JP5759039B1 - Optical coupling structure - Google Patents
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- 230000003287 optical effect Effects 0.000 title claims abstract description 163
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Abstract
【課題】高密度な光配線が可能な多層光導波路の層間を、より高い効率で光結合できる光結合構造を提供する。【解決手段】第１光結合領域１３１を、他の領域の第１コア層１０３より細く形成する。また、第１光結合領域１３１の上部に、層間クラッド層を介して重なって平行に配置された第２光結合領域１５１も、他の領域の第２コア層１０５より細く形成する。また、層間クラッド層は、第１光結合領域１３１と第２光結合領域１５１との間は光結合が可能とされ、第１光結合領域１３１と第２光結合領域１５１との間以外の第１コア層１０３と第２コア層１０５との間では光結合が起きない厚さとされている。【選択図】図２An optical coupling structure capable of optically coupling between layers of a multilayer optical waveguide capable of high-density optical wiring with higher efficiency. A first optical coupling region is formed narrower than a first core layer in another region. Further, the second optical coupling region 151 disposed in parallel and overlapping the interlayer cladding layer on the upper portion of the first optical coupling region 131 is also formed narrower than the second core layer 105 in the other region. The interlayer clad layer is capable of optical coupling between the first optical coupling region 131 and the second optical coupling region 151, and the interlayer cladding layer other than between the first optical coupling region 131 and the second optical coupling region 151. The thickness is such that no optical coupling occurs between the first core layer 103 and the second core layer 105. [Selection] Figure 2
Description
本発明は、多層光導波路の層間を光結合する光結合構造に関する。 The present invention relates to an optical coupling structure that optically couples layers of a multilayer optical waveguide.
近年、電子回路の処理能力の向上や消費電力の低減にむけて、電気配線に代えて光配線を電子回路チップ上に構築する技術の開発が進められている。これらの技術においては、電気配線と同様に光配線にも多層配線が求められ、この要求に応えるために、アモルファスシリコンや窒化シリコンを用いた多層光導波路システムが提案されている。通常、光導波路は、平面内に回路を構築するが、上述した多層光導波路システムにおいては、各光導波路層間の光信号の交換、即ち多層光導波路層間の光結合が必要である。 In recent years, in order to improve the processing capability of an electronic circuit and reduce power consumption, development of a technique for constructing an optical wiring on an electronic circuit chip instead of an electric wiring has been advanced. In these techniques, multilayer wiring is required for optical wiring as well as electrical wiring, and a multilayer optical waveguide system using amorphous silicon or silicon nitride has been proposed to meet this demand. Normally, an optical waveguide constructs a circuit in a plane. However, in the above-described multilayer optical waveguide system, exchange of optical signals between optical waveguide layers, that is, optical coupling between multilayer optical waveguide layers is necessary.
このような多層光導波路層間の光結合構造としては、現在、図７の（ａ）に示すような、グレーティングカップラを用いた構造が提案されている（非特許文献１）。また、図７の（ｂ）に示す方向性結合器を用いた構造（非特許文献２）、および図７の（ｃ）に示す対向逆テーパーを用いた構造（非特許文献３）なども提案されている。 As such an optical coupling structure between multilayer optical waveguide layers, a structure using a grating coupler as shown in FIG. 7A is currently proposed (Non-Patent Document 1). In addition, a structure using the directional coupler shown in FIG. 7B (Non-patent Document 2) and a structure using opposed reverse taper shown in FIG. 7C (Non-Patent Document 3) are also proposed. Has been.
しかしながら、上述した多層光導波路層間の光結合構造は、いずれも通信用の１５５０ｎｍ近傍波長帯域で実現されているが、実用上大きな問題をかかえている。まず、グレーティングカップラを用いた光結合構造は、回折を利用するので一般に結合効率が低く、非特許文献１によれば結合効率は２０％程度と非常に低い。また、グレーティングカップラを用いた光結合構造は、波長帯域も狭く波長１５５０ｎｍ帯の赤外光における９０％動作帯域は計算上でも１０ｎｍ程度である。 However, all of the optical coupling structures between the multilayer optical waveguide layers described above are realized in a wavelength band near 1550 nm for communication, but have a large practical problem. First, since the optical coupling structure using the grating coupler uses diffraction, the coupling efficiency is generally low. According to Non-Patent Document 1, the coupling efficiency is as low as about 20%. Further, the optical coupling structure using the grating coupler has a narrow wavelength band and a 90% operating band in infrared light having a wavelength of 1550 nm is about 10 nm in calculation.
次に、方向性結合器を用いた光結合構造は、そもそも隣接層の光導波路が結合できるよう近づけた層間距離になっているため、隣接層の光導波路は、チップ面内の同じ位置に重ねて並走配置することができない。この問題を避けるため、非特許文献２では、隣接層の光導波路は、光導波路進行方向に対して垂直方向にずらした位置に配置し、曲線光導波路を用いて光結合部だけを重ねる構造となっている。しかしながら、このような構造では光導波路の水平面内の配列間隔を広くせざるを得ず、高密度な光配線が困難となる。 Next, since the optical coupling structure using a directional coupler has an interlayer distance that is close enough to allow coupling of adjacent optical waveguides, the adjacent optical waveguides overlap each other in the chip surface. Cannot be placed side by side. In order to avoid this problem, in Non-Patent Document 2, the optical waveguide of the adjacent layer is disposed at a position shifted in the direction perpendicular to the traveling direction of the optical waveguide, and only the optical coupling portion is overlapped using a curved optical waveguide. It has become. However, with such a structure, the arrangement interval in the horizontal plane of the optical waveguide must be widened, and high-density optical wiring becomes difficult.
次に、対向逆テーパーを用いた光結合構造は、まず入力側光導波路は途中で消失してしまうため、任意の分岐比での層間結合が不可能であり、光スイッチなどの干渉計を構成することができない。また、非特許文献２の技術と同様に、層間距離が近いため、高密度な光配線は困難である。さらに、非特許文献２の参考文献５にあるように、この種の逆テーパーデバイスでは層間結合に必要な距離は一般に数百μｍと非常に長くなり、やはり高密度な光配線が困難となる。 Next, in the optical coupling structure using the opposite reverse taper, the optical waveguide on the input side disappears in the middle, so interlayer coupling at an arbitrary branching ratio is impossible, and an interferometer such as an optical switch is constructed. Can not do it. Further, as with the technique of Non-Patent Document 2, since the interlayer distance is short, high-density optical wiring is difficult. Further, as described in Reference 5 of Non-Patent Document 2, in this type of reverse taper device, the distance required for interlayer coupling is generally very long, such as several hundred μm, and high-density optical wiring is also difficult.
本発明は、以上のような問題点を解消するためになされたものであり、高密度な光配線が可能な多層光導波路の層間を、より高い効率で光結合できるようにすることを目的とする。 The present invention has been made to solve the above-described problems, and an object thereof is to enable optical coupling between layers of a multilayer optical waveguide capable of high-density optical wiring with higher efficiency. To do.
本発明に係る光結合構造は、基板の上に形成された下部クラッド層と、下部クラッド層の上に形成されて、第１光結合領域を備える第１コア層と、第１コア層の上に形成された層間クラッド層と、層間クラッド層の上に形成されて、第１光結合領域の上部に重なって平行に配置された第２光結合領域を備える第２コア層と、第２コア層の上に形成された上部クラッド層とを備え、第１光結合領域は、基板を平面視したときに、他の領域の第１コア層より細く形成され、第２光結合領域は、基板を平面視したときに、他の領域の第２コア層より細く形成され、層間クラッド層は、第１光結合領域と第２光結合領域との間は光結合が可能とされ、第１光結合領域と第２光結合領域との間以外の第１コア層と第２コア層との間は光結合が起きない厚さとされ、前記第１コア層、前記第２コア層、前記層間クラッド層は、いずれも、全域において厚さが一定とされている。 An optical coupling structure according to the present invention includes a lower cladding layer formed on a substrate, a first core layer formed on the lower cladding layer and provided with a first optical coupling region, and an upper surface of the first core layer. An interlayer clad layer formed on the second clad layer, a second core layer formed on the interlayer clad layer and having a second optical coupling region disposed in parallel over the first optical coupling region, and a second core An upper clad layer formed on the layer, and the first optical coupling region is formed to be narrower than the first core layer in the other region when the substrate is viewed in plan , and the second optical coupling region is formed on the substrate In plan view , the interlayer cladding layer is formed to be thinner than the second core layer in the other region, and the interlayer cladding layer is capable of optical coupling between the first optical coupling region and the second optical coupling region. Thickness that does not cause optical coupling between the first core layer and the second core layer other than between the coupling region and the second optical coupling region Is a, the first core layer, said second core layer, said interlayer cladding layer are both thickness in the entire region is constant.
以上説明したことにより、本発明によれば、高密度な光配線が可能な多層光導波路の層間が、より高い効率で光結合できるという優れた効果が得られる。 As described above, according to the present invention, it is possible to obtain an excellent effect that the layers of the multilayer optical waveguide capable of high-density optical wiring can be optically coupled with higher efficiency.
以下、本発明の実施の形態について図を参照して説明する。図１は、本発明の実施の形態における光結合構造の構成を示す断面図である。また、図２は、本発明の実施の形態における光結合構造の一部構成を示す斜視図である。また、図３は、本発明の実施の形態における光結合構造の一部構成を示す平面図である。 Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a cross-sectional view showing a configuration of an optical coupling structure according to an embodiment of the present invention. FIG. 2 is a perspective view showing a partial configuration of the optical coupling structure according to the embodiment of the present invention. FIG. 3 is a plan view showing a partial configuration of the optical coupling structure in the embodiment of the present invention.
基板１０１の上に形成された下部クラッド層１０２と、下部クラッド層１０２の上に形成された第１コア層１０３と、第１コア層１０３の上に形成された層間クラッド層１０４と、層間クラッド層１０４の上に形成された第２コア層１０５と、第２コア層１０５の上に形成された上部クラッド層１０６とを備える。第１コア層１０３とこの上下のクラッド層とにより第１光導波路が構成され、第２コア層１０５とこの上下のクラッド層とにより第２光導波路が構成されている。 A lower cladding layer formed on the substrate 101; a first core layer 103 formed on the lower cladding layer; an interlayer cladding layer 104 formed on the first core layer 103; and an interlayer cladding A second core layer 105 formed on the layer 104 and an upper cladding layer 106 formed on the second core layer 105 are provided. The first core layer 103 and the upper and lower cladding layers constitute a first optical waveguide, and the second core layer 105 and the upper and lower cladding layers constitute a second optical waveguide.
また、第１コア層１０３は、第１光結合領域１３１を備え、第２コア層１０５は、第２光結合領域１５１を備える。また、第２光結合領域１５１は、第１光結合領域１３１の上部に重なって平行に配置されている。加えて、第１光結合領域１３１は、他の領域の第１コア層１０３より平面視で細いコア幅とされている。同様に、第２光結合領域１５１は、他の領域の第２コア層１０５より平面視で細いコア幅とされている。なお、第１光結合領域１３１と第２光結合領域１５１とは、光導波方向に完全に同じ長さに形成する必要はないが、これらを同じ長さとした方がよりよい。 The first core layer 103 includes a first optical coupling region 131, and the second core layer 105 includes a second optical coupling region 151. The second optical coupling region 151 is arranged in parallel so as to overlap the upper portion of the first optical coupling region 131. In addition, the first optical coupling region 131 has a narrower core width in plan view than the first core layer 103 in other regions. Similarly, the second optical coupling region 151 has a narrower core width in plan view than the second core layer 105 in other regions. The first optical coupling region 131 and the second optical coupling region 151 do not have to be formed to have the same length in the optical waveguide direction, but it is better to make them the same length.
また、層間クラッド層１０４は、第１光結合領域１３１と第２光結合領域１５１との間は光結合が可能とされ、第１光結合領域１３１と第２光結合領域１５１との間以外の第１コア層１０３と第２コア層１０５との間では光結合が起きない厚さとされている。なお、層間クラッド層１０４は、全域において実質的に均一な厚さに形成されている。 Further, the interlayer cladding layer 104 is capable of optical coupling between the first optical coupling region 131 and the second optical coupling region 151, and other than between the first optical coupling region 131 and the second optical coupling region 151. The thickness is such that optical coupling does not occur between the first core layer 103 and the second core layer 105. The interlayer clad layer 104 is formed to have a substantially uniform thickness over the entire area.
なお、第１コア層１０３は、第１光結合領域１３１を挾んで配置された入力コア部１３２，出力コア部１３３を備える。入力コア部１３２は、テーパーコア部１３４により第１光結合領域１３１の一端に接続し、出力コア部１３３は、テーパーコア部１３５により第１光結合領域１３１の他端に接続する。入力コア部１３２および出力コア部１３３による光導波路は、第１光導波路を構成する図示しない光配線部に接続している。 The first core layer 103 includes an input core part 132 and an output core part 133 that are arranged with the first optical coupling region 131 interposed therebetween. The input core portion 132 is connected to one end of the first optical coupling region 131 by the tapered core portion 134, and the output core portion 133 is connected to the other end of the first optical coupling region 131 by the tapered core portion 135. The optical waveguide formed by the input core unit 132 and the output core unit 133 is connected to an optical wiring unit (not shown) constituting the first optical waveguide.
同様に、第２コア層１０５は、第２光結合領域１５１を挾んで配置された入力コア部１５２，出力コア部１５３を備える。入力コア部１５２は、テーパーコア部１５４により第２光結合領域１５１の一端に接続し、出力コア部１５３は、テーパーコア部１５５により第２光結合領域１５１の他端に接続する。入力コア部１５２および出力コア部１５３による光導波路は、第２光導波路を構成する図示しない光配線部に接続している。 Similarly, the second core layer 105 includes an input core portion 152 and an output core portion 153 that are arranged with the second optical coupling region 151 interposed therebetween. The input core portion 152 is connected to one end of the second optical coupling region 151 by the tapered core portion 154, and the output core portion 153 is connected to the other end of the second optical coupling region 151 by the tapered core portion 155. The optical waveguide formed by the input core unit 152 and the output core unit 153 is connected to an optical wiring unit (not shown) constituting the second optical waveguide.
各テーパーコア部は、各光結合領域にかけて徐々に平面視の幅が狭くなるテーパー形状とされている。このようなテーパー形状のテーパーコア部により接続することで、接続損失の低減が図れる。なお、各入力コア部および各出力コア部は、各光結合領域に直接接続してもよい。 Each tapered core portion has a tapered shape in which the width in plan view gradually becomes narrower toward each optical coupling region. By connecting with such a tapered core portion, the connection loss can be reduced. Each input core part and each output core part may be directly connected to each optical coupling region.
例えば、よく知られたＳＯＩ（Silicon on Insulator）基板を用い、ＳＯＩ基板の埋め込み酸化層を下部クラッド層１０２とすればよい。また、ＳＯＩ基板の表面シリコン層を、公知のリソグラフィー技術およびエッチング技術によりパターニングすることで、第１コア層１０３を形成すればよい。また、第１コア層１０３を形成した後、よく知られた化学的気相成長法やスパッタ法などの堆積法によりＳｉＯ2を堆積し、堆積したＳｉＯ2膜の表面を公知の平坦化技術により平坦化することで、層間クラッド層１０４を形成すればよい。 For example, a well-known SOI (Silicon on Insulator) substrate may be used, and the buried oxide layer of the SOI substrate may be the lower cladding layer 102. Further, the first core layer 103 may be formed by patterning the surface silicon layer of the SOI substrate by a known lithography technique and etching technique. Further, after the first core layer 103 is formed, SiO 2 is deposited by a well-known deposition method such as chemical vapor deposition or sputtering, and the surface of the deposited SiO 2 film is formed by a known planarization technique. The interlayer clad layer 104 may be formed by planarization.
次に、層間クラッド層１０４を形成した後、化学的気相成長法やスパッタ法などの堆積法によりＳｉを堆積し、堆積したＳｉ膜を公知のリソグラフィー技術およびエッチング技術によりパターニングすることで、第２コア層１０５を形成すればよい。また、第２コア層１０５を形成した後、よく知られた化学的気相成長法やスパッタ法などの堆積法によりＳｉＯ2を堆積し、上部クラッド層１０６を形成すればよい。 Next, after forming the interlayer clad layer 104, Si is deposited by a deposition method such as chemical vapor deposition or sputtering, and the deposited Si film is patterned by a known lithography technique and etching technique. A two-core layer 105 may be formed. Further, after the second core layer 105 is formed, SiO 2 is deposited by a well-known deposition method such as chemical vapor deposition or sputtering, and the upper cladding layer 106 may be formed.
上述した実施の形態によれば、入力コア部１３２と入力コア部１５２との間、および出力コア部１３３と出力コア部１５３との間では、上述した厚さの層間クラッド層１０４により、積層されている層間（上下）方向の光結合はなく、これらによる光導波路においては、各々独立に光が伝搬する。これに対し、第１光結合領域１３１および第２光結合領域１５１は、コア幅が細くなっているため、コアへの光の閉じ込めが不十分になり、コアから光のモードフィールドがはみ出し、層間方向への光結合が可能となる。この層間方向への光結合の結合度は、第１光結合領域１３１および第２光結合領域１５１の重なっている領域（層間結合部）の長さ（光導波路長）で調整が可能である。 According to the above-described embodiment, the layers are stacked between the input core portion 132 and the input core portion 152 and between the output core portion 133 and the output core portion 153 by the interlayer cladding layer 104 having the thickness described above. There is no optical coupling in the interlayer (up and down) direction, and light propagates independently in each of the optical waveguides. On the other hand, since the first optical coupling region 131 and the second optical coupling region 151 have a narrow core width, the confinement of light in the core becomes insufficient, and the mode field of light protrudes from the core. Optical coupling in the direction becomes possible. The degree of coupling of the optical coupling in the interlayer direction can be adjusted by the length (optical waveguide length) of the region (interlayer coupling portion) where the first optical coupling region 131 and the second optical coupling region 151 overlap.
以下に、波長１５５０ｎｍ近傍の赤外線において、コアにシリコン（屈折率３．４７８）、クラッドに酸化シリコン（屈折率１．４４４）に適用して、上述した実施の形態の光結合構造を形成した場合の例を示す。シリコンコアの断面形状は、光配線部，入力コア部および出力コア部に、通常の単一モード光導波路を想定し、概ね４００×２００ｎｍ程度とした（非特許文献５）。光伝搬シミュレーションによれば、光配線部や入力コア部および出力コア部における層間結合は、層間クラッド層の層厚が１．２μｍ以上であれば抑制されることが見いだされており、ここでは１．２μｍとする。なお、層間結合については、層間クラッド層を介して上下に各コアが重なっている領域を対象としている。 In the case where the optical coupling structure of the above-described embodiment is formed by applying silicon (refractive index: 3.478) for the core and silicon oxide (refractive index: 1.444) for the clad in the infrared near the wavelength of 1550 nm. An example of The cross-sectional shape of the silicon core is approximately 400 × 200 nm assuming a normal single mode optical waveguide in the optical wiring portion, input core portion, and output core portion (Non-patent Document 5). According to the light propagation simulation, it has been found that interlayer coupling in the optical wiring section, the input core section, and the output core section is suppressed when the layer thickness of the interlayer cladding layer is 1.2 μm or more. .2 μm. Note that the interlayer coupling is intended for a region in which the cores overlap each other with the interlayer cladding layer interposed therebetween.
第１光結合領域および第２光結合領域による層間結合部の光導波路のシリコンコアの断面形状は、幅を光配線部や入出力部の半分とし２００×２００ｎｍとする。また、テーパーコア部は、導波方向の長さを５μｍのテーパー構造としている。また、入射偏波はＴＥモードとする。 The cross-sectional shape of the silicon core of the optical waveguide of the interlayer coupling portion formed by the first optical coupling region and the second optical coupling region is 200 × 200 nm with the width being half that of the optical wiring portion and the input / output portion. The taper core portion has a taper structure with a length in the waveguide direction of 5 μm. Further, the incident polarization is set to the TE mode.
以上の構造に対して上側の第２光導波路の入力コア部１５２による光導波路に光を入射した場合の、下側の第１光導波路への光透過率の層間結合部の長さ依存性の計算結果を図４に示す。計算方法は、実施の形態における光結合構造の各部分の垂直断面における伝搬固有モードを有限差分法（ＦＤＭ法）により求め、入力コア部の伝搬モードを層間結合部の固有モードに展開して固有モード毎に伝搬させ、伝搬後の各固有モードを出力コア部の伝搬モードに展開し、入力から出力への強度比を求めた（固有モード伝搬法、非特許文献４参照）。 When light is incident on the optical waveguide formed by the input core portion 152 of the upper second optical waveguide with respect to the above structure, the light transmittance to the lower first optical waveguide depends on the length of the interlayer coupling portion. The calculation results are shown in FIG. In the calculation method, the propagation eigenmode in the vertical cross section of each part of the optical coupling structure in the embodiment is obtained by the finite difference method (FDM method), and the propagation mode of the input core section is expanded to the eigenmode of the interlayer coupling section. Propagation was performed for each mode, and each eigenmode after propagation was developed into a propagation mode of the output core unit, and the intensity ratio from input to output was obtained (see eigenmode propagation method, Non-Patent Document 4).
図４に示すように、本発明の光結合構造によれば、上下の光導波路は結合が可能となることがわかる。結合度は層間結合部の長さに応じて変化し、層間結合部の長さが３１μｍの時に完全に光は相手側の光導波路に移動する。本発明の光結合構造により、層間結合部の長さは非特許文献３の構造に比べ非常に短くすることが可能である。また、結合効率はほぼ１００％であり、非特許文献１のグレーティングカップラの５倍の高効率である。また、下側の第１光導波路に結合しなかった光は、上側の第２光導波路に伝搬しているので、層間結合部の長さを調整することにより、任意の結合度が実現でき、上下に２分岐させる構成にも適用可能である。 As shown in FIG. 4, according to the optical coupling structure of the present invention, it is understood that the upper and lower optical waveguides can be coupled. The degree of coupling changes according to the length of the interlayer coupling portion, and when the length of the interlayer coupling portion is 31 μm, the light completely moves to the counterpart optical waveguide. With the optical coupling structure of the present invention, the length of the interlayer coupling portion can be made much shorter than that of the non-patent document 3. Further, the coupling efficiency is almost 100%, which is five times as high as the grating coupler of Non-Patent Document 1. In addition, since the light that has not been coupled to the lower first optical waveguide propagates to the upper second optical waveguide, by adjusting the length of the interlayer coupling portion, an arbitrary degree of coupling can be realized, The present invention can also be applied to a configuration that is bifurcated vertically.
ところで、層間結合部のコア幅を他の領域と同一にした構成についても、上述同様の計算を実施したが、この場合は、層間結合は発生せず、上下の光導波路は独立に伝搬可能であることが判明している。従って、本発明における光結合構造において、層間結合部以外の上下の光配線部の光導波路は自由に配置でき、上下に隣り合う光導波路を、同じ位置に重ねて並走配置することが可能であり、非特許文献２の課題が解決される。 By the way, the same calculation as described above was performed for the configuration in which the core width of the interlayer coupling portion was made the same as that of the other regions. However, in this case, interlayer coupling did not occur, and the upper and lower optical waveguides can propagate independently It turns out that there is. Therefore, in the optical coupling structure according to the present invention, the optical waveguides in the upper and lower optical wiring portions other than the interlayer coupling portion can be freely arranged, and the upper and lower adjacent optical waveguides can be arranged side by side at the same position. Yes, the problem of Non-Patent Document 2 is solved.
次に、層間結合部の長さを３１μｍとした場合の、波長依存性について、図５を用いて説明する。図５は、長さを３１μｍとした層間結合部における結合度の波長依存を示す特性図である。図５に示すように、９０％動作帯域が、少なくとも１５０ｎｍ（１．４５〜１．６μｍ）と非常に広い。 Next, wavelength dependency when the length of the interlayer coupling portion is 31 μm will be described with reference to FIG. FIG. 5 is a characteristic diagram showing the wavelength dependence of the degree of coupling in the interlayer coupling section having a length of 31 μm. As shown in FIG. 5, the 90% operating band is very wide, at least 150 nm (1.45 to 1.6 μm).
次に、層間結合部の長さを３１μｍとした場合の、光の伝搬状態について図６を用いて説明する。図６は、層間結合部の長さを３１μｍとした本発明の光結合構造における、側方から見た波長１５５０ｎｍの光の伝搬状態を示す説明図である。図６に示すように、上側の第２コア層１０５による第２光導波路から、下側の第１コア層１０３による第１光導波路に、光パワーが移行している。 Next, the light propagation state when the length of the interlayer coupling portion is 31 μm will be described with reference to FIG. FIG. 6 is an explanatory diagram showing the propagation state of light having a wavelength of 1550 nm as viewed from the side in the optical coupling structure of the present invention in which the length of the interlayer coupling portion is 31 μm. As shown in FIG. 6, the optical power is shifted from the second optical waveguide formed by the upper second core layer 105 to the first optical waveguide formed by the lower first core layer 103.
以上に説明したように、本発明によれば、第１光結合領域を、他の領域の第１コア層より細く形成し、第１光結合領域の上部に重なって平行に配置された第２光結合領域も、他の領域の第２コア層より細く形成したので、多層光導波路の層間を、より高い効率で光結合できるようになる。また、光配線の層間結合が起きないようにできるため、光配線を自由にレイアウトすることができ、高密度に配線することができる。 As described above, according to the present invention, the first optical coupling region is formed narrower than the first core layer in the other region, and the second optical coupling region is arranged in parallel so as to overlap the upper portion of the first optical coupling region. Since the optical coupling region is also formed thinner than the second core layer in the other region, the layers of the multilayer optical waveguide can be optically coupled with higher efficiency. In addition, since the interlayer coupling of the optical wiring can be prevented, the optical wiring can be freely laid out and can be wired with high density.
なお、本発明は以上に説明した実施の形態に限定されるものではなく、本発明の技術的思想内で、当分野において通常の知識を有する者により、多くの変形および組み合わせが実施可能であることは明白である。例えば、上述した説明では、シリコンコアおよび酸化シリコンクラッドを用いた場合について例示したが、これに限るものではなく、本発明は様々な材料系に適用可能である。 The present invention is not limited to the embodiment described above, and many modifications and combinations can be implemented by those having ordinary knowledge in the art within the technical idea of the present invention. It is obvious. For example, in the above description, the case where a silicon core and a silicon oxide clad are used is illustrated, but the present invention is not limited to this, and the present invention can be applied to various material systems.
例えば、コアは、シリコン，窒化シリコン，酸窒化シリコン，インジウム燐系半導体，ガリウムヒ素系半導体などから構成してもよい。また、クラッドは、酸化シリコン，酸窒化シリコン，酸化アルミニウム，アルミニウムとインジウム燐系あるいはガリウムヒ素系半導体との化合物，エポキシ系ポリマー，ポリイミド系ポリマー，アクリル系ポリマーなどから構成してもよい。これらの材料では屈折率はそれぞれ異なるが、本発明の各部分の寸法は材料の屈折率を考慮して任意に設計が可能であることは、本発明の基本原理からして明らかである。 For example, the core may be made of silicon, silicon nitride, silicon oxynitride, indium phosphorus semiconductor, gallium arsenide semiconductor, or the like. The clad may be made of silicon oxide, silicon oxynitride, aluminum oxide, a compound of aluminum and indium phosphide or gallium arsenide semiconductor, epoxy polymer, polyimide polymer, acrylic polymer, or the like. Although these materials have different refractive indexes, it is apparent from the basic principle of the present invention that the dimensions of each part of the present invention can be arbitrarily designed in consideration of the refractive index of the material.
１０１…基板、１０２…下部クラッド層、１０３…第１コア層、１０４…層間クラッド層、１０５…第２コア層、１０６…上部クラッド層、１３１…第１光結合領域、１３２…入力コア部、１３３…出力コア部、１３４…テーパーコア部、１３５…テーパーコア部、１５１…第２光結合領域、１５２…入力コア部、１５３…出力コア部、１５４…テーパーコア部、１５５…テーパーコア部。 DESCRIPTION OF SYMBOLS 101 ... Substrate, 102 ... Lower clad layer, 103 ... First core layer, 104 ... Interlayer clad layer, 105 ... Second core layer, 106 ... Upper clad layer, 131 ... First optical coupling region, 132 ... Input core portion, 133 ... Output core portion, 134 ... Tapered core portion, 135 ... Tapered core portion, 151 ... Second optical coupling region, 152 ... Input core portion, 153 ... Output core portion, 154 ... Tapered core portion, 155 ... Tapered core portion.
Claims (1)
前記下部クラッド層の上に形成されて第１光結合領域を備える第１コア層と、
前記第１コア層の上に形成された層間クラッド層と、
前記層間クラッド層の上に形成されて、前記第１光結合領域の上部に重なって平行に配置された第２光結合領域を備える第２コア層と、
前記第２コア層の上に形成された上部クラッド層と
を備え、
前記第１光結合領域は、前記基板を平面視したときに、他の領域の前記第１コア層より細く形成され、
前記第２光結合領域は、前記基板を平面視したときに、他の領域の前記第２コア層より細く形成され、
前記層間クラッド層は、前記第１光結合領域と前記第２光結合領域との間は光結合が可能とされ、前記第１光結合領域と前記第２光結合領域との間以外の前記第１コア層と前記第２コア層との間は光結合が起きない厚さとされ、
前記第１コア層、前記第２コア層、前記層間クラッド層は、いずれも、全域において厚さが一定とされ
ていることを特徴とする光結合構造。 A lower cladding layer formed on the substrate;
A first core layer formed on the lower cladding layer and having a first optical coupling region;
An interlayer cladding layer formed on the first core layer;
A second core layer formed on the interlayer clad layer and having a second optical coupling region disposed in parallel and overlapping the upper portion of the first optical coupling region;
An upper cladding layer formed on the second core layer,
The first optical coupling region is formed narrower than the first core layer in another region when the substrate is viewed in plan view .
The second optical coupling region is formed narrower than the second core layer in the other region when the substrate is viewed in plan view .
The interlayer clad layer is capable of optical coupling between the first optical coupling region and the second optical coupling region, and the interlayer cladding layer other than between the first optical coupling region and the second optical coupling region. The thickness between the first core layer and the second core layer is such that no optical coupling occurs ,
The optical coupling structure characterized in that the first core layer, the second core layer, and the interlayer clad layer are all constant in thickness .
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| JPH0643328A (en) * | 1992-07-27 | 1994-02-18 | Nippon Telegr & Teleph Corp <Ntt> | Multilayered optical waveguide and its production |
| JP2002062446A (en) * | 2000-08-18 | 2002-02-28 | Nippon Telegr & Teleph Corp <Ntt> | Laminated interlayer optical directional coupler and its manufacturing method |
| WO2008111447A1 (en) * | 2007-03-14 | 2008-09-18 | Nec Corporation | Optical waveguide and method for fabricating the same |
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| JPH0643328A (en) * | 1992-07-27 | 1994-02-18 | Nippon Telegr & Teleph Corp <Ntt> | Multilayered optical waveguide and its production |
| JP2002062446A (en) * | 2000-08-18 | 2002-02-28 | Nippon Telegr & Teleph Corp <Ntt> | Laminated interlayer optical directional coupler and its manufacturing method |
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