JP4115292B2 - Semiconductor optical device for wavelength division multiplexing - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a semiconductor optical device for wavelength division multiplexing (WDM), and more particularly to a semiconductor optical device for wavelength division multiplexing according to a wavelength grid stabilization technique for a semiconductor optical device used in a WDM communication system.
[0002]
[Prior art]
As one of the measures to cope with high speed and large capacity of communication systems in recent years, research on wavelength division multiplexing (WDM) system that superimposes and transmits optical signals with different wavelengths on a single optical fiber is actively conducted. However, some commercialization has begun. Furthermore, research on lightwave networks that route signals as they are is progressing, and the use of optical wavelength information for the identification and switching of signals at routing points (nodes) is being studied. In such a system, since the wavelength of light is used as a signal identification, its stability and controllability are important.
[0003]
A typical device that performs identification and separation based on the wavelength of light is an arrayed waveguide grating (AWG). By arranging optical waveguides with slightly different optical path lengths, it is possible to cause a phase shift of light to interfere and guide light to different optical waveguides for each wavelength. In this way, it is possible to separate signals of a plurality of wavelengths superimposed in the WDM system. Moreover, it is possible to multiplex light of different wavelengths propagating through a plurality of different waveguides into one waveguide by an operation principle completely opposite to this.
[0004]
At this time, the wavelength of the light to be multiplexed / demultiplexed by the AWG is determined by the optical path length difference of the arrayed waveguide, but since this optical path length depends on the refractive index of the waveguide medium, in order to control the wavelength grid of the AWG, It is necessary to control the temperature of the element to stabilize the refractive index. The AWG that has been mainly used so far uses a quartz optical waveguide, so the temperature fluctuation of the refractive index due to temperature is small, and the element itself does not generate heat. A method of making the temperature constant is used.
[0005]
On the other hand, in recent years, research on AWG using a semiconductor as an optical waveguide medium has been actively conducted. This is a monolithically integrated semiconductor device such as a semiconductor optical amplifier (SOA) or an electroabsorption optical modulator (EAM), which enables a very small and multifunctional optical semiconductor device. This is because it can be realized.
[0006]
Major examples thereof include a semiconductor optical device in which semiconductor AWGs 401 and 402 and SOAs 403 and 404 are monolithically integrated as in the wavelength selector shown in FIG. 4 (see, for example, Non-Patent Document 1), and multi-wavelength light shown in FIG. A semiconductor optical device in which semiconductor AWGs 501, SOA 502, and EAM 503 are monolithically integrated like a modulation device (for example, see Non-Patent Document 2) has been reported.
[0007]
In these elements, SOA and EAM are monolithically integrated together with AWG, so the chip itself generates heat due to Joule heating due to the injection current to these elements and the current when applying an electric field, etc. In comparison, temperature control is difficult.
[0008]
In a device that monolithically integrates such functional elements that generate heat, the amount of heat generated by the chip itself varies depending on the operating conditions such as the amount of injected current, and thus a temperature shift due to this must be calibrated. However, in a monolithically integrated semiconductor device, it is difficult to mount the thermistor directly on the semiconductor chip.
[0009]
Therefore, as shown in FIG. 6, a temperature calibration method is adopted in which the semiconductor device 604 and the thermistor 605 are respectively fixed to the heat sink 603 on the Peltier 602 with solder and the temperature is made constant by the Peltier element by monitoring the temperature with the thermistor. It is done. In this case, since the temperature monitored by the thermistor 605 is the temperature of the heat sink 603, the temperature of the semiconductor device 604 is indirectly measured. In particular, in a device having a semiconductor AWG that has a large refractive index change with temperature, the setting accuracy is not sufficient.
[0010]
For this reason, when matching the AWG to the wavelength grid, it is necessary to actually input dummy signal light having the same wavelength as the optical signal and control (calibrate) the temperature while monitoring the output signal of the dummy signal light. In addition, if the operating conditions such as the amount of current injected into the SOA are changed after setting, it is necessary to perform temperature calibration again using dummy input light, which is a problem when dealing with long-term continuous operation or changes in operating conditions. It is possible that
[0011]
[Non-Patent Document 1]
N. Kikuchi et al., “64-channel WDM channel selector”, 27 ^th European Conference on Optical Communication (ECOC2001)
[0012]
[Non-Patent Document 2]
Y. Suzaki other, "DWDM Monolithic Photonic Integrated Circuit" , 14 th Indium Phosphide and Related Materials Conference (IPRM2002)
[0013]
[Problems to be solved by the invention]
In a WDM semiconductor optical device using an AWG that monolithically integrates elements that generate heat, even if there is a change in the amount of heat generated by the element, in order to keep the AWG wavelength grid consistent with the WDM wavelength channel, the element ( In particular, control is required to keep the temperature of AWG) constant. In the conventional method, since it is necessary to control (calibrate) while inputting a dummy signal and monitoring the output signal, it is difficult to always monitor and control in actual use.
[0014]
The present invention has been made in view of such problems. The object of the present invention is to perform continuous monitoring and continuous control under actual use conditions even when the operating conditions of the heating element are changed without using a dummy signal. An object of the present invention is to provide a semiconductor optical device for wavelength division multiplexing that can be realized.
[0015]
[Means for Solving the Problems]
In order to achieve such an object, the wavelength division multiplexing semiconductor optical device of the present invention is a wavelength division multiplexing semiconductor optical device in which semiconductor elements are monolithically integrated, and the wavelength input to the signal light input port. An arrayed waveguide grating (AWG) that demultiplexes the multiplexed signal light into individual wavelength light, combines the individual wavelength light, and outputs the wavelength-division multiplexed signal light to the signal light output port; A light generating means for generating light , controlling the intensity of light of each wavelength demultiplexed by the AWG and output from the demultiplexing output port, and the light of the controlled individual wavelength by the AWG A semiconductor optical amplifier (SOA) that inputs to a multiplexing input port for multiplexing, the light generated by the light generating means is amplified spontaneous emission light (ASE), and the ASE is the demultiplexing output port or the A light generating means to be inputted to the AWG through any wave input port, the light generated by said light generating means, a light composed of the ASE spectrum input to the AWG, the signal light input port The signal light input to the signal light and the signal light output to the signal light output port are extracted and output as ASE light that is different from the signal light, and the ASE light that is the other light is monitored. And an optical output means for adjusting the temperature of the optical device (corresponding to Embodiments 1 to 3 and FIGS. 1 to 3).
[0017]
Further, the light output means, a light composed of the spectrum of the ASE inputted into the through the demultiplexer output port AWG, and the signal light output to the signal light output port which is another optical ASE The light is output to the signal light output port (corresponding to Embodiment 1 and FIG. 1).
[0018]
With the above configuration, when the AWG that demultiplexes the WDM signal light and the AWG that is multiplexed when output are performed with the same AWG, amplified spontaneous emission light having a wavelength spectrum different from the wavelength of the signal light output ( As ASE (amplified spontaneous emission) output, it can be extracted as a wavelength multiplexed signal at the same output port. This is the same function as a case where signals from different input ports are multiplexed with respect to the same output port (Embodiment 1).
[0019]
The optical output means outputs light having the spectrum of the ASE input to the AWG through the demultiplexing output port to the signal light input port, and from the output light to the signal light input port. It is characterized in that ASE light , which is light different from the input signal light, is output (corresponding to Embodiment 2 and FIG. 2).
[0020]
With the above configuration, when demultiplexing and multiplexing of WDM signal light are performed by the same AWG, it is possible to extract the ASE output as an optical output in the reverse direction to the signal light input port. In this case, ASE is output as a spectrum having the same wavelength as the signal light wavelength, but since the propagation direction is reversed, the signal light input and the ASE output can be separated externally using a circulator or the like (embodiment). 2).
[0021]
Further, the light output means outputs the ASE light which is the different light to a port different from the signal light input port and the signal light output port (corresponding to Embodiment 3 and FIG. 3). ).
[0022]
With the above configuration, it is possible to create an ASE output port on the AWG. In this case, as a matter of course, it is possible to extract the ASE output independent of the signal light (Embodiment 3).
[0023]
In addition, embodiment and figure number corresponding to a claim are shown by (). However, the constituent elements described in the claims are not limited to the constituent parts in the embodiment of the above () part.
[0024]
With the above configuration of the present invention, when an AWG is used as an element for multiplexing / demultiplexing a wavelength-multiplexed signal, each position of the input optical port and the output optical port, which is one of the features of the AWG, is input / output. By utilizing the fact that it depends on the wavelength difference of light and does not depend on the absolute value of the wavelength of the light, it is possible to output the ASE output to a wavelength different from the original signal light output or to another port.
[0025]
The ASE output extracted separately from the signal light with the above configuration is determined by the filter characteristics of the AWG. Also, because of the operating principle that AWGs multiplex and demultiplex due to light interference, the wavelength (frequency) intervals of output ports are equal. Therefore, by aligning the peak position of the ASE output spectrum with the wavelength grid, the AWG grid can be matched with the wavelength grid for the signal light.
[0026]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In addition, the same code | symbol is attached | subjected to the location which has the same function in each drawing, and duplication of description is abbreviate | omitted.
[0027]
[Embodiment 1]
FIG. 1 is an explanatory diagram of a WDM semiconductor optical device according to the first embodiment, and shows an outline when an ASE output wavelength-multiplexed at a signal light output port is taken out. An embodiment in which an ASE signal is extracted from an output port 105 in the WDM semiconductor optical device 100 using the same AWG 106 for multiplexing and demultiplexing will be described with reference to FIG. In the figure, reference numeral 100 is a WDM semiconductor optical device, 101 is a WDM signal light input port, 102 is a demultiplexing output port, 103 is SOA, 104 is a multiplexing input port, and 105 is a multiplexing output port (also an ASE output port). 106 is an AWG.
[0028]
The wavelength-multiplexed optical signal is input to the WDM signal light input port 101 of the AWG 106, demultiplexed for each wavelength at the demultiplexing output port 102, and guided to different optical waveguides. In each waveguide, an SOA 103 that enables switching and amplification of light intensity is arranged. The light amplified here is input to another port of the multiplexing input port 104 of the same AWG 106 again, and is multiplexed at one port of the multiplexing output port 105. When a current flows through the SOA 103, an ASE in which spontaneous emission light from the SOA 103 is amplified is generated regardless of the presence or absence of signal light input, and this is combined with the AWG 106 for multiplexing the incident optical signal. In addition to being incident on the wave input port 104, it is also incident on the demultiplexing output port 102 that is demultiplexed and output from the AWG 106 toward the SOA 103.
[0029]
At this time, the ASE traveling in the direction opposite to the traveling direction of the signal light from the demultiplexing output port 102 travels through the arrayed waveguide from the demultiplexing output port 102 to the multiplexing output port 105 and is multiplexed by the AWG 106. The optical signals from different ports (wavelengths) of the demultiplexing output port 102 are wavelength multiplexed and output to the multiplexing output port 105. The ASE spectrum at this time has a wavelength spectrum of light corresponding to the combined output port 105 in order to reflect the filter characteristics of the AWG 106. Since the wavelength spectrum of the ASE at this time depends only on the position of the ports (demultiplexing output port 102, multiplexing output port 105, etc.) coupled to the AWG 106, the input / output ports (demultiplexing output port 102, multiplexing output port) 105), the wavelength of the ASE output spectrum can be determined arbitrarily.
[0030]
[Embodiment 2]
FIG. 2 is an explanatory diagram of the WDM semiconductor optical device according to the second embodiment, and shows an outline in the case where the ASE output is extracted by running backward to the signal light input port. An embodiment in which an ASE signal is extracted to the input port 201 in the WDM semiconductor optical device 200 using the same AWG 207 for multiplexing and demultiplexing will be described with reference to FIG. In the figure, reference numeral 200 denotes a WDM semiconductor optical device, 201 denotes a WDM signal light input port (also ASE output port), 202 denotes a demultiplexing output port, 203 denotes an SOA, 204 denotes a multiplexing input port, and 205 denotes a multiplexing output port. 206 is a circulator, and 207 is an AWG.
[0031]
The wavelength-multiplexed optical signal is first input to the WDM signal light input port 201 of the AWG 207 through the circulator 206, demultiplexed for each wavelength at the demultiplexing output port 202, and guided to different optical waveguides. Each of the waveguides is provided with an SOA 203 that enables switching and amplification of light intensity. The light amplified here is input again from another port of the multiplexing input port 204 of the same AWG 207 and multiplexed into one port of the multiplexing output port 205. When a current flows through the SOA 203, an ASE occurs regardless of the presence or absence of signal light input, which is incident on the multiplexing input port 204 to the AWG 207 for multiplexing the incident optical signal and separated. The light is also incident on the demultiplexing output port 202 that is output from the AWG 207 toward the SOA 203.
[0032]
The ASE traveling in the direction opposite to the traveling direction of the signal light from the demultiplexing output port 202 propagates in the reverse direction through the AWG 207 along the same path as when the signal light is demultiplexed (from the demultiplexing output port 202 to the WDM signal light). It travels through the arrayed waveguide to the input port 201) and is multiplexed and output to the WDM signal light input port 201. Then, it can be taken out as an ASE output through the circulator 206.
[0033]
[Embodiment 3]
FIG. 3 is an explanatory diagram of the WDM semiconductor optical device according to the third embodiment, and shows an outline when an ASE output port is fabricated in the AWG. An embodiment in which a port 307 for extracting an ASE signal is attached to the AWG 306 will be described with reference to FIG. In addition, this is the case where the AWG is shared by multiplexing and demultiplexing (the same AWG is used for multiplexing and demultiplexing as in the first and second embodiments) and when each is used (the AWG is combined and demultiplexed). And use different AWGs).
In the figure, reference numeral 300 is a WDM semiconductor optical device, 301 is a WDM signal light input port, 302 is a demultiplexing output port, 303 is SOA, 304 is a multiplexing input port, 305 is a multiplexing output port, 306 is an AWG, and 307 is ASE output port.
[0034]
The wavelength-multiplexed optical signal is input to the WDM signal light input port 301 of the AWG 306, demultiplexed for each wavelength at the demultiplexing output port 302, and guided to different optical waveguides. Each of the waveguides is provided with an SOA 303 that enables switching and amplification of light intensity. The light amplified here is input again from another port of the multiplexing input port 304 of the same AWG 306 and multiplexed at one port of the multiplexing output port 305. When a current flows through the SOA 303, an ASE occurs regardless of the presence or absence of signal light input, which is incident on the multiplexing input port 304 to the AWG 306 for multiplexing the incident optical signal, and is separated. The light is also incident on the demultiplexing output port 302 that is output from the AWG 306 toward the SOA 303.
[0035]
An ASE output port 307, which is a multiplexing port for extracting these ASE signals, is prepared in the AWG 306, so that an ASE output port 307 having a wavelength spectrum different from that of the output signal light is different from that of the combined output port 305. The output can be taken out.
[0036]
That is, the ASE traveling in the direction opposite to the traveling direction of the signal light from the demultiplexing output port 302 travels through the arrayed waveguide from the demultiplexing output port 302 to the ASE output port 307 and is multiplexed by the AWG 306, and then demultiplexed. Wavelength multiplexed as an optical signal from the wave output port 302 is output to the ASE output port 307.
[0037]
Note that this ASE output port 307 can be produced for both the AWG on the multiplexing side and the AWG on the demultiplexing side when separate AWGs are used for the AWG for multiplexing and demultiplexing.
[0038]
[Effect of the embodiment]
If the WDM semiconductor optical device configured as in Embodiments 1 to 3 described above is used, the spectrum of ASE multiplexed and output as signals of different wavelength spectra is monitored, so that it is completely independent of the signal light. It is possible to confirm the wavelength grid of AWG. By controlling the temperature of the element so that the peak wavelength of the ASE output having the spectrum of this AWG wavelength grid is always constant, the wavelength grid can always be monitored and controlled.
[0039]
In the temperature calibration method shown in FIG. 6 according to the above-described conventional technology, this is replaced with the conventional control (calibration) in which a dummy signal is input and the output signal is monitored. What is necessary is just to monitor the spectrum of ASE in ~ 3.
[0040]
For this reason, the AWG wavelength grid can always be controlled to be constant regardless of the presence or absence of input signal light, and regardless of changes in the operating conditions of elements that generate heat, such as SOA, even under actual usage conditions. It becomes.
[0041]
【The invention's effect】
As described above, according to the present invention, the semiconductor optical device for wavelength division multiplexing in which the semiconductor elements are monolithically integrated, converts the wavelength division multiplexed signal light input to the signal light input port into light of each wavelength. An arrayed waveguide grating (AWG) that demultiplexes and combines the light of each wavelength and outputs the wavelength division multiplexed signal light to the signal light output port, light generating means for generating light, and generated thereby Light output means for extracting and outputting signal light input to the signal light input port and light different from the signal light output to the signal light output port.
[0042]
As a result, if the semiconductor optical device for wavelength division multiplexing according to the present invention is used, it is possible to check the AWG wavelength grid completely independently of the signal light by monitoring the other light. By controlling the temperature of the element so that the peak wavelength of the other light having the spectrum of the AWG wavelength grid is always constant, the wavelength grid can always be monitored and controlled.
[0043]
For this reason, it is possible to constantly monitor and constantly control even when the operating conditions of the heating element are changed without using a dummy signal under the actual use state.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram of a WDM semiconductor optical device according to a first embodiment of the present invention.
FIG. 2 is an explanatory diagram of a WDM semiconductor optical device according to a second embodiment of the present invention.
FIG. 3 is an explanatory diagram of a WDM semiconductor optical device according to a third embodiment of the present invention.
FIG. 4 is a diagram illustrating a conventional wavelength selector.
FIG. 5 is a diagram showing a conventional multi-wavelength light modulation element.
FIG. 6 is a diagram showing a conventional temperature calibration method.
[Explanation of symbols]
100, 200, 300 WDM semiconductor optical devices 101, 201, 301 WDM signal light input ports 102, 202, 302 Demultiplexed output ports 103, 203, 303 SOA
104, 204, 304 Combined input port 105, 205, 305 Combined output port 106, 207, 306 AWG
206 Circulator

Claims (4)

A semiconductor optical device for wavelength division multiplexing in which semiconductor elements are monolithically integrated,
The wavelength division multiplexed signal light input to the signal light input port is demultiplexed into light of each wavelength, and the light of each wavelength is combined and output to the signal light output port. An arrayed waveguide grating (AWG),
Light generating means for generating light , controlling the intensity of light of each wavelength demultiplexed by the AWG and output from the demultiplexing output port, and combining the light of the controlled individual wavelength by the AWG. A semiconductor optical amplifier (SOA) that inputs to a multiplexing input port for waves, and the light generated by the light generating means is amplified spontaneous emission light (ASE), and the ASE is the demultiplexing output port or the multiplexing output port; Light generating means input to the AWG via any of the wave input ports ;
The signal light input to the signal light input port and the signal light output to the signal light output port from the light generated by the light generation means to the light composed of the ASE spectrum input to the AWG Light output means for extracting and outputting the ASE light as another light, monitoring the ASE light as the other light, and adjusting the temperature of the optical device based on the monitoring result. Semiconductor optical device for wavelength division multiplexing. In the wavelength division multiplexing semiconductor optical device according to claim 1,
The light output means converts light having the spectrum of the ASE input to the AWG through the demultiplexing output port as ASE light that is light different from the signal light output to the signal light output port. A wavelength division multiplexing semiconductor optical device that outputs to the signal light output port. In the wavelength division multiplexing semiconductor optical device according to claim 1,
The light output means outputs light having the spectrum of the ASE input to the AWG through the demultiplexing output port to the signal light input port, and the output light is input to the signal light input port. A wavelength division multiplexing semiconductor optical device characterized in that it outputs ASE light that is different from signal light. In the wavelength division multiplexing semiconductor optical device according to claim 1,
The optical output means outputs the ASE light which is the different light to a port different from the signal light input port and the signal light output port. A wavelength division multiplexing semiconductor optical device.

Images