JPH11119173A - Light wavelength selective filter and light wavelength tuning type transceiver - Google Patents

Abstract

PROBLEM TO BE SOLVED: To increase the number of selective wavelengths by providing an optical switch part consisting of a 4-terminal optical circulator, an optical switch, and a light reflector in a return optical path which couples a specific input/output part of an array waveguide diffraction grating type optical multiplexer demultiplexer. SOLUTION: To extract one wavelength from a 16-wavelength multiplex signal when a wavelength multiplex signal of 16 waves is inputted to an input/ output port #1a of the array waveguide diffraction grating type multiplexer demultiplexer 1 and outputted from an optical fiber 5 for output from an input/ output port #9a of the said multiplexer demultiplexer 1, an optical switch 8b provided in a return optical path 6 connected between, for example, an input/ output port #16b and an input/output port 8b is only driven and then a wavelength signal λ16 is selected and can be taken out of the optical fiber 5 for output. Then the optical switch is switched and an optical switch 8a is driven to select another wavelength signal λ8 this time, so that it can be taken out of the optical fiber 5 for output.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical wavelength selective filter and an optical wavelength tunable transceiver, and more particularly, to a wavelength division multiplex (WDM).
ng) The present invention relates to a technique effective in extracting an optical multiplexed signal of a desired plurality of wavelengths from an optical wavelength multiplexed signal in a system, an optical switching system, or the like.

[0002]

2. Description of the Related Art Conventionally, in an optical communication system, for example, a wavelength division multiplexing system, an optical switching system, etc., an optical wavelength selection filter is used to extract a desired plurality of wavelengths of optical multiplex signals from optical wavelength multiplex signals. Is done.

FIG. 4 is a block diagram showing a schematic configuration of a conventional optical wavelength selection filter using an arrayed waveguide diffraction grating type duplexer. The optical wavelength selection filter shown in FIG.
An input optical fiber (optical fiber transmission line) 16 as an input optical line, an output optical fiber (optical fiber transmission line) 15 as an output optical line, a 16 × 16 array waveguide diffraction grating type optical multiplexer / demultiplexer 10. , Folded optical path 17, optical switch group 1
And 8. The arrayed waveguide grating optical multiplexer / demultiplexer 10 includes a first input / output optical waveguide group 13, a slab optical waveguide 11, an arrayed waveguide diffraction grating 105, a slab optical waveguide 12, and a second input / output optical waveguide group. 14. In addition, each optical switch (181,
183, 185, 187, 189, 1811, 181
3, 1815) is an arrayed waveguide grating type multiplexer 10
Are provided in the folded optical paths 17 connected between the two optical waveguides of the second input / output optical waveguide group 14 in total, each of which is provided with a total of eight optical switches. It is provided for the purpose of blocking. In the optical wavelength selection filter shown in FIG. 4, when a desired signal light is selected from the 16 wavelength multiplexed signal lights, the optical switches of the switch group 18 through which the corresponding wavelength light passes are driven. Make it pass. Hereinafter, the operation of the optical wavelength selection filter shown in FIG. 4 will be described in detail with reference to the input / output comparison table of the passing wavelength of the arrayed waveguide grating type optical multiplexer / demultiplexer 10 shown in FIG.

As shown in FIG. 3, for example, from λ1 to λ1
Sixteen wavelength multiplexed signal lights of up to six were input to the eighth input / output port 138a of the first input / output port of the arrayed waveguide grating optical multiplexer / demultiplexer 10 via the optical fiber transmission line 15. At this time, λ8 is output to the first input / output port 141b of the second input / output port, and λ10 is output to the third input / output port 143b of the second input / output port. Λ16 is finally output to the input / output port 149b. That is, the wavelength multiplexed signal is demultiplexed to each input / output port assigned to each wavelength.

In FIG. 3, the numbers (1 to 16) in the horizontal direction representing the first input / output waveguide a are the first input / output ports of the arrayed waveguide grating type optical multiplexer / demultiplexer 10. The 16th input / output port 1 to the 16th input / output port 131a
316a, and the vertical numbers (1 to 16) representing the second input / output waveguides b are the first input / output ports of the second input / output ports of the arrayed waveguide grating optical multiplexer / demultiplexer 10. 1
The 16th input / output port 1416b from 41b is shown.

Here, for example, as shown by a broken line in FIG. 3, the folded optical path 17 connected between the input / output port 141b and the input / output port 142b of the arrayed waveguide grating type optical multiplexer / demultiplexer 10 is provided. If the provided optical switch 181 is driven to be in the passing state, only the signal light of λ8 passes through the optical switch 181 and is input to the input / output port 142b of the arrayed waveguide grating optical multiplexer / demultiplexer 10, and as a result, As shown in FIG. 3, an arrayed waveguide diffraction grating type optical multiplexer / demultiplexer 1
The seventh input / output port 137 of the first input / output port of 0
a to the optical fiber transmission line 16. In this case, the optical switch 181 allows the signal lights of λ8 and λ9 to pass therethrough, but the signal light of λ9 from the input / output port 142b of the arrayed waveguide grating type optical multiplexer / demultiplexer 10 receives the arrayed waveguide grating type light. Input / output port 141b of optical multiplexer / demultiplexer 10
, But is not output from the input / output port 137a. As a result, selection cannot be made for the signal light of λ9.

As described above, in the conventional optical wavelength selection filter, by driving each of the optical switches of the switch group 18, only the maximum predetermined eight wavelengths out of the 16 wavelengths are selected. It was not possible to select a desired one or a plurality of wavelengths from the limited 16 wavelength multiplexed signals. Such a technique is described in JP-A-7-327024.

In an optical communication system, for example, a wavelength division multiplexing system, an optical switching system, etc., light for transmitting and receiving a desired wavelength signal from optical wavelength multiplexing signals without using a light source and its wavelength controller. A wavelength tuned transceiver is used.

FIG. 5 is a block diagram showing a schematic configuration of a conventional optical wavelength tuning type transceiver using an arrayed waveguide diffraction grating type optical multiplexer / demultiplexer. The optical wavelength tunable transceiver shown in FIG. 5 includes a 1 × N frequency routing device (41, 42) composed of two identical arrayed waveguide grating type optical multiplexers / demultiplexers, and an optical amplifier (active region) ( 481-48
n) and electronic control units (501 to 50n). The 1 × N input frequency routing device 41 and the 1 × N output frequency routing 42 are interconnected by N optical waveguides (451 to 45n, 461 to 46n). In FIG. 5, reference numeral 40 denotes an InP wafer.

This optical wavelength tuning type transceiver has a 1 × N
From the optical wavelengths separated by the input frequency routing device 41, a predetermined optical wavelength is assigned to each optical amplifier (active region).
(481-48n) to selectively modulate, demodulate and amplify. For example, optical frequency multiplexed signal light having N frequencies from F1 to Fn is transmitted through the input optical waveguide 43 to 1
× N input port # 4 of input frequency routing device 41
When input to 1a, F1 is output to output port # 411b, F2 is output to output port # 412b, and so on, and is output separately to different output ports according to each optical frequency. Fn is output port # 41nb
Output to That is, the optical frequency multiplexed signal is separated and output to different output ports assigned to each optical frequency.

Here, for example, if the optical amplifier 483 is driven with a constant current in the forward direction (forward bias), only the signal light of F3 is amplified by the optical amplifier 483, and the input port # of the N × 1 output frequency routing device 42 423a, and as a result, output from the output port # 42b of the N × 1 output frequency routing device 42 to the output optical waveguide 44.

Also, an optional optical amplifier (481-48n)
If a pulse current is applied to the optical signal and the light intensity is modulated, the wavelength signal subjected to the light intensity modulation becomes an N × 1 output frequency routing device 4.
2 is output to the output optical waveguide 44 from the output port # 42b. If the terminal voltage change induced in the optical amplifiers (481 to 48n) by the constant current driving (reverse bias) in the reverse direction is detected, the transmitted wavelength signal is demodulated. Such a technique is described in JP-A-7-202818.

[0013]

The optical wavelength selection filter shown in FIG. 4 has a configuration in which an arbitrary optical switch in the optical switch group 18 is driven to select a predetermined N / 2 wavelength from N wavelengths. In principle, it has been impossible to freely select a desired one or a plurality of waves from the wavelength multiplexed signals of N wavelengths. This is because the selectable wavelength is 1 /
This is because it is limited to 2.

As described above, in the optical wavelength selection filter shown in FIG. 4, the N × N array waveguide diffraction grating type optical multiplexer / demultiplexer 10 is used.
Has a multiplexing / demultiplexing function of N wavelengths, the number of selected wavelengths is limited to 、, that is, the optical wavelength selection filter shown in FIG. In a high-density wavelength division multiplexing communication system for a wave, there is a problem in that when one or more arbitrary wavelengths are selected from N wavelengths, a serious drawback occurs.

The optical wavelength tunable transceiver shown in FIG. 5 has a configuration in which two identical arrayed waveguide grating optical multiplexer / demultiplexers (41, 42) are used in combination.
Both wavelength characteristics had to be completely matched. Also,
Since the optical integrated amplifiers (481 to 48n) are driven to selectively modulate and demodulate a predetermined wavelength from N wavelengths, the optical amplifiers (481 to 48n) are close to each other. When pulse modulation is performed on one optical amplifier, a current leaks into an adjacent optical amplifier, causing an increase in electric crosstalk, or an influence of electric crosstalk from an adjacent optical amplifier when a predetermined wavelength signal is received. There is a problem that can not be ignored. There is also a problem with the temperature dependence of the wavelength characteristics of the two arrayed waveguide grating optical multiplexers / demultiplexers (41, 42).
-45n, 461-46n) and the input optical waveguide 43 (or the output optical waveguide 44) have a problem that the coupling loss increases due to the mode mismatch. Further, two array waveguide diffraction grating type optical multiplexer / demultiplexers (4
1, 42), there is a problem that the load on each of the optical amplifiers (481 to 48n) increases when trying to compensate for this loss.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems of the prior art, and an object of the present invention is to provide an optical wavelength selection filter capable of improving the degree of freedom in wavelength selection. Is to provide.

Another object of the present invention is to provide an optical wavelength tunable transceiver using one arrayed waveguide grating type optical multiplexer / demultiplexer to solve the problem of wavelength matching and to simplify the circuit configuration. It is an object of the present invention to provide a technology that can be realized.

The above and other objects and novel features of the present invention will become apparent from the description of the present specification and the accompanying drawings.

[0019]

SUMMARY OF THE INVENTION Among the inventions disclosed in the present application, the outline of a representative one will be briefly described.
It is as follows.

In the optical wavelength selection filter of the present invention,
At least a first input / output optical waveguide group including a plurality of optical waveguides and an array waveguide diffraction grating type optical multiplexer / demultiplexer including a second input / output optical waveguide group including a plurality of optical waveguides; A four-terminal optical circulator is disposed in at least one folded optical path connecting two different optical waveguides of the second input / output optical waveguide group of the waveguide grating optical multiplexer / demultiplexer. An optical switch having a light reflector is connected to two terminals.

In the optical wavelength-tunable transceiver according to the present invention, at least a first input / output optical waveguide group including a plurality of optical waveguides and an array waveguide including a second input / output optical waveguide group including a plurality of optical waveguides are provided. A second example of the arrayed waveguide grating type optical multiplexer / demultiplexer using a waveguide grating type optical multiplexer / demultiplexer.
A four-terminal optical circulator is disposed in at least one folded optical path connecting two different optical waveguides of the input / output optical waveguide group of the above, and the other two terminals of the four-terminal optical circulator are provided with light reflectors at the other two terminals, respectively. It is characterized in that modems are connected respectively.

The first input / output optical waveguide group and the second input / output optical waveguide group of the arrayed waveguide grating optical multiplexer / demultiplexer each have N (N is an integer) optical waveguides. The input optical line is the i-th optical waveguide of the first input / output optical waveguide group of the arrayed waveguide grating type optical multiplexer / demultiplexer, and the output optical line is the arrayed waveguide diffraction device. The j-th optical waveguide of the first input / output optical waveguide group of the grating type optical multiplexer / demultiplexer is further connected to the j-th optical waveguide, and the at least one folded optical path is connected to the second one of the array waveguide diffraction grating type optical multiplexer / demultiplexer. Of the first input / output optical waveguide group of the array waveguide diffraction grating type optical multiplexer / demultiplexer, the second input / output optical waveguide group being connected between the l-th and k-th optical waveguides of the input / output optical waveguide group. Let λi, l (l be an integer) the passing wavelength of the input / output optical waveguide group to the l-th optical waveguide. ), And the first i th optical waveguides of the input and output optical waveguide group of the second output optical waveguide group k
Let λi, k (k is an integer) be the wavelength transmitted to the optical waveguide,
The transmission wavelength from the l-th optical waveguide of the second input / output optical waveguide group of the array waveguide grating optical multiplexer / demultiplexer to the j-th optical waveguide of the first input / output optical waveguide group is λl, j, And the k-th optical waveguide of the second input / output optical waveguide group
Λi, l = λk, j, λi, k =
λ, j, (ji) = (lk) = N / 2.

[0023]

Embodiments of the present invention will be described below in detail with reference to the drawings.

In all the drawings for describing the embodiments, those having the same functions are denoted by the same reference numerals, and their repeated description will be omitted.

[First Embodiment] FIG. 1 is a block diagram showing a schematic configuration of an optical wavelength selection filter according to a first embodiment of the present invention. The optical wavelength selection filter according to the present embodiment includes an input optical fiber 4 as an input optical line, an output optical fiber 5 as an output optical line, a 16 × 16 arrayed waveguide grating optical multiplexer / demultiplexer 1, It comprises a folded optical path 6 and an optical switch section 80. Here, the arrayed waveguide grating type optical multiplexer / demultiplexer 1 includes a first input / output optical waveguide group 2, a slab optical waveguide (not shown), and an arrayed waveguide grating (shown in the figure), as in the above-described conventional example. ), A slab optical waveguide (not shown), and a second input / output optical waveguide group 3. Further, the optical switch unit 80 includes the optical circulator 7,
It comprises an optical switch (8a, 8b) and an optical reflector 9. Array waveguide diffraction grating type optical multiplexer / demultiplexer 1
Can be manufactured on a silicon (Si) substrate or a quartz (SiO 2) substrate with a quartz glass optical waveguide or the like, or on a silicon (Si) substrate, a polymer optical waveguide such as fluorinated polyimide, lithium niobate ( LN) Lithium niobate (LiNbO3) with titanium (Ti) diffusion on substrate
Optical waveguide, InGaAsP on InP or GaAs substrate,
It is made of an optical semiconductor optical waveguide such as GaAlAs.

The optical switches (8a, 8b) pass and block light having a wavelength determined between the input and output ports of the arrayed waveguide grating type multiplexer 1, and include, for example, an optical fiber switch, InGaAsP or GaAlAs. Optical semiconductor amplifier or lithium niobate (LiNbO3)
An optical waveguide switch or the like is preferably used. Input optical fiber 4 and output optical fiber 5 as transmission optical lines
Is a normal single mode fiber, dispersion shifted fiber,
A polarization maintaining fiber or the like is used.

In general, the transmission wavelength of the arrayed waveguide grating optical multiplexer / demultiplexer 1 is determined in principle by the input / output port used. Hereinafter, this arrayed waveguide diffraction grating type optical multiplexer / demultiplexer 1 will be described.
Will be described using an input / output comparison table showing the relationship between the input and output of the arrayed waveguide grating type optical multiplexer / demultiplexer 1 shown in FIG.

As shown in FIG. 3, for example, when a 16-wavelength multiplexed signal is input to the input / output port # 1a of the arrayed waveguide grating type multiplexer / demultiplexer 1 via the input optical fiber 4, From the input / output port # 1b to the input / output port # 16b,
Wavelengths of λ1 to λ16 are output, respectively.

In FIG. 3, the numbers (1 to 16) in the horizontal direction indicating the first input / output waveguide a are the first input / output ports of the arrayed waveguide grating type optical multiplexer / demultiplexer 1. 16th input / output port # 16 to 16th input / output port # 1a
a, and the vertical numerals (1 to 16) representing the second input / output waveguide b are the arrayed waveguide diffraction grating type optical multiplexer / demultiplexer 1.
The first input / output port # 1b to the 16th input / output port # 16b of the second input / output port are shown.

As shown by the solid line in FIG. 3, when the input / output port # 8b and the input / output port # 16b of the arrayed waveguide grating type multiplexer / demultiplexer 1 are connected, the wavelengths of λ8 and λ16 are both input and output. Output from port # 9a. Similarly, when the input / output port # 9b and the input / output port # 1b of the arrayed waveguide grating type multiplexer / demultiplexer 1 are connected, both the wavelengths λ1 and λ9 are output from the input / output port # 9a. In this way, when the other input / output ports are connected by a folded optical path, a transmission characteristic of 16 wavelengths, which was impossible with the prior art, is obtained. Further, an optical switch section 80 is provided in the folded optical path 6 provided between these input / output ports through which each wavelength passes, and the optical switches (8a, 8a) of the optical switch section 80 are provided.
By driving b), 1 which was impossible in the prior art
An arbitrary wavelength signal can be selected from the wavelength multiplexed signal light of six wavelengths.

The operation of the optical wavelength selection fiber according to the present embodiment will now be described with reference to FIG. 1 between the input / output port # 8b and the input / output port # 16b of the arrayed waveguide grating type optical multiplexer / demultiplexer 1. A four-terminal optical circulator 7 is arranged in the connected folded optical path 6 such that the folded optical path 6 is connected to the terminal 1 and the terminal 3, respectively.
The operation of selecting a wavelength-multiplexed signal when the optical switches (8a, 8b) each having the optical reflector 9 are provided at the remaining terminals (terminals 2 and 4) of the optical circulator 7 will be described in detail.

A 16-wavelength multiplexed signal is input to the input / output port # 1a of the arrayed waveguide grating type multiplexer / demultiplexer 1 via the input optical fiber 4, and the arrayed waveguide grating type multiplexer / demultiplexer 1 is input. Output from the output optical fiber 5 from the input / output port # 9a, and one wavelength is extracted from the 16-wavelength multiplexed signal.
By driving the optical switch 8b provided in the folded optical path 6 connected between the input / output port #b and the input / output port # 8b, the wavelength signal λ16 can be selected and extracted from the output optical fiber 5. Next, when the optical switch is switched and the optical switch 8a is driven, another wavelength signal λ8 is selected and can be extracted from the output optical fiber 5 this time. In this way, the optical switch (8a, 8a) connected to the optical circulator 7 in the folded optical path 6 through which the corresponding wavelength passes.
By driving b), a desired wavelength can be selected.
In the above description, the optical signal input port is # 1a and the optical signal output port is # 9a. However, the present invention is not limited to this, and other input / output ports may be used.

That is, an input optical fiber 4 is connected to the i-th optical waveguide of the first input / output optical waveguide group 2 of the arrayed waveguide diffraction grating type optical multiplexer / demultiplexer 1, and the arrayed waveguide diffraction is connected. First input / output optical waveguide group 2 of grating type optical multiplexer / demultiplexer 1
, An output optical fiber 5 is connected to the j-th optical waveguide, and furthermore, the second optical waveguide
A folded optical path 6 is connected between the l-th and k-th optical waveguides of the input / output optical waveguide group 3 of the i-th optical waveguide group of the array waveguide diffraction grating type optical multiplexer / demultiplexer. The transmission wavelength from the waveguide to the l-th optical waveguide of the second input / output optical waveguide group is λi, l (1 is an integer), and the second input waveguide from the i-th optical waveguide of the first input / output optical waveguide group. The passing wavelength of the output optical waveguide group to the k-th optical waveguide is λi, k (k is an integer), and the second wavelength of the array waveguide diffraction grating type optical multiplexer / demultiplexer.
Let λl be the transmission wavelength from the l-th optical waveguide of the input / output optical waveguide group to the j-th optical waveguide of the first input / output optical waveguide group.
j, and λi, l = λk, where λk, j is the passing wavelength from the kth optical waveguide of the second input / output optical waveguide group to the jth optical waveguide of the first input / output optical waveguide group. j, λ
It suffices to satisfy the following relationship: i, k = λl, j, (ji) = (lk) = N / 2. This makes it possible to balance the propagation loss between the input optical line and the output optical line for N wavelengths.

For example, when N = 16, i = 1 and j =
When 9 and k = 8 and 1 = 16, the signal light wavelength passing through the return optical path 6 is λi, 1 = λk, j = λ16 and λi,
k = λ1, j = λ8, (ji) = (lk) = N / 2
= 8, and as shown in the input / output comparison table of FIG. 2, wavelength selection for two wavelengths of λ8 and λ16 becomes possible. The same holds for other combinations of l and k. Finally, selection for 16 wavelengths becomes possible.

In this embodiment, since the arrayed waveguide grating type optical multiplexer / demultiplexer 1 operates as a narrow-band optical filter, unnecessary noise light components can be removed and optical crosstalk can be improved. It is possible to do.

In the present embodiment, the folded optical path 6, the optical switch unit 80 (four-terminal optical circulator 7,
It is also possible to integrate the optical switch (8a, 8b), the optical reflector 9), and the optical fiber connecting these components on the same optical substrate as the arrayed waveguide grating optical multiplexer / demultiplexer 1.

As a result, the number of components such as the optical fiber for connection and the optical connector can be reduced, and the size and the price can be reduced. As a result, the stability and reliability of the operating characteristics can be improved (high reliability can be achieved). ) Can be achieved.

[Second Embodiment] FIG. 2 is a block diagram showing a schematic configuration of an optical wavelength tunable transceiver according to a second embodiment of the present invention. The optical wavelength tunable transceiver according to the present embodiment includes an input optical fiber 4 serving as an input optical line, an output optical fiber 5 serving as an output optical line, and a 16 × 16 array waveguide diffraction grating type optical multiplexer / demultiplexer 1. , A folded optical path 6, and an optical modulation / demodulation unit 81. Here, similarly to the first embodiment, the arrayed waveguide grating type optical multiplexer / demultiplexer 1 includes a first input / output optical waveguide group 2, a slab optical waveguide (not shown), and an arrayed waveguide grating (not shown). (Not shown), a slab optical waveguide (not shown), and a second input / output optical waveguide group 3. The optical modulator / demodulator 81 includes the optical circulator 7, the optical modulator / demodulator (88, 816), and the optical reflector 9.

As in the first embodiment, the arrayed waveguide diffraction grating type optical demultiplexer 1 is formed on a silicon (Si) substrate or a quartz (SiO 2) substrate with a quartz glass optical waveguide or the like, or , A polymer optical waveguide such as fluorinated polyimide on a silicon (Si) substrate, and Ti-diffused lithium niobate (Li) on a lithium niobate (LN) substrate.
NbO3) Optical waveguide, InG on InP or GaAs substrate
It is made of an optical semiconductor optical waveguide such as aAsP or GaAlAs. The optical modulator / demodulator (88, 816) modulates, demodulates, or amplifies the wavelength light determined between the input and output ports of the arrayed waveguide grating type multiplexer / demultiplexer 1. For example, InG
an optical semiconductor amplifier such as aAsP or GaAlAs, an electroabsorption type optical semiconductor modulator, lithium niobate (LiN
dO3) An optical waveguide modulator, an optical fiber switch, or the like is suitably used, so that it is possible to flexibly respond to the requirements of the system to be applied. The light reflector 9 is directly N-faced to one cleavage end face of the optical modulator / demodulator (88, 816).
It is manufactured by forming a metal thin film of i, Au, or the like by vapor deposition, or by forming a dielectric multilayer film. As the input optical fiber 4 and the output optical fiber 5, which are transmission optical lines, ordinary single mode fibers, dispersion shift fibers, polarization maintaining fibers, and the like are used.

The operation of the optical wavelength tuning type transceiver using the arrayed waveguide grating type multiplexer / demultiplexer 1 of the present embodiment will be described with reference to FIG. I / O port # 8b and I / O port # 16b
The four-terminal optical circulator 7 is arranged in the folded optical path 6 connected between them so that the folded optical path 6 is connected to the terminal 1 and the terminal 3, and the remaining terminals of the optical circulator 7 (the terminal 2 and the terminal 2). Modulation and demodulation of a wavelength multiplexed signal when the optical semiconductor amplifier 31 having the optical reflector 9 at the terminal 4) is provided as an optical modulator / demodulator (88, 816).
The amplification operation will be described in detail below.

The 16 wavelength multiplexed signal light is input to the input / output port # 1a of the arrayed waveguide grating type multiplexer / demultiplexer 1 via the input optical fiber 4, and the arrayed waveguide grating type multiplexer / demultiplexer is used. 1 output optical fiber 5 from input / output port # 9a
Out of the 16-wavelength multiplexed signal,
If the wavelength is taken out, for example, the input / output port # 16
The optical modulator / demodulator 816 (ie, the optical semiconductor amplifier 31) in the folded optical path 6 connected between #b and # 8b is forward biased via the bias terminal (T), and the bias terminal (T) When a pulse signal is input from the high frequency port, the wavelength signal λ 16 is pulse-modulated and can be transmitted from the output optical fiber 5.

The optical modulator / demodulator 816 is biased in the forward direction via the bias terminal (T), and the PN of the optical semiconductor amplifier 31 is transmitted from the high frequency port of the bias terminal (T).
If the terminal voltage induced at the junction is detected, the pulse-modulated wavelength signal λ16 is demodulated. In this case, the optical signal receives no loss even if demodulated. Rather, the optical semiconductor amplifier 31
, It can function as a lossless optical tap.

If the optical modulator / demodulator 816 is set to zero or reverse bias, the optical signal is absorbed by the active layer, so that the wavelength signal λ16 is completely dropped and is not transmitted from the output optical fiber 5. Can also. Further, when the optical modulator / demodulator 816 is biased in the forward direction to give a gain, a weak optical signal attenuated while propagating through the fiber transmission line can be amplified and transmitted from the output optical fiber 5.

Next, when the optical modulator / demodulator is switched to drive the optical modulator / demodulator 88 (ie, the optical semiconductor amplifier), the modulation, demodulation, and amplification operations can be performed on another wavelength signal λ8.

In this way, if the optical modulator / demodulator (88, 816) (optical semiconductor amplifier 31) connected to the optical circulator 7 in the folded optical path 6 through which the corresponding wavelength passes is driven, the signal for the desired wavelength is obtained. Can be processed.

In the above description, the optical signal input port is # 1a and the optical signal output port is # 9a. However, the present invention is not limited to this, and other input / output ports may be used.

That is, similarly to the first embodiment, the input optical fiber 4 is connected to the i-th optical waveguide of the first input / output optical waveguide group 2 of the arrayed waveguide grating type optical multiplexer / demultiplexer 1. Further, an output optical fiber 5 is connected to the j-th optical waveguide of the first input / output optical waveguide group 2 of the arrayed waveguide grating type optical multiplexer / demultiplexer 1. A folded optical path 6 is connected between the l-th and k-th optical waveguides of the second input / output optical waveguide group 3 of the optical multiplexer / demultiplexer 1, and the first input / output of the arrayed waveguide grating optical multiplexer / demultiplexer is connected. The transmission wavelength from the i-th optical waveguide of the optical waveguide group to the l-th optical waveguide of the second input / output optical waveguide group is λi, l (l is an integer), and the i-th optical waveguide of the first input / output optical waveguide group is Let λi, k be the passing wavelength from the optical waveguide to the k-th optical waveguide of the second input / output optical waveguide group. (K is an integer), passing from the l-th optical waveguide of the second input / output optical waveguide group to the j-th optical waveguide of the first input / output optical waveguide group of the arrayed waveguide grating type optical multiplexer / demultiplexer. When the wavelength is λl, j and the passing wavelength from the k-th optical waveguide of the second input / output optical waveguide group to the j-th optical waveguide of the first input / output optical waveguide group is λk, j, λi, l = λk, j, λi, k = λl, j, (j−
i) = (lk) = N / 2.
This makes it possible to balance the propagation loss between the input optical line and the output optical line for N wavelengths.

For example, when N = 16, i = 1 and j = 9
And when k = 8 and l = 16, the signal light wavelength passing through the return optical path 6 is λi, l = λk, j = λ16 and λi, k
= Λ1, j = λ8, (ji) = (lk) = N / 2 =
8, which makes it possible to select wavelengths for two wavelengths, λ8 and λ16. The same holds for other combinations of l and k. Finally, selection for 16 wavelengths becomes possible.

Further, in the optical wavelength tuning type transceiver of the present embodiment, the light source and its wavelength control device are not required, and as a result, maintenance becomes easy and it is possible to contribute to reduction of the device cost.

In the optical wavelength-tunable transceiver according to the second embodiment, the folded optical path 6, the optical modulator / demodulator 81 (optical circulator 7, optical modulator / demodulator (88, 816), optical reflector 9), and their components are used. The optical fibers to be connected can be integrated on the same optical substrate as the arrayed waveguide grating type optical multiplexer / demultiplexer 1. Thus, the number of components such as the connection optical fiber and the optical connector can be reduced, and the cost can be reduced. As a result, the stability and reliability of the operating characteristics can be improved.

As described above, the invention made by the present inventor is:
Although a specific description has been given based on the above-described embodiment, the present invention is not limited to the above-described embodiment, and it is needless to say that various modifications can be made without departing from the gist of the invention.

[0052]

The effects obtained by typical ones of the inventions disclosed in the present application will be briefly described as follows.

(1) According to the present invention, a four-terminal optical circulator, an optical switch, and an optical reflector are provided in a folded optical path connecting predetermined input / output sections of an arrayed waveguide grating optical multiplexer / demultiplexer. Since the optical switch section is provided, wavelengths that cannot be selected in the conventional example can be selected, and the number of selected wavelengths can be doubled in the conventional example.

(2) According to the present invention, the same number of wavelengths as the number of input / output ports of the arrayed waveguide grating type optical multiplexer / demultiplexer can be arbitrarily selected. The so-called loss equalization in which the transmission loss with respect to the transmission wavelength of the arrayed waveguide diffraction grating type optical multiplexer / demultiplexer with an optical path is equal for each wavelength is possible.

(3) According to the present invention, a four-terminal optical circulator, an optical modulator / demodulator, and an optical reflector are provided in a folded optical path connecting predetermined input / output sections of the arrayed waveguide grating type multiplexer / demultiplexer. Since the optical modulation / demodulation unit is provided, the conventional example requires two arrayed waveguide grating type optical multiplexer / demultiplexers having the same characteristics, but only one needs to solve the problem of wavelength matching. The configuration is simplified.

(4) According to the present invention, since the arrayed waveguide grating type optical multiplexer / demultiplexer operates as a narrow band optical filter, unnecessary noise light components can be removed and optical crosstalk can be improved. Is done.

(5) According to the present invention, since all components are optically integrated on the same substrate as the arrayed waveguide grating type optical multiplexer / demultiplexer, miniaturization, cost reduction and high reliability can be achieved. is there.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a schematic configuration of an optical wavelength selection filter according to a first embodiment of the present invention.

FIG. 2 is a block diagram illustrating a schematic configuration of an optical wavelength tunable transceiver according to a second embodiment of the present invention.

FIG. 3 is a diagram showing an input / output comparison table of an arrayed waveguide grating optical multiplexer / demultiplexer.

FIG. 4 is a block diagram showing a schematic configuration of a conventional optical wavelength selection filter.

FIG. 5 is a block diagram illustrating a schematic configuration of an optical wavelength tunable transceiver according to a conventional embodiment.

[Explanation of symbols]

1,10 ... 16 × 16 array waveguide diffraction grating type optical multiplexer / demultiplexer, 2,13 ... first input / output optical waveguide group, 3,14 ... second input / output optical waveguide group, 4,16 ... for input Optical fiber (input optical line), 5, 15 ... output optical fiber (output optical line), 6, 17 ... folded optical path, 7 ... optical circulator, 8a, 8b, 181, 183, 185, 187,
189, 1811, 1813, 1815 ... optical switch,
9: Optical reflector, 11, 12: Slab optical waveguide, 18: Optical switch group, 31: Optical semiconductor amplifier, 40: InP wafer, 41: 1 × N input frequency routing device, 42:
N × 1 output frequency routing device, 43, 44, 45
1 to 45n, 461 to 46n ... optical waveguides, 481 to 48
n: Optical amplifier (active (doped) region), 501 to 50n
... Electronic control device, 80 ... Optical switch unit, 81 ... Optical modulator / demodulator, 88,816 ... Optical modulator / demodulator, 105 ... Array waveguide diffraction grating.

Claims (7)

[Claims] 1. A first input / output optical waveguide group including a plurality of optical waveguides, a first planar optical waveguide, an optical waveguide group having different lengths, a second planar optical waveguide, and a plurality of optical waveguides An arrayed waveguide grating type optical multiplexer / demultiplexer having a second input / output optical waveguide group comprising: and an arbitrary one of the first input / output optical waveguide group of the arrayed waveguide grating optical multiplexer / demultiplexer. At least one input optical line connected to the optical waveguide; and at least one optical waveguide in a first input / output optical waveguide group of the arrayed waveguide grating type optical multiplexer / demultiplexer;
At least one output optical line connected to an optical waveguide different from the optical waveguide to which the input optical lines are connected; and a second input / output optical waveguide group of the arrayed waveguide grating optical multiplexer / demultiplexer. And at least one folded optical path connecting any two of the optical waveguides, and at least one of the at least one folded input / output terminal is provided in the at least one folded optical path.
One terminal is connected to each of a four-terminal optical circulator connected to the folded optical path, and an even-numbered or odd-numbered input / output terminal that is not connected to the at least one folded optical path of the four-terminal optical circulator. An optical wavelength selection filter, comprising: two optical switches to be used; and two optical reflectors connected to the other terminals of the respective optical switches. 2. A first input / output optical waveguide group and a second input / output optical waveguide group of the arrayed waveguide grating optical multiplexer / demultiplexer each have N (N is an integer) optical waveguides. The input optical line is an i-th optical waveguide of a first input / output optical waveguide group of the arrayed waveguide grating type optical multiplexer / demultiplexer, and the output optical line is an arrayed waveguide diffraction grating. The j-th optical waveguide of the first input / output optical waveguide group of the grating type optical multiplexer / demultiplexer is further connected to the j-th optical waveguide, and the at least one folded optical path is connected to the second one of the array waveguide diffraction grating type optical multiplexer / demultiplexer. And between the l-th and k-th optical waveguides of the input / output optical waveguide group, and the second from the i-th optical waveguide of the first input / output optical waveguide group of the arrayed waveguide grating type optical multiplexer / demultiplexer. Let λi, l (l is an integer) the passing wavelength of the input / output optical waveguide group to the l-th optical waveguide. And λi, k (k is an integer) a transmission wavelength from the i-th optical waveguide of the first input / output optical waveguide group to the k-th optical waveguide of the second input / output optical waveguide group; Wavelengths from the l-th optical waveguide of the second input / output optical waveguide group to the j-th optical waveguide of the first input / output optical waveguide group are λl, j, and the second input / output. When the transmission wavelength from the k-th optical waveguide in the optical waveguide group to the j-th optical waveguide in the first input / output optical waveguide group is λk, j, λi, l = λk, j, λi, k = λl, j, (j-
2. The optical wavelength selection filter according to claim 1, wherein the following relationship is satisfied: i) = (1−k) = N / 2. 3. The optical waveguide according to claim 1, wherein the arrayed waveguide grating type optical multiplexer / demultiplexer, the folded optical path, the optical circulator, the optical switch, and the optical reflector are integrated on the same optical substrate. Claim 1 or Claim 2
3. An optical wavelength selection filter according to claim 1. 4. A first input / output optical waveguide group including a plurality of optical waveguides, a first planar optical waveguide, an optical waveguide group having different lengths, a second planar optical waveguide, and a plurality of optical waveguides. An arrayed waveguide grating type optical multiplexer / demultiplexer having a second input / output optical waveguide group comprising: and an arbitrary one of the first input / output optical waveguide group of the arrayed waveguide grating optical multiplexer / demultiplexer. At least one input optical line connected to the optical waveguide; and at least one optical waveguide in a first input / output optical waveguide group of the arrayed waveguide grating type optical multiplexer / demultiplexer;
At least one output optical line connected to an optical waveguide different from the optical waveguide to which the input optical lines are connected; and a second input / output optical waveguide group of the arrayed waveguide grating optical multiplexer / demultiplexer. And at least one folded optical path connecting any two of the optical waveguides, and at least one of the at least one folded input / output terminal is provided in the at least one folded optical path.
One terminal is connected to each of a four-terminal optical circulator connected to the folded optical path, and an even-numbered or odd-numbered input / output terminal that is not connected to the at least one folded optical path of the four-terminal optical circulator. Two optical modulators and demodulators, two optical reflectors provided at the other terminals of the respective optical modulators and demodulators, and selectively modulate and demodulate predetermined wavelength light of a plurality of wavelength multiplexed lights. Or at least one electronic circuit for selectively applying electrical energy to a predetermined optical modulator / demodulator to be amplified or selectively detecting electrical energy generated by the optical modulator / demodulator. . 5. The first input / output optical waveguide group and the second input / output optical waveguide group of the arrayed waveguide grating optical multiplexer / demultiplexer each have N (N is an integer) optical waveguides. The input optical line is an i-th optical waveguide of a first input / output optical waveguide group of the arrayed waveguide grating type optical multiplexer / demultiplexer, and the output optical line is an arrayed waveguide diffraction grating. The j-th optical waveguide of the first input / output optical waveguide group of the grating type optical multiplexer / demultiplexer is further connected to the j-th optical waveguide, and the at least one folded optical path is connected to the second one of the array waveguide diffraction grating type optical multiplexer / demultiplexer. And between the l-th and k-th optical waveguides of the input / output optical waveguide group, and the second from the i-th optical waveguide of the first input / output optical waveguide group of the arrayed waveguide grating type optical multiplexer / demultiplexer. Let λi, l (l is an integer) the passing wavelength of the input / output optical waveguide group to the l-th optical waveguide. And λi, k (k is an integer) a transmission wavelength from the i-th optical waveguide of the first input / output optical waveguide group to the k-th optical waveguide of the second input / output optical waveguide group, Wavelengths from the l-th optical waveguide of the second input / output optical waveguide group to the j-th optical waveguide of the first input / output optical waveguide group are λl, j, and the second input / output. When the transmission wavelength from the k-th optical waveguide in the optical waveguide group to the j-th optical waveguide in the first input / output optical waveguide group is λk, j, λi, l = λk, j, λi, k = λl, j, (j-
5. The optical wavelength tunable transceiver according to claim 4, wherein the following relationship is satisfied: i) = (lk) = N / 2. 6. The array waveguide diffraction grating optical multiplexer / demultiplexer, the folded optical path, the optical circulator, the optical modulator / demodulator, and the optical reflector are integrated on the same optical substrate. Claim 4 or Claim 5
An optical wavelength-tunable transceiver according to claim 1. 7. The optical modulator / demodulator includes an optical semiconductor amplifier, an electroabsorption type optical semiconductor modulator, a lithium niobate optical modulator,
7. The optical wavelength tunable transceiver according to claim 4, wherein the transceiver is an optical fiber type switch.