JP2004062105A - Device with built-in wavelength variable light source, and wavelength variable light forming method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a device with built-in a wavelength variable light source capable of outputting light which does not contain unnecessary light and has only a desired wavelength. <P>SOLUTION: The unnecessary light is intercepted by an optical gate unit 104 so as not to be outputted by providing the optical gate unit 104 at an output part of the wavelength variable light source 101 and switching and controlling the optical gate unit 104 by an optical gate controlling signal while the wavelength variable light source 101 outputs the unnecessary light when the wavelength variable light source 101 switches the wavelength in the device with built-in the wavelength variable light source. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a wavelength-tunable light source built-in device that incorporates a wavelength-tunable light source that oscillates at various wavelengths and a wavelength-tunable light generation method in an optical transmission system that performs optical communication, optical switching, optical information processing, and the like.
[0002]
[Prior art]
In a flexible wavelength division multiplexing (WDM) network that freely handles light of various wavelengths, a device with a built-in wavelength variable light source that incorporates a variable wavelength light source that can oscillate at various wavelengths is required.
[0003]
FIG. 12 shows the configuration of a conventional wavelength-tunable light source built-in device. In FIG. 12, reference numeral 1001 denotes a variable wavelength light source, 1002 denotes a device with a built-in variable wavelength light source, and 1003 denotes an output optical waveguide. The tunable light source 1001 oscillates at one of a plurality of oscillatable wavelengths according to the wavelength control signal, and output light is output from the output optical waveguide 1003.
[0004]
[Problems to be solved by the invention]
In general, when the wavelength selection signal (wavelength control signal) to the wavelength tunable light source 1001 is switched, oscillation at an undesired wavelength can occur for a short period of time. (Hereinafter, such light is referred to as unnecessary light). This is shown in FIG. In the figure, the horizontal axis and the vertical axis represent time and oscillation wavelength, respectively. The horizontal line indicates that there is an output from the output optical waveguide at that wavelength within that time. First, it is assumed that not oscillate at a wavelength λ _0. At a certain time, it is assumed that a wavelength control signal for switching the wavelength from λ _{0 to} λ ₁ is given to the tunable light source 1001. Since the wavelength tunable light source 1001 can not respond instantaneously to the wavelength control signal, the wavelength variable light source 1001 after finite time Δt starts to oscillate at a desired wavelength lambda _1. In other words, oscillation occurs at an unnecessary wavelength (undesired wavelength) during the finite time Δt, so that unnecessary light is output from the output optical waveguide 1003. When this unnecessary light is output to the outside, it interferes with light of the same wavelength from other places, which is not preferable in an optical transmission system.
[0005]
The present invention has been made in view of the above points, and an object of the present invention is to block unnecessary light output to an output optical waveguide by shutting off output of unnecessary light while a wavelength tunable light source outputs unnecessary light. It is an object of the present invention to provide a wavelength tunable light source built-in device and a wavelength tunable light generation method which are designed not to output the light.
[0006]
[Means for Solving the Problems]
In order to achieve the above object, a first embodiment of the wavelength-tunable light source built-in device of the present invention is as follows.
A wavelength tunable light source capable of selecting an oscillation wavelength by a wavelength control signal, an optical gate device connected to an output unit of the wavelength tunable light source, and having a function of blocking light of an unnecessary wavelength, and connected to the gate device. An output optical waveguide and the optical gate device are cut off before the tail of the light of the wavelength before the switching of the oscillation wavelength reaches the optical gate device, and the head of the light of the switched wavelength is the optical gate. And an optical gate control signal generating means for generating an optical gate control signal that passes through the optical gate device after reaching the optical gate device.
[0007]
Here, preferably, the variable wavelength light source and the optical gate device are integrated.
[0008]
A second embodiment of the wavelength-tunable light source built-in device according to the present invention includes a wavelength-tunable light source capable of selecting an oscillation wavelength by a wavelength control signal, and a port connected to the wavelength-tunable light source and inputting an external optical signal. A wavelength conversion circuit that converts the wavelength of the external input optical signal into a wavelength corresponding to the oscillation wavelength of the variable wavelength light source, and is connected to an output port of the wavelength conversion circuit and blocks light of an unnecessary wavelength. An optical gating device having a function of performing the above operation, an output optical waveguide connected to the gating device, and the optical gating device before the tail of light having a wavelength before switching of the oscillation wavelength reaches the optical gating device. And an optical gate control signal generating means for generating an optical gate control signal for transmitting light through the optical gate after the head of the light having the switched wavelength reaches the optical gate.
[0009]
Here, preferably, the wavelength conversion circuit is a cross-phase modulation (XPM) wavelength converter using a semiconductor optical amplifier.
[0010]
Preferably, the wavelength conversion circuit is a mutual gain modulation (XGM) wavelength converter using a semiconductor optical amplifier.
[0011]
Preferably, the variable wavelength light source, the wavelength conversion circuit, and the optical gate device are integrated.
[0012]
Also, preferably, the optical gate control signal generating means, said timing t _A switching of the wavelength signal, and the time Delta] t ₀₁ that unnecessary light from the wavelength-variable light source is output by the switching of the wavelength signal, the variable wavelength The optical gate control signal is switched based on the time Δt _{AB of the} optical signal traveling the distance L from the light source to the optical gate device.
[0013]
Further, preferably, the optical gate control signal generating means sets Δt _{C as} a time from a time immediately before the end of the light of the wavelength before the switching is input to the optical gate device until the input of the wavelength, and the wavelength after the switching. of the head of light substantially immediately after time from the output from the optical gate device as Delta] t _D, and cut off the optical gate device at time _{t a} + Δt _{AB -Δt C,} time _{t a} + Δt _AB + Δt ₀₁ to transmit the optical gate device at the timing of + Delta] t _D, switching the optical gate control signal.
[0014]
In order to achieve the above object, a first embodiment of a tunable light generation method according to the present invention includes a tunable light source capable of selecting an oscillation wavelength by a wavelength control signal, and an output unit of the tunable light source, which is unnecessary. An optical gate device having a function of blocking light of various wavelengths, and a wavelength tunable light generating method of a device with a built-in wavelength tunable light source having an output optical waveguide connected to the gate device. Shutting off the optical gate device before the end of the light reaches the optical gate device, and transmitting the optical gate device after the head of the light of the switched wavelength reaches the optical gate device. Features.
[0015]
According to a second aspect of the wavelength tunable light generation method of the present invention, there is provided a wavelength tunable light source capable of selecting an oscillation wavelength by a wavelength control signal, and a port connected to the wavelength tunable light source and inputting an external optical signal. A wavelength conversion circuit that converts the wavelength of the external input optical signal into a wavelength corresponding to the oscillation wavelength of the variable wavelength light source, and is connected to an output port of the wavelength conversion circuit and blocks light of an unnecessary wavelength. In the wavelength tunable light generation method of the wavelength tunable light source built-in device having an optical gate device having a function of performing the above operation and an output optical waveguide connected to the gate device, the last light of the wavelength before switching the oscillation wavelength is The optical gate device is shut off before reaching the optical gate device, and the head of the light having the switched wavelength is transmitted through the optical gate device after reaching the optical gate device.
[0016]
Here, preferably, the timing t _A switching of the wavelength signal, and the time Delta] t ₀₁ that unnecessary light from the wavelength-variable light source is output by the switching of the wavelength signals, from the wavelength-variable light source to the optical gate device The optical gate control signal is switched based on the time Δt _{AB of the} optical signal traveling the distance L.
[0017]
Preferably, the time from when the last of the light of the wavelength before the switching is input to the optical gate device until immediately before the input is Δt _C, and the head of the light of the wavelength after the switching is the optical gate device. as Delta] t _D substantially immediately after time from the output from the time _{t a} + Δt _AB at the timing of -.DELTA.t _C to block the optical gate device, the optical gate device at time _{t a + Δt AB + Δt 01} + Δt D The optical gate control signal is switched so as to transmit light.
[0018]
Preferably, the optical gate control signal is switched by setting the time Δt _AB to zero in accordance with the integration of the wavelength-tunable light source built-in device.
[0019]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
[0020]
[First Embodiment]
FIG. 1 shows a configuration of a wavelength-tunable light source built-in device according to a first embodiment of the present invention. In FIG. 1, reference numeral 101 denotes a wavelength variable light source, 102 denotes a device with a built-in wavelength variable light source, 103 denotes an output optical waveguide, and 104 denotes an optical gate device. The light output from the wavelength tunable light source 101 reaches the optical gate device 104. In a steady state where the wavelength is not changed, the optical gate device 104 is in a transmission state.
[0021]
The transmission and shielding timings of the optical gate device 104 will be described with reference to FIGS. The horizontal axis and the vertical axis in FIG. 2 indicate the position (location) and oscillation wavelength between the wavelength variable light source and the optical gate device, respectively. The horizontal line indicates that light is present at that position (location) at that time.
[0022]
It is assumed that the wavelength tunable light source 101 oscillates at the wavelength λ ₀ at _first , and then switches from the wavelength λ ₀ to the wavelength λ ₁ . Further, it is assumed that the optical gate unit 104 is initially in a transmission state by the optical gate control signal. In FIG. 2, the position of the wavelength variable light source 101 is described as a point A, and the position of the optical gate device 104 is described as a point B.
[0023]
Now, the results gave the wavelength control signal to the variable wavelength light source 101, the wavelength variable light source 101, and stopped the oscillation wavelength lambda ₀ to time t _A [in Fig. 2 (a)].
[0024]
Variable wavelength light source 101 (a Delta] t ₀₁₎ is the time the unnecessary light after outputting, and starts oscillation at a desired wavelength lambda ₁ [in FIG. 2 (b)]. That is, at time t _A + Δt ₀₁ , oscillation starts at the desired wavelength λ ₁ . Assuming that the average speed of the light is v, at this time, the tail of the light of the wavelength λ ₀ before switching is advanced by the distance v · Δt ₀₁ .
[0025]
On the other hand, assuming that the time required for the light to reach the optical gate device 104 from the wavelength tunable light source 101 is Δt _AB , at the time t _A + Δt _AB , the tail of the light (wavelength λ ₀ ) of the wavelength before switching is just The light will reach the optical gate 104. Assuming that the distance between the wavelength variable light source 101 and the optical gate unit 104 is L, Δt _AB = L / v can be written. FIG. 2C shows a state immediately before the end of the light (wavelength λ ₀ ) of the wavelength before switching (wavelength λ ₀ ) reaches the optical gate 104 (time t _A + Δt _AB −t _C ).
[0026]
FIG. 2D shows a state immediately after the head of the light (wavelength λ ₁ ) after the switching arrives at the optical gate device 104 (time t _A + Δt _AB + Δt ₀₁ + Δt _D ). As shown in FIG. 2D, it can be understood that unnecessary light is output to the outside of the wavelength-variable light source built-in device 102 when the optical gate device 104 is kept in a transmission state without being controlled.
[0027]
Here, at time t _A + Δt _AB −Δt _C, it is assumed that the optical gate device 104 is in a state of being cut off from transmission and at time t _A + Δt _AB + Δt ₀₁ + Δt _D, that the optical gate device 104 is in a state of being cut off and transmitting. . That is, just before the tail of the light of wavelength λ ₀ before switching reaches the optical gate device 104, the light is blocked by switching the optical gate device 104 to the blocking state, and the light of wavelength λ ₁ after the switching is switched off. Immediately after the head reaches the optical gate device 104, it is assumed that the optical gate device 104 is switched to the transmission state and light is transmitted.
[0028]
FIG. 3 shows the situation at time t _A + Δt _AB + Δt ₀₁ + Δt _D in that case. As shown in FIG. 3, when the optical gate device 104 is appropriately controlled by an optical gate control signal, unnecessary light is not output from the wavelength-variable light source built-in device 102.
[0029]
Note that FIG. 2 and FIG. 3 is drawn for the case of Δt _AB> Δt _01, may be a Δt _AB <Δt _{0 1.} Further, the variable wavelength light source 101 and the optical gate device 104 may be integrated. At that time, since it can be considered that L ≒ 0, the time Δt _AB can be made substantially zero.
[0030]
FIG. 4 shows the time dependency of the optical output of the wavelength tunable light source built-in device 102. FIG. 4A shows a case where the optical gate device 104 is kept in a transmission state. It can be seen that unnecessary light is output during the time Δt ₀₁ . FIG. 4C shows the optical output when the optical gate control signal of FIG. It can be seen that no unnecessary light is output from the wavelength-variable light source built-in device 102 at all.
[0031]
As the variable wavelength light source 101, a distributed Bragg reflector (DBR) laser, a superstructure grating (SSG) DBR laser, a GCSR (Grating-assisted relayed external recognized radiation relay) Any device can be used as long as it oscillates light of various wavelengths, such as a resonator type laser and a distributed feedback laser (DFB) with a temperature control mechanism.
[0032]
As an example of the wavelength tunable light source 101, FIG. 5A shows a cross-sectional structure of a distributed reflection (DBR) laser. Here, reference numeral 501 denotes an active region, 502 denotes a distributed reflection region, 503 denotes a drive electrode, and 504 denotes a wavelength control electrode. A current is injected into the active region 501 via the driving electrode 503 to cause laser oscillation. Further, a current is injected into the distributed reflection region 502 via the wavelength controlling electrode 504 to change the refractive index. Since the reflection wavelength in the distributed reflection region 502 changes due to the change in the refractive index, the oscillation wavelength of the laser can be changed.
[0033]
FIG. 5B shows a typical example of the dependency of the oscillation wavelength of the above-mentioned distributed reflection (DBR) laser on the wavelength control current. From the figure, it is understood that the oscillation wavelength can be controlled by controlling the current value of the wavelength control current.
[0034]
As the optical gate device 104, an optical gate device using a semiconductor optical amplifier (SOA), an optical gate device using electroabsorption (EA), or the like is used to transmit or block light intensity. Anything that has a function may be used.
[0035]
As an example of the optical gate device 104, FIG. 6 shows a cross-sectional structure of an optical gate device using a semiconductor optical amplifier. Here, 601 is an active region, and 602 is an electrode. When a current is injected into the active region 601 via the electrode 602, the input light is amplified by the active region 601 and the gate is in a transmission state. On the other hand, when no current is injected into the active region 601, the active region 601 serves as a loss medium, so that input light causes a loss and the gate is cut off.
[0036]
[Second embodiment]
FIG. 7 shows a configuration of a wavelength-tunable light source built-in device according to the second embodiment of the present invention. In FIG. 7, reference numeral 705 denotes an input optical waveguide, and 706 denotes a wavelength conversion circuit.
[0037]
The optical signal input from the input optical waveguide 705 is converted into a wavelength corresponding to the oscillation wavelength of the variable wavelength light source 101 in the wavelength conversion circuit 706 and output. Hereinafter, this output optical signal is referred to as a wavelength-converted optical signal. The wavelength-converted optical signal output from the wavelength conversion circuit 706 enters the optical gate device 104.
[0038]
Since the wavelength tunable light source 101 can oscillate for a short time at an undesirable wavelength when the oscillation wavelength is switched, the wavelength of the wavelength-converted optical signal is also undesirable during that time. Therefore, as in the above-described first embodiment of the present invention, while the wavelength conversion circuit 706 is outputting light having an undesired wavelength, the optical gate control signal is switched to shut off the optical gate unit 104 to thereby shut off the optical gate unit 104. , So that light of an undesired wavelength is not output to the output optical waveguide 103.
[0039]
Note that the wavelength tunable light source 101, the wavelength conversion circuit 706, and the optical gate device 104 may be integrated.
[0040]
The wavelength conversion circuit 706 is realized by using, for example, a cross-phase modulation (XPM) wavelength converter or a cross-gain modulation (XGM) wavelength converter using a semiconductor optical amplifier. it can.
[0041]
As an example of the wavelength conversion circuit 706, FIG. 8 shows a configuration example of an XPM wavelength converter. Here, 801a, 801b, and 801c are multimode interference (MMI) type couplers or directional couplers, and 802a and 802b are semiconductor optical amplifiers. The input optical signal passes through the input optical waveguide 705, enters the second multi-mode interference (MMI) coupler or the directional coupler 801b, and then enters the first semiconductor optical amplifier 802a. At this time, the refractive index of the first semiconductor optical amplifier 802a changes according to ON / OFF of each bit of the input optical signal of the first semiconductor optical amplifier 802a.
[0042]
On the other hand, it is assumed that the wavelength variable light source 101 oscillates at a wavelength (referred to as λ _CW ) according to the wavelength control signal. This oscillated light is split into two by a first multimode interference (MMI) coupler or directional coupler 801a, and one split light is split into a second multimode interference (MMI) coupler or directional coupler. The light enters the first semiconductor optical amplifying element 802a via the optical amplifier 801b, and the other branched light directly enters the second semiconductor optical amplifying element 802b. Output lights from the first semiconductor optical amplifier 802a and the second semiconductor optical amplifier 802b are recombined by a third multi-mode interference (MMI) coupler or directional coupler 801c. That is, a Mach-Zehnder interference system is formed. At this time, since the refractive index of the semiconductor optical amplifier 802a is modulated by the input signal light, the phase difference between the interference paths changes. By setting the phase difference between the interference paths to be an odd multiple or an even multiple of π when the bit of the input signal light is ON or OFF, the wavelength-converted optical signal whose wavelength has been converted to λ _CW is Output from the conversion circuit 706. At the same time, an input optical signal input from the input optical waveguide 705 is also output from the wavelength conversion circuit 706. If an input optical signal is unnecessary, an optical filter (not shown) may be arranged on the input optical waveguide 705 to remove the input optical signal.
[0043]
As another example of the wavelength conversion circuit 706, FIG. 9 shows a configuration example of a cross gain modulation type (XGM) wavelength converter. Here, 811 is an optical multiplexer, and 812 is a semiconductor optical amplifier. As the optical multiplexer 811, for example, an optical coupler or the like can be used. The input optical signal passes through the input optical waveguide 705, enters the optical multiplexer 811, and then enters the semiconductor optical amplifier 812. At this time, the gain of the semiconductor optical amplifier 812 changes in accordance with ON / OFF of each bit of the input optical signal.
[0044]
On the other hand, it is assumed that the wavelength variable light source 101 oscillates at a wavelength (referred to as λ _CW ) according to the wavelength control signal. This oscillated light passes through the optical multiplexer 811 and enters the semiconductor optical amplifier 812. At this time, the gain of the semiconductor optical amplifier 812 is modulated by the input optical signal. That is, when the bit of the input optical signal is ON and OFF, the gain is small and large, respectively. That is, the signal information of the input optical signal is inverted, and the wavelength conversion optical signal whose wavelength has been converted to λ _CW is output from the wavelength conversion circuit 706. At the same time, an input optical signal input from the input optical waveguide 705 is also output from the wavelength conversion circuit 706 via the optical multiplexer 811 and the semiconductor optical amplifier 812. If an input optical signal is unnecessary, an optical filter (not shown) may be arranged on the input optical waveguide 705 to remove the input optical signal.
[0045]
FIG. 10 shows another configuration example of the XPM wavelength converter as the wavelength conversion circuit 706. Here, 821a, 821b, and 821c are multimode interference (MMI) couplers or directional couplers, and 822a and 822b are semiconductor optical amplifiers. The input optical signal passes through the input optical waveguide 705, enters the second multimode interference (MMI) coupler or the directional coupler 821b, and then enters the first semiconductor optical amplifier 822a. At this time, the refractive index of the first semiconductor optical amplifier 822a changes according to ON / OFF of each bit of the input optical signal.
[0046]
On the other hand, it is assumed that the wavelength variable light source 101 oscillates at a wavelength (referred to as λ _CW ) according to the wavelength control signal. The oscillated light is branched by a first multi-mode interference (MMI) type coupler or directional coupler 821a, and is incident on a first semiconductor optical amplifier 822a and a second semiconductor optical amplifier 822b. Output light from the first semiconductor optical amplifier 822a passes through a second multi-mode interference (MMI) coupler or directional coupler 821b, and output light from the second semiconductor optical amplifier 822b The light enters the third multi-mode interference (MMI) coupler or directional coupler 821c and is multiplexed again. That is, a Mach-Zehnder interference system is formed. At this time, since the refractive index of the semiconductor optical amplifier 822a is modulated by the input signal light, the phase difference between the interference paths changes. By setting the phase difference between the interference paths to be an odd or even multiple of π when the bit of the input signal light is ON or OFF, the wavelength converted optical signal whose wavelength has been converted to λ _CW can be converted into a wavelength. Output from the circuit 706. On the other hand, an input optical signal incident from the input optical waveguide 705 is not output from the wavelength conversion circuit 706.
[0047]
FIG. 11 shows another configuration example of the cross gain modulation type (XGM) wavelength converter as the wavelength conversion circuit 706. Here, 831 is a semiconductor optical amplifying element, and 832 is an optical multiplexer. As the optical multiplexer 832, for example, an optical coupler or the like can be used.
[0048]
The input optical signal passes through the input optical waveguide 705, enters the optical multiplexer 832, and then enters the semiconductor optical amplifier 831. At this time, the gain of the semiconductor optical amplifier 831 changes according to ON / OFF of each bit of the input optical signal. On the other hand, it is assumed that the wavelength variable light source 101 oscillates at a wavelength (referred to as λ _CW ) according to the wavelength control signal. This oscillation light is incident on the semiconductor optical amplifier 831. At this time, the gain of the semiconductor optical amplifier 831 is modulated by the input optical signal. That is, when the bit of the input signal light is ON and OFF, the gain is small and large, respectively. That is, the signal information of the input optical signal is inverted in the semiconductor optical amplifying element 831, and the wavelength-converted optical signal whose wavelength has been converted to λ _CW is output from the wavelength conversion circuit 706 via the optical multiplexer 832. On the other hand, an input optical signal incident from the input optical waveguide 705 is not output from the wavelength conversion circuit 706.
[0049]
(Other embodiments)
In FIG. 7, the optical gate device 104 is considered separately from the wavelength conversion circuit 706, but the wavelength conversion circuit 706 may also have the optical gate function. For example, in the example of FIG. 8, the semiconductor optical amplifier 802a and the semiconductor optical amplifier 802b also have an optical gate function.
[0050]
In the above-described second embodiment of the present invention, a cross-phase modulation (XPM) wavelength converter and a cross-gain modulation (XGM) wavelength converter using a semiconductor optical amplifying element are used as the wavelength conversion circuits. However, a wavelength converter based on another wavelength conversion method may be used. Examples thereof include four-wave mixing using a semiconductor optical amplifying element, four-wave mixing using a fiber, and a substance having second-order nonlinearity (LiNbO ₃ , KTiOPO ₄ , BaB ₂ O ₄ , 2-adaminantlamino-5). -Nitropyridine (AlGaAs) and a wavelength conversion method such as the generation of a difference frequency of LiNbO ₃ having a domain-inverted structure.
[0051]
【The invention's effect】
As described above, according to the present invention, the optical gate device is disposed at the output unit of the variable wavelength light source, and while the variable wavelength light source outputs unnecessary light, the unnecessary light is blocked by the optical gate device. Therefore, only light having a desired wavelength can be output from the output optical waveguide.
[Brief description of the drawings]
FIG. 1 is a block diagram illustrating a configuration of a wavelength-tunable light source built-in device according to a first embodiment of the present invention.
FIG. 2 is a conceptual diagram showing position (location) dependence of light output in the apparatus of FIG.
FIG. 3 is a conceptual diagram showing the position (location) dependency of the light output, continued from FIG. 2;
FIG. 4 is a timing chart showing a relationship between a time dependency of an optical output and a control timing of an optical gate device in the apparatus of FIG. 1;
5A is a longitudinal sectional view showing the configuration of a branch reflection type (DBR) laser as an example of the wavelength tunable light source 101 in FIG. 1, and FIG. 5B is a characteristic diagram showing the relationship between the wavelength control current and the output wavelength. It is.
FIG. 6 is a longitudinal sectional view showing a configuration of an optical gate device using a semiconductor optical amplifier as the optical gate device of FIG.
FIG. 7 is a block diagram illustrating a configuration of a wavelength-tunable light source built-in device according to a second embodiment of the present invention.
8 is a block diagram illustrating a configuration of a cross-phase modulation (XPM) wavelength converter that is an example of the wavelength conversion circuit of FIG. 7;
9 is a block diagram illustrating a configuration of a cross gain modulation (XGM) wavelength converter that is another example of the wavelength conversion circuit of FIG. 7;
FIG. 10 is a block diagram showing a configuration of a cross-phase modulation (XPM) wavelength converter as still another example of the wavelength conversion circuit of FIG. 7;
11 is a block diagram illustrating a configuration of a cross gain modulation (XGM) wavelength converter that is still another example of the wavelength conversion circuit of FIG. 7;
FIG. 12 is a block diagram showing a configuration of a conventional wavelength-tunable light source built-in device.
FIG. 13 is a timing chart showing an optical output of a conventional device with a built-in variable wavelength light source.
[Explanation of symbols]
101 Wavelength variable light source 102 Wavelength variable light source built-in device 103 Output optical waveguide 104 Optical gate device 501 Active region 502 Distributed reflection region 503 Driving electrode 504 Wavelength control electrode 601 Active region 602 Electrode 705 Input optical waveguide 706 Wavelength conversion circuit 801a -801c Multi-mode interference (MMI) coupler or directional coupler 802a, 802b Semiconductor optical amplifier 811 Optical multiplexer 812 Semiconductor optical amplifier 821a-821c Multi-mode interference (MMI) coupler or directional coupler 822a, 822b Semiconductor optical amplifying element 831 Semiconductor optical amplifying element 832 Optical multiplexer 1001 Variable wavelength light source 1002 Built-in variable wavelength light source device 1003 Output optical waveguide

Claims (13)

A wavelength tunable light source capable of selecting an oscillation wavelength by a wavelength control signal,
An optical gate device connected to the output unit of the variable wavelength light source, and having a function of blocking light of an unnecessary wavelength,
An output optical waveguide connected to the gate device,
The optical gate device is cut off before the tail of the light of the wavelength before the switching of the oscillation wavelength reaches the optical gate device, and the head of the light of the wavelength after the switching reaches the optical gate device after the switching. An optical gate control signal generating means for generating an optical gate control signal for transmitting through the optical gate device. The device with a built-in wavelength tunable light source according to claim 1, wherein the wavelength tunable light source and the optical gate device are integrated. A wavelength tunable light source capable of selecting an oscillation wavelength by a wavelength control signal,
A wavelength conversion circuit that is connected to the wavelength tunable light source and has a port for inputting an external optical signal, and that converts the wavelength of the external input optical signal into a wavelength corresponding to the oscillation wavelength of the wavelength tunable light source;
An optical gate device connected to the output port of the wavelength conversion circuit and having a function of blocking light of an unnecessary wavelength,
An output optical waveguide connected to the gate device,
The optical gate device is cut off before the tail of the light of the wavelength before the switching of the oscillation wavelength reaches the optical gate device, and the head of the light of the wavelength after the switching reaches the optical gate device after the switching. An optical gate control signal generating means for generating an optical gate control signal for transmitting through the optical gate device. 4. The wavelength tunable light source built-in device according to claim 3, wherein the wavelength conversion circuit is a cross phase modulation (XPM) wavelength converter using a semiconductor optical amplifier. 4. The wavelength tunable light source built-in device according to claim 3, wherein the wavelength conversion circuit is a mutual gain modulation (XGM) wavelength converter using a semiconductor optical amplifier. 6. The wavelength-tunable light source built-in device according to claim 3, wherein the wavelength-tunable light source, the wavelength conversion circuit, and the optical gate device are integrated. Said optical gate control signal generating means, said timing t _A switching wavelength signals, and said wavelength variable time unwanted light is output from the light source Delta] t ₀₁ by the switching of the wavelength signal, the optical gate from said variable wavelength light source The wavelength-tunable light source built-in device according to any one of claims 1 to 6, wherein the optical gate control signal is switched based on a time Δt _{AB of the} optical signal traveling a distance L to the device. The optical gate control signal generation means sets Δt _{C as} a time from a time immediately before the last light of the wavelength before the switching is input to the optical gate device to an input of the wavelength, and the head of the light of the wavelength after the switching is Δt _C. Assuming that a time almost immediately after output from the optical gate unit is Δt _D , the optical gate unit is shut off at a timing of time t _A + Δt _AB −Δt _{C, and at} a timing of time t _A + Δt _AB + Δt ₀₁ + Δt _D. 8. The wavelength-tunable light source built-in device according to claim 7, wherein the optical gate control signal is switched so as to transmit through the optical gate device. A wavelength tunable light source capable of selecting an oscillation wavelength by a wavelength control signal,
A wavelength tunable device with a built-in wavelength tunable light source having an optical gate device connected to the output unit of the wavelength tunable light source and having a function of blocking light of an unnecessary wavelength, and an output optical waveguide connected to the gate device; In the light generation method,
Before the end of the light of the wavelength before the switching of the oscillation wavelength reaches the optical gate device, the optical gate device is shut off,
A wavelength tunable light generating method, wherein the light having the switched wavelength is transmitted through the optical gate device after reaching the optical gate device. A wavelength variable light source capable of selecting an oscillation wavelength by a wavelength control signal, a port connected to the wavelength variable light source, and having a port for inputting an optical signal from the outside, wherein the wavelength of the external input optical signal is A wavelength conversion circuit for converting to a wavelength corresponding to the oscillation wavelength, an optical gate device connected to an output port of the wavelength conversion circuit, and having a function of blocking light of an unnecessary wavelength, and an output connected to the gate device. In the wavelength tunable light generation method of the wavelength tunable light source built-in device having an optical waveguide for,
Before the end of the light of the wavelength before the switching of the oscillation wavelength reaches the optical gate device, the optical gate device is shut off,
A wavelength tunable light generating method, wherein the light having the switched wavelength is transmitted through the optical gate device after reaching the optical gate device. The switching timing t _A of the wavelength signal, the time Δt ₀₁ during which unnecessary light is output from the variable wavelength light source due to the switching of the wavelength signal, and the optical signal traveling the distance L from the variable wavelength light source to the optical gate device. 11. The method according to claim 9, wherein the optical gate control signal is switched based on the time Δt _AB . The time from when the tail of the light of the wavelength before the switching is almost immediately before input to the optical gate unit until it is input is Δt _C, and after the head of the light of the wavelength after the switching is output from the optical gate unit. almost immediately after the time as Delta] t _D, and cut off the optical gate device at time _{t a} + Δt _{AB -Δt C,} so as to transmit the optical gate device at time _{t a + Δt AB + Δt 01} + Δt D of The method according to claim 11, wherein the optical gate control signal is switched. 13. The tunable light generation method according to claim 12, wherein the optical gate control signal is switched by setting the time Δt _AB to zero in accordance with the integration of the tunable light source built-in device.

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