JP2005026725A - Optical element integrated module - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical element integrated module in which optical elements being module components are commonized and the optical elements can be mass-produced and easily. <P>SOLUTION: The optical element integrated module is provided with: an optical demultiplexer 34; an optical multiplexer 36; a first optical modulator 40a; a second optical modulator 40b; and a delay fine-adjustment unit 48. The demultiplexer demultiplexes an optical pulse train into an optical pulse train propagated through a first optical path and an optical pulse train propagated through a second optical path. The multiplexer multiplexes the optical pulse trains respectively propagated through the first and second optical paths. On the other hand, the first optical modulator is inserted into the first optical path, and the second optical modulator and the delay fine-adjustment unit are inserted into the second optical path. The length of the optical path from the demultiplexer to the first optical modulator, the length of the optical path from the demultiplexer to the second optical modulator, and the length of the optical path from the first optical modulator to the multiplexer are made equal to each other, and the difference between the length of the optical path from the first optical modulator to the multiplexer and the length of the optical path from the second optical modulator to the multiplexer is selected to be equal to the difference of the optical path for causing a time difference equivalent to a half of the pulse interval of the optical pulse train made incident onto the demultiplexer. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an optical element integrated module formed by integrating optical passive elements such as multiplexers and demultiplexers, and optical active elements such as optical modulators, and particularly in optical time division multiplexing communication. The present invention relates to a module for multiplexing optical pulse signals.
[0002]
[Prior art]
Optical time division multiplex communication (OTDM: Optical time division multiplex) generates optical pulse signals in parallel (optical modulation of an optical pulse train to convert electric pulse signals into optical pulse signals) (hereinafter also referred to as “coding”). ), Multiplexed on the time axis (optical MUX) and transmitted, and the optical signal is separated (hereinafter also referred to as “gating”) on the receiving side by a gate signal which is the reverse operation of the transmitting side. The communication adopts a method of returning to the original parallel optical pulse signal (optical DEMUX).
[0003]
Hereinafter, the expression “optical pulse signal” is used only when it means an optical pulse train reflecting a binary digital electric signal obtained by optically modulating the optical pulse train and converting the electric pulse signal into an optical pulse signal. And On the other hand, the expression “optical pulse train” is used as an optical pulse train in which optical pulses are arranged at regular regular intervals (a time interval corresponding to the reciprocal of the frequency corresponding to the bit rate). It may also be used to mean the optical pulse signal described above.
[0004]
In optical fiber communication, OTDM is an optical communication system that operates at the processing speed required by this market because the processing speed related to coding and gating required in the market exceeds the limit of these processing speeds by electronic circuits. It is expected as a technology for realizing the apparatus at the lowest possible cost.
[0005]
In optical fiber communication, it is necessary to increase the communication speed as much as possible in order to effectively use optical communication resources such as an optical fiber communication network. Here, the communication speed is a speed indicating how many bits of information can be transmitted / received per unit time, and is also referred to as a bit rate. In addition, when a speed indicating how many bits of information can be transmitted / received per unit time is expressed by a frequency, this frequency is called a clock frequency.
[0006]
One of the measures taken to increase the bit rate is a technique called bit interleaving. In this method, two optical pulse signals are combined so that an optical pulse of an optical pulse train of the other optical pulse signal enters between adjacent optical pulses of the optical pulse train of one optical pulse signal, In this method, an optical pulse signal having a bit rate that is the sum of the bit rates of both optical pulse signals is obtained. That is, it is one of the techniques for multiplexing optical pulse signals in OTDM.
[0007]
For example, if an optical pulse signal with a bit rate of 40 Gb / s and an optical pulse signal with a bit rate of 40 Gb / s are multiplexed by bit interleaving, a bit of 80 Gb / s corresponding to the sum of both bit rates is obtained. It can be transmitted as a rate optical pulse signal. The optical pulse signal transmitted in this way is optically demultiplexed in the receiving device, and again becomes an optical pulse signal with a bit rate of 40 Gb / s and an optical pulse signal with a bit rate of 40 Gb / s. The signal is separated and reproduced.
[0008]
Hereinafter, to obtain an optical pulse signal having a double bit rate by bit interleaving the optical pulse signal of 40 Gb / s and the optical pulse signal of 40 Gb / s in this way is referred to as doubling the bit rate. Generally bit-interleaved, N = 2 ⁿ Obtaining an optical pulse signal having a bit rate twice (n is a natural number) is referred to as multiplying the bit rate by N.
[0009]
The inventors of the present invention have already described the above-described optical MUX (here, for bit interleaving) configured by integrating a half mirror, a total reflection mirror, and an electro-absorption modulator (EAM). Have developed optical device integrated modules.
[0010]
For example, a 20 GHz optical pulse train is divided into two optical paths using a planar optical waveguide and a lens, and each optical pulse train is reflected by a reflection type EAM inserted in each of the two optical paths. Successfully modulated. Then, the same optical circuit is traced again, and the optical pulse train is multiplexed by shifting by half a bit on the time axis (two optical pulse signals are combined between the optical pulse trains of one optical pulse signal and the other optical pulse train). An experiment for generating an optical pulse signal of 40 Gb / s has been successful (for example, see Non-Patent Document 1).
[0011]
Further, a modular EAM constructed by integrating a lens and an EAM is prototyped, and light having a bit rate of 80 Gb / s is obtained by bit interleaving a 40 Gb / s optical pulse signal and a 40 Gb / s optical pulse signal. It has also succeeded in generating a pulse signal (see, for example, Non-Patent Document 2).
[0012]
[Non-Patent Document 1]
Hiromi Yamada, Yukihiro Ozeki, Toshikazu Yamagata, Kiyoshi Nagai: Proceedings of the IEICE Communication Society Conference, page 227
[Non-Patent Document 2]
Masatoshi Kagawa, Hitoshi Murai, Hiromi Yamada, Shigeru Takasaki, Kozo Fujii: IEICE Tech. 101, no. 448, 89-92 pages
[0013]
[Problems to be solved by the invention]
However, when an optical element integrated module that performs multiplexing of 4 times or more with a high degree of multiplicity is designed by the same design method as that of the device that doubles the optical pulse signal disclosed in Non-Patent Document 1, the structure is as follows. It becomes complicated and impractical. Further, the device for doubling the optical pulse signal disclosed in Non-Patent Document 2 is symmetrical to the arrangement of optical elements such as an EAM element, a reflector (mirror), a lens, a multiplexer, or a duplexer (half mirror). Due to the lack of properties, there has been a problem that the process for manufacturing the device is complicated.
[0014]
Here, the symmetry of the arrangement of the optical elements means that the distance from the passive element to the active element is the same with respect to the active element, and the function is the same. Assume that the arrangement of the optical elements is symmetrical when the passive elements are arranged so that the arrangement patterns of the passive elements with respect to the active elements are congruent with respect to the plurality of active elements. That is, the arrangement of optical elements formed by combining a plurality of arrangement patterns in which the arrangement patterns of passive elements and active elements are congruent is referred to as arrangement with good objectivity.
[0015]
SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to realize an arrangement of optical elements so that the structure thereof is not complicated even when a device that performs multiplication of four or more times is configured. That is, an object of the present invention is to provide an optical element integrated module for multiplication that can be easily produced while maintaining the technical idea of the configuration of the device for multiplying the optical pulse signal by two. For example, a device that performs quadruple multiplication can be configured by combining two devices that perform double convolution. In addition, the device that performs the multiplication by two is configured by combining a first optical path including each of the optical modulators and a second optical path that is congruent with the first optical path.
[0016]
Another object of the invention is to unify the specifications of optical elements such as EAM, reflector (mirror), lens, optical multiplexer / demultiplexer (half mirror) and to arrange the optical elements symmetrically. Another object of the present invention is to provide an optical element integrated module that can be manufactured by a simple manufacturing process.
[0017]
[Means for Solving the Problems]
In order to achieve the above object, an optical element integrated module according to the present invention comprises a duplexer, a multiplexer, a first optical modulator, a second optical modulator, and a delay fine adjuster. The duplexer demultiplexes the optical pulse train into an optical pulse train propagating through the first optical path and an optical pulse train propagating through the second optical path. The multiplexer multiplexes the optical pulse trains propagated through the first optical path and the second optical path, respectively. On the other hand, a first optical modulator is inserted in the first optical path, and a second optical modulator and a delay fine adjuster are inserted in the second optical path.
[0018]
An optical element integrated module according to the present invention includes a duplexer, a multiplexer, a first optical modulator, a second optical modulator, and a delay fine adjuster having functions similar to those of the above-described optical element integrated module. The delay fine adjuster and the first optical modulator may be inserted in the first optical path, and the second optical modulator may be inserted in the second optical path.
[0019]
By adopting one of the configurations as described above, the optical pulse signal double device disclosed in Non-Patent Document 1 differs from the technical idea of the arrangement method of the optical element, and is multiplied by 4 or more. Even when a device that performs the above is configured, the configuration is not complicated. Further, with this configuration, the first optical path and the second optical path can be arranged symmetrically with the exception of the delay fine adjuster.
[0020]
By inserting the delay fine adjuster into the optical path, an optical path difference is generated that causes a time difference corresponding to half of the pulse interval of the optical pulse train incident on any of the optical element integrated modules described above. As will be described later, this optical path difference is about 7.5 mm, that is, by inserting a delay fine adjuster, the geometrical symmetry with respect to the arrangement of the optical elements is hardly impaired. There is no obstacle in the manufacturing process of the optical element integrated module, such as adjustment of the position where the multiplexer, the first optical modulator, the second optical modulator, and the delay fine adjuster should be arranged.
[0021]
In the optical element integrated module described above, the first optical modulator is inserted into the first optical path, and the second optical modulator and the delay fine adjuster are inserted into the second optical path. In the case of an optical element integrated module, the following configuration is preferable.
[0022]
That is,
(1) A delay fine adjuster is inserted between the second optical modulator and the multiplexer, the optical path length from the demultiplexer to the first optical modulator, and the optical path from the demultiplexer to the second optical modulator. And the optical path length from the first optical modulator to the multiplexer, and the optical path length from the first optical modulator to the multiplexer and the optical path length from the second optical modulator to the multiplexer The difference is configured to be equal to the optical path difference that causes a time difference corresponding to half the pulse interval of the optical pulse train incident on the duplexer.
[0023]
(2) Or, a delay fine adjuster is inserted between the demultiplexer and the second optical modulator, the optical path length from the demultiplexer to the first optical modulator, and the first optical modulator to the multiplexer Is equal to the optical path length from the second optical modulator to the multiplexer, the optical path length from the demultiplexer to the first optical modulator, and the optical path length from the demultiplexer to the second optical modulator. May be configured to be equal to the optical path difference that causes a time difference corresponding to half the pulse interval of the optical pulse train incident on the duplexer.
[0024]
Further, in the above-described optical element integrated module, the first optical modulator and the delay fine adjuster are inserted in the first optical path, and the second optical modulator is inserted in the second optical path. In the case of an optical element integrated module, the following configuration is preferable.
[0025]
That is,
(3) A delay fine adjuster is inserted between the demultiplexer and the first optical modulator, the optical path length from the demultiplexer to the second optical modulator, and between the first optical modulator and the multiplexer. The optical path length is equal to the optical path length from the second optical modulator to the multiplexer, the optical path length from the demultiplexer to the first optical modulator, and the optical path length from the demultiplexer to the second optical modulator, Is equal to the optical path difference that causes a time difference corresponding to half the pulse interval of the optical pulse train incident on the duplexer.
[0026]
(4) Or, a delay fine adjuster is inserted between the first optical modulator and the multiplexer, the optical path length from the demultiplexer to the second optical modulator, and between the second optical modulator and the multiplexer. And the optical path length from the demultiplexer to the first optical modulator are equal, and the optical path length from the first optical modulator to the multiplexer is equal to the optical path length from the second optical modulator to the multiplexer. May be configured to be equal to the optical path difference that causes a time difference corresponding to half the pulse interval of the optical pulse train incident on the duplexer.
[0027]
As described above, by adopting the configuration of any one of (1) to (4) described above, the optical path length from the demultiplexer to the first optical modulator and the optical path from the demultiplexer to the second optical modulator. Since the length, the optical path length from the first optical modulator to the multiplexer, and the optical path length from the second optical modulator to the multiplexer are equal, the optical pulse train is added to the first optical modulator or the second optical modulator. The optical element such as a lens used for the incident light can be made common (by inserting a delay fine adjuster, the geometrical symmetry with respect to the arrangement of the optical elements is hardly impaired). Further, even if a delay fine adjuster is inserted in the first or second optical path, the optical path length does not become longer than the optical path that causes a time difference corresponding to half the pulse interval of the optical pulse train. With such a difference in optical path length, optical elements having the same specifications can be used as optical elements such as lenses used for making an optical pulse train incident on the first optical modulator and the second optical modulator.
[0028]
That is, in order to configure the optical element integrated module of the present invention, the specifications of the optical elements such as the above-mentioned lenses can be made common, so that the mass production of parts is possible, and this optical element integrated module is manufactured. In the process, since the alignment work of these optical elements can be made common, there is an advantage that the process can be simplified.
[0029]
Further, as described above, an optical element integrated module that can be configured while maintaining the technical idea of the configuration of the device that doubles the optical pulse signal even when the device that performs multiplication of 4 times or more is configured. For this purpose, the configuration described below may be used.
[0030]
That is, an optical element integrated module according to the present invention includes an Nth demultiplexer, an Nth multiplexer, a first N / 2 multiplier, a second N / 2 multiplier, and an Nth delay fine adjuster. Consists of. The Nth demultiplexer demultiplexes the optical pulse train into an optical pulse train propagating through the N1 optical path and an optical pulse train propagating through the N2 optical path. The Nth multiplexer multiplexes the optical pulse trains propagated through the N1 optical path and the N2 optical path, respectively. The N1 optical path includes a first N / 2 multiplier, and the N2 optical path includes a second N / 2 multiplier and an Nth delay fine adjuster.
[0031]
Further, the optical element integrated module of the present invention is the same as described above, in the Nth demultiplexer, the Nth multiplexer, the first N / 2 multiplier, the second N / 2 multiplier, and the Nth multiplexer. It is configured with a delay fine adjuster. A second N / 2 multiplier is provided in the N2 optical path, an Nth delay fine adjuster and a first N / 2 multiplier are provided in the N1 optical path, and in the N2 optical path. May comprise a second N / 2 multiplier. Where N = 2 ⁿ And n is a natural number of 2 or more.
[0032]
With such a configuration, 2 ⁿ (= N) When configuring a multiplier, 2 ^n-1 (= N / 2) Two multipliers can be combined. Therefore, if a doubler can be configured, by combining the doubler as a basic component, no matter how many n, ⁿ A multiplier can be configured. That is, while maintaining the technical idea for the configuration of the device that doubles the optical pulse signal, it is ⁿ Can be multiplied 2 ⁿ An optical element integrated module for multiplication can be provided.
[0033]
In the above-described optical element integrated module, a first N / 2 multiplier is inserted in the N1 optical path, and a second N / 2 multiplier and an Nth delay fine adjuster are inserted in the N2 optical path. In the case of an optical element integrated module configured by inserting and, the following configuration is preferable.
[0034]
That is,
(5) An Nth delay fine adjuster is inserted between the second N / 2 multiplier and the Nth multiplexer, and the optical path length from the Nth demultiplexer to the first N / 2 multiplier; The optical path length from the Nth demultiplexer to the second N / 2 multiplier is configured to be equal to the optical path length from the first N / 2 multiplier to the Nth multiplexer. On the other hand, the difference between the optical path length from the first N / 2 multiplier to the Nth multiplexer and the optical path length from the second N / 2 multiplier to the Nth multiplexer is incident on the Nth duplexer. The optical pulse difference is equal to the optical path difference causing a time difference corresponding to 1 / N of the pulse interval of the optical pulse train.
[0035]
(6) Or an Nth delay fine adjuster is inserted between the Nth demultiplexer and the second N / 2 multiplier, and the optical path from this Nth demultiplexer to the first N / 2 multiplier The length, the optical path length from the first N / 2 multiplier to the Nth multiplexer, and the optical path length from the second N / 2 multiplier to the Nth multiplexer are configured to be equal. On the other hand, the difference between the optical path length from the Nth demultiplexer to the first N / 2 multiplier and the optical path length from the Nth demultiplexer to the second N / 2 multiplier is incident on the Nth demultiplexer. The optical path difference may be equal to the optical path difference that causes a time difference corresponding to 1 / N of the pulse interval of the optical pulse train.
[0036]
In the above-described optical element integrated module, the Nth delay fine adjuster and the first N / 2 multiplier are inserted in the N1 optical path, and the second N / 2 multiplier is inserted in the N2 optical path. In the case of an optical element integrated module configured by inserting a light source, the following configuration is preferable.
[0037]
That is,
(7) An Nth delay fine adjuster is inserted between the Nth demultiplexer and the first N / 2 multiplier, and the optical path length from the Nth demultiplexer to the second N / 2 multiplier is The optical path length from the first N / 2 multiplier to the Nth multiplexer is configured to be equal to the optical path length from the second N / 2 multiplier to the Nth multiplexer. On the other hand, the difference between the optical path length from the Nth demultiplexer to the first N / 2 multiplier and the optical path length from the Nth demultiplexer to the second N / 2 multiplier is incident on the Nth demultiplexer. The optical pulse difference is equal to the optical path difference causing a time difference corresponding to 1 / N of the pulse interval of the optical pulse train.
[0038]
(8) Alternatively, an optical path length from the Nth demultiplexer to the second N / 2 multiplier is inserted by inserting the Nth delay fine adjuster between the first N / 2 multiplier and the Nth multiplexer. The optical path length from the second N / 2 multiplier to the Nth multiplexer is configured to be equal to the optical path length from the Nth demultiplexer to the first N / 2 multiplier. On the other hand, the difference between the optical path length from the first N / 2 multiplier to the Nth multiplexer and the optical path length from the second N / 2 multiplier to the Nth multiplexer is incident on the Nth duplexer. The optical path difference may be equal to the optical path difference that causes a time difference corresponding to 1 / N of the pulse interval of the optical pulse train. Where N = 2 ⁿ And n is a natural number of 2 or more.
[0039]
As described above, when any one of the above-described configurations (5) to (8) is used, the configuration is not complicated even when a device that performs multiplication of four or more times is configured as described above. . Further, with this configuration, the optical elements can be arranged symmetrically. In other words, since optical elements such as lenses can be shared, parts can be mass-produced, and in the process of manufacturing this optical element integrated module, the alignment work of these optical elements can be shared, simplifying the process. There are advantages you can do.
[0040]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to FIGS. Each figure shows an example of the configuration according to the present invention, and only schematically shows the cross-sectional shape and arrangement relationship of each component to the extent that the present invention can be understood. Is not limited to the illustrated example. In the following description, specific materials and conditions may be used. However, these materials and conditions are only one of preferred examples, and are not limited to these. Moreover, in each figure, the same component is shown with the same number, and the overlapping description may be omitted.
[0041]
In the drawings shown below, the path of an optical signal such as an optical fiber is indicated by a thick line, and the path of an electrical signal is indicated by a thin line. The numbers and symbols given to these thick and thin lines mean optical signals or electrical signals, respectively.
[0042]
<Electroabsorption optical modulator (EAM) module>
With reference to FIG. 1, an EAM module which is an optical active element constituting the optical element integrated module of the present invention will be described.
[0043]
The EAM module (the housing of this module is assumed to be 10) is for applying a bias voltage to the EAM element 20, the lenses 12a and 12b, the electrical connector 26 made for high-speed electrical signals, and the EAM element 20. A DC power source 18 and an electrical resistor 16 that connects the DC power source 18 and the EAM element 20 are provided. The EAM element 20 is supplied with an electric pulse signal from an electric pulse signal supply device 22 via an electric cable 24 and an electric connector 26. The electrical connector 26 and the electrical cable 24 are designed for high-speed electrical signals. For example, the electrical cable 24 is a coaxial cable, and the electrical connector 26 is a V connector or the like.
[0044]
The EAM element 20 is a semiconductor element and includes an optical waveguide. The light propagating through the optical waveguide may or may not be guided depending on the voltage applied to the EAM element 20. That is, the optical pulse train propagating through the optical waveguide is modulated into an optical pulse signal by the electric pulse signal supplied to the EAM element 20 from the electric pulse signal supply device 22. The voltage applied to the EAM element 20 is supplied from the electric pulse signal supply device 22 via the DC power source 18 for applying a bias voltage, the electric cable 24 and the electric connector 26. Among these, the electric pulse signal supply device for supplying an electric pulse signal to modulate the optical pulse train and the EAM element are disconnected by a capacitor (not shown) in a direct current.
[0045]
The EAM module shown in FIG. 1 includes windows 28a and 28b that transmit light to the housing 10 of the EAM module. For example, when the optical pulse train 14a is incident from the right side of FIG. The light is condensed by a lens 12a and incident on an optical waveguide (not shown) of the element 20. The optical pulse train guided through the optical waveguide of the EAM element 20 is modulated to become an optical pulse signal, which is emitted from the optical waveguide of the EAM element 20 and is converted into an optical pulse signal 14b via the lens 12b. The light exits from the window 28b.
[0046]
The lens 12b emits light from the optical waveguide of the EAM element 20 so that the optical pulse signal 14b can be condensed so as to maximize the light intensity at a desired position with respect to the optical element incident after exiting the EAM module. It works to adjust the equiphase wavefront of the incident light (light pulse signal).
[0047]
<First Embodiment>
With reference to FIG. 2, the structure of the optical element integrated module which is the 1st Embodiment of this invention and the function of each part are demonstrated. The optical element integrated module of the present invention includes an EAM module and a lens in its housing 30 (also referred to as the optical element integrated module 30 when referring to the optical element integrated module itself of the first embodiment). , A reflector (mirror), a multiplexer / demultiplexer (half mirror) and the like are arranged. The EAM module is used as a first optical modulator and a second optical modulator.
[0048]
The incident side of the optical element integrated module 30 of the present invention is configured to include an optical fiber terminal 32a, and the optical pulse train 33 incident through the optical fiber terminal 32a is incident on the duplexer 34. As will be described later, the optical fiber terminal 32a has a structure in which the tip of the optical fiber is fixed, and also has a built-in lens, and the light of the EAM element that constitutes an EAM module described later by this lens. At the incident end of the waveguide, the lens position is adjusted so as to form a real image of the tip of the optical fiber.
[0049]
The optical pulse train 33 incident on the demultiplexer 34 is demultiplexed by the demultiplexer 34 into optical pulse trains 35a and 35b. The optical pulse train 35a exits the demultiplexer 34, enters the EAM module 40a, which is the first optical modulator, and is modulated to become an optical pulse signal 41, which is reflected by the first reflector 38a and incident on the multiplexer 36. To do. In the embodiments described below, a mirror is used as a reflector and a half mirror is used as a multiplexer. Here, a path starting from the demultiplexer 34, passing through the EAM module 40a, reflected by the first reflector 38a, and reaching the multiplexer 36 is referred to as a first optical path.
[0050]
On the other hand, the optical pulse train 35b exits from the demultiplexer 34, is reflected by the second reflector 38b, enters the EAM module 40b, which is an optical modulator, is modulated there to become an optical pulse signal 43, and a delay fine adjuster. It passes through 48 and reaches the multiplexer 36. Here, a path starting from the duplexer 34, reflected by the second reflector 38b, passing through the EAM module 40b and the delay fine adjuster 48, and reaching the multiplexer 36 is referred to as a second optical path.
[0051]
The delay fine adjuster 48 plays a role of adding an optical path length to the second optical path so that a time delay corresponding to half the pulse interval of the optical pulse signal is generated in the optical pulse signal incident on the delay fine adjuster 48. . As a result, the difference between the optical path length from the EAM module 40a that is the first optical modulator to the multiplexer 36 and the optical path length from the EAM module 40b that is the second optical modulator to the multiplexer 36 is the demultiplexer. 34 is equal to the optical path difference that causes a time difference corresponding to half of the pulse interval of the optical pulse train incident on 34. That is, the delay fine adjuster 48 adds an optical path length corresponding to an optical path difference that causes a time difference corresponding to half the pulse interval of the optical pulse train incident on the duplexer 34 to the second optical path.
[0052]
Here, the straight line connecting the center positions of the light bundles, which is the propagation mode (propagation form) of the optical pulse train or optical pulse signal, is called the optical pulse train or the propagation axis of the optical pulse signal. Further, the distance from the demultiplexer 34 to the optical modulator 40a or 40b refers to the optical modulator 40a from the intersection of the optical pulse train or the propagation axis of the optical pulse signal and the demultiplexing surface for demultiplexing the light from the demultiplexer 34. Or it shall mean the optical path length to the entrance end surface (not shown) of the optical waveguide of 40b. The distance from the optical modulator 40a or 40b to the multiplexer 36 refers to the optical pulse train or propagation axis of the optical pulse signal from the emission end face (not shown) of the optical waveguide of the optical modulator 40a or 40b and the multiplexer. It means the optical path length to the intersection with the multiplexing surface that multiplexes 36 lights.
[0053]
The delay fine adjuster 48, for example, combines two parallel flat glasses and tilts the two parallel flat glasses with respect to the propagation axis of the optical pulse train, so that the light flux of the optical pulse train is changed to the two parallel flat glasses. The distance passing through the glass can be adjusted. When a light beam is incident perpendicular to the propagation axis, the distance passing through these parallel flat glasses is the thickness of the parallel flat glass itself. If the normal of the plane of the parallel flat glass is tilted by the angle θ with respect to the propagation axis, the distance that the light beam passes through the parallel flat glass is (1 / cos θ) times the thickness of the parallel flat glass. The distance by which the light beam passes through the parallel flat glass can be increased as the angle is inclined. In this way, the optical path length added to the second optical path can be adjusted.
[0054]
The reason for configuring the delay fine adjuster 48 by combining two parallel flat glasses is to insert the single parallel flat glass into the second optical path and adjust the optical path length by using the parallel flat glass. This is to avoid a situation in which the propagation axis of the optical pulse signal shifts in parallel when tilted. That is, by combining two parallel flat glasses, the normal of one parallel flat glass is inclined by an angle + θ with respect to the propagation axis, and the normal of the other parallel flat glass is only by an angle −θ with respect to the propagation axis. By tilting, it is possible to avoid a situation in which the propagation axis of the optical pulse signal is shifted in parallel.
[0055]
In order to demultiplex the optical pulse train 33 incident on the demultiplexer 34 into the optical pulse trains 35a and 35b by the demultiplexer 34 and to modulate the EAM module 40a to obtain the optical pulse signal 41, the propagation mode of the optical pulse train Must be incident on the optical waveguide of the EAM element constituting the EAM module 40a. For this purpose, it is necessary to form the real image of the end of the optical fiber fixed to the optical fiber terminal 32a on the incident end of the optical waveguide of the EAM element constituting the EAM module 40a. For this purpose, an imaging system using a lens must be installed between the end of the optical fiber fixed to the optical fiber terminal 32a and the incident end of the optical waveguide of the EAM element.
[0056]
With reference to FIGS. 3A and 3B, a description will be given of an imaging system using a lens installed between the optical fiber end and the incident end of the optical waveguide of the EAM element.
[0057]
The optical fiber terminals 52a and 52b fix the optical fibers 50a and 50b and incorporate lenses 58a and 58b. On the other hand, the EAM modules 54a and 54b include EAM elements 62a and 62b and lenses 60a and 60b. 3A and 3B, the EAM elements 62a and 62b are connected by a lens installed between the optical fiber ends 56a and 56b and the incident ends 64a and 64b of the optical waveguides 66a and 66b of the EAM element. The portions other than those necessary for the description of the image system are omitted. The lenses 60a and 60b correspond to the lens 12a in the EAM module shown in FIG.
[0058]
In FIG. 3A, the lens 58a is arranged so that the light emitted from the optical fiber end 56a becomes a parallel light bundle as a Gaussian beam in which the light emitted from the optical fiber end 56a is characteristic in optical fiber communication. It is a depiction of the case. However, as a result of the inventor's study on the process of manufacturing the optical element integrated module according to the present invention, the light emitted from the optical fiber end 56a is a Gaussian beam, and the optical fiber end and the incident end of the optical waveguide of the EAM element are It has been found that a favorable result cannot be obtained even if the lens system installed between them is formed as a so-called collimator optical system.
[0059]
That is, when the lenses 58a and 60a are arranged as collimator lenses, as shown in FIG. 3A, most of the energy of the emitted light from the optical fiber end 56a is input to the incident end 64a of the optical waveguide 66a of the EAM element 62a. It has been found that the light does not reach the optical waveguide 66a. When the position of the optical fiber end 56a is set to be the front focal position of the lens 58a, the emitted light from the optical fiber end 56a could not be a parallel light flux as shown in FIG. . This indicates that in forming the optical element integrated module of the present invention, it cannot be ignored that the light emitted from the optical fiber end 56a is not a point light source but a Gaussian beam.
[0060]
Therefore, it means that the lens system installed between the end of the optical fiber and the incident end of the optical waveguide of the EAM element must be formed as an imaging system, not as a so-called collimator optical system. Yes.
[0061]
In general, the core system of the optical fiber used for optical fiber communication and the waveguide end face of the optical modulator have the same size. Therefore, in the design of the optical element integrated module used for optical fiber communication, the optical fiber described above is used. The technical problem that the lens system installed between the end and the incident end (or exit end) of the optical waveguide of the light modulation element has to be formed as an imaging system is common.
[0062]
With reference to FIG. 3B, an imaging system installed between the optical fiber end and the incident end of the optical waveguide of the EAM element will be described. This imaging system is constituted by lenses 58b and 60b. The lens 58b is built in the optical fiber terminal 52b. On the other hand, the lens 60b is built in the EAM module 54b. The imaging system constituted by the lenses 58b and 60b has a function of forming a beam waist (neck of the light bundle) at the center position (L / 2) between the lenses. Speaking of this as a point light source, it can be said to be an imaging system that focuses on the center position (L / 2) between the lenses.
[0063]
Therefore, if the distance L between the lens 58b and the lens 60b is determined in advance, the distance between the lens 58b and the fiber end 56b and the distance between the lens 60b and the waveguide end 64b of the EAM are uniquely determined. Further, by making the aperture ratio of the optical waveguide 66b of the optical fiber 50b and the EAM element 62b equal to the aperture ratio of the lenses 58b and 60b, the energy of the light emitted from the optical fiber end 56b is most efficiently increased. This is a condition for entering the optical waveguide 66b. The focal lengths of the lenses 58b and 60b are determined in consideration of conditions for configuring the optical fiber terminal 52b and the EAM module 54b to be the most compact in addition to the above-described conditions regarding the aperture ratio.
[0064]
The circumstances regarding the distance L between the lens 58b and the lens 60b related to the imaging system installed between the optical fiber terminal 32a and the incident ends of the optical waveguides of the EAM modules 40a and 40b described above are as follows. The same applies to the imaging system installed between the exit ends of the optical waveguides 40a and 40b and the optical fiber terminal 32b.
[0065]
For example, the duplexer 34 and the second reflector 38b are inserted between the optical fiber terminal 32a and the EAM module 40b, which is the second optical modulator. In this case, the lens 58b and the lens 60b are inserted. Is the optical path length from the position of the lens built in the optical fiber terminal to the demultiplexer, the optical path length from the demultiplexer to the second reflector, and built in the EAM module from the second reflector Obviously, it means the sum of the optical path lengths up to the lens position.
[0066]
Similarly, the first reflector 38a and the multiplexer 36 are also inserted between the EAM module 40a that is the first optical modulator and the optical fiber terminal 32b. From the position of the lens on the output end side of the optical waveguide of the EAM element of the EAM module 40a which is a modulator, the position of the lens incorporated in the optical fiber terminal 32b is reached via the first reflector 38a and the multiplexer 36. It is clear that the optical path length up to is the inter-lens distance L.
[0067]
As described above, the optical element integrated module 30 which is the clock frequency doubling device of the present invention has the lens system installed between the optical fiber end and the incident end of the optical waveguide of the EAM element, or the light of the EAM element. Since the lens system installed between the exit end of the waveguide and the end of the optical fiber must be formed by an imaging system, the distance between the end of the optical fiber and the entrance end of the optical waveguide of the EAM element, or the EAM element If the distance between the exit end of the optical waveguide and the end of the optical fiber is constant, the alignment operation for determining the lens position can be performed with the same optical system.
[0068]
That is, as a lens system installed between the optical fiber end and the incident end of the optical waveguide of the EAM element, or a lens system installed between the output end of the optical waveguide of the EAM element and the optical fiber end, a collimator system is used. Cannot be used. Accordingly, in configuring the optical element integrated module 30 according to the present invention, it is important that the distance L between the lenses of the lens system in the module 30 is equal. It can be said that it is small.
[0069]
Therefore, the path starting from the demultiplexer 34, passing through the EAM module 40a, reflected by the first reflector 38a and reaching the multiplexer 36 is defined as the first optical path, and starting from the demultiplexer 34, the second When a path that is reflected by the reflector 38b, passes through the EAM module 40b and the delay fine adjuster 48, and reaches the multiplexer 36 is a second optical path, the optical path length of the first optical path is equal to the optical path length of the second optical path. It is necessary to make it. Further, it is necessary to make the optical path length from the demultiplexer 34 to the first or second optical modulator equal to the optical path length from the first or second optical modulator to the multiplexer 36. In other words, it is necessary to arrange optical elements such as a multiplexer, a duplexer, and an EAM module symmetrically.
[0070]
The lens constituting the lens system installed between the optical fiber end and the incident end of the optical waveguide of the EAM element or the lens system installed between the exit end of the optical waveguide of the EAM element and the optical fiber end Aspherical lenses are used to increase performance. The aspherical lens used for optical fiber communication is almost determined for each application. However, if the optical path lengths to be imaged are different, it is necessary to set an alignment system for determining the position of the aspherical lens according to the optical path length, which requires a lot of man-hours.
[0071]
Therefore, the optical element integrated module 30 that can be configured by arranging optical elements such as a multiplexer, a demultiplexer, and an EAM module symmetrically can share the specifications of the constituent optical elements. In addition, the mass production can be performed at a low cost by making the alignment process common.
[0072]
Here, in order to explain that the optical element integrated module 30 of the present invention is a module that has a function of optically MUXing information of two channels and realizes double the clock frequency, an optical pulse train having a clock frequency of 20 GHz is used. A case where the light is incident on the optical element integrated module 30 is assumed. It should be noted that the contents of the description given below are not limited to the case where an optical pulse train having a clock frequency of 20 GHz is incident on the optical element integrated module 30, and it is obvious that the contents are applicable to an optical pulse train having any clock frequency.
[0073]
Hereinafter, an optical pulse train having a clock frequency of 20 GHz may be simply referred to as a 20 GHz optical pulse train. An optical pulse train with a clock frequency of 20 GHz has the potential to send information at a transmission rate of 20 Gb / s, and may be an optical pulse train with a bit rate of 20 Gb / s.
[0074]
The optical pulse train of 20 GHz that has entered the optical element integrated module 30 from the optical fiber terminal 32a is divided by the demultiplexer 34 to become optical pulse trains 35a and 35b, respectively.
[0075]
The optical pulse train 35a is incident on the EAM module 40a that is the first optical modulator. The EAM module 40a is supplied with data to be transmitted as the first channel from the electric pulse signal supply device 42a through the electric cable 44a and the V connector 46a as a binary digital electric signal. The optical pulse train 35a incident on the EAM module 40a is transmitted as a first channel reflected in the binary digital electrical signal by the binary digital electrical signal supplied from the electrical pulse signal supply device 42a to the EAM module 40a. Are modulated and output to an optical pulse signal 41 corresponding to. The optical pulse signal 41 enters the multiplexer 36 via the first reflector 38a.
[0076]
On the other hand, it enters the EAM module 40b, which is the second modulator, via the optical pulse train 35b and the second reflector 38b. The EAM module 40b is supplied with data to be transmitted as a second channel as a binary digital electric signal from the electric pulse signal supply device 42b through the electric cable 44b and the V connector 46b. The optical pulse train 35b incident on the EAM module 40b is converted into data to be transmitted as a second channel reflected in the binary digital electric signal by the binary digital electric signal supplied from the electric pulse signal supply device 42b to the EAM module 40b. The light is modulated to the corresponding optical pulse signal 43 and enters the delay fine adjuster 48. The optical pulse signal 43 becomes an optical pulse signal 45 to which an optical path difference equal to an optical path difference causing a time difference corresponding to half the pulse interval of the optical pulse train 33 is added in the delay fine adjuster 48, and is supplied to the multiplexer 36. Incident.
[0077]
In FIG. 2, V connectors 46a and 46b are connected to EAM modules 40a and 40b, respectively, in a direction parallel to the paper surface of FIG. That is, the V connectors 46a and 46b are connected in a direction parallel to a plane including the optical path of this module (the propagation axis of the optical pulse train). However, in FIG. 2, the V connectors 46a and 46b are in the positions drawn by broken-line circles with respect to the EAM modules 40a and 40b, respectively, with respect to the plane including the optical path of this module (the propagation axis of the optical pulse train). You may connect in the vertical direction. Rather, it may be preferable to connect the V connector in a direction perpendicular to a plane including the optical path (propagation axis of the optical pulse train) of this module, as will be described later.
[0078]
In the delay fine adjuster 48, the optical path difference added to the optical pulse signal 43 is as follows. The pulse width of the optical pulse train 33 is sufficiently narrow as a pulse width required to generate a 40 Gb / s optical pulse signal. For example, the full width at half maximum is about 12 ps. The time difference corresponding to half of the pulse interval of the optical pulse train 33 is 25 ps because the clock frequency of the optical pulse train 33 is 20 GHz. The distance traveled by light during 25 ps is about 7.5 mm. Therefore, the optical path length added by inserting the delay fine adjuster 48 in the path from the second optical modulator 40b to the multiplexer 36, that is, the optical path difference added to the optical pulse signal 43 is about 7.5 mm. is there.
[0079]
The optical pulse signal 41 that reaches the multiplexer 36 from the first optical path and the optical pulse signal 45 that reaches the multiplexer 36 from the second optical path are superposed in the multiplexer 36. With respect to the optical pulse signal 41, the optical pulse signal 45 is provided with a time delay corresponding to half of the pulse interval of the 20 Gb / s optical pulse train by the delay fine adjuster 48. The optical pulse signal 41 and the optical pulse signal 45 are superposed in the multiplexer 36 so that one optical pulse of the optical pulse signal 45 can exist just in the middle of the adjacent optical pulses.
[0080]
As apparent from the above description, the clock frequency of the optical pulse signal 37 obtained by superimposing the optical pulse signal 41 and the optical pulse signal 45 is 40 GHz. That is, it can be seen that the optical element integrated module 30 shown in FIG. 2 is a module that has a function of optically MUXing information of two channels and that doubles the clock frequency.
[0081]
<Second Embodiment>
The configuration of the optical element integrated module according to the second embodiment of the present invention and the function of each part will be described. The optical element integrated module according to the second embodiment is a module that has a function of optically MUXing N-channel information and realizes N-times multiplication of the clock frequency. Where N = 2 ⁿ Where n is a natural number of 2 or more.
[0082]
In general, in order to construct an optical element integrated module that realizes multiplication by 8 corresponding to the case where n = 3 and N = 8, two optical element integrated modules that realize quadruple multiplication can be used. That is, 2 ⁿ To configure an optical element integrated module that realizes (= N) multiplication, 2 ^n-1 It can be configured by using two optical element integrated modules that realize (= N / 2) multiplication. Therefore, if a method for constructing an optical element integrated module that realizes quadruple multiplication is established, the same method can be used. ^n-1 (= N / 2) Two optical element integrated modules that realize multiplication are used, and 2 ⁿ An optical element integrated module that realizes (= N) multiplication can be configured.
[0083]
In other words, the optical element integrated module according to the second embodiment of the present invention is a congruent 2 ^n-1 Constructed using two optical element integrated modules that realize multiplication 2 ⁿ Since this is a multiplication optical element integrated module, ⁿ It can be said that the multiplication optical element integrated module is a module excellent in symmetry. Therefore, there are advantages that the specifications of optical elements used as parts can be unified and that the alignment process in manufacturing can be made common.
[0084]
Moreover, the optical element integrated module which is 2nd Embodiment comprises the optical element integrated module which is 1st Embodiment mentioned above, for example, an optical fiber terminal, a multiplexer, a splitter, and optical modulation A module and a common optical element are used. Even if there are differences related to design matters such as the focal length of the lens built into the optical fiber terminal, the basic configuration is the same. Omitted.
[0085]
With reference to FIG. 4, a description will be given of an optical element integrated module that has a function of optically MUXing information on four channels and realizes quadruple multiplication of a clock frequency. That is, it is an optical element integrated module corresponding to the case where n = 2 and N = 4. In the case where N = 4 (n = 2), that is, when a module that realizes four times the clock frequency having the function of optically MUXing information on four channels can be realized, n is 3 or more. That is, 2 ⁿ (= N) 2 of the clock frequency having the function of optically MUXing channel information ⁿ (= N) The optical element integrated module realizing the multiplication is 2 ^n-1 (= N / 2) Two optical element integrated modules that achieve multiplication can be used in the same manner.
[0086]
The optical element integrated module that realizes quadruple multiplication of the clock frequency according to the second embodiment of the present invention is the case 100 (the optical element integrated module even when referring to the optical element integrated module itself of the second embodiment). The optical fiber terminal 102 for receiving the optical pulse train and the optical fiber terminal 154 for outputting the optical pulse signal in which the information on the four channels is optically MUXed are configured. . Further, it is configured to include an EAM module that is an optical modulator, a duplexer, a multiplexer, and a delay fine adjuster.
[0087]
First, it is assumed that the optical element integrated module according to the second embodiment is an optical element integrated module that realizes quadruple clock frequency, which is configured by using two optical element integrated modules that realize double multiplication. explain.
[0088]
The optical element integrated module 180 that realizes the first double is the optical pulse train 111a that propagates the optical pulse train 105a demultiplexed by the fourth demultiplexer 104 through the 21st optical path and the optical pulse train 111b that propagates through the 22nd optical path. A second demultiplexer 110a for demultiplexing into the second optical path, a second multiplexer 110b for multiplexing the optical pulse trains 131a and 131b propagated through the 21st optical path and the 22nd optical path, respectively, and the 21st optical path in the 21st optical path. An optical modulator 130a is provided, and a 22nd optical modulator 130b and a second delay fine adjuster 150 are provided in the 22nd optical path.
[0089]
Further, second reflectors 120a and 120b constituted by mirrors are inserted in the 21st optical path and the 22nd optical path. The second reflector 120a is inserted to change the optical path of the optical pulse signal 131a output from the twenty-first optical modulator 130a in the direction toward the second multiplexer 110b. On the other hand, the second reflector 120b is inserted to change the optical path of the optical pulse signal 111b reflected from the second demultiplexer 110a in the direction toward the twenty-second optical modulator 130b.
[0090]
Here, the reason why the demultiplexer 104 is fourth is to clearly indicate that the demultiplexer is used in an optical element integrated module that realizes quadruple multiplication. The numbers 21 and 22 expressed as the 21st optical path and the 22nd optical path, and the meanings of the 21st and 22nd numerals 21 and 22 in the optical modulator 130a and the optical modulator 130b, respectively, 2 means an optical path or an optical element in the optical element integrated module realizing double multiplication, and 1 and 2 at the first place are codes for identifying two existing optical paths or optical elements.
[0091]
Similarly, the fact that each of the duplexer 110a and the duplexer 110b is set as the second clearly indicates that these are the duplexers and duplexers used in the optical element integrated module that realizes the multiplication by two. Because. That is, when a two-digit numerical value such as the NM is added as the identification number, N in the tenth place means N multiplication, and M in the first place is used for identification within the same optical element integrated module. It means that it is attached for the purpose. Further, when a one-digit numerical value such as Nth is attached as the identification number, N means N multiplication. In the following explanation, this principle will be followed.
[0092]
As described above, the first optical element integrated module 180 that realizes double multiplication has the same configuration as the optical element integrated module that realizes double multiplication according to the first embodiment. Therefore, as already described, the optical element integrated module 180 has the same function as the optical element integrated module that realizes the double multiplication according to the first embodiment, that is, doubles the clock pulse of the optical pulse signal. .
[0093]
In addition, for example, the first optical element integrated module 180 that realizes the multiplication by two is connected to the second demultiplexer 110a, the second multiplexer 110b, the twenty-first optical modulator 130a, the twenty-second optical modulator 130b, and the second. The delay fine adjuster 150 is configured, the second delay fine adjuster 150 and the 21st optical modulator 130a are inserted in the 21st optical path, and the 22nd optical modulator 130b is inserted in the 22nd optical path, The configuration of the above-described optical element integrated module 180 may be modified. The reason why this type of configuration is allowed to be modified is the same reason as described when the configuration and function of the optical element integrated module realizing double multiplication are described.
[0094]
Further, by inserting the second delay fine adjuster 150 in the 21st optical path or the 22nd optical path, the geometric symmetry regarding the arrangement of the optical elements constituting the optical element integrated module that realizes the first double is lost. It is possible to conclude that this is not the case as in the case of the optical element integrated module that realizes the double multiplication according to the first embodiment. In general, the present invention is not limited to the case where the second delay fine adjuster 150 is inserted into the 21st optical path or the 22nd optical path, but the geometrical arrangement relating to the arrangement of the optical elements constituting the optical element integrated module by inserting the delay fine adjuster into the optical path. Symmetry is not compromised.
[0095]
Since it is clear that the above-described modified embodiment is similarly established in the second optical element integrated module 190 that realizes the second multiplication described below, the description thereof will not be repeated.
[0096]
The optical element integrated module 190 that realizes the second multiplication is an optical pulse train 115a that propagates the optical pulse train 105b demultiplexed by the fourth demultiplexer 104 through the 21st optical path and an optical pulse train 115b that propagates through the 22nd optical path. A second demultiplexer 114a for demultiplexing into the first optical path, a second multiplexer 114b for multiplexing the optical pulse trains 141a and 141b propagated through the 21st optical path and the 22nd optical path, respectively, and the 21st optical path in the 21st optical path. An optical modulator 140a is provided, and a 22nd optical modulator 140b and a second delay fine adjuster 160 are provided in the 22nd optical path.
[0097]
Further, second reflectors 124a and 124b constituted by mirrors are inserted in the 21st optical path and the 22nd optical path. The second reflector 124a is inserted to change the optical path of the optical pulse signal 141a output from the twenty-first optical modulator 140a in the direction toward the second multiplexer 114b. On the other hand, the second reflector 124b is inserted to change the optical path of the optical pulse signal 115b transmitted through the second demultiplexer 114a in the direction toward the twenty-second optical modulator 140b.
[0098]
As described above, the optical device integrated module 100 that has the function of optically MUXing information of four channels and that realizes quadruple clock frequency is the first doubler that realizes the first doubler. The device integrated module 180 and the second optical doubler are configured using an optical device integrated module 190 that realizes the second multiplication.
[0099]
The optical pulse train 103 incident on the optical device integrated module 100 through the optical fiber terminal 102 is divided into optical pulse trains 105a and 105b by the fourth demultiplexer 104, and an optical device integrated module 180 that realizes double multiplication, respectively. It is supplied to the optical element integrated module 190 that realizes double multiplication.
[0100]
The optical pulse train 105a is supplied to the optical element integrated module 180 that realizes the first double multiplication, and is an optical pulse signal obtained by combining the optical pulse signal of the first channel and the optical pulse signal of the second channel. The optical pulse signal is output from the optical element integrated module 180 and supplied to the fourth multiplexer 106 via the fourth reflector 108. Here, a path from the fourth demultiplexer 104 to the fourth multiplexer 106 via the optical element integrated module 180 is referred to as a 41st optical path.
[0101]
On the other hand, the optical pulse train 105b is supplied to the optical element integrated module 190 that realizes the second double, and the optical pulse signal multiplied by 2 is obtained by combining the optical pulse signal of the third channel and the optical pulse signal of the fourth channel. A signal is output from the optical element integrated module 190 and supplied to the fourth multiplexer 106 via the fourth delay fine adjuster 170. Here, a path from the fourth demultiplexer 104 to the fourth multiplexer 106 via the optical element integrated module 190 is referred to as a forty-second optical path.
[0102]
In the optical device integrated module 180 as the first doubler, the 21st optical modulator 130a generates the optical pulse signal 131a as the first channel, and the 22nd optical modulator 130b generates the optical pulse signal 131b as the second channel. Is generated. The optical pulse signal 131a of the first channel and the optical pulse signal of the second channel are combined by the second multiplexer 110b, and the optical pulse signals of the first channel and the second channel are optically MUXed and doubled. It is output as a pulse signal 111.
[0103]
On the other hand, in the optical device integrated module 190 as the second doubler, the 21st optical modulator 140a generates the optical pulse signal 141a as the third channel, and the 22nd optical modulator 140b generates the optical pulse as the fourth channel. A signal 141b is generated. The optical pulse signal 141a of the third channel and the optical pulse signal of the fourth channel are combined by the second multiplexer 114b, and the optical pulse signals of the third channel and the fourth channel are optically MUXed and doubled. It is output as a pulse signal 115.
[0104]
The optical pulse signal 115 is added with an optical path length corresponding to an optical path difference that causes a time difference corresponding to ¼ of the pulse interval of the optical pulse train 103 incident on the fourth demultiplexer 104 by the fourth delay fine adjuster 170. Is output as the optical pulse signal 171 and enters the fourth multiplexer 106.
[0105]
The optical pulse signal 171 is added by the fourth delay fine adjuster 170 with an optical path length corresponding to an optical path difference that causes a time difference corresponding to ¼ of the pulse interval of the optical pulse train 103 incident on the fourth demultiplexer 104. Therefore, when the optical pulse signal 111 and the optical pulse signal 171 are combined, one of the optical pulses of the optical pulse signal 171 is inserted just between the positions of adjacent optical pulses of the optical pulse signal 111 on the time axis. Is done.
[0106]
Therefore, in the fourth multiplexer 106, the optical pulse signals 111 of the first channel and the second channel are optically muxed and doubled, and the optical pulse signals of the third channel and the fourth channel are optical signals. The optical pulse signal 171 that has been MUXed and multiplied by 2 is combined, and the optical pulse signals of the first to fourth channels are output as optical pulse signal 107 that has been optically muxed and multiplied by 4 and passed through the optical fiber terminal 154. Output to the outside.
[0107]
With such a configuration, when a quadruple multiplier is configured, it can be configured by combining two doublers. Therefore, if a doubler can be configured, a quadrupler can be configured by combining the doubler as a basic component. That is, it is possible to provide an optical element integrated module for quadruple that can easily perform quadruple while maintaining the technical idea for the configuration of the device that doubles the optical pulse signal.
[0108]
In general, with such a configuration, 2 ⁿ (= N) When configuring a multiplier, 2 ^n-1 (= N / 2) Two multipliers can be combined. Therefore, if a doubler can be configured, by combining the doubler as a basic component, no matter how many n, ⁿ (= N) A multiplier can be configured. That is, while maintaining the technical idea for the configuration of the device that doubles the optical pulse signal, it is ⁿ An optical element integrated module for multiplication can be provided.
[0109]
Here, in the optical element integrated module 100 that realizes the above-described quadruple multiplication, the following configuration is preferable. That is, a fourth delay fine adjuster 170 is inserted between the second doubler 190 and the fourth multiplexer 106, and the optical path length from the fourth duplexer 104 to the first doubler 180 is The optical path length from the fourth demultiplexer 104 to the second doubler 190 and the optical path length from the first doubler 180 to the fourth multiplexer 106 are configured to be equal. On the other hand, the difference between the optical path length from the first doubler 180 to the fourth multiplexer 106 and the optical path length from the second doubler 190 to the fourth multiplexer 106 becomes the fourth demultiplexer 104. The optical path difference is equal to the optical path difference that causes a time difference corresponding to ¼ of the pulse interval of the incident optical pulse train.
[0110]
Here, the optical path length from the fourth demultiplexer 104 to the first doubler 180 is the intersection of the propagation axis of the optical pulse train and the demultiplexing surface that demultiplexes the light from the fourth demultiplexer 104. It means the optical path length to the intersection of the propagation axis of the optical pulse train and the demultiplexing surface for demultiplexing the light from the second demultiplexer 110a.
[0111]
The optical path length from the fourth demultiplexer 104 to the second doubler 190 is the propagation of the optical pulse train from the intersection of the propagation axis of the optical pulse train and the demultiplexing surface that demultiplexes the light of the fourth demultiplexer 104. It shall mean the optical path length to the intersection of the axis and the demultiplexing surface that demultiplexes the light from the second demultiplexer 114a.
[0112]
The optical path length from the first doubler 180 to the fourth multiplexer 106 is the fourth reflection from the intersection of the propagation axis of the optical pulse signal and the multiplexing surface that combines the light of the second multiplexer 110b. It means the optical path length to the intersection of the propagation axis of the optical pulse signal and the multiplexing surface for multiplexing the light of the fourth multiplexer 106 via the optical device 108.
[0113]
The optical path length from the second doubler 190 to the fourth multiplexer 106 is the fourth delay from the intersection of the propagation axis of the optical pulse signal and the multiplexing surface that combines the light of the second multiplexer 114b. It means the optical path length to the intersection of the propagation axis of the optical pulse signal via the fine adjuster 170 and the multiplexing surface that combines the light of the fourth multiplexer 106.
[0114]
In general, the Nth delay fine adjuster is inserted between the second N / 2 multiplier and the Nth multiplexer, the optical path length from the Nth splitter to the first N / 2 multiplier, The optical path length from the N demultiplexer to the second N / 2 multiplier is configured to be equal to the optical path length from the first N / 2 multiplier to the Nth multiplexer.
[0115]
On the other hand, the difference between the optical path length from the first N / 2 multiplier to the Nth multiplexer and the optical path length from the second N / 2 multiplier to the Nth multiplexer is incident on the Nth duplexer. The optical pulse difference is equal to the optical path difference causing a time difference corresponding to 1 / N of the pulse interval of the optical pulse train.
[0116]
Further, the Nth delay fine adjuster is inserted between the second N / 2 multiplier and the Nth multiplexer, or inserted between the Nth duplexer and the second N / 2 multiplier. Whether to insert between the Nth demultiplexer and the first N / 2 multiplier or between the first N / 2 multiplier and the Nth multiplexer is a design matter. It is a matter that belongs to the range. Any configuration is essentially equivalent.
[0117]
By comprising in this way, an optical element can be arrange | positioned symmetrically. In other words, since optical elements such as lenses can be shared, parts can be mass-produced, and in the process of manufacturing this optical element integrated module, the alignment work of these optical elements can be shared, simplifying the process. There are advantages you can do.
[0118]
Next, with reference to FIGS. 5A and 5B, the arrangement of electrical connection terminals used for supplying an electrical signal to the optical modulator will be described. In FIG. 5A, an optical modulator 202a is disposed on a surface 204a of a substrate 200a on which an optical element is disposed, and the optical modulator 202a is used to supply an electric signal to the surface 204a of the substrate. This shows a case where the electrical connection terminal 210 is configured such that the axial direction 208a of the electrical connection terminal 210 is parallel. On the other hand, in FIG. 5B, the optical modulator 202b is disposed on the surface 204b of the substrate 200b on which the optical element is disposed, and an electric signal is supplied to the optical modulator 202b with respect to the surface 204b of the substrate. The case where the electrical connection terminal 212 used in the configuration is configured such that the axial direction 208b of the electrical connection terminal 212 is vertical is shown.
[0119]
The electrical connection terminal 210 and the electrical connection terminal 212 are provided to connect the electrical cables 206a and 206b to the optical modulator 202a and the optical modulator 202b, respectively.
[0120]
When the optical element integrated module 30 according to the first embodiment shown in FIG. 2 is configured, the electrical connection terminals used for supplying an electrical signal to the optical modulator are shown in FIGS. Any configuration shown in B) can be used. In FIG. 2, the case where the electrical connection terminals 46a and 46b connected to the light modulation elements 40a and 40b are configured so that the axial direction of the electrical connection terminals is parallel to the substrate surface on which the optical elements are arranged is illustrated. did. In FIG. 2, the electrical connection terminals 46a and 46b are connected to circular portions indicated by broken lines in the light modulation elements 40a and 40b, so that the electrical connection terminals 46a and 46b are connected to the substrate surface on which the optical elements are arranged. It has been shown that the axial direction of 46a and 46b can also be configured to be vertical.
[0121]
However, when the optical element integrated module 100 according to the second embodiment shown in FIG. 4 is configured, the electrical connection terminals used for supplying an electrical signal to the optical modulator are shown in FIG. As shown in the figure, it cannot be configured without using a configuration in which the axial direction of the electrical connection terminal is perpendicular to the surface of the substrate on which the optical element is arranged.
[0122]
As is clear from FIG. 4, since many optical elements are two-dimensionally arranged on the substrate on which the optical elements are arranged, the light modulation that constitutes a part of these optical elements. In order to arrange a cable for supplying an electric signal to the element, it must be arranged so as to cross a part of the optical path. That is, since a part of the optical path and a cable for supplying an electrical signal intersect, a part of the light beam propagating through the optical path is interrupted.
[0123]
Therefore, an optical element integrated module that realizes a high multiplication of four times or more of the clock frequency of the optical pulse signal has an electrical connection terminal with respect to the surface of the substrate on which the optical element is arranged as shown in FIG. It cannot be configured without using a configuration in which the axial direction of the is vertical.
[0124]
In general, when the number of optical elements arranged on a plane is large and the optical path connecting these optical elements is high density, an electric cable for supplying an electric signal to the active optical element among these optical elements is arranged. The axis direction of the electric connection terminal for connecting the electric cable for supplying the electric signal is shifted from the parallel direction with respect to the plane on which the optical element is arranged so that it is as close as possible to the vertical direction. It is preferable to configure.
[0125]
In general, an electric signal supplied to an optical active element such as an optical modulation element is an electric signal modulated at high speed. This electric signal is supplied via a capacitor for cutting the DC component, an electric element such as a coil for supplying the DC component to these optical active elements, an electric amplifier, and the like.
[0126]
Furthermore, if an electric circuit element that generates an electric signal to be supplied to the optical active element is arranged on the same substrate as the optical element is arranged, the electric circuit element is distorted when the electric circuit element is mounted on the board. May occur. Further, when an electric cable is directly connected to an optical active element arranged on the substrate from an electric circuit element arranged on the same substrate, distortion may occur in the electric signal input terminal of the optical active element. . For these reasons, the optical active element malfunctions, or the optical path is affected so that an optical pulse signal cannot be supplied to the optical active element.
[0127]
A method for solving the above-described problem will be described with reference to FIG. FIG. 6 shows an example of a module having a configuration in which an electric circuit element and an optical active element are connected by a flexible cable. FIG. 6 shows only the parts necessary for explaining the technical idea of connecting an electric circuit element and an optical active element with a flexible cable. The arrangement and the like are simplified.
[0128]
Optical elements are arranged on the optical element arrangement substrate 220, and among these optical elements, electrical connection terminals 230a, 230b, 230c, and 230d are formed on optical active elements that receive an electric signal. On the other hand, on the electric circuit element arrangement substrate 224, electric circuit elements 226a, 226b, 226c and 226d and electric circuit elements 228a, 228b, 228c and 228d are arranged. Here, the electric circuit elements 226a and 228a are connected, the electric circuit elements 226b and 228b are connected, the electric circuit elements 226c and 228c are connected, and the electric circuit elements 226d and 228d are connected to each other. The case where it is connected is shown. The connection between these electric circuit elements is not an essential problem, and it is important that many electric circuit elements are arranged on the same substrate at a high density.
[0129]
As described above, when there are a large number of electric circuit elements and they are connected at a high density and the total weight is large, when the electric circuit elements and the optical elements are arranged and connected on the same substrate, as described above, There is a failure that the device malfunctions or that the optical path is affected and the optical pulse signal cannot be supplied to the optical active device.
[0130]
Therefore, as shown in FIG. 6, using the flexible cables 234a, 234b, 234c and 234d, the electric circuit element 228a and the electric connection terminal 230a, the electric circuit element 228b and the electric connection terminal 230b, and the electric circuit element 228c and the electric circuit element 228c, respectively. The connection terminal 230c and the electric circuit element 228d are connected to the electric connection terminal 230d. With such a configuration, the flexible cables 234a, 234b, 234c, and 234d absorb the stress applied from the electric circuit element to the optical active element, and the strain applied to the optical active element can be reduced.
[0131]
The technical idea regarding the configuration of the optical element integrated module according to the first and second embodiments is that an optical element such as an EAM element, a reflector (mirror), a lens, a multiplexer or a duplexer (half mirror) is used. It is to arrange symmetrically. That is, with reference to an active element such as an EAM element, the distance of the passive element arranged with respect to the active element is equal to the active element, and each passive element is set with reference to a plurality of active elements having the same function. By arranging the passive elements so that the arrangement patterns with respect to the elements are congruent, symmetry is provided in the arrangement of the optical elements.
[0132]
Therefore, the technical idea of the present invention, which is the basis of the first and second embodiments, is not limited to the optical MUX module that realizes N multiplication. It is obvious that the present invention can also be applied to an optical DeMUX module that separates optical pulse signals of channels.
[0133]
In the embodiment of the present invention, an EAM element is used as an optical modulator. However, for example, LiNbO having a function of converting an electric pulse signal into an optical pulse signal. ₃ It is clear that even an optical modulator using the above can be used.
[0134]
In the embodiment of the present invention, the optical element integrated module is configured by a so-called spatial coupling method, which is configured by forming an optical path using a lens, a reflector, or the like. An optical element integrated module can be configured. Even when the optical path is composed of an optical fiber, if the doubler, which is a feature of the present invention, can be configured, the doubler can be combined as a basic component so that no matter how many n 2 ⁿ While maintaining the technical idea for the configuration of the device for multiplying the optical pulse signal by 2 that a multiplier can be configured, ⁿ Can be multiplied 2 ⁿ Needless to say, an optical element integrated module for multiplication can be provided.
[0135]
【The invention's effect】
As described above, according to the optical element integrated module of the present invention, 2 ⁿ (= N) When configuring a multiplier, 2 ^n-1 (= N / 2) Two multipliers can be combined. Therefore, if a doubler can be configured, by combining the doubler as a basic component, no matter how many n, ⁿ A multiplier can be configured. That is, while maintaining the technical idea for the configuration of the device that doubles the optical pulse signal, it is ⁿ (= N) can be multiplied 2 ⁿ There is a design advantage that an optical element integrated module for multiplication can be provided.
[0136]
Even when a device that performs multiplication of four or more times is configured, the configuration is not complicated. Further, with this configuration, the optical elements can be arranged symmetrically. In other words, since optical elements such as lenses can be shared, parts can be mass-produced, and in the process of manufacturing this optical element integrated module, the alignment work of these optical elements can be shared, simplifying the process. There are advantages you can do.
[Brief description of the drawings]
FIG. 1 is a schematic diagram of an EAM module.
FIG. 2 is a configuration diagram of an optical element integrated module according to the first embodiment.
FIGS. 3A and 3B are diagrams for explaining an image forming system using a lens installed between an optical fiber end and an incident end of an optical waveguide of an EAM element. FIGS.
FIG. 4 is a configuration diagram of an optical element integrated module according to a second embodiment.
FIGS. 5A and 5B are diagrams for explaining the arrangement of electrical connection terminals for supplying an electrical signal to the optical modulator. FIGS.
FIG. 6 is a diagram for explaining an example in which an electric circuit element and an optical active element are connected by a flexible cable.
[Explanation of symbols]
10: EAM module housing
12a, 12b: Lens
16: Electrical resistance
18: DC power supply
20: EAM element
22, 42a, 42b: Electric pulse signal supply device
26: Electrical connector
28a, 28b: windows
30, 100: Case of optical element integrated module
32a, 32b, 52a, 52b, 102, 154: optical fiber terminals
34: duplexer
36: Multiplexer
38a: first reflector
38b: second reflector
40a, 40b, 54a, 54b: EAM module
46a, 46b: V connector
48: Delay fine adjuster
50a, 50b: optical fiber
56a, 56b: optical fiber ends
58a, 58b, 60a, 60b :: Lens
62a, 62b: EAM element
64a, 64b: incident end of the optical waveguide of the EAM element
66a, 66b: Optical waveguide of EAM element
104: Fourth duplexer
106: Fourth multiplexer
108: Fourth reflector
110a, 114a: second duplexer
110b, 114b: second multiplexer
120a, 120b, 124a, 124b: second reflector
130a, 140a, 21st optical modulator
130b, 140b: 22nd optical modulator
150, 160: second delay fine adjuster
170: Fourth delay fine adjuster
180, 190: Optical element integrated module
200a, 200b: substrates on which optical elements are arranged
202a, 202b: optical modulator
206a, 206b: Electric cable
210, 212: Electrical connection terminals
220: Optical element placement substrate
224: Electric circuit element placement substrate
226a, 226b, 226c, 226d, 228a, 228b, 228c, 228d: electric circuit elements
230a, 230b, 230c, 230d: Electrical connection terminals
234a, 234b, 234c, 234d: Flexible cable

Claims (8)

A demultiplexer for demultiplexing the optical pulse train into an optical pulse train propagating through the first optical path and an optical pulse train propagating through the second optical path;
A multiplexer for multiplexing the optical pulse trains respectively propagated in the first optical path and the second optical path;
A first optical modulator provided in the first optical path;
An optical element integrated module comprising a second optical modulator and a delay fine adjuster respectively provided in the second optical path. The optical element integrated module according to claim 1,
An optical path length from the duplexer to the first optical modulator, an optical path length from the duplexer to the second optical modulator, and an optical path length from the first optical modulator to the multiplexer. And the difference between the optical path length from the first optical modulator to the multiplexer and the optical path length from the second optical modulator to the multiplexer is an optical pulse train incident on the duplexer. An optical element integrated module characterized by being equal to an optical path difference causing a time difference corresponding to half of a pulse interval. A demultiplexer for demultiplexing the optical pulse train into an optical pulse train propagating through the first optical path and an optical pulse train propagating through the second optical path;
A multiplexer for multiplexing the optical pulse trains respectively propagated in the first optical path and the second optical path;
A delay fine adjuster and a first optical modulator respectively provided in the first optical path;
An optical element integrated module comprising: a second optical modulator provided in the second optical path. In the optical element integrated module according to claim 3,
An optical path length from the duplexer to the second optical modulator, an optical path length from the first optical modulator to the multiplexer, and an optical path length from the second optical modulator to the multiplexer. And the difference between the optical path length from the duplexer to the first optical modulator and the optical path length from the duplexer to the second optical modulator is an optical pulse train incident on the duplexer. An optical element integrated module characterized by being equal to an optical path difference causing a time difference corresponding to half of a pulse interval. An Nth demultiplexer for demultiplexing the optical pulse train into an optical pulse train propagating through the N1 optical path and an optical pulse train propagating through the N2 optical path;
An Nth multiplexer for multiplexing optical pulse trains respectively propagated through the N1 optical path and the N2 optical path;
A first N / 2 multiplier provided in the N1 optical path;
An optical element integrated module comprising a second N / 2 multiplier and an Nth delay fine adjuster respectively provided in the N2 optical path.
Here, N = ²ⁿ , and n is a natural number of 2 or more. The optical element integrated module according to claim 5,
An optical path length from the Nth demultiplexer to the first N / 2 multiplier, an optical path length from the Nth demultiplexer to the second N / 2 multiplier, and the first N / The optical path length from the second multiplier to the Nth multiplexer is equal, and the optical path length from the first N / 2 multiplier to the Nth multiplexer and from the second N / 2 multiplier The difference from the optical path length to the Nth multiplexer is equal to the optical path difference that causes a time difference corresponding to 1 / N of the pulse interval of the optical pulse train incident on the Nth demultiplexer. Optical element integrated module.
Here, N = ²ⁿ , and n is a natural number of 2 or more. An Nth demultiplexer for demultiplexing the optical pulse train into an optical pulse train propagating through the N1 optical path and an optical pulse train propagating through the N2 optical path;
An Nth multiplexer for multiplexing optical pulse trains respectively propagated through the N1 optical path and the N2 optical path;
An Nth delay fine adjuster and a first N / 2 multiplier respectively provided in the N1 optical path;
An optical element integrated module comprising: a second N / 2 multiplier provided in the N2 optical path.
Here, N = ²ⁿ , and n is a natural number of 2 or more. The optical element integrated module according to claim 7,
An optical path length from the Nth demultiplexer to the second N / 2 multiplier, an optical path length from the first N / 2 multiplier to the Nth multiplexer, and the second N / The optical path length from the N doubler to the Nth multiplexer is equal, and the optical path length from the Nth demultiplexer to the first N / 2 multiplier is from the Nth demultiplexer to the second The difference between the optical path lengths between the N / 2 multipliers is equal to the optical path difference that causes a time difference corresponding to 1 / N of the pulse interval of the optical pulse train incident on the Nth demultiplexer. Optical element integrated module.
Here, N = ²ⁿ , and n is a natural number of 2 or more.

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