の間隔を十分あけなければならない。そのため、筐体の長手方向寸法を大きくする必要があった。しかしながら、本発明の実施の形態１に係る光モジュール１０によれば、第１発光素子１４ｂが第１側面１２ａに固定され、受光素子１６ｂが第２側面１２ｂに固定されることで、これらが対向して設けられている。よって、第１発光素子１４ｂと受光素子１６ｂとの距離を十分確保しつつ、光モジュールの長手方向の寸法を短くできる。長手方向の寸法を短くすると、第２集光レンズ１８ａと光ファイバ１５との距離を短くできるので、集光レンズ１８ａの結像倍率を下げて動作温度の変動による結合効率の変化(トラッキングエラー)を小さくすることが可能となる。 When the first light-emitting element and the light-receiving element are arranged on one side surface, the first light-emitting element and the light-receiving element must be sufficiently spaced to suppress mutual interference. Therefore, it is necessary to increase the longitudinal dimension of the housing. However, according to the optical module 10 according to the first embodiment of the present invention, the first light emitting element 14b is fixed to the first side surface 12a, and the light receiving element 16b is fixed to the second side surface 12b. Is provided. Therefore, the longitudinal dimension of the optical module can be shortened while ensuring a sufficient distance between the first light emitting element 14b and the light receiving element 16b. If the length in the longitudinal direction is shortened, the distance between the second condenser lens 18a and the optical fiber 15 can be shortened. Therefore, the coupling magnification changes due to fluctuations in operating temperature by reducing the imaging magnification of the condenser lens 18a (tracking error). Can be reduced.

比較例のように光アイソレータを発光素子の直近に配置すると、光ケラレを防ぐために受光径の大きな光アイソレータが必要となり、光モジュールの小型化に不利である。光アイソレータは、送信信号光のスポット径がより絞られる光ファイバ１５近傍に配置することが望ましい。本発明の実施の形態１に係る光モジュール１０によれば、光アイソレータ２４を第１光フィルタ２２と第２光フィルタ２６の間に配置したため、光アイソレータ２４を光ファイバ１５の近傍に配置できる。よって、光アイソレータ２４の小型化と低コスト化を図ることができる。 If the optical isolator is disposed in the immediate vicinity of the light emitting element as in the comparative example, an optical isolator having a large light receiving diameter is required to prevent optical vignetting, which is disadvantageous for miniaturization of the optical module. The optical isolator is desirably disposed in the vicinity of the optical fiber 15 where the spot diameter of the transmission signal light is further reduced. According to the optical module 10 according to Embodiment 1 of the present invention, since the optical isolator 24 is disposed between the first optical filter 22 and the second optical filter 26, the optical isolator 24 can be disposed in the vicinity of the optical fiber 15. Therefore, the optical isolator 24 can be reduced in size and cost.

ところで、前述の戻り光を抑制するために、光アイソレータの最適入力波長の変化を抑制することが望ましい。しかしながら、光アイソレータの最適入力波長は、温度依存性がある。つまり、光モジュールの温度変化量に略比例して、光アイソレータの最適入力波長が変化する。そのため、例えば、光アイソレータの最適入力波長を、「１０℃」に最適化して、第１発光素子１４ｂの発光波長と第２発光素子１８ｂの発光波長の中間の値に設定すると、０℃の場合は光アイソレータの最適入力波長の変化は小さいが、８０℃の場合はそれが非常に大きくなってしまう。 By the way, in order to suppress the above-mentioned return light, it is desirable to suppress a change in the optimum input wavelength of the optical isolator. However, the optimum input wavelength of the optical isolator is temperature dependent. That is, the optimum input wavelength of the optical isolator changes in proportion to the temperature change amount of the optical module. Therefore, for example, when the optimum input wavelength of the optical isolator is optimized to “10 ° C.” and set to an intermediate value between the emission wavelength of the first light emitting element 14 b and the emission wavelength of the second light emitting element 18 b, The change in the optimum input wavelength of the optical isolator is small, but at 80 ° C., it becomes very large.

そこで、光アイソレータ２４の最適入力波長は、光モジュール１０の動作温度範囲の最大値と最小値の中間の温度（４０℃）に最適化し、第１発光素子１４ｂの発光波長と第２発光素子１８ｂの発光波長の中間の値に設定した。そのため、光モジュールの温度が０℃となった場合も８０℃となった場合も、光アイソレータの最適入力波長の変化が大きくなることを回避できる。こうして、最適入力波長の変化を抑制しつつ、１つの光アイソレータ２４で第１送信光と第２送信光のうち第１発光素子１４ｂと第２発光素子１８ｂに戻る成分（戻り光）を減衰させることができる。なお、戻り光の減衰は相対強度雑音の規格を満足する必要がある。 Therefore, the optimum input wavelength of the optical isolator 24 is optimized to an intermediate temperature (40 ° C.) between the maximum value and the minimum value of the operating temperature range of the optical module 10, and the emission wavelength of the first light emitting element 14b and the second light emitting element 18b. An intermediate value of the emission wavelength was set. Therefore, even when the temperature of the optical module becomes 0 ° C. or 80 ° C., it is possible to avoid the change in the optimum input wavelength of the optical isolator from becoming large. In this way, the component (return light) that returns to the first light-emitting element 14b and the second light-emitting element 18b in the first transmission light and the second transmission light is attenuated by one optical isolator 24 while suppressing the change in the optimum input wavelength. be able to. The attenuation of the return light needs to satisfy the standard of relative intensity noise.

本発明の実施の形態１に係る光モジュールは様々な変形が可能である。例えば、光モジュール１０の動作温度範囲は０℃〜８０℃に限定されない。 The optical module according to Embodiment 1 of the present invention can be variously modified. For example, the operating temperature range of the optical module 10 is not limited to 0 ° C. to 80 ° C.

実施の形態２．
図５は、本発明の実施の形態２に係る光モジュールを示す図である。本発明の実施の形態２に係る光モジュールは、前述した実施の形態１に係る光モジュールと共通点が多い。そのため、前述した実施の形態１に係る光モジュールとの相違点を中心に説明する。 Embodiment 2. FIG.
FIG. 5 is a diagram illustrating an optical module according to Embodiment 2 of the present invention. The optical module according to Embodiment 2 of the present invention has much in common with the optical module according to Embodiment 1 described above. Therefore, the difference from the optical module according to Embodiment 1 described above will be mainly described.

光アイソレータ２４の第４側面１２ｄ側には第１光フィルタ５０が固定されている。一方、光アイソレータ２４の第３側面１２ｃ側には第２光フィルタ５２が固定されている。第１光フィルタ５０、光アイソレータ２４、及び第２光フィルタ５２は１つの部品５４を形成するように一体化されている。 A first optical filter 50 is fixed on the fourth side surface 12 d side of the optical isolator 24. On the other hand, the second optical filter 52 is fixed to the third side surface 12 c side of the optical isolator 24. The first optical filter 50, the optical isolator 24, and the second optical filter 52 are integrated so as to form one component 54.

本発明の実施の形態２に係る光モジュールによれば、第１光フィルタ５０、光アイソレータ２４、及び第２光フィルタ５２は１つの部品５４とすることで構成を簡易化できるので、光モジュールを小型化できる。なお、本発明の実施の形態２に係る光モジュールは少なくとも実施の形態１に係る光モジュールと同程度の変形は可能である。 According to the optical module according to the second embodiment of the present invention, the configuration of the first optical filter 50, the optical isolator 24, and the second optical filter 52 can be simplified by using one component 54. Can be downsized. Note that the optical module according to Embodiment 2 of the present invention can be modified at least as much as the optical module according to Embodiment 1.

実施の形態３．
図６は、本発明の実施の形態３に係る光モジュールを示す図である。本発明の実施の形態３に係る光モジュールは、前述した実施の形態２に係る光モジュールと共通点が多い。そのため、前述した実施の形態２に係る光モジュールとの相違点を中心に説明する。 Embodiment 3 FIG.
FIG. 6 is a diagram illustrating an optical module according to Embodiment 3 of the present invention. The optical module according to Embodiment 3 of the present invention has much in common with the optical module according to Embodiment 2 described above. Therefore, the difference from the optical module according to the second embodiment will be mainly described.

光アイソレータ６０に第１光フィルタ６２と第２光フィルタ６４が固定されて、１つの部品６６が形成されている。そして、第２光フィルタ６４の光アイソレータ６０に固定された面と反対の面は、光ファイバ１５の端面に固定されている。 The first optical filter 62 and the second optical filter 64 are fixed to the optical isolator 60 to form one component 66. The surface of the second optical filter 64 opposite to the surface fixed to the optical isolator 60 is fixed to the end surface of the optical fiber 15.

第１送信光と第２送信光は、光ファイバ１５に近づくほどスポット径が絞られる。そのため、光アイソレータ６０は光ファイバ１５に近づけるほど小さくできる。本発明の実施の形態３に係る光モジュールによれば、部品６６を光ファイバ１５の端面に接触させて光アイソレータ６０を光ファイバ１５に近接させるので、光アイソレータ６０を小型化できる。なお、本発明の実施の形態３に係る光モジュールは少なくとも実施の形態１に係る光モジュールと同程度の変形は可能である。 The spot diameters of the first transmission light and the second transmission light are narrowed toward the optical fiber 15. Therefore, the optical isolator 60 can be made smaller as it is closer to the optical fiber 15. According to the optical module according to Embodiment 3 of the present invention, the optical isolator 60 can be reduced in size because the optical isolator 60 is brought close to the optical fiber 15 by bringing the component 66 into contact with the end face of the optical fiber 15. The optical module according to Embodiment 3 of the present invention can be modified at least as much as the optical module according to Embodiment 1.

１０光モジュール、１２筐体、１４第１発光装置、１４ａ第１集光レンズ、１４ｂ第１発光素子、１５光ファイバ、１６受光装置、１６ａ受光用集光レンズ、１６ｂ受光素子、１８第２発光装置、１８ａ第２集光レンズ、１８ｂ第２発光素子、２２第１光フィルタ、２４光アイソレータ、２６第２光フィルタ DESCRIPTION OF SYMBOLS 10 Optical module, 12 Housing | casing, 14 1st light-emitting device, 14a 1st condensing lens, 14b 1st light-emitting element, 15 Optical fiber, 16 Light-receiving device, 16a Condensing lens for light reception, 16b Light-receiving element, 18 2nd light emission Device, 18a second condenser lens, 18b second light emitting element, 22 first optical filter, 24 optical isolator, 26 second optical filter

Claims

A housing formed such that the first side surface and the second side surface face each other, and the third side surface and the fourth side surface face each other while connecting the first side surface and the second side surface;
A first condensing lens and a first light emitting element, wherein the first condensing lens is located inside the housing, and is provided so as to enter the housing from the first side surface; A first light emitting device;
A light receiving device having a light receiving condensing lens and a light receiving element, provided on the second side surface;
An optical fiber provided on the third side surface for transmitting an optical signal bidirectionally;
A second light-emitting device having a second condenser lens and a second light-emitting element, the fourth light-emitting device being provided on the second side surface from an intermediate position between the first side surface and the second side surface on the fourth side surface;
The first transmission light emitted from the first light emitting element is reflected and incident on the end face of the optical fiber, and the second transmission light emitted from the second light emitting element is transmitted and incident on the end face of the optical fiber. A first optical filter provided in the housing;
Received light from the optical fiber that is provided between the first optical filter and the optical fiber in the housing, transmits the first transmission light and the second transmission light, and enters the end surface of the optical fiber. A second optical filter that reflects the light and makes it incident on the light receiving element;
A component that is provided between the first optical filter and the second optical filter in the casing and returns to the first light emitting element and the second light emitting element among the first transmission light and the second transmission light. and an optical isolator for blocking,
The amount of entry of the first light emitting device into the housing is greater than the amount of entry of the light receiving device into the housing,
The line connecting the second light emitting element and the optical fiber is inclined with respect to the longitudinal direction of the housing,
An optical module , wherein a distance from the first side surface to the first optical filter is larger than a distance from the first side surface to the second optical filter .

The optimum input wavelength of the optical isolator is optimized to an intermediate temperature between the maximum value and the minimum value of the operating temperature range of the optical module, and is intermediate between the emission wavelength of the first light emitting element and the emission wavelength of the second light emitting element. The optical module according to claim 1, wherein the optical module is set to a value of

The optical module according to claim 1, wherein an end face of the optical fiber is obliquely polished.

A housing formed such that the first side surface and the second side surface face each other, and the third side surface and the fourth side surface face each other while connecting the first side surface and the second side surface;
A first condensing lens and a first light emitting element, wherein the first condensing lens is located inside the housing, and is provided so as to enter the housing from the first side surface; A first light emitting device;
A light receiving device having a light receiving condensing lens and a light receiving element, provided on the second side surface;
An optical fiber provided on the third side surface for transmitting an optical signal bidirectionally;
A second light-emitting device having a second condenser lens and a second light-emitting element, the fourth light-emitting device being provided on the second side surface from an intermediate position between the first side surface and the second side surface on the fourth side surface;
The first transmission light emitted from the first light emitting element is reflected and incident on the end face of the optical fiber, and the second transmission light emitted from the second light emitting element is transmitted and incident on the end face of the optical fiber. A first optical filter provided in the housing;
Received light from the optical fiber that is provided between the first optical filter and the optical fiber in the housing, transmits the first transmission light and the second transmission light, and enters the end surface of the optical fiber. A second optical filter that reflects the light and makes it incident on the light receiving element;
A component that is provided between the first optical filter and the second optical filter in the casing and returns to the first light emitting element and the second light emitting element among the first transmission light and the second transmission light. An optical isolator for blocking
The first optical filter is fixed to the fourth side surface of the optical isolator, and the second optical filter is fixed to the third side surface of the optical isolator, so that the first optical filter, an optical isolator, and an optical module that is characterized in that integrated the second optical filter.

The optical module according to claim 4, wherein a surface of the second optical filter opposite to a surface fixed to the optical isolator is fixed to an end surface of the optical fiber.