JP2007033853A - SOA array optical module - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an SOA (Semiconductor Optical Amplifier) array optical module which switches an optical signal, an SOA array being airtightly sealed and a normal lens array being made applicable. <P>SOLUTION: The SOA array optical module having the SOA array 1 constituted so that end surfaces on an optical signal input side and an optical signal output side tilt in a propagation direction of the optical switch respectively is equipped with lens arrays 3 and 2 of the optical signal input side and optical signal output side which are arranged on the end surfaces of the optical signal input side and optical signal output side of the SOA array 1 in parallel, and fiber arrays of the optical signal input side and optical signal output side arranged so that the arrays 3 and 2, and end surfaces of the optical signal input side and optical signal output side are parallel to each other. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an SOA array optical module in which an SOA (Semiconductor Optical Amplifier) array and an optical fiber array that enable high-speed switching of optical signals are optically coupled.

  Along with the increase in communication demand due to broadband services in recent years, the long distance and large capacity of optical communication networks have progressed, and the WDM (Wavelength Division Multiplex) method that enables high-speed and large-capacity data transmission. Development is underway. On the other hand, with the rapid spread of the Internet and an increase in large-capacity content, there is a demand for an optical communication network with higher speed, larger capacity, and flexibility. Optical packet switching technology has attracted attention as a technology for constructing such an optical communication network.

  Optical packet switching is a technology for exchanging packets of communication information as it is completely light. Compared with conventional switching that temporarily converts optical signals into electrical signals, there is no restriction on the electronic processing speed, and optical propagation delay time is reduced. High-speed and large-capacity transmission is possible because it can be processed. As described above, when an optical signal is switched on a packet basis, a gate switch is used to turn the optical signal on and off. There are two types of gate switches that turn on and off an optical signal by electrical control, one that changes absorption mainly by using the effect of electric field absorption, and another that changes gain by driving current to a semiconductor optical amplifier.

  Although the electroabsorption gate switch has a disadvantage that a loss is large even in a transmission state, a semiconductor optical amplifier (SOA: Semiconductor) that performs a switching operation by changing a gain for an input optical signal by a driving current to the semiconductor optical amplifier. Optical Amplifier) has not only a function as an optical gate for turning light ON and OFF, but also an amplification function. Therefore, it is currently attracting attention as an optical element that has a small optical signal loss and performs high-speed switching. .

  When this SOA is used as a gate switch, the extinction ratio of the gate ON (open) / OFF (close) is high, and the optical loss can be reduced by the amplification mechanism. Furthermore, since the optical element is formed of a semiconductor, the semiconductor integrated circuit technology has an advantage that it can be reduced in cost and reduced in size.

  3A and 3B show an outline of a conventional example of an optical coupling configuration between an SOA and an optical fiber that transmits an optical signal when such an SOA is used as an optical signal gate switch. . (A) of the figure shows a case where the SOA 11 and the fibers 14 and 15 are optically coupled via the lenses 12 and 13, and (B) of the figure shows the SOA 21 and the front lens fibers 24 and 25 that are optically coupled. Indicates the case of joining. The alternate long and short dash line indicates the propagation path of the optical signal.

  The SOA 11 needs to reduce the reflection of the chip end face to −50 dB or less and suppress unnecessary oscillation due to the return light. For this reason, if the chip end face is only provided with an AR (Anti Reflection) coat, it is about −30 dB. Therefore, as shown in the figure, the chip end surface is slanted so that the vertical line of the chip end surface and the optical waveguide in the chip have an angle relationship of, for example, 7 degrees. Depending on the relationship between the refractive index of the waveguide and the refractive index of the space, the optical signal is transmitted to the lens 12 or the front lens fiber as indicated by a one-dot chain line in a direction of 22.7 degrees, for example, with respect to the vertical line (dotted line) of the chip end face. The light is emitted in 24 directions. The lenses 12 and 13 in FIG. 3A are for optical coupling between the fibers 14 and 15 and the SOA 11, and the tips of the front lens fibers 24 and 25 in FIG. 3B are spherical. The lens 12 and 13 in FIG. 3A can be omitted.

In addition, a semiconductor optical amplifier and an external resonator using a fiber grating are combined, and the tip of the fiber grating is formed into a spherical shape so as to be optically coupled to the light emitting side on which the low reflection film of the semiconductor optical amplifier is formed. It is known to configure (see, for example, Patent Document 1). In addition, a silica-based lightwave circuit board in which an SOA array as a gate switch is made into a hybrid integrated circuit and a silica-based lightwave circuit board on which an arrayed waveguide grating is formed are coupled to switch an optical signal such as an optical cross-connect. Is also known (see, for example, Patent Document 2).
JP 2000-236138 A JP 2003-149614 A

  The SOAs 11 and 21 in the conventional example shown in FIGS. 3A and 3B have an array structure, and the optical coupling structure of the optical signal input and output fiber arrays with respect to the SOA array is as follows. This is shown in FIGS. 4A and 4B. The alternate long and short dash line indicates the propagation path of the optical signal. 4A shows a configuration in which the SOA array 41 and the lens arrays 42 and 43 are sealed in an airtight package 46 and optically coupled to the fiber arrays 44 and 45 through the airtight windows 47 and 48. FIG. Since the SOA array 41 has a configuration of a semiconductor integrated circuit, the SOA array 41 is sealed by an airtight package 46 so as to be isolated from the outside air.

  The SOA array 41 is formed by integrating a plurality of SOAs 11 shown in FIG. 3A, and has an optical signal input side and output side end face inclined as shown in the figure. Generally, the end surfaces of the fiber arrays 44 and 45, the airtight windows 47 and 48, and the lens arrays 42 and 43 are fixed in parallel by sealing with the airtight package 46. Therefore, the distances between the SOAs constituting the SOA array 41 and the lens arrays 42 and 43, that is, the distances for each channel are different. Therefore, in order to improve the optical coupling for each channel, the optical characteristics such as the focal length of each lens of the lens arrays 42 and 43 need to be different for each channel. Since each lens of the lens arrays 42 and 43 has a small diameter and needs to be arranged adjacent to each other, when the optical characteristics are different for each channel, the manufacture thereof is not easy. There is a problem that the lens arrays 42 and 43 are expensive.

  4B shows a case where the configuration shown in FIG. 3B is an array configuration, and the fiber arrays 64 and 65 each have a tip lens lens fiber and an optical signal input side of the SOA array 61. In addition, the optical coupling for each channel is facilitated compared to the case shown in FIG. 4A. However, the SOA array 61 is sealed in an airtight package as shown in FIG. 4A in order to arrange the front spherical lenses of the fiber arrays 64 and 65 close to the end face of the SOA array 61. Is impossible to do. Therefore, there is a problem that the reliability of the SOA array 61 cannot be ensured.

  The present invention solves the above-described problems, and aims to facilitate optical coupling between the SOA array and the fiber array and facilitate hermetic sealing.

  The SOA array optical module of the present invention is an SOA array optical module having a SOA array having a configuration in which the end faces of the optical signal input side and the optical signal output side are inclined with respect to the propagation direction of the optical signal. The optical signal input side and optical signal output side lens arrays arranged in parallel with the optical signal input side and optical signal output side end surfaces, respectively, and the optical signal input side and optical signal output side lens arrays and the end surfaces are parallel to each other. The optical signal input side and the optical signal output side fiber array are arranged as described above.

  Further, the SOA array can be hermetically sealed by an airtight package having airtight windows parallel to the optical signal input side and optical signal output side end faces of the SOA array.

  Further, a plurality of lens arrays can be arranged in parallel to the end surfaces of the SOA array on the optical signal input side and the optical signal output side, respectively.

  The surface perpendicular to the optical axis of each lens of the optical signal input side and optical signal output side lens array is arranged in parallel with the end surface of the SOA array on the optical signal input side and optical signal output side, respectively. can do.

  Since the optical coupling distances of the SOA array, the lens array, and the fiber array are the same for each channel, the lens array can be applied to a configuration that is already on the market, and the cost can be reduced. Further, the SOA array can be hermetically sealed by the hermetic package, and there is an advantage that the reliability of the SOA array can be ensured.

  Referring to FIG. 1, the SOA array optical module of the present invention is an SOA array optical module having a SOA array 1 having a configuration in which the end surfaces of the optical signal input side and the optical signal output side are inclined with respect to the propagation direction of the optical signal. The optical signal input side and optical signal output side lens arrays 3 and 2 arranged in parallel with the optical signal input side and optical signal output side end faces of the SOA array 1, and the optical signal input side and optical signal output, respectively. The side lens arrays 3 and 2 and the optical signal input side and optical signal output side fiber arrays arranged so that the end faces thereof are parallel to each other are provided.

  FIG. 1 is an explanatory diagram of the principle of the present invention, showing an SOA array 1, lens arrays 2 and 3 and a fiber array 4 constituting an SOA array optical module. Each SOA of the SOA array 1 has an optical signal ON, As the electrode configuration for applying the drive voltage for controlling OFF, a known configuration can be applied, and the illustration is omitted. If the fiber array 4 is on the optical signal output side, the fiber array on the optical signal input side is arranged on the lens array 3 side, but the fiber array on the optical signal input side is not shown. Further, the end face of the SOA array 1, the lens arrays 2 and 3, and the end face of the fiber array 4 which are inclined with respect to the optical signal propagation path indicated by the alternate long and short dash line are arranged in parallel.

  Further, an optical signal indicated by an alternate long and short dash line is input from each fiber of the fiber array on the optical signal input side to each lens of the lens array 3, and the fiber array 4 on the optical signal output side from each lens of the lens array 2. The end face angle with respect to the optical axis in each fiber is selected based on the refractive index of the core of each fiber so that the optical signal indicated by the alternate long and short dash line is input to each fiber end face. For example, when the refractive index n1 of the SOA array 1 is 3.17, the refractive index of air is n2 = 1.0, and the refractive index of the core of the fiber constituting the fiber array is n3 = 1.56, The inclination angle (the angle between the dotted line in the SOA array 1 perpendicular to the end surface of the SOA array 1 and the one-dot chain line) is 7 degrees, and the light emission angle of the SOA (the outer dotted line perpendicular to the end surface of the SOA array 1 and the one-dot chain line) The angle is 22.7 degrees, and the angle of inclination with respect to the end face of the fiber core (the angle between the dotted line perpendicular to the end face and the alternate long and short dash line in the core) is 14.3 degrees.

  Thereby, between the optical signal input side and optical signal output side end surfaces of each SOA of the SOA array 1 and the lenses of the lens arrays 2 and 3, and between the lenses of the lens arrays 2 and 3 and the fiber array 4, respectively. The distance between the fibers can be the same. That is, the optical coupling distance for each channel can be made the same. The surfaces perpendicular to the optical axes of the lenses of the lens arrays 2 and 3 on the optical signal input side and the optical signal output side can be arranged in parallel with the end surfaces on the optical signal input side and the optical signal output side of the SOA array 1, respectively. .

  Accordingly, since the lenses of the lens arrays 2 and 3 can have optical characteristics at the same optical distance, the conventional lens array can be used. The optical axes of the lenses of the lens arrays 2 and 3 are inclined with respect to the propagation path of the optical signal indicated by the alternate long and short dash line. However, in the short distance arrangement, the optical coupling loss is caused by the optical characteristics of the lenses. Is negligible. Further, the distance between the SOA array 1 and the lens arrays 2 and 3 or between the lens array 2 and 3 and the fiber array 4 is set according to the optical characteristics of the lenses of the lens arrays 2 and 3. The reliability of the SOA array 1 can be ensured by arranging an airtight package for hermetically sealing the SOA array 1.

  FIG. 2 is an explanatory diagram of Embodiment 1 of the present invention. The SOA array 1 and the lens arrays 2 and 3 shown in FIG. 1 are combined with an airtight package 6 having light-transmitting airtight windows 7 and 8 such as sapphire. A configuration is shown in which the end face of the optical signal input side fiber array 5 is arranged to face the airtight window 8 and the end face of the optical signal output side fiber array 4 is arranged to face the airtight window 7. In this case, the airtight windows 7 and 8 are arranged between the lens arrays 2 and 3 and the fiber arrays 4 and 5 in parallel with the lens arrays 2 and 3. The hermetic package 6 is generally made of a metal having a small thermal expansion coefficient, and the conventional technique can be applied to the structure for fixing the hermetic windows 7 and 8. An inert gas can also be sealed in the hermetic package 6. Note that the control voltage applying means for switching control of the optical signal can be an already known means, and is not shown.

  The distances between the fibers of the fiber array 5 on the optical signal input side and the lenses of the lens array 3 and between the lenses of the lens array 3 and the input side end surfaces of the SOAs of the SOA array 1 are equal. The distances between the output side end surfaces of the SOAs of the SOA array 1 and the lenses of the lens array 2 and between the lenses of the lens array 2 and the fibers of the fiber array 4 on the optical signal output side are equal. Become. That is, the optical coupling distance for each channel can be made equal. Although only the SOA array 1 can be hermetically sealed in the hermetic package 6, the configuration shown in the figure is common.

  In addition, although the optical signal input side and the output side lens array for the SOA array 1 are each shown as being one, a plurality of lens arrays can be provided. As described above, when a plurality of lens arrays are provided, the lens arrays can be arranged on both sides of the airtight windows 7 and 8. The fiber array 5, the hermetic package 6, and the fiber array 4 are adjusted and fixed on a substrate (not shown) so that their optical axes coincide with each other to constitute an SOA array optical module. As the matching means and fixing means, known means can be applied.

It is a principle explanatory view of the present invention. It is explanatory drawing of Example 1 of this invention. It is explanatory drawing of a prior art example. It is explanatory drawing of the problem of a prior art example.

Explanation of symbols

1 SOA array 2, 3 Lens array 4, 5 Fiber array 6 Airtight package 7, 8 Airtight window

Claims (4)

In an SOA array optical module having a SOA array in which the end faces of the optical signal input side and the optical signal output side are inclined with respect to the propagation direction of the optical signal,
An optical signal input side and an optical signal output side lens array arranged in parallel with the optical signal input side and optical signal output side end faces of the SOA array, respectively;
An SOA array optical module comprising: the optical signal input side and optical signal output side lens arrays; and the optical signal input side and optical signal output side fiber arrays arranged so that the end faces thereof are parallel to each other.   2. The SOA array light according to claim 1, wherein the SOA array is hermetically sealed by an airtight package having an airtight window parallel to the optical signal input side and optical signal output side end faces of the SOA array. module.   3. The SOA array optical module according to claim 1, wherein a plurality of lens arrays are arranged in parallel with respect to the optical signal input side and optical signal output side end faces of the SOA array. 4.   The surface perpendicular to the optical axis of each lens of the lens array on the optical signal input side and the optical signal output side is arranged in parallel with the end surfaces on the optical signal input side and the optical signal output side of the SOA array. The SOA array optical module according to any one of claims 1 to 3, wherein

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