JP2001228021A - Optical signal measuring circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical signal measuring circuit, having a small size and using a small number of signal outputting terminals. SOLUTION: This optical signal measuring circuit is obtained by forming, in batch an arrayed waveguide diffraction grating composed of slab waveguides 102 and 104, an arrayed waveguide 103, an optical waveguide 105, etc., which change the outputting position of an inputted optical signal 1 according to the wavelength of the signal 1, and a light-receiving device 110, which outputs electric signals from a pair of output electrodes 113 and 114 at a different ratio on the same semiconductor substrate 100.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical signal measuring circuit which can easily measure the wavelength and intensity of an optical signal.

[0002]

2. Description of the Related Art In the field of optical communication, it is essential to measure the wavelength and intensity (optical signal information) of an optical signal having a single wavelength. To measure this optical signal information,
Conventionally, an optical spectrum analyzer using a diffraction grating (for example, Q8381A manufactured by Advantest Co., Ltd.)
(Model number) and the like. It is also known to use a small channel monitor optical circuit in which an optical filter that changes the output position of an optical signal according to the wavelength of an input optical signal and a light receiver are combined (for example,
M. Koutoku et al., IEICE Trans.Electron., Vol.E81-C, N
o.8, pp.1195-1204, August 1998, etc.).

[0003]

However, the optical spectrum analyzer as described above has a large device configuration.
Since it is necessary to secure a relatively large installation place to constantly measure optical signal information, it has been difficult to incorporate the optical signal information into an optical communication system. On the other hand, the channel monitor optical circuit as described above has a large number of photodetectors, so that the number of electric signal output terminals is enormous.

Accordingly, an object of the present invention is to provide an optical signal measuring circuit which is small and has a small number of signal output terminals.

[0005]

According to the present invention, there is provided an optical signal measuring circuit for changing an output position of an optical signal according to a wavelength of an input optical signal. A light receiver that is connected to an optical filter and changes the ratio of electric signals output from the pair of output electrodes depending on the difference in the input position of the optical signal.

In the above-described optical signal measuring circuit, the optical filter is an arrayed waveguide diffraction grating.

The above-mentioned optical signal measuring circuit is characterized in that a bypass means is provided for converting a part of the optical signal before being inputted to the optical filter into an electric signal as it is and outputting the electric signal.

In the above-mentioned optical signal measuring circuit, the optical filter and the light receiver are monolithically integrated.

In the above-described optical signal measuring circuit, the optical filter and the light receiver are hybrid-integrated.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the optical signal measuring circuit according to the present invention will be described below, but the present invention is not limited to the following embodiments.

[First Embodiment] A first embodiment of an optical signal measuring circuit according to the present invention will be described with reference to FIGS. 1 is an overall schematic configuration diagram of an optical signal measurement circuit, FIG. 2 is an enlarged view of an arrow II section in FIG. 1, FIG. 3 is a sectional view taken along line III-III in FIG. 2, and FIG. FIG.

As shown in FIG. 1, an optical signal 1 is applied to a substrate 100 made of a compound semiconductor such as InP or GaAs.
Is formed in a single-mode optical waveguide 101. The optical waveguide 101 is connected to a slab waveguide 102 formed on the substrate 100 to diffuse the optical signal 1 from the optical waveguide 101. The slab waveguide 102 is connected to a compound semiconductor array waveguide 103 having a plurality of waveguides formed on the substrate 100 and having slightly different lengths. This array waveguide 1
Numeral 03 is connected to a slab waveguide 104 formed on the substrate 100 and causing an optical signal 1 from the array waveguide 103 to interfere and form an image. In the slab waveguide 104,
A plurality of single-mode optical waveguides 105 formed on the substrate 100 and transmitting the optical signal 1 for each wavelength are connected.

In this embodiment, the slab waveguide 1
02, 104, the array waveguide 103, the optical waveguide 105, etc., constitute an array waveguide diffraction grating, and the array waveguide diffraction grating constitutes an optical filter.

The optical waveguide 105 is connected to a light receiver 110 which is formed on the substrate 100 and changes the ratio of electric signals output from the pair of output electrodes 113 and 114 depending on the input position of the optical signal 1. And the relevant light receiver 11
0 has a structure as shown in FIGS.

As shown in FIGS. 2 and 3, a plurality of array light receiving sections 111 having a pn junction are formed on the substrate 100 at intervals corresponding to the intervals of the optical waveguides 105. These array light receiving portions 111 are covered so as to be connected by position detection electrodes 112 made of a material having a relatively large electric resistance. This position detection electrode 112
Output electrodes 113 and 114 for extracting an output electric signal are formed in pairs at both ends in the arrangement direction of the array light receiving unit 111 so as to be spaced apart from each other. In addition,
In FIG. 3, reference numeral 115 denotes an insulator.

In such an optical signal measuring circuit, when the optical signal 1 is input from the optical waveguide 101, the optical signal 1 spreads in the slab waveguide 102 and is uniformly coupled to each waveguide of the array waveguide 103. The light propagates through the array waveguide 103 and reaches the slab waveguide 104. At this time, since the lengths of the respective waveguides of the array waveguide 103 are slightly different from each other, the time required for the optical signal 1 to reach the slab waveguide 104 is shifted for each waveguide of the array waveguide 103. An image is formed by interference in the slab waveguide 104. Since the imaging position differs for each wavelength, the optical signal 105 is transmitted by the optical waveguide 105 corresponding to the imaging position for each wavelength.
Are the respective array light receiving units 111 of the light receiver 110 for each wavelength.
Respectively.

Here, as shown in FIG. 4A, for example, when the optical signal 1 is input to the array light receiving section 111 at the position A near one of the output electrodes 113, the light is received by the array light receiving section 111 at the position A. An electromotive force is generated, and the voltage of the photoelectromotive force, which is an output electric signal, propagates to the output electrodes 113 and 114 while the voltage drops at the position detection electrode 112.

At this time, since the length between the array light receiving section 111 at the position A and the one output electrode 113 and the other output electrode 114 via the position detection electrode 112 is different, a solid line in FIG. As shown, the output electrodes 113, 1
A difference occurs in the voltage values detected at 14. For this reason, the ratio of the voltage values generated at the output electrodes 113 and 114 is determined, and thereby the array light receiving unit 111 at the position A where the optical signal 1 is input is obtained.
Can be specified, and the input optical signal 1 can be monitored for each wavelength.

As shown in FIG. 4A, an optical signal is transmitted to the array light receiving portion 111 at a position B near the other output electrode 114 and the array light receiving portion 111 at a position C between the output electrodes 113 and 114. Even when 1 is input, similar to the case where the optical signal 1 is input to the array light receiving unit 111 at the position A, a voltage difference as shown by a dashed line or a dotted line in FIG. Thus, the array light receiving unit 111 at the positions B and C can be specified, and the input optical signal 1 can be monitored for each wavelength.

Therefore, according to such an optical signal measuring circuit, it is possible to monitor the input optical signal 1 for each wavelength, but also to collectively arrange the array waveguide 103 and the optical receiver 110 on the same semiconductor substrate 100. It is possible to eliminate the need for an optical fiber or the like in the optical connection part, and not only to improve the mechanical vibration resistance due to its small size, but also to reduce the temperature gradient inside the circuit due to the small circuit size. Can be almost eliminated, and stable operation can be achieved.

Further, since the circuit can be manufactured by monolithic integration, the alignment operation can be made unnecessary, the coupling efficiency can be increased, and the manufacturing cost can be reduced.

[Second Embodiment] A second embodiment of the optical signal measuring circuit according to the present invention will be described with reference to FIG. FIG. 5 is a schematic configuration diagram of the optical signal measurement circuit.
However, the same members as those in the first embodiment described above are denoted by the same reference numerals as those used in the description of the first embodiment, and the description thereof is omitted.

As shown in FIG. 5, a single mode optical waveguide 201 made of quartz glass for inputting an optical signal 1 is formed on a substrate 200 made of silicon. The optical waveguide 201 is connected to a quartz glass slab waveguide 202 formed on the substrate 200 and diffusing the optical signal 1 from the optical waveguide 201. The slab waveguide 202 is connected to an arrayed waveguide 203 made of quartz glass and having a plurality of waveguides formed on the substrate 200 and having slightly different lengths from each other. This array waveguide 20
3 is an arrayed waveguide 2 formed on the substrate 200
It is connected to a slab waveguide 204 made of quartz glass that forms an image by interfering with the optical signal 1 from the optical signal 03. A plurality of single-mode optical waveguides 205 made of quartz glass and formed on the substrate 200 and transmitting the optical signal 1 for each wavelength are connected to the slab waveguide 204.

In this embodiment, the slab waveguide 2
02, 204, the arrayed waveguide 203, the optical waveguide 205, etc., constitute an arrayed waveguide grating, and the arrayed waveguide grating constitutes an optical filter.

The optical waveguide 205 is formed on a compound semiconductor substrate and is hybrid-integrated with the substrate 200. The optical waveguide 205 is connected to a photodetector 210 in which the ratio of the output electric signal changes depending on the input position of the optical signal 1. The light receiver 210 is the light receiver 110 of the above-described embodiment.
It has the same structure as.

That is, in the above-described first embodiment, the array waveguide 103, the light receiver 110, and the like are collectively formed on the same substrate 100. In the present embodiment, the array waveguide 203 and the like are formed. Silicon substrate 200 formed
Then, the light receiver 210 formed on the substrate made of a compound semiconductor is hybrid-integrated and connected.

Therefore, according to such an optical signal measuring circuit, as in the case of the first embodiment described above, the optical fiber of the optical connection section can be dispensed with, and it is compact and mechanically resistant. Not only can the oscillator be improved, but the temperature gradient inside the circuit can be almost eliminated due to the small size of the circuit. Therefore, although an alignment operation is required, optical components such as the array waveguide 203 and the light receiver 210 can be manufactured in an optimal state, so that high-performance optical components can be used, and the circuit performance can be improved. Can be improved.

[Third Embodiment] A third embodiment of the optical signal measuring circuit according to the present invention will be described with reference to FIG. FIG. 6 is a schematic configuration diagram of the optical signal measurement circuit.
However, for the same members as those in the first and second embodiments described above, the same reference numerals as those used in the description of the first and second embodiments are used to describe the same members. Is omitted.

As shown in FIG. 6, a branch waveguide 106 connected to the optical waveguide 101 is formed on the substrate 100. The branch waveguide 106 is connected to a single-channel light receiving device 120 formed on the substrate 100 and having a pn junction.

That is, in the present embodiment, the optical waveguide 101
Is input to the single-channel light receiver 120 via the branch waveguide 106 without passing through the array waveguide 103 or the like. Such a branch waveguide 106, a single-channel light receiver 120
Thus, in the present embodiment, a bypass unit is configured.

Therefore, in such an optical signal measuring circuit, a part of the optical signal 1 input to the optical waveguide 101 can be directly input to the single-channel optical receiver 120, converted into an electric signal, and output. , The intensity at the time of input of the signal light 1 can be monitored.

Therefore, according to such an optical signal measuring circuit, the same effect as that of the first embodiment can be obtained, and the light receiving device 1 can be obtained.
By monitoring the intensity of the signal light 1 after transmission through the arrayed waveguide 103 and the like based on the sum signal of the output voltages from 10 and comparing with the output from the single-channel light receiver 120,
Since the amount of intensity attenuation of the signal light 1 by the array waveguide 103 and the like can be obtained, the transmission characteristics of the array light 103 and the like measured in advance are taken into consideration, and the array waveguide of the input signal light 1 is considered. It is possible to detect a deviation from the maximum transmission wavelength due to 103 or the like.

[Fourth Embodiment] A fourth embodiment of the optical signal measuring circuit according to the present invention will be described with reference to FIG. FIG. 7 is a schematic configuration diagram of the optical signal measurement circuit.
However, for members similar to those in the first to third embodiments described above, the same reference numerals as those used in the description of the first to third embodiments described above are used to explain the same members. Is omitted.

As shown in FIG. 7, a branch waveguide 206 connected to the optical waveguide 201 is formed on the substrate 200. The substrate 200 has a plurality of photodetectors 210 connected to the plurality of single-mode optical waveguides 205.
And a light receiving device 230 in which a single channel light receiving device 220 having a pn junction connected to the branch waveguide 206 is integrally formed on a compound semiconductor substrate.

That is, in the third embodiment described above, the array waveguide 103, the branch waveguide 106, the light receiver 1
10 and the single-channel light receiver 120 etc.
In this embodiment, the compound semiconductor in which the light receiver 210 and the single-channel light receiver 220 are formed with respect to the silicon substrate 200 on which the array waveguide 203 and the branch waveguide 206 are formed. The light receiving device 230 of the substrate made of hybrid is integrated and connected.

Therefore, according to such an optical signal measuring circuit, the effects obtained in the third embodiment and the fourth embodiment described above can be obtained together.

[0037]

According to the optical signal measuring circuit of the present invention, the size and the number of signal output terminals can be reduced, so that the optical signal information can be always measured or the installation place is small. Thus, it can be easily incorporated into an optical communication system.

[Brief description of the drawings]

FIG. 1 is an overall schematic configuration diagram of a first embodiment of an optical signal measurement circuit according to the present invention.

FIG. 2 is an enlarged enlarged view of an arrow II in FIG. 1;

FIG. 3 is a sectional view taken along the line III-III in FIG. 2;

FIG. 4 is a diagram illustrating the operation of the light receiver.

FIG. 5 is an overall schematic configuration diagram of a second embodiment of the optical signal measurement circuit according to the present invention.

FIG. 6 is an overall schematic configuration diagram of a third embodiment of the optical signal measurement circuit according to the present invention.

FIG. 7 is an overall schematic configuration diagram of a fourth embodiment of the optical signal measurement circuit according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Optical signal 100 Substrate 101 Optical waveguide 102 Slab waveguide 103 Array waveguide 104 Slab waveguide 105 Optical waveguide 106 Branch waveguide 110 Optical receiver 111 Array light receiving part 112 Position detection electrode 113,114 Output electrode 115 Insulator 120 Single channel light reception Device 200 Substrate 201 Optical waveguide 202 Slab waveguide 203 Array waveguide 204 Slab waveguide 205 Optical waveguide 206 Branch waveguide 210 Optical receiver 220 Single channel optical receiver 230 Optical receiver

 ────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hiroyuki Ishii 2-3-1 Otemachi, Chiyoda-ku, Tokyo F-term in Nippon Telegraph and Telephone Corporation (reference) 2G020 AA03 AA04 BA20 CB42 CB43 CC06 CC63 CD04 CD11 CD24 2H047 KA02 KA03 KA12 LA01 LA19 MA07 QA02 QA04 RA00 TA01

Claims (5)

[Claims] 1. An optical filter for changing an output position of an optical signal according to a wavelength of an input optical signal, and an optical filter connected to the optical filter and outputting from a pair of output electrodes according to a difference in an input position of the optical signal. An optical signal measuring circuit, comprising: 2. The optical signal measuring circuit according to claim 1, wherein the optical filter is an arrayed waveguide diffraction grating. 3. The optical signal measurement according to claim 1, further comprising a bypass unit configured to convert part of the optical signal before being input to the optical filter into an electrical signal as it is and output the electrical signal. circuit. 4. The optical signal measuring circuit according to claim 1, wherein the optical filter and the light receiver are monolithically integrated. 5. The optical signal measuring circuit according to claim 1, wherein the optical filter and the light receiver are hybrid-integrated.