TW202032244A - Semiconductor Mach-Zehnder optical modulator and IQ modulator that has out-leading lines at an output side that are curved in a direction intersecting an extension direction of waveguides in a plane of a dielectric layer and are connected with terminal resistors - Google Patents
Semiconductor Mach-Zehnder optical modulator and IQ modulator that has out-leading lines at an output side that are curved in a direction intersecting an extension direction of waveguides in a plane of a dielectric layer and are connected with terminal resistors Download PDFInfo
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發明領域 本發明是關於以電訊號來調變光訊號之半導體馬赫曾德爾光調變器、以及使用了半導體馬赫曾德爾光調變器之IQ調變器。Invention field The present invention relates to a semiconductor Mach-Zehnder optical modulator that modulates optical signals with electrical signals, and an IQ modulator that uses a semiconductor Mach-Zehnder optical modulator.
為了對應增大的通訊流量之需要,而要求對應高水準之光調變方式的高速光調變器。特別是使用了數位同調(digital coherent)技術的多值光調變器在實現超過100Gbps的大容量收發訊器上發揮有重大的作用。在這些多值光調變器中,為了使分別獨立的訊號附加於光的振幅及相位,而並列多段地內裝有馬赫曾德爾(MZ:Mach-Zehnder)干涉型之可零啁啾(zero chirp)驅動的光調變器。In order to meet the needs of increased communication traffic, high-speed optical modulators corresponding to high-level optical modulation methods are required. In particular, multi-value optical modulators using digital coherent technology play a significant role in realizing high-capacity transceivers exceeding 100Gbps. In these multi-value optical modulators, in order to add independent signals to the amplitude and phase of the light, a MZ: Mach-Zehnder interference-type zero-chirp (zero chirp) driven optical modulator.
近年來,光發訊模組的小型化和低驅動電壓化成為了課題,而致力於進行可小型且低驅動電壓化之半導體MZ光調變器的研究開發(參照非專利文獻1、非專利文獻2)。圖8A、圖8B顯示習知的半導體MZ光調變器之一例。圖8A是半導體MZ光調變器的平面圖,圖8B是圖8A的c-c’線截面圖。In recent years, the miniaturization and low driving voltage of optical transmission modules have become issues, and efforts have been made to research and develop semiconductor MZ optical modulators that can be miniaturized and low driving voltage (see Non-Patent
在圖8A、圖8B中,101是半導體MZ光調變器的輸入波導,102是輸出波導,103是將傳播於輸入波導101的光波分波至2條波導104、105之光分波器,106是將傳播於2條波導104、105的光波朝輸出波導102合波之光合波器,109、110是共面帶線(coplanar stripline),111、112是用以將電壓施加於波導104、105之電極。In Figures 8A and 8B, 101 is the input waveguide of the semiconductor MZ optical modulator, 102 is the output waveguide, and 103 is the optical splitter that splits the light propagating in the
在圖8B中,113是n-InP層,114是由InP組成之下部被覆層,115是供光波傳播的半導體核心層,116是由InP組成之上部被覆層,117是SI-InP基板。In FIG. 8B, 113 is an n-InP layer, 114 is a lower cladding layer composed of InP, 115 is a semiconductor core layer for light wave propagation, 116 is an upper cladding layer composed of InP, and 117 is an SI-InP substrate.
輸入波導101、輸出波導102、光分波器103、波導104、105、及光合波器106構成MZ干涉儀。在MZ干涉儀中,施加電壓於波導104、105,藉此在半導體核心層115中藉由電光效應而發生折射率變化,其結果,光的相位會變化。此時,藉由賦予波導104、105電位差,因而在光合波器106中之光的干涉狀態改變,而可對光進行調變(亦即,輸出波導102的輸出光有時成為on,有時成為off)。The
在2條共面帶線109、110之中其中一方連接於輸入電訊號(S)的情況下,另一方連接於基準電位或地(G),此為SG構成。In the case where one of the two
傳播於共面帶線109、110之微波是藉由電極111、112而被施加於波導104、105。電極111、112與共面帶線109、110整體形成行進波型電極。亦即,意圖下述電極構造:盡量使傳播於波導104、105之光波的速度與傳播於上述行進波型電極之微波的速度一致,並取得光波與微波的相位匹配,藉此提升調變帶寬的電極構造。只要沒有微波的損失,且完全滿足光波與微波的速度匹配條件,則調變帶寬會成為無限大。The microwaves propagating on the
然而,實際上由於微波的損失或阻抗不匹配而會產生微波的反射、光波與微波的相位偏移,故,因為這些理由而使調變帶寬遭到限制。However, in fact, due to microwave loss or impedance mismatch, microwave reflection and phase shift between light waves and microwaves will occur. Therefore, the modulation bandwidth is limited for these reasons.
如前述般,由於電極111、112之下存在有上部被覆層116、半導體核層115、與下部被覆層114,因此存在有一定的元件電容。亦即,在圖8A中,成為電極111、112對共面帶線109、110附加電容的形式。As described above, since the
也就是說,藉由最佳地設計電極111、112的數量及間隔、對波導104、105之接觸長度,而可自由地設計對共面帶線109、110之電容的附加量,可將共面帶線109、110的阻抗匹配及微波的速度設計為任意的值。又,為了減低微波的損失,並實現寬頻帶化,將共面帶線109、110較粗地設計成100μm程度。In other words, by optimally designing the number and spacing of the
如以上所述,在電容負載構造的半導體MZ光調變器中,藉由設計對共面帶線109、110之最佳的電容的附加量,可提升光波與微波的速度匹配,並且也可取得對50Ω的阻抗匹配,其結果,使高速的光調變成為可能。As mentioned above, in the semiconductor MZ optical modulator with a capacitive load structure, by designing the optimal amount of additional capacitance for the
圖8A、圖8B所示之構成的半導體MZ光調變器雖然為單相驅動,但若考慮到與差動驅動之驅動器的連接、及消耗電力,則宜將光調變器側也設為差動驅動型(例如GSSG構成)(參照非專利文獻3)。Although the semiconductor MZ optical modulator of the configuration shown in Fig. 8A and Fig. 8B is single-phase drive, if the connection with the differential drive driver and power consumption are considered, it is advisable to set the optical modulator side as Differential drive type (for example, GSSG configuration) (see Non-Patent Document 3).
進而言之,與單相驅動型不同,差動驅動型的光調變器在串擾(crosstalk)的抑制上是優秀的,因此在實現集積於1晶片之偏振多工IQ調變器上是有利的。若考慮到調變器晶片的布局(layout),為了將訊號線路與驅動器(driver)及終端電阻連接,必須將某個部分彎曲以使訊號線到達晶片端。然而,在將光調變器設為差動驅動型的情況下,則與如非專利文獻4所揭示之單相驅動之IQ調變器的情況同樣地,有下述課題:若將差動構成的訊號線路彎曲成大約直角,在構成差動對的2條訊號線路間會大幅發生相位差,而使差動特性劣化、激發雜訊成分即共模而使調變器之傳送特性劣化的課題。Furthermore, unlike the single-phase drive type, the differential drive type optical modulator is excellent in the suppression of crosstalk, so it is advantageous in realizing a polarization multiplexed IQ modulator integrated on 1 chip of. Considering the layout of the modulator chip, in order to connect the signal line to the driver and the terminal resistor, a certain part must be bent to make the signal line reach the chip end. However, when the optical modulator is a differential drive type, as in the case of a single-phase drive IQ modulator disclosed in Non-Patent Document 4, there is the following problem: The formed signal line is bent at approximately a right angle, and a large phase difference occurs between the two signal lines forming a differential pair, which deteriorates the differential characteristics and excites the noise component that is the common mode, which deteriorates the transmission characteristics of the modulator. Subject.
圖9是非專利文獻4所揭示之習知的單相驅動型IQ調變器的平面圖。單相驅動型IQ調變器是由以下所構成:輸入波導200;1×2多模干涉(MMI:MultiMode Interference)耦合器201,將傳播於輸入波導200的光分波為2系統;波導202、203,對藉由1×2MMI耦合器201分波的2條光進行波導;1×2MMI耦合器204,將傳播於波導202的光分波為2系統;1×2MMI耦合器205,將傳播於波導203的光分波為2系統;波導206、207,對藉由1×2MMI耦合器204分波的2條光進行波導;波導208、209,對藉由1×2MMI耦合器205分波的2條光進行波導;訊號線路210~213,用以施加電壓於波導206~209;電極214~217,將從訊號線路210~213供給的電壓施加於波導206~209;相位調整電極218~221,用以調整傳播於波導206~209之經調變的訊號光的相位;2×1MMI耦合器222,將傳播於波導206、207之2系統的訊號光合波;2×1MMI耦合器223,將傳播於波導208、209之2系統的訊號光合波;波導224,對2×1MMI耦合器222的輸出光進行波導;波導225,對2×1MMI耦合器223的輸出光進行波導;相位調整電極226、227,用以調整傳播於波導224、225之訊號光的相位;2×1MMI耦合器228,將傳播於波導224、225之2系統的訊號光合波;以及輸出波導229。訊號線路210~213的其中一端與驅動器230、231連接,訊號線路210~213的另一端與終端電阻(不圖示)連接。FIG. 9 is a plan view of a conventional single-phase drive type IQ modulator disclosed in Non-Patent Document 4. The single-phase drive type IQ modulator is composed of the following:
在差動驅動的情況下會變得難以彎曲訊號線路的理由,是由於在電容負載構造的半導體MZ光調變器的情況,訊號線路的寬度為100μm程度粗,因此若彎曲差動構成的2條訊號線路,會在該2條訊號線路間產生電長度差,藉由該電長度差,差模(differential mode)的頻率特性會劣化,會激發成為雜訊之原因的共模(common mode)及混合模式(mixed mode)。因此,必須有下述構造:不激發共模,且不使差模的頻率特性劣化,可彎曲差動構成的訊號線路之構造。The reason why it becomes difficult to bend the signal line in the case of a differential drive is that in the case of a semiconductor MZ optical modulator with a capacitive load structure, the width of the signal line is about 100μm thick, so if the 2 A signal line will generate an electrical length difference between the two signal lines. With the electrical length difference, the frequency characteristics of the differential mode will be degraded and the common mode that is the cause of the noise will be excited. And mixed mode (mixed mode). Therefore, it is necessary to have a structure that does not excite the common mode, and does not degrade the frequency characteristics of the differential mode, and can bend the signal line of the differential configuration.
又,也可如非專利文獻4地將單相驅動的調變器與驅動器連接,而設為差動(SS)驅動。但是由於有下述疑慮,因此較不適合:在該情況下,由於在半導體MZ光調變器的高頻線路中無法傳播共模,因此在驅動器與半導體MZ光調變器間,共模會全反射,而成為串擾等的原因,且成為頻率特性和驅動器之驅動力下降的原因。In addition, as in Non-Patent Document 4, a modulator for single-phase drive may be connected to the driver and set as differential (SS) drive. However, due to the following doubts, it is less suitable: In this case, since the common mode cannot be propagated in the high-frequency line of the semiconductor MZ optical modulator, the common mode will be completely between the driver and the semiconductor MZ optical modulator. Reflection becomes a cause of crosstalk, etc., as well as a cause of decrease in frequency characteristics and driving force of the driver.
[先行技術文獻] [非專利文獻] [非專利文獻1]L.Morl et al.,“A travelling wave electrode Mach-Zehnder 40 Gb/s demultiplexer based on strain compensated GaInAs/AlInAs tunnelling barrier MQW structure”,1998 International Conference on Indium Phosphide and Related Materials,pp.403-406,1998 [非專利文獻2]H.N.Klein et al.,“1.55μm Mach-Zehnder Modulators on InP for optical 40/80 Gbit/s transmission networks”,OFC2006,pp.171-173,2006 [非專利文獻3]K.Prosyk et al.,“Travelling Wave Mach-Zehnder Modulators”,IPRM2013,MoD3-1,2013 [非專利文獻4]S.Lange et al.,“Low Power InP-Based Monolithic DFB-Laser IQ Modulator With SiGe Differential Driver for 32-GBd QPSK Modulation”,JOURNAL OF LIGHTWAVE TECHNOLOGY,VOL.34,NO.8,APRIL 15,2016[Advanced Technical Literature] [Non-Patent Literature] [Non-Patent Document 1] L. Morl et al., "A travelling wave electrode Mach-Zehnder 40 Gb/s demultiplexer based on strain compensated GaInAs/AlInAs tunnelling barrier MQW structure", 1998 International Conference on Indium Phosphide and Related Materials, pp .403-406, 1998 [Non-Patent Document 2] H.N. Klein et al., "1.55μm Mach-Zehnder Modulators on InP for optical 40/80 Gbit/s transmission networks", OFC2006, pp.171-173, 2006 [Non-Patent Document 3] K. Prosyk et al., "Travelling Wave Mach-Zehnder Modulators", IPRM2013, MoD3-1, 2013 [Non-Patent Document 4] S. Lange et al., "Low Power InP-Based Monolithic DFB-Laser IQ Modulator With SiGe Differential Driver for 32-GBd QPSK Modulation", JOURNAL OF LIGHTWAVE TECHNOLOGY, VOL.34, NO.8, APRIL 15, 2016
[發明概要] [發明欲解決的課題] 本發明是為了解決上述課題而作成,其目的在於提供下述半導體馬赫曾德爾光調變器及IQ調變器,即:在差動驅動型的電容負載構造的半導體馬赫曾德爾光調變器中,為了與訊號線輸出端的終端電阻連接,於必要的高頻配線中,抑制在習知構造中成為問題的彎曲部中因為差模的相位差造成之特性劣化、和伴隨彎曲部分之共模的激發,而可解決調變器之高頻特性的劣化,具有優異之傳送特性的半導體馬赫曾德爾光調變器及IQ調變器。 [用以解決課題之手段][Summary of the invention] [The problem to be solved by the invention] The present invention was made to solve the above-mentioned problems, and its object is to provide the following semiconductor Mach-Zehnder optical modulator and IQ modulator, namely: a semiconductor Mach-Zehnder optical modulator with a differential drive type capacitive load structure In order to connect with the terminal resistance of the output end of the signal line, in the necessary high-frequency wiring, suppress the characteristic degradation caused by the phase difference of the differential mode in the bent part that is a problem in the conventional structure, and the common mode accompanying the bent part The semiconductor Mach-Zehnder optical modulator and IQ modulator with excellent transmission characteristics can solve the deterioration of the high-frequency characteristics of the modulator. [Means to solve the problem]
本發明之半導體馬赫曾德爾光調變器具備有:第1、第2臂波導,形成於基板上;第1輸入側引出線路,形成於前述基板上的介電體層之上,且其中一端供調變訊號輸入;第2輸入側引出線路,形成於該第1輸入側引出線路旁邊的前述介電體層上,且其中一端供與前述調變訊號互補的訊號輸入;第1、第2相位調變電極線路,形成於前述介電體層上,且其中一端分別與前述第1、第2輸入側引出線路的另一端連接;第1、第2輸出側引出線路,形成於前述介電體層上,且其中一端分別與前述第1、第2相位調變電極線路的另一端連接;第1、第2電極,將傳播於前述第1、第2相位調變電極線路的調變訊號分別施加至前述第1、第2臂波導;第1地線,沿著前述調變訊號的傳播方向且形成於前述第1輸入側引出線路、前述第1相位調變電極線路、與前述第1輸出側引出線路之外側的前述介電體層上;第2地線,沿著前述調變訊號的傳播方向且形成於前述第2輸入側引出線路、前述第2相位調變電極線路、與前述第2輸出側引出線路之外側的前述介電體層上;以及終端電阻,連接於前述第1、第2輸出側引出線路的另一端,前述第1、第2相位調變電極線路是沿著前述第1、第2臂波導形成,前述第1、第2輸出側引出線路是朝前述介電體層的面內與前述第1、第2臂波導之延伸方向交叉的方向彎曲,且與前述終端電阻連接。 [發明的效果]The semiconductor Mach-Zehnder optical modulator of the present invention is provided with: the first and second arm waveguides are formed on a substrate; the first input-side lead-out line is formed on the dielectric layer on the substrate, and one end is supplied Modulation signal input; the second input side lead-out line is formed on the aforementioned dielectric layer next to the first input side lead-out line, and one end is for the signal input complementary to the aforementioned modulation signal; the first and second phase modulation The variable electrode circuit is formed on the dielectric layer, and one end is connected to the other end of the first and second input-side lead-out circuits respectively; the first and second output-side lead-out circuits are formed on the dielectric layer, And one end is connected to the other end of the first and second phase modulation electrode circuits; the first and second electrodes apply the modulation signals propagating to the first and second phase modulation electrode circuits to the aforementioned The first and second arm waveguides; the first ground wire, along the propagation direction of the modulation signal, is formed on the first input side lead line, the first phase modulation electrode circuit, and the first output side lead line On the outer dielectric layer; a second ground line, along the propagation direction of the modulation signal, is formed on the second input side lead line, the second phase modulation electrode line, and the second output side lead On the aforementioned dielectric layer on the outer side of the circuit; and a terminating resistor connected to the other end of the aforementioned first and second output-side lead wires, and the aforementioned first and second phase modulation electrode circuits are along the aforementioned first and second The arm waveguide is formed, and the first and second output-side lead lines are bent in a direction intersecting the extending direction of the first and second arm waveguides in the plane of the dielectric layer, and are connected to the terminating resistor. [Effects of the invention]
根據本發明,沿著第1、第2臂波導形成第1、第2相位調變電極線路,並將第1、第2輸出側引出線路朝介電體層的面內與第1、第2臂波導之延伸方向交叉的方向彎曲而與終端電阻連接,藉此可解決在習知構造中成為問題之高頻特性的劣化,實現寬頻帶且與驅動器的連接優異的半導體馬赫曾德爾光調變器。According to the present invention, the first and second phase modulation electrode lines are formed along the first and second arm waveguides, and the first and second output side lead lines are directed toward the surface of the dielectric layer and the first and second arms The extending direction of the waveguide is bent and connected to the terminating resistor. This solves the problem of the deterioration of high frequency characteristics in the conventional structure, and realizes a semiconductor Mach-Zehnder optical modulator with a wide frequency band and excellent connection with the driver. .
[用以實施發明的形態]
[第1實施例]
以下,針對本發明的實施例參照圖式來進行說明。圖1是表示本發明的第1實施例之IQ調變器的構成的平面圖。IQ調變器具備有:輸入波導10;1×2MMI耦合器11,將傳播於輸入波導10的光分波為2系統;波導12、13,對藉由1×2MMI耦合器11分波的2條光進行波導;1×2MMI耦合器14,將傳播於波導12的光分波為2系統;1×2MMI耦合器15,將傳播於波導13的光分波為2系統;波導16、17(第1、第2臂波導),對藉由1×2MMI耦合器14分波的2條光進行波導;波導18、19(第1、第2臂波導),對藉由1×2MMI耦合器15分波的2條光進行波導;輸入側引出線路20、21(第1、第2輸入側引出線路),用以將I調變訊號施加於波導16、17,且由導體所組成;輸入側引出線路22、23(第1、第2輸入側引出線路),用以將Q調變訊號施加於波導18、19,且由導體所組成;相位調變電極線路24、25(第1、第2相位調變電極線路),與輸入側引出線路20、21連接,且由導體所組成;相位調變電極線路26、27(第1、第2相位調變電極線路),與輸入側引出線路22、23連接,且由導體所組成;輸出側引出線路28、29(第1、第2輸出側引出線路),與相位調變電極線路24、25連接,且由導體所組成;輸出側引出線路30、31(第1、第2輸出側引出線路),與相位調變電極線路26、27連接,且由導體所組成;電極32、33(第1、第2電極),將從相位調變電極線路24、25供給的I調變訊號施加於波導16、17,且由導體所組成;以及電極34、35,將從相位調變電極線路26、27供給的Q調變訊號施加於波導18、19,且由導體所組成。[Form to implement the invention]
[First Embodiment]
Hereinafter, embodiments of the present invention will be described with reference to the drawings. Fig. 1 is a plan view showing the configuration of an IQ modulator according to a first embodiment of the present invention. The IQ modulator is equipped with:
進而,IQ調變器具備有:相位調整電極36~39,用以調整傳播於波導16~19之經調變的訊號光的相位,且由導體所組成;2×1MMI耦合器40,將傳播於波導16、17之2系統的訊號光合波;2×1MMI耦合器41,將傳播於波導18、19之2系統的訊號光合波;波導42,對2×1MMI耦合器40的輸出光進行波導;波導43,對2×1MMI耦合器41的輸出光進行波導;相位調整電極44、45,用以調整傳播於波導42、43之訊號光的相位,且由導體所組成;2×1MMI耦合器46,將傳播於波導42、43之2系統的訊號光合波;輸出波導47;地線48,配設於輸入側引出線路20、相位調變電極線路24、與輸出側引出線路28的外側,且由導體所組成;地線49,配設於輸入側引出線路21、相位調變電極線路25及輸出側引出線路29,與輸入側引出線路22、相位調變電極線路26及輸出側引出線路30之間,且由導體所組成;地線50,配設於輸入側引出線路23、相位調變電極線路27、與輸出側引出線路31的外側,且由導體所組成;以及終端電阻51~54,連接於輸出側引出線路28~31的端部。Furthermore, the IQ modulator is equipped with:
圖2是本實施例之IQ調變器的a-a’截面圖。圖2中,60是n-InP層,61是由InP所組成的下部被覆層,62是半導體核心層,63是由InP所組成的上部被覆層,64是SI-InP基板,65是形成於n-InP層60之上的介電體層。Fig. 2 is a cross-sectional view of a-a' of the IQ modulator of this embodiment. In Figure 2, 60 is the n-InP layer, 61 is the lower cladding layer composed of InP, 62 is the semiconductor core layer, 63 is the upper cladding layer composed of InP, 64 is the SI-InP substrate, and 65 is formed on The dielectric layer above the n-
如圖2所示,輸入側引出線路20~23、相位調變電極線路24~27、輸出側引出線路28~31、與地線48~50形成於介電體層65之上。As shown in FIG. 2, the input-side lead lines 20-23, the phase modulation electrode lines 24-27, the output-side lead lines 28-31, and the ground lines 48-50 are formed on the
接著,針對這些高頻線路圖案進一步詳細說明。本實施例的高頻線路圖案是以形成於介電體層65上的2條訊號線路與2條地線所組成的GSSG(Ground-Signal-Signal-Ground)差動共面帶線為基本構造,前述介電體層65是由低介電系數的材料所組成。Next, these high-frequency line patterns will be described in further detail. The high-frequency line pattern of this embodiment is based on a GSSG (Ground-Signal-Signal-Ground) differential coplanar strip line composed of two signal lines and two ground lines formed on the
但是,在本實施例中,是將以I調變訊號為輸入的半導體MZ光調變器、與以Q調變訊號為輸入的半導體MZ調變器並列設置於基板上,且做成I調變訊號側之半導體MZ光調變器的高頻線路圖案與Q調變訊號側之半導體MZ光調變器的高頻線路圖案共用中央的地線49。However, in this embodiment, a semiconductor MZ optical modulator with an I modulation signal as input and a semiconductor MZ modulator with a Q modulation signal as input are arranged in parallel on the substrate, and are made of I modulation. The high-frequency circuit pattern of the semiconductor MZ optical modulator on the signal-changing side and the high-frequency circuit pattern of the semiconductor MZ optical modulator on the Q-modulated signal side share the
訊號線路是由輸入側引出線路20~23的部分、相位調變電極線路24~27的部分、輸出側引出線路28~31的部分之3個部分所形成,以全部的部分來成為已取得阻抗匹配的差動線路構造(GSSG構成)。由於為差動線路構成,因此可藉由能量效率高的差動輸入訊號(差動驅動器)來驅動調變器。The signal line is formed by three parts of the input side lead lines 20-23, the phase modulation electrode line 24-27 part, and the output side lead lines 28-31. The entire part becomes the acquired impedance. Matched differential line structure (GSSG structure). Due to the differential circuit configuration, the modulator can be driven by a differential input signal (differential driver) with high energy efficiency.
在輸入側引出線路20,從形成於SI-InP基板64上的差動驅動器(不圖示)輸入I調變訊號,並將與之互補的I調變訊號(bar I)從差動驅動器輸入至輸入側引出線路21。同樣地,在輸入側引出線路22,從差動驅動器輸入Q調變訊號,並將與之互補的Q調變訊號(bar Q)從差動驅動器輸入至輸入側引出線路23。Lead out the
輸出側引出線路28~31各自的端部經由終端電阻51~54而端接。
地線48~50的其中一端(圖1的左端部)與差動驅動器的地連接。The respective ends of the output-side lead lines 28 to 31 are terminated via terminating
1×2MMI耦合器14、波導16、17、輸入側引出線路20、21、相位調變電極線路24、25、輸出側引出線路28、29、電極32、33、以及2×1MMI耦合器40構成I調變訊號側的半導體MZ光調變器。該半導體MZ光調變器因應從電極32、33施加於波導16、17的I調變訊號,對傳播於波導16、17的光進行相位調變。1×
同樣地,1×2MMI耦合器15、波導18、19、輸入側引出線路22、23、相位調變電極線路26、27、輸出側引出線路30、31、電極34、35、以及2×1MMI耦合器41構成Q調變訊號側的半導體MZ光調變器。該半導體MZ光調變器因應從電極34、35施加於波導18、19的Q調變訊號,對傳播於波導18、19的光進行相位調變。Similarly, 1×2
2×1MMI耦合器40將傳播於波導16、17之經調變的訊號光合波。2×1MMI耦合器41將傳播於波導18、19之經調變的訊號光合波。藉由在相位調整電極44、45施加電壓,可進行相位調整,以使從2×1MMI耦合器40輸出之I側的訊號光與從2×1MMI耦合器41輸出之Q側的訊號光之相位差成為90度。The 2×1
2×1MMI耦合器46藉由將傳播於波導42之I側的訊號光與傳播於波導43側之Q側的訊號光合波,而得到光IQ調變訊號。如此,在本實施例中,可實現IQ調變器。The 2×1
接著,針對本實施例之特徵的構成依序說明。相位調變電極線路24~27是與構成半導體MZ光調變器的波導16~19平行地配設。
與該相位調變電極線路24~27連接之輸入側引出線路20~23,必須與相位調變電極線路24~27形成在同一直線上。又,宜為完全沒有彎曲的構造。其理由是因為在輸入側引出線路20~23中,若於差動線路構造產生彎曲,則彎曲部分所造成之相位差的影響,可能會有:產生共模、伴隨其之差動傳送特性大幅劣化、產生共振、以及訊號在彎曲部分反射即回到驅動器側而使驅動器的驅動力大幅地劣化。Next, the features of the present embodiment will be described in order. The phase modulation electrode lines 24-27 are arranged in parallel with the waveguides 16-19 constituting the semiconductor MZ optical modulator.
The input-side lead wires 20-23 connected with the phase modulation electrode circuits 24-27 must be formed on the same straight line with the phase modulation electrode circuits 24-27. In addition, it is desirable to have a structure without any bending. The reason is that in the lead-out
又,若在輸入側引出線路20~23產生彎曲,則比起直線狀的線路,線路變長而傳送損失增加,再加上產生彎曲損失,因此差動訊號的高頻特性會劣化。特別是,輸入側引出線路20~23中的損失是直接關聯於調變頻寬的劣化,因此在實現寬頻帶化上,將輸入側引出線路20~23中的損失降至最小是重要的。In addition, if the
為了將輸入側引出線路20~23的損失降至最小,不僅要如上述般將輸入側引出線路20~23與相位調變電極線路24~27形成於同一直線上,還必須將波導16~19與輸入側引出線路20~23及相位調變電極線路24~27的配置最佳化。In order to minimize the loss of the input-side lead lines 20-23, not only the input-side lead lines 20-23 and the phase modulation electrode lines 24-27 must be formed on the same straight line as described above, but also the waveguides 16-19 must be formed. Optimized the configuration of the lead wires 20-23 on the input side and the phase modulation electrode wires 24-27.
例如,若採用如本實施例的配置,可使輸入側引出線路20~23的長度最短。在本實施例中,將輸入波導10與1×2MMI耦合器11形成為輸入波導10的光傳播方向(圖1上下方向)及1×2MMI耦合器11的光輸入輸出方向(圖1上下方向) 相對於波導16~19的延伸方向(圖1左右方向)為正交,並且將1×2MMI耦合器14、15、40、41、46形成為1×2MMI耦合器14、15、40、41、46的光輸入輸出方向(圖1左右方向)相對於波導16~19的延伸方向為同一方向。藉此,構成為波導圖案為L字形的布局。For example, if the configuration as in this embodiment is adopted, the length of the
根據如此的布局,可將輸入側引出線路20~23的長度作成700μm以下,與文獻「N.Kono et al.,“Compact and Low Power DP-QPSK Modulator Module with InP-Based Modulator and Driver ICs”,OFC2013,OW1G.2,2013」所記載的習之構成相比,可縮短1mm程度長。According to such a layout, the length of the input-
接著,針對相位調變電極線路24~27進行說明。相位調變電極線路24~27以及與之連接的電極32~35是在阻抗匹配、微波與光波的速度匹配上優異的差動電容負載構造(GSSG構成)。亦即,是如下排列的構成:地線48;相位調變電極線路24,輸入有I調變訊號;電極32,被供給來自相位調變電極線路24之I調變訊號;電極33,輸入有與I調變訊號互補之訊號(bar I);相位調變電極線路25,將訊號供給至電極33;地線49;相位調變電極線路26,輸入有Q調變訊號;電極34,被供給來自相位調變電極線路26之Q調變訊號;電極35,輸入有與Q調變訊號互補之訊號(bar Q);相位調變電極線路27,將訊號供給至電極35;以及地線50。Next, the phase
藉由最佳地設計將電容負載部之電極32~35的數量、間隔、長度,而可自由地設計對相位調變電極線路24~27之電容的附加量,因此可以將相位調變電極線路24~27的阻抗、以及傳播於相位調變電極線路24~27的微波之速度設計成任意值,前述電容負載部的電極32~35是從主線路即相位調變電極線路24~27分歧且週期性地形成。By optimally designing the number, spacing, and length of the
因此,成為可以同時實現阻抗匹配、以及微波與光波的速度匹配,且可以實現調變器之30GHz以上的寬頻帶動作之電極構造。又,為了使半導體MZ光調變器進行寬頻帶動作,必須設計成可將電極32~35看做進行波型電極,因此必須以可看做分佈常數的方式將每個訊號之電極32~35的週期,設為管內波長λeff
之最低限度1/4以下,理想為1/8以下,前述管內波長λeff
是傳播於相位調變電極線路24~27及電極32~35之最大頻率的調變訊號的管內波長。Therefore, it becomes an electrode structure that can realize impedance matching and the speed matching of microwave and light waves at the same time, and can realize the wideband operation of the modulator above 30 GHz. In addition, in order for the semiconductor MZ optical modulator to perform broadband operation, it must be designed so that the
由於沿著波導16~19的延伸方向週期性地配置各電極32~35,一般來說也必須考慮布拉格(Bragg)頻率。但是,在本實施例中,由於布拉格頻率為比對應於上述管內波長的頻率還高頻域側的頻率,因此在將每個訊號之電極32~35的週期設為管內波長λeff
之最低限度1/4以下(理想為1/8以下)之滿足上述條件的情況下,不必考慮布拉格頻率。Since the
接著,針對輸出側引出線路28~31進行說明。圖3是將輸出側引出線路28~31的部分擴大的平面圖。輸出側引出線路28~31是在介電體層65的面內(圖3的紙面內)與波導16~19的延伸方向(輸入側引出線路20~23及相位調變電極線路24~27的延伸方向)交叉的方向(本實施例為正交的方向)彎曲之構造。由於如上述般本實施例的高頻線路圖案是GSSG差動線路構造,因此輸出側引出線路28~31的彎曲方式變得重要。Next, the output-side lead lines 28 to 31 will be described. Fig. 3 is an enlarged plan view of the output-side lead lines 28 to 31. The output-side lead lines 28 to 31 are in the plane of the dielectric layer 65 (in the paper surface of FIG. 3) and the extension direction of the
例如,在將輸出側引出線路28~31的寬度設為任意之阻抗的寬度,並直接以該寬度將輸出側引出線路28~31彎曲成直角的情況下,於差動構成的2條線路28與29間、及線路30與31間會分別產生訊號的電長度差,而發生大的相位差。由相位差、及彎曲的非對稱性,會產生共模、差模的高頻特性劣化而使調變頻寬劣化、傳送特性劣化,因此不適合。For example, when the width of the output-side lead lines 28 to 31 is set to an arbitrary impedance width, and the output-side lead lines 28 to 31 are directly bent at right angles with this width, the differential configuration of the two
於是,在本實施例中,將輸出側引出線路28~31以對應所需的阻抗之一定寬度W1來形成,並且做成:在從比曲部(圖3的70、71)靠近相位調變電極線路24~27的位置起長度50μm程度之楔形部(圖3的72、73)中,輸出側引出線路28~31的寬度漸漸變窄,且曲部70、71中的輸出側引出線路28~31的寬度比上述一定寬度W1更窄。又,將輸出側引出線路28與29間的距離、以及輸出側引出線路30與31間的距離,做成比相位調變電極線路24與25間的距離、以及相位調變電極線路26與27間的距離短。進而,在曲部70、71中,將輸出側引出線路28與地線48間的距離、輸出側引出線路29與地線49間的距離、輸出側引出線路30與地線49間的距離、以及輸出側引出線路31與地線50間的距離,做成比其他部分之輸出側引出線路與地線間的距離短。但是,此時地線48~50的寬度與輸出側引出線路28~31的寬度不同,彎曲部與直線部分全部為同一寬度。其理由是為了使共模特性良好,並確保串擾特性。Therefore, in this embodiment, the output-side lead lines 28 to 31 are formed with a certain width W1 corresponding to the required impedance, and are made to be closer to the phase modulation from the curved part (70, 71 in FIG. 3) In the wedge-shaped portion (72, 73 in Fig. 3) with a length of about 50 μm from the position of the
如此,在本實施例中,對於彎曲部分的波長,僅以足夠小(1/4以下)的微小區間來將線路寬度做細,因此無論是對差模及共模的任一者而言,即使將輸出側引出線路28~31高阻抗化,也可以將輸出側引出線路28~31彎曲且不出現阻抗不匹配造成的特性劣化。In this way, in this embodiment, for the wavelength of the curved portion, the line width is narrowed only in a small enough (1/4 or less) interval, so whether it is for either differential mode or common mode, Even if the output-side lead lines 28 to 31 are made high-impedance, the output-side lead lines 28 to 31 can be bent without performance degradation caused by impedance mismatch.
在曲部70、71中,將輸出側引出線路28~31的寬度做窄,藉此可將輸出側引出線路28與29的電長度差及相位差、以及輸出側引出線路30與31的電長度差及相位差足夠地縮小,因此可以抑制共模的發生及差模的高頻特性劣化。In the
在本實施例中,與將輸出側引出線路的寬度保持原樣來配線的習知構成相比,可於50GHz將穿透特性(Sdd21)例如大約改善0.5dB程度,進而言之,可將顯示從差模朝共模轉換(共模的激發)的Sdc21,例如改善10dB程度。In this embodiment, compared with the conventional structure in which the width of the lead-out line on the output side is wired as it is, the transmission characteristic (Sdd21) can be improved, for example, by about 0.5 dB at 50 GHz. In other words, the display can be changed from Sdc21, which converts the differential mode to the common mode (excitation of the common mode), is improved by, for example, 10 dB.
又,為了防止共模的特性劣化,宜將構造的非對稱性做成最小限度,並且地線48~50的寬度W2為一定。
進而,採用迴旋曲線(clothoid)作為輸出側引出線路28~31的曲部70、71邊緣的軌跡,藉此可以進一步改善高頻特性。若採用迴旋曲線,則例如與通常的曲線相比,可以將差動反射特性(Sdd11)提升數dB程度。In addition, in order to prevent the deterioration of the common mode characteristics, it is preferable to minimize the asymmetry of the structure and keep the width W2 of the ground wire 48-50 constant.
Furthermore, a clothoid is used as the trajectory of the edges of the
在本實施例中,如上述將曲部70、71中的輸出側引出線路28~31的寬度,做成比已取得阻抗匹配之直線部分的一定寬度W1還窄。但是,曲部的傳遞距離過長時,由於將輸出側引出線路28~31的寬度做窄而造成之些許的阻抗不匹配的影響,會有曲部70、71成為訊號的反射點,而使高頻特性劣化的可能性。為了抑制阻抗不匹配的影響,宜將曲部70、71的傳播長度做成上述管內波長λeff
的1/4以下,可能的話宜做成1/8以下。又,從將長度縮短的觀點,於楔形部72、73的部分,傳播長度宜為50μm以下。In this embodiment, as described above, the widths of the output-side lead lines 28 to 31 in the
又,基本上輸出側引出線路28~31形成於介電體層65上。然而,如顯示圖3的b-b’線截面圖的圖4,藉由彎曲輸出側引出線路28~31,會發生輸出側引出線路28~31形成於波導16~19上之處。也就是說,與構成介電體層65之低介電係數材料的一例即苯並環丁烯(BCB)相比,是橫越在介電系數約為4倍的半導體上,因此若照著介電體層65上的線路寬度形成於波導16~19上,則會有輸出側引出線路28~31的阻抗大幅下降,而產生阻抗不匹配的可能性。Furthermore, basically, the output-side lead lines 28 to 31 are formed on the
於是,即使在曲部70、71以外的橫越處(圖3、圖4的74)中,亦可與曲部70、71同樣地,將輸出側引出線路28~31的寬度做成比對應於所需之阻抗匹配的一定寬度W1更窄,並且將輸出側引出線路28與29間的距離、輸出側引出線路28與地線48間的距離、以及輸出側引出線路29與地線49間的距離縮短。Therefore, even in the crossing places other than the
藉由如此的構造,可以在輸出側引出線路28~31橫越於波導16~19上之處,使輸出側引出線路28~31的阻抗大幅降低,減低產生阻抗不匹配的可能性。但是,在如以上的橫越處中之輸出側引出線路28~31與地線48、49的構造並非本發明之必要的構成要件,在輸出側引出線路28~31橫越於波導16~19上的區域較小的情況下,由於看不出阻抗不匹配的影響,因此不需要本構造。With such a structure, the output-side lead lines 28 to 31 can cross the
又,在本實施例中,與相位調變電極線路24~27的部分相比,藉由將輸出側引出線路28與29間的距離、以及輸出側引出線路30與31間的距離縮短,而可以做成電性封閉較強的構造,可以防止電磁波朝基板方向洩漏及基板共振。Furthermore, in this embodiment, compared with the phase modulation electrode lines 24-27, the distance between the output-side lead lines 28 and 29 and the distance between the output-side lead lines 30 and 31 are shortened, and It can be made into a structure with strong electrical sealing, which can prevent electromagnetic waves from leaking toward the substrate and substrate resonance.
又,輸出側引出線路28~31的端部連接於滿足所需的差模阻抗及共模阻抗的終端電阻51~54而差動端接。In addition, the ends of the output-side lead lines 28 to 31 are connected to
又,如圖5所示,實際上,宜設置將地線48~50間電連接的線路55、56。線路55將地線48與49間連接。線路56將地線49與50間連接。在沒有線路55、56的情況下,地線48~50的電位會不穩定而擺動,因此在依附於傳播長度之任意的頻率中,會發生共振。因此,難以實現寬頻帶之調變器。為了抑制該共振,宜沿著訊號的傳播方向,以對於訊號波長來說足夠短的週期,也就是上述管內波長λeff
的1/4~1/8以下的週期,來設置將地線48~50間連結的線路55、56。In addition, as shown in Fig. 5, in fact, it is advisable to provide
在圖5的例中,僅在輸出側引出線路28~31之處設置線路55、56,但關於在輸入側引出線路20~23及相位調變電極線路24~27之處,也同樣地宜在地線48~50間設置線路55、56。In the example of FIG. 5, only the
藉由設置線路55、56,可使輸入側引出線路20~23、相位調變電極線路24~27、以及輸出側引出線路28~31之兩側的地線48~50的電位穩定化,且抑制地線48~50的電位的共振,而可實現寬頻帶的調變器。在以比管內波長λeff
的1/4~1/8還長的週期設置線路55、56的情況下,雖然可以減低漣波量,但無法完全抑制地線48~50的電位的共振。By setting
又,如圖6所示,也可經由設置於半導體基板(SI-InP基板64)背面之接地電極80、與將半導體基板加工而製作之接地通孔81~84,而將地線48~50間連接,藉此可使地線48~50的電位穩定化。接地通孔81將地線48與接地電極80連接。接地通孔82、83將地線49與接地電極80連接。接地通孔84將地線50與接地電極80連接。Also, as shown in FIG. 6, the
在圖6中,為了使構成容易理解,畫出連結一對接地電極81、82的線85,前述接地電極81、82是以上述管內波長λeff
之1/4~1/8以下的週期而週期性地設置於地線48、49。同樣地,畫出連結一對接地電極83、84的線86,前述接地電極83、84是以管內波長λeff
之1/4~1/8以下的週期而週期性地設置於地線49、50。
與圖5同樣地,在圖6中,僅在輸出側引出線路28~31之處設置有接地通孔81~84,但關於輸入側引出線路20~23及相位調變電極線路24~27之處,也宜在地線48~50設置接地通孔81~84。In FIG. 6, in order to make the structure easy to understand, a
另,在圖6之例中,雖然在半導體基板的背面形成有接地電極80,但亦可在圖1~圖4所示構造之上形成介電體層,並在該介電體層上形成接地電極80。In addition, in the example of FIG. 6, although the
[第2實施例]
接著,針對本發明的第2實施例說明。圖7是表示本發明的第2實施例之IQ調變器的構成的平面圖,且與圖1相同的構成附上有相同的的符號。在第1實施例中,相對於波導16~19的延伸方向(圖1左右方向),輸入波導10的光傳播方向為正交。[Second embodiment]
Next, the second embodiment of the present invention will be described. FIG. 7 is a plan view showing the structure of the IQ modulator of the second embodiment of the present invention, and the same structure as in FIG. 1 is attached with the same reference numeral. In the first embodiment, the light propagation direction of the
相對於此,在本實施例中,光從與波導16~19的延伸方向平行的方向入射至輸入波導10a,並在與1×2MMI耦合器11連接的稍前方將輸入波導10a彎曲。藉此,構成波導圖案為U字形之布局。其他構成如第1實施例中所說明。In contrast, in this embodiment, light enters the
在本實施例中,也可將輸入側引出線路20~23的長度做成700μm以下,且與文獻「N.Kono et al.,“Compact and Low Power DP-QPSK Modulator Module with InP-Based Modulator and Driver ICs”,OFC2013,OW1G.2,2013」所記載之習知構成相比,可將長度縮短1mm程度。In this embodiment, the length of the lead-out
另,在第1、第2實施例中,半導體MZ光調變器的波導16~19是如下構造:於SI-InP基板64上,依次積層有由InP所組成的下部被覆層61、無摻雜(non-doped)的半導體核心層62、以及由InP所組成的上部被覆層63之構造。其他的波導10、10a、12、13、42、43、47也是同樣的。In addition, in the first and second embodiments, the
半導體核心層62是作為光波導層而發揮功能,例如由InGaAsP及InGaAlAs等的材料所組成。半導體核心層62亦能以單一組成之四元混晶的塊層(bulk layer)及多重量子井層來構成。又,亦可將形成光封閉層的構造作為半導體核心層62,前述光封閉層是在多重量子井層的上下,能隙比多重量子井層大,且比起下部被覆層61及上部被覆層63,能隙較小。The
四元混晶的塊層及多重量子井層的能隙波長是設定成:在使用之光波長中,電光效應會有效地作用,且不會成為光吸收的問題。The energy gap wavelength of the bulk layer and the multiple quantum well layer of the quaternary mixed crystal is set to: in the light wavelength used, the electro-optic effect will effectively work, and will not become a problem of light absorption.
若從特性地觀點來考慮,在已設計所需之阻抗線路的情況下,由於可減低電極損失,因此介電體層65宜由例如有機材料的聚醯亞胺及BCB等低介電係數材料所組成。又,本發明不限定於InP系列材料,例如使用與GaAs基板匹配的材料系列也無妨。From a characteristic point of view, when the required impedance line is designed, the electrode loss can be reduced. Therefore, the
上部被覆層63與下部被覆層61任一方為n型半導體、另一方為p型半導體也無妨。
又,亦可以採取上部被覆層63與下部被覆層61雙方為n型半導體,並在上部被覆層63與半導體核心層62之間,或是下部被覆層61與半導體核心層62之間,插入第3p型被覆層的構造。
[產業上的利用可能性]Either the
本發明可適用於以電訊號來調變光訊號的半導體馬赫曾德爾光調變器。The present invention can be applied to a semiconductor Mach-Zehnder optical modulator that modulates optical signals with electrical signals.
10、10a、101、200:輸入波導 11、14、15、204、205:1×2MMI耦合器 12、13、16、17、18、19、42、43、104、105、202、203、206、207、208、209、224、225:波導 20、21、22、23:輸入側引出線路 24、25、26、27:相位調變電極線路 28、29、30、31:輸出側引出線路 32、33、34、35、111、112、214、215、216、217:電極 36、37、38、39、44、45、218、219、220、221、224、225:相位調整電極 40、41、46、222、223、228:2×1MMI耦合器 47、102、229:輸出波導 48、49、50:地線 51、52、53、54:終端電阻 55、56:線路 60、113:n-InP層 61、114:下部被覆層 62、115:半導體核心層 63、116:上部被覆層 64、117:SI-InP基板 65:介電體層 70、71:曲部 72、73:楔形部 80:接地電極 81、82、83、84:接地通孔 85、86:線 103:光分波器 106:光合波器 109、110:共面帶線 201:1×2多模干涉耦合器(1×2MMI耦合器) 210、211、212、213:訊號線路 230、231:驅動器 I:I調變訊號:與I調變訊號互補的訊號 Q:Q調變訊號:與Q調變訊號互補的訊號 W1:一定寬度 W2:寬度 λeff:管內波長10, 10a, 101, 200: Input waveguide 11, 14, 15, 204, 205: 1×2 MMI coupler 12, 13, 16, 17, 18, 19, 42, 43, 104, 105, 202, 203, 206 , 207, 208, 209, 224, 225: waveguide 20, 21, 22, 23: input side lead line 24, 25, 26, 27: phase modulation electrode line 28, 29, 30, 31: output side lead line 32 , 33, 34, 35, 111, 112, 214, 215, 216, 217: Electrodes 36, 37, 38, 39, 44, 45, 218, 219, 220, 221, 224, 225: Phase adjustment electrodes 40, 41 , 46, 222, 223, 228: 2×1 MMI coupler 47, 102, 229: output waveguide 48, 49, 50: ground wire 51, 52, 53, 54: terminal resistance 55, 56: line 60, 113: n -InP layer 61, 114: lower coating layer 62, 115: semiconductor core layer 63, 116: upper coating layer 64, 117: SI-InP substrate 65: dielectric layer 70, 71: curved portion 72, 73: wedge portion 80 : Ground electrodes 81, 82, 83, 84: ground through holes 85, 86: line 103: optical splitter 106: optical multiplexer 109, 110: coplanar strip line 201:1×2 multimode interference coupler (1 ×2MMI coupler) 210, 211, 212, 213: signal line 230, 231: driver I: I modulation signal : A signal complementary to the I modulated signal Q: Q modulated signal : A signal complementary to the Q modulation signal W1: A certain width W2: Width λ eff : In-tube wavelength
圖1是表示本發明的第1實施例之IQ調變器的構成的平面圖。 圖2是本發明的第1實施例之IQ調變器的截面圖。 圖3是將本發明的第1實施例之IQ調變器的輸出側引出線路的部分擴大的平面圖。 圖4是本發明的第1實施例之IQ調變器的輸出側引出線路的曲部的截面圖。 圖5是表示在本發明的第1實施例中將地線間連接的線路的平面圖。 圖6是表示在本發明的第1實施例中將地線間連接的接地通孔(ground via)的平面圖。 圖7是表示本發明的第2實施例之IQ調變器的構成的平面圖。 圖8A是表示習知的半導體馬赫曾德爾光調變器的構成的平面圖。 圖8B是表示習知的半導體馬赫曾德爾光調變器的構成的截面圖。 圖9是表示習知的單相驅動型IQ調變器的構成的平面圖。Fig. 1 is a plan view showing the configuration of an IQ modulator according to a first embodiment of the present invention. Fig. 2 is a cross-sectional view of the IQ modulator according to the first embodiment of the present invention. Fig. 3 is an enlarged plan view of a part of a lead-out line on the output side of the IQ modulator of the first embodiment of the present invention. 4 is a cross-sectional view of the curved portion of the lead-out line on the output side of the IQ modulator of the first embodiment of the present invention. Fig. 5 is a plan view showing a circuit connecting ground wires in the first embodiment of the present invention. Fig. 6 is a plan view showing a ground via connecting ground wires in the first embodiment of the present invention. Fig. 7 is a plan view showing the configuration of an IQ modulator according to a second embodiment of the present invention. Fig. 8A is a plan view showing the configuration of a conventional semiconductor Mach-Zehnder light modulator. Fig. 8B is a cross-sectional view showing the configuration of a conventional semiconductor Mach-Zehnder light modulator. Fig. 9 is a plan view showing the configuration of a conventional single-phase drive type IQ modulator.
10:輸入波導 10: Input waveguide
11、14、15:1×2MMI耦合器 11, 14, 15:1×2MMI coupler
12、13、16、17、18、19、42、43:波導 12, 13, 16, 17, 18, 19, 42, 43: waveguide
20、21、22、23:輸出側引出線路 20, 21, 22, 23: output side lead wire
24、25、26、27:相位調變電極線路 24, 25, 26, 27: phase modulation electrode circuit
28、29、30、31:輸出側引出線路 28, 29, 30, 31: output side lead wire
32、33、34、35:電極 32, 33, 34, 35: electrodes
36、37、38、39、44、45:相位調整電極 36, 37, 38, 39, 44, 45: Phase adjustment electrode
40、41、46:2×1MMI耦合器 40, 41, 46: 2×1MMI coupler
47:輸出波導 47: output waveguide
48、49、50:地線 48, 49, 50: ground wire
51、52、53、54:終端電阻 51, 52, 53, 54: terminal resistance
I:I調變訊號 I: I modulation signal
:與I調變訊號互補的訊號 : A signal complementary to the I modulation signal
Q:Q調變訊號 Q: Q modulation signal
:與Q調變訊號互補的訊號 : A signal complementary to the Q modulated signal
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