JP3819922B2 - Multi-wavelength batch generator - Google Patents

Description

  The present invention relates to the technical field of optical communication, and relates to an apparatus that collectively generates multi-wavelength light having a plurality of center wavelengths from light having a single center wavelength.

  Conventionally, in optical communication, as a multi-wavelength simultaneous generation method having a flat optical spectrum used for wavelength division multiplexing (WDM), a flattened continuous optical spectrum obtained by supercontinuum generation by nonlinear optical fiber transmission is used. There are a method of cutting out with an optical filter, and a method of transmitting an optical spectrum arranged on the frequency axis at a repetition frequency interval of an optical pulse obtained by generating an optical short pulse to an optical filter having a reverse frequency characteristic.

  However, in the flattened multi-wavelength generation method in Supercontinuum generation, there is a problem that it is not easy to manufacture a non-linear optical fiber, and it takes time and cost. Also, in the flattening multi-wavelength generation method in which the optical spectrum obtained by the optical short pulse generation is transmitted through the inverse characteristic optical filter, in order to realize a flat optical spectrum, the duty of the optical short pulse and the corresponding light There was a problem that it was difficult to design the transmission characteristics of the filter.

  The present invention has been made to solve the above-described problems, and by modulating light having a single center wavelength with an electric signal having a specific repetition period without designing a complicated optical circuit, An object of the present invention is to provide a multi-wavelength collective apparatus capable of generating a WDM signal having a flat optical spectrum with a simple and low-cost configuration.

  In one embodiment of the present invention for achieving the above object, incident light having a single center wavelength is modulated using a repetitive signal voltage having a predetermined period, and multi-wavelength light having a plurality of center wavelengths is collectively processed. A multi-wavelength collective generator for generating and outputting, wherein a plurality of optical paths each having an optical modulation means are coupled in series, and the first-stage optical modulation means is an amplitude modulator for receiving the incident light. And the remaining stage of the optical modulation means is a modulation unit that is a one-stage or multiple-stage phase modulator connected in series with the modulator, and adjusts the amplitude of the signal voltage to adjust the light of the modulation unit. A plurality of voltage applying means for applying to the input port of the modulation means, and a plurality of incident lights each having a different single center wavelength are arranged at a predetermined frequency, and the plurality of incident lights on the frequency axis Every other incident light of the modulator A first multiplexing means for entering and multiplexing the light modulation means at the stage, and a second multiplexing means for entering and multiplexing the rest of the plurality of incident lights every other light modulation means of the modulation section The modulation unit includes a first modulation unit that modulates multiplexed light from the first multiplexing unit and a second modulation unit that modulates multiplexed light from the second multiplexing unit. In addition, first light multiplexing / demultiplexing means for demultiplexing and multiplexing the output light from the first modulation unit for each different single center wavelength, and the output light from the second modulation unit, Second multiplexing / demultiplexing means for demultiplexing and multiplexing for each different single center wavelength, and multiplexed light having the alternate components and the second multiplexing / demultiplexing by the first multiplexing / demultiplexing means. And means for combining the remaining combined light having the remaining components by means, and the modulation section comprises a single wave The phase of the incident light is linearly modulated with respect to the signal voltage waveform applied to the input port of the light modulation means to obtain a phase modulation function, and the signal voltage is a continuous half of the predetermined period. An amplitude period that increases monotonically in a period of time and a decrease period that decreases symmetrically with the monotonic increase in the increase period in the remaining half of the continuous period. The amplitude of the modulated incident light is gated, and the amplitude is gated in a portion that is not continuous with the portion of the decrease period.

  A multi-wavelength collective device that modulates incident light having a single center wavelength by using a repetitive signal voltage of a predetermined period, and generates and outputs multi-wavelength light having a plurality of center wavelengths, respectively. A plurality of optical paths having optical modulation means are coupled in series, the first-stage optical modulation means is an amplitude modulator to which the incident light is input, and the remaining-stage optical modulation means is the modulator. A modulation unit that is a one-stage or a plurality of stages of phase modulators connected in series, and a plurality of voltage application units that adjust the amplitude of the signal voltage and apply it to the input port of the light modulation unit of the modulation unit A plurality of incident lights each having a different single center wavelength are arranged at a predetermined frequency, and each of the plurality of incident lights on the frequency axis is placed at the first stage of the modulation unit. First multiplex that enters and multiplexes into the light modulation means And a second multiplexing unit that multiplexes the remainder of the plurality of incident lights every other incident on the first-stage light modulation unit of the modulation unit, the modulation unit including the first A first modulation unit that modulates the multiplexed light from the first multiplexing unit, and a second modulation unit that modulates the multiplexed light from the second multiplexing unit, and further outputs the output light from the first modulation unit First multiplexing / demultiplexing means for demultiplexing and multiplexing each different single center wavelength, and output light from the second modulation unit is demultiplexed for each different single center wavelength and multiplexed. Second multiplexing / demultiplexing means, multiplexed light having the alternate components by the first multiplexing / demultiplexing means, and multiplexed light having the remaining alternate components by the second multiplexing / demultiplexing means. And means for combining the phase of the incident light of a single wavelength with the input of the light modulating means. The signal voltage waveform applied to the port is linearly modulated to obtain a phase modulation function, and the predetermined period includes an increasing period in which the signal voltage increases monotonously in the 1/2 continuous period, and the remaining 1 / The amplitude modulator includes a decrease period that decreases symmetrically with a monotonic increase in the increase period, and the amplitude modulator is continuous with the portion of the increase period that is closer to the decrease period and the portion of the decrease period. The amplitude of the modulated incident light is gated for a predetermined period across the portion.

  Here, the first modulation unit generates (2N + m) wavelength side modes (N is a natural number, m is an integer) at its output, and the fluctuation range of the optical power between the side modes is within a certain value. The output is flattened so that the second modulation section generates (2N−m) wavelength side modes (N is a natural number and m is an integer) at the output, and the light between the side modes is generated. The output can be flattened so that the power fluctuation range is within a certain value.

  Here, an optical amplifier can be provided in an optical path from which at least a multi-wavelength signal is output.

  Here, the amplitude modulator may simultaneously operate as a phase modulator.

  According to the present invention, one or more light modulation means arranged in a predetermined position of a plurality of optical paths including an optical path to which incident light having a single central wavelength and coupled in series are input. And a signal voltage and a signal voltage that are adjusted and applied in a configuration including a modulation unit having a plurality of voltage application units that adjust the amplitude of a signal voltage having a predetermined period and apply the amplitude to the input port of the light modulation unit Since multi-wavelength light is generated by flattening incident light according to a predetermined period of time, it is multi-wavelength light having a flat light spectrum with a simple and low-cost configuration without designing a complicated optical circuit. There is an effect that a WDM signal can be generated.

  The basic principle of the multi-wavelength batch generation apparatus according to the present invention will be described with reference to FIG.

  The apparatus of the present invention includes one or more optical modulators arranged at predetermined positions of a plurality of optical paths including optical paths that are coupled in series with each other and receive incident light having a single central wavelength. The optical modulator group 2 is provided, and a plurality of power adjusters 4 that independently adjust signal voltages of a predetermined period and apply them to the input ports of the respective optical modulators. The light source 1 generates incident light having the single center wavelength. The light modulator is preferably capable of modulating the amplitude or phase of incident light. The plurality of optical paths in the optical modulator group 2 may include paths coupled in parallel.

Here, the output electric field E (t) when the amplitude and phase of incident light having a single center wavelength are modulated by functions a (t) and b (t), respectively,
E (t) = a (t) cos (ω _c t + b (t))
The shape of the output light spectrum can be designed according to the functions a (t) and b (t). Where ω _c is the central angular frequency of incident light having a single central wavelength, and t is time.

  In the device of the present invention, an optical modulator capable of modulating the amplitude and / or phase (or both) is arranged at an arbitrary position of the optical path coupled in series and / or in parallel in the modulation unit, and the optical modulator group is arranged as follows. In order to modulate the function a (t) and / or the phase for modulating the amplitude of incident light having a single central wavelength by adjusting the power of the signal voltage of a predetermined period applied to the constituent optical modulator By appropriately setting the function b (t), it is possible to flatten the output multi-wavelength light spectrum generated in a lump as will be described in detail below.

  In addition, by arranging optical modulators in multiple stages, it is possible to perform amplitude and phase modulation with a higher degree of freedom, contributing to the improvement of flatness of the output light spectrum and increasing the bandwidth of the output light spectrum by increasing the modulation degree. The effect that can be obtained.

  Next, specific embodiments will be described.

[First embodiment]
The configuration of the first embodiment of the multi-wavelength batch generation apparatus according to the present invention is shown in FIG.

  As shown in FIG. 2, the multi-wavelength batch generation apparatus of the present embodiment includes a light source 1, an optical modulator group (modulation unit) 2 including optical modulators shown in n (≧ 1), and a repetitive periodic signal generator 3. , N power regulators 4, and n power variable DC power sources 5. The light source 1 generates light having a single center wavelength and makes it incident on an input side optical modulator in the optical modulator group 2. Each optical modulator in the optical modulator group 2 is arranged at an arbitrary position of a plurality of optical paths coupled in series and / or in parallel (arranged in series in FIG. 2), and the incident light is amplified and / or Phase modulation is also performed. Multi-wavelength light is output from the output side optical modulator.

  The repetitive periodic signal generator 3 generates a signal voltage that is repeated at a predetermined period, and this power is appropriately adjusted by the power adjuster 4 and applied to each optical modulator. Further, a power variable DC power source 5 is coupled to each optical modulator as necessary, and a bias whose power is appropriately adjusted is applied from the power variable DC power source 5. The incident light is modulated by each optical modulator based on the signal voltage and the bias, and the amplitude and / or phase of the incident light from the light source 1 is modulated.

  Here, the output optical spectrum spread on both sides of the carrier frequency due to phase modulation has a small optical power region near the carrier frequency, but by applying a pulsed gate to the time waveform by amplitude modulation, the power in that region is It can be raised to flatten the output light spectrum. The flatness of the output light spectrum is determined by the relationship between the phase modulation amount and the pulse width. In the present embodiment, a signal voltage of a predetermined period to be applied to the optical modulator is adjusted by the power adjuster 4 and a bias applied by the power variable DC power supply 5 is varied to determine the relationship between the two, thereby flatness. Is decided.

  With reference to FIG. 3 and FIG. 4, it will be described that the output light spectrum from the optical modulator group 2 can be flattened by the above configuration of the present embodiment.

  The time waveform of the output signal voltage from the repetitive periodic signal generator 3 is a mountain function as shown in FIG. When the light source light having a single center wavelength is phase-modulated according to this function, the multi-wavelength output light spectrum is as shown in FIG. This can be explained as follows.

The angular frequency of this phase modulation is a square wave that reciprocates between the instantaneous value ω _m and the instantaneous value −ω _m with a predetermined period, as shown in FIG. As shown by the solid line in FIG. 3D, when the angular frequency of this square wave is gated with a repetitive NRZ (Non Return to Zero) signal for the portion represented by the instantaneous value ω _m , the optical spectrum becomes An optical spectrum of a repeated NRZ signal represented by (e) in FIG. 3 and having an angular frequency centered at (ω _c + ω _m ) is obtained. Further, as shown in solid line in FIG. 3 (f), the angular frequency of this square wave gating similarly the portion represented by the instantaneous value - [omega] _m, the optical spectrum is in Figure 3 (g) And an optical spectrum of a repeated NRZ signal with an angular frequency centered at (ω _c −ω _m ) is obtained.

The superposition of these optical spectra on the angular frequency axis is represented by (b) in FIG. 3 in which (e) in FIG. 3 and (g) in FIG. 3 are added, and the instantaneous value ω _c of the angular frequency (center frequency) In other words, the optical spectrum intensity in the vicinity of the carrier frequency) becomes small, and flattening of the optical spectrum cannot be realized.

Therefore, adjustment using the power adjuster 4 and the power variable DC power supply 5 is performed, and flattening is performed as follows.
As shown in FIG. 4 (a), the instantaneous value omega _m and the angular frequency - considering the output light spectrum when adjusted to gating a repeating NRZ signal so as to straddle the instantaneous value omega _m.

On the other hand, similarly to the above, as shown by the solid line in FIG. 4C, when the portion represented by the instantaneous value ω _m of the angular frequency is gated with a repetitive RZ (Return to Zero) signal, The optical spectrum is represented by (d) in FIG. 4, and an optical spectrum of a repetitive RZ signal centered on the angular frequency (ω _c + ω _m ) is obtained. Also, as shown by the solid line in FIG. 4E, when the portion represented by the instantaneous value −ω _m of the angular frequency is gated with a repetitive RZ (Return to Zero) signal, the optical spectrum is as shown in FIG. The optical spectrum of the repetitive RZ signal represented by (f) and centered on the angular frequency (ω _c −ω _m ) is obtained. Both optical spectra have a wider band than the optical spectrum of the repetitive NRZ signal.

The superposition of both optical spectra on the angular frequency axis is represented by (b) in FIG. 4 and has a large optical spectrum intensity even in the vicinity of the angular frequency ω _c , resulting in a flat output light spectrum. be able to.

  According to this embodiment, the function for modulating the amplitude and phase of the light source light having a single center wavelength is set as appropriate, and the amplitude adjustment and phase modulation are performed by adjusting the power of the signal voltage and variably setting the bias accordingly. By doing so, it is possible to improve the flatness of the output light spectrum with a simple and low-cost configuration.

[Modification of First Embodiment]
FIG. 5 shows the configuration of a modification of the first embodiment of the multi-wavelength batch generation apparatus according to the present invention.

  As shown in FIG. 5, the multi-wavelength batch generation apparatus of the present modification can employ a configuration in which an optical amplifier 50 is disposed in an optical path through which multi-wavelength light is emitted from the light source 1. In the figure, optical amplifiers 50 are arranged in all of a plurality of optical paths coupled in series to each other including an optical path through which incident light from the light source 1 is input. The amplification gain of the multistage optical amplifier 50 arranged in this way compensates for the power loss caused by the incident light passing through the optical modulator and the power loss per wavelength caused by the increase in the number of wavelengths, and the output SNR. Can be greatly improved.

  However, when the optical amplifier 50 is arranged only at the subsequent stage of the optical modulator group 2 and the optical amplifier group 2 is not provided with the optical amplifier in the optical modulator group 2 and the preceding stage, the optical power loss generated at the subsequent stage of the optical amplifier 50 It is possible to prevent a decrease in SNR caused by the above. As shown in the drawing, if the optical amplifiers 50 are additionally arranged in all of the plurality of optical paths, it is possible to contribute to the improvement of the SNR of the multi-wavelength light obtained at the output.

  Further, when all of the optical modulators in the optical modulator group 2 are phase modulators, the repetitive periodic signal generator 4 generates a sum of sine wave signal voltages applied to the input ports of the respective optical modulators. By setting the value to be converted into the phase modulation index, the power deviation between channels can be suppressed.

  FIG. 6 is a characteristic diagram showing an example in which the inter-channel power deviation is changed in such a modification of the first embodiment.

  FIG. 6 shows the case where the number of channels is 7, 9, and 11. For example, in the case of 7 channels, the minimum channel of 5 to 6 dB is obtained when each sine wave signal voltage is adjusted so that the sum of the sine wave signal voltages is converted to a phase modulation index to be approximately 1.0π. Power deviation can be realized. In the case of 7 channels or 11 channels, the minimum channel-to-channel power deviation can be realized when each sine wave signal voltage is adjusted to be approximately 1.4π.

  In FIG. 4A in the first embodiment, when the gate is applied to the amplitude of the incident light that has undergone phase modulation by the mountain-shaped modulation function, the gate is gated at time intervals across the mountain-shaped modulation function. An example of realizing spectral flattening by applying. That is, in the first embodiment, the phase of the incident light having a single wavelength is linearly modulated with respect to the signal voltage waveform applied to the input port, and the period of the signal voltage is a half of the signal voltage. An increasing period (the differential coefficient of the phase modulation function is determined at this time). The signal voltage waveform was gated at the timing of (a) in FIG. 4 so as to continue over a positive period and a decreasing period (the differential coefficient of the phase modulation function is negative at this time).

  In the modification described here, it will be described with reference to FIG. 7 that the spectrum flattening of the output multi-wavelength light can also be realized by individually gating the signal voltage waveform in the increase period and the decrease period. To do.

  As already described (see (a) to (c) of FIG. 3), if the incident light is only subjected to phase modulation with a mountain-shaped modulation function, the optical power decreases near the carrier frequency, and the output multi-wavelength light The spectrum is not flattened.

  Therefore, in the modification described here, as shown in FIG. 7A, when the differential coefficient of the phase modulation function is positive (phase modulation function increasing period) and negative (phase modulation function decreasing period). Spectra flattening was realized as shown in (b) by individually gating the signal voltage waveform.

  The waveform shown in (a) is divided into two (c) and (e). By gating on the waveform shown in (c), an RZ signal spectrum is generated around the instantaneous angular frequency (ωc + ωm) as shown in (d). By gating on the waveform shown in (e), an RZ signal spectrum is generated around the instantaneous angular frequency (ωc−ωm) as shown in (f). Therefore, it can be seen from these superpositions that the spectrum of the output multi-wavelength light can be flattened as in the first embodiment by gating with the waveform shown in FIG.

  Other time waveforms can also be used as the modulation function. For example, a sinusoidal time waveform that monotonously increases and decreases at a constant cycle can be used.

[Second Embodiment]
As shown in FIG. 8, in the second embodiment of the multi-wavelength batch generation apparatus according to the present invention, an optical path coupled in parallel is provided in the optical modulator group 2a, and at least one of the optical paths (in FIG. 2) All of a plurality of optical paths coupled in parallel are provided with an amplitude modulation section 25 having a configuration in which an optical modulator is arranged. An input side optical modulator and an output side optical modulator are coupled to the amplitude modulation unit 25 in series via optical paths. Each of the plurality of optical modulators itself is a phase modulator, but the amplitude modulation unit 25 can operate as an amplitude modulator by the cooperation of each optical path (optical modulator). Is performed based on the power-adjusted signal voltage and the power-variable bias.

[Third Embodiment]
The configuration of the third embodiment of the multi-wavelength batch generation apparatus according to the present invention is shown in FIG.

  As shown in FIG. 9, the multi-wavelength collective generator of this embodiment generates a light source 1 that generates light having a single center wavelength, a bipolar Mach-Zehnder intensity modulator 20, and a signal voltage that is repeated at a predetermined period. And an oscillator 3, a power regulator 4, a variable power DC power source 5, and a phase regulator 6. The power regulator 4 and the phase regulator 6 are coupled in series with each other.

  The bipolar Mach-Zehnder intensity modulator 20 has a known configuration in which incident light is branched into two optical paths, and output light from the optical modulators arranged in each path is combined and converged to be emitted. is doing. Optical modulation means (phase modulation means) is arranged in each of the branched paths. The plurality of light modulation means, although one element itself is a phase modulation means, can perform an amplitude modulation operation by cooperating with each other. Note that, as described above, the light modulation means may be provided in both of the two optical paths, but the same action can be obtained even if provided in either one.

  The signal voltage from the oscillator 3 is appropriately adjusted by the power regulator 4 and applied to one electrode of the Mach-Zehnder intensity modulator 20. Further, the signal voltage is applied to the other electrode of the Mach-Zehnder intensity modulator 20 by adjusting the time position of both by the phase adjuster 6 and adjusting the power appropriately by the power adjuster 4. A bias appropriately adjusted in power from the power variable DC power supply 5 is also applied to the latter electrode.

  The light from the light source 1 enters the Mach-Zehnder intensity modulator 20, and the modulation operation of the incident light by the Mach-Zehnder intensity modulator 20 is performed based on the signal voltage and the bias, and the amplitude and / or phase of the light source light is modulated. .

  In the present embodiment, the Mach-Zehnder intensity modulator 20 can simultaneously modulate amplitude and phase modulation by appropriately adjusting the power of the signal voltage applied via the power regulator 4 and the bias applied from the power variable DC power supply 5. A simple configuration is realized using this.

[Fourth embodiment]
The configuration of the fourth embodiment of the multi-wavelength batch generation apparatus according to the present invention is shown in FIG.

  The multi-wavelength collective generator of this embodiment shown in FIG. 10 uses an oscillator 3a that generates a sinusoidal signal voltage as an oscillator that generates a signal voltage that is repeated at a predetermined period, instead of the oscillator 3 in the third embodiment. Furthermore, a multiplier 7 connected in series with the power regulator 4 is provided.

  With this configuration, the frequency of the signal voltage applied to both electrodes of the Mach-Zehnder intensity modulator 20 is changed. That is, the frequency of the output signal voltage of the oscillator 3a is multiplied and applied to one electrode by the multiplier 7, and the output frequency of the oscillator 3a is applied to the other electrode.

  In this embodiment, since a single-frequency sine wave signal is used as a signal voltage repeated at a predetermined period to be applied to the Mach-Zehnder intensity modulator 20, an oscillator 3a and an electric circuit (phase adjuster) to which the sine wave signal is input. 6 and the subsequent stage) can be limited in frequency band required for the electrical elements, and the cost required for these electrical elements can be suppressed. Further, by multiplying the frequency of the signal voltage by the multiplier 7, it is possible to broaden the output light spectrum.

[Fifth Embodiment]
FIG. 11 shows the configuration of a fifth embodiment of the multi-wavelength batch generation apparatus according to the present invention.

  The multi-wavelength batch generation apparatus of the present embodiment shown in FIG. 11 includes a light source 1 that generates light having a single center wavelength, a single pole Mach-Zehnder intensity modulator 20 and a phase modulator 28 coupled in series with each other. It comprises a modulator group 2c, an oscillator 3 that generates a signal voltage repeated at a predetermined period, a power regulator 4, a power variable DC power source 5, and a phase regulator 6.

  The signal voltage from the oscillator 3 is appropriately adjusted by the power regulator 4 and applied to the Mach-Zehnder intensity modulator 20. Further, the signal voltage is applied to the phase modulator 28 after the time position of the signal voltage is adjusted by the phase adjuster 6 and the power of the signal voltage is appropriately adjusted by the power adjuster 4. The Mach-Zehnder intensity modulator 20 is also applied with a bias whose power is appropriately adjusted from the power variable DC power supply 4.

  Light from the light source 1 enters the light modulator group 2c, and the modulation operation of the incident light by the light modulator group 2c is performed based on the signal voltage and the bias, and the amplitude and / or phase of the light source light is modulated. .

  In the present embodiment, since the optical modulators (Mach-Zehnder intensity modulator 20 and phase modulator 28) are arranged in two stages in series, the output light spectrum can be broadened compared to the third and fourth embodiments. Can be achieved.

  FIG. 12 shows an experimental result according to the present embodiment when a 10 GHz sine wave is used as a signal voltage repeated from the oscillator 3 at a predetermined cycle. As shown in FIG. 12, it was observed that a flatness of <3 dB can be realized for a 9-channel signal including the center wavelength of the light from the light source 1.

[Sixth Embodiment]
The sixth embodiment of the multi-wavelength collective generator according to the present invention has a configuration in which the positions of the Mach-Zehnder intensity modulator 20 and the phase modulator 28 in the fifth embodiment are switched as shown in FIG. A modulation operation similar to that of the embodiment can be performed.

  As shown in this example, even if the order of the optical modulators coupled in series with each other in the multi-wavelength batch generation apparatus of the present invention is changed, the obtained output optical spectrum is not affected, and the same effect as in the above embodiment. Can be obtained.

[Seventh Embodiment]
In the seventh embodiment of the multi-wavelength collective generator according to the present invention, an optical modulator group using an electroabsorption-type intensity modulator 200 as shown in FIG. 14 instead of the Mach-Zehnder intensity modulator 20 in the fifth embodiment. 2e. According to the multi-wavelength batch generation apparatus of the present embodiment, the same operation result as that of the fifth embodiment can be obtained as shown below.

  FIG. 15 shows an experimental result according to the present embodiment when a 10 GHz sine wave is used as a signal voltage repeated from the oscillator 3 at a predetermined period. As shown in FIG. 15, it was observed that a flatness of <3 dB can be realized for a 9-channel signal including the center wavelength of light from the light source 1 as in the fifth embodiment (FIG. 12).

[Eighth Embodiment]
In the eighth embodiment of the multi-wavelength batch generation apparatus according to the present invention, a phase modulator 28a is further added to the subsequent stage of the optical modulator group 2c in the fifth embodiment as shown in FIG.
In this configuration, a power regulator 4 and a phase regulator 6 coupled in series are added. That is, a three-stage optical modulator group is provided, and the first stage is an amplitude modulator, and the second and third stages are phase modulators.

  As a result, it is possible to obtain an output light spectrum having a wider band than that of the fifth to seventh embodiments.

[Ninth Embodiment]
As shown in FIG. 17, in the ninth embodiment of the multi-wavelength collective generator according to the present invention, an optical splitter 8 is arranged between the light source 1 and the Mach-Zehnder intensity modulator 20 in the fifth embodiment, and the Mach-Zehnder intensity modulation is performed. The optical branching device 9 is arranged between the optical modulator 20 and the phase modulator 28, and the optical branching device 8 and the optical branching device 9 are further coupled. A configuration in which cascade circuits of the controller 12 are combined is provided. That is, the optical branching units 8 and 9 are provided on the input side and the output side of the Mach-Zehnder intensity modulator 20, respectively. The controller 12 controls the bias of the Mach-Zehnder intensity modulator 20 by the power variable DC power supply 5.

  In the above-described configuration, the Mach-Zehnder intensity modulator is configured such that the branched light obtained by branching the light from the light source 1 by the input-side optical branching unit 8 enters the output-side optical branching unit 9 and is transmitted in the opposite direction to the output multiwavelength light. 20 is incident. The transmitted light in the reverse direction has the same center wavelength as the light source light having a single center wavelength incident on the Mach-Zehnder intensity modulator 20 and is taken out by the optical branching device 8 on the input side to be converted into a photoelectric converter. 10 is incident. Then, it is converted into an electrical signal corresponding to the power monitored by the photoelectric converter 10. The calculator 11 calculates the difference between the level of the converted electric signal and a preset target value. The controller 12 can flatten the output light spectrum by adjusting the output power of the power variable DC power supply 5 based on the calculation result and controlling the bias point of the Mach-Zehnder intensity modulator 20.

  An optical circulator (not shown) is added after the optical branching device 8 on the input side, and the function of branching the light from the light source 1 is taken out to the optical branching device 8 and the transmitted light in the reverse direction is taken out to perform photoelectric conversion. It is also possible to divide the function incident on the vessel 10 into the functions of this optical circulator. Further, a configuration using an optical circulator as the output side optical branching unit 9 is also possible.

[Tenth embodiment]
As shown in FIG. 18, the tenth embodiment of the multi-wavelength batch generation apparatus according to the present invention includes an optical branching device 9 disposed between the Mach-Zehnder intensity modulator 20 and the phase modulator 28 in the fifth embodiment, The output of the optical branching device 9 has a configuration in which the photoelectric converter 10, the arithmetic unit 11, and the cascade circuit of the controller 12 are coupled. That is, the optical branching device 9 is provided on the output side of the Mach-Zehnder intensity modulator 20. The controller 12 controls the bias of the Mach-Zehnder intensity modulator 20 by the power variable DC power supply 5.

  In the above configuration, the output light from the Mach-Zehnder intensity modulator 20 branched by the optical branching device 9 enters the photoelectric converter 10 and is converted into an electrical signal corresponding to the power monitored here. The calculator 11 calculates the difference between the level of the converted electric signal and a preset target value. The controller 12 can flatten the output light spectrum by adjusting the output power of the power variable DC power supply 5 based on the calculation result and controlling the bias point of the Mach-Zehnder intensity modulator 20.

[Eleventh embodiment]
FIG. 19 is a configuration diagram showing an eleventh embodiment of a multi-wavelength batch generation apparatus according to the present invention.

  In the ninth and tenth embodiments described above, the target bias value varies when the light source 1 has a power variation. The eleventh embodiment is intended to eliminate the harmful effects caused by this power fluctuation.

  In addition to the configuration of the tenth embodiment, the configuration of the present embodiment includes an optical branching device 8 and a photoelectric converter 10a at the output of the light source 1. The computing unit 11 monitors the input optical power level and the output optical power level of the Mach-Zehnder intensity modulator 20 through the photoelectric converter 10a and the photoelectric converter 10b. The controller 12 controls the power variable DC power supply 5 in accordance with the two monitored values, and the ratio of both optical power levels is maintained constant by a bias applied from the power variable DC power supply 5 to the Mach-Zehnder intensity modulator 20. Thus, according to the eleventh embodiment, the power fluctuation of the light source 1 does not affect the target bias value.

[Twelfth embodiment]
FIG. 20 is a block diagram showing a twelfth embodiment of the multi-wavelength batch generation apparatus according to the present invention.

  In the multi-wavelength batch generation apparatus according to the present embodiment, the light source light from 2n (n is a natural number of 1 or more) lasers that generate light having different single center wavelengths is divided into two to perform two systems of processing. And the result of the processing is combined to obtain a final multiple output. Hereinafter, this configuration and operation will be described in detail.

In FIG. 20, 16 ₁ , 16 ₂ , 16 ₃ , 16 ₄ ,... 16 _2n−1 , 16 _2n are laser light emitting elements, each emitting light at a single center wavelength, and each center wavelength being different, They are arranged at equal intervals in the order of the subscript numbers on the frequency axis. Reference numeral 1600 denotes an optical multiplexer that multiplexes light from odd-numbered laser light emitting elements. Reference numeral 1610 denotes an optical multiplexer that multiplexes light from even-numbered laser light emitting elements independently of the optical multiplexer 1600. The optical multiplexers 1600 and 1610 may be optical couplers.

  FIG. 21A shows the measurement result of the output optical spectrum from the optical multiplexer 1600 when n = 8, and FIG. 21B shows the measurement result of the output optical spectrum from the optical multiplexer 1610 when n = 8. It can be seen that the eight light source lights are equally spaced on the frequency axis. It can also be seen that the power of each light source light is substantially the same.

  Each of the optical multiplexer output lights having such a spectrum is incident on a multi-wavelength collective generator (IM / PM) 1620 and the other is incident on a multi-wavelength collective generator (IM / PM) 1630. The For example, the multi-wavelength collective generators 1620 and 1630 can have the same configuration as that of the multi-wavelength collective generator (see FIG. 11) in the fifth embodiment, and each has a Mach-Zehnder intensity modulator (IM) and a phase. An optical modulator group composed of modulators (PM), a power regulator, a power variable DC power source, and a phase regulator (see FIG. 11), and a signal voltage repeated from the oscillators 1640 and 1650 at a predetermined cycle. Entered. In addition, the multi-wavelength collective apparatus having another configuration disclosed in the first to tenth embodiments can be used.

  Therefore, for example, according to the measurement result when n = 8, the output light spectrum from the multi-wavelength collective generator 1620 is flattened as shown in FIG. The optical spectrum is also flattened as shown in FIG.

  Next, the output light from the multi-wavelength batch generator 1620 is demultiplexed for each wavelength by the demultiplexer 1660 and then multiplexed by the multiplexer 1680. Further, the output light from the multi-wavelength collective generator 1630 is demultiplexed for each wavelength by the demultiplexer 1670 and then multiplexed by the multiplexer 1690. The lights combined by both multiplexers are combined with each other by an optical coupler 1700.

  When the light shown in FIGS. 22A and 22B is incident on the demultiplexers 1660 and 1670, the measurement result of the output light spectrum from the optical coupler 1700 is as shown in FIG. More WDM signals can be generated than in the above-described embodiments in which light is modulated, and the output light spectrum can be broadened.

[Modification Example of 12th Embodiment]
In the twelfth embodiment, when multi-wavelength light is obtained collectively, it is considered that the influence of crosstalk becomes a problem between the system composed of elements 1600-1680 and the system composed of elements 1610-1690. .

In this modified example, the demultiplexer 1660 and the output port ₁₇ 1 of _1670, 17 3, ... _{17 2n-1} and _{17 2,} 17 4, ... _{17 2n} laser light emitting element _{16 1,} 16 3 for, ... _{16 2n -1} and 16 ₂ , 16 ₄ ,... 16 _2n are extracted for each center wavelength, so that the modulation output from the multi-wavelength batch generators 1620 and 1630 is finally unnecessary as signal light. The mode is deleted by the multiplexer / demultiplexer (demultiplexer 1660 and multiplexer 1680, demultiplexer 1670 and multiplexer 1690).

Obtained this way, for example, when the n = 8, the output of FIG. 22 thick frame ₁₈ 1 in _{(a), 18 3, 18} 5, 18 7 light multiplexer 1680 that has been removed the regions indicated by It is done. Further, FIG. 22 (a) thick frame in _{18 2,} 18 _4, 18 6, 18 light delete each region indicated by ₈ is obtained at the output of multiplexer 1690. At both multiplexer outputs, the optical power in each of these regions becomes 0 (not shown), so that the optical output WDM signal finally obtained by multiplexing by the optical coupler 1700 has crosstalk between the two systems. It can be removed.

[Application of the twelfth embodiment]
FIG. 24 is a schematic diagram for explaining the applied operation of the twelfth embodiment of the multi-wavelength batch generation apparatus according to the present invention.

  In the configuration of FIG. 20, the modulation units included in the multi-wavelength batch generation devices 1620 and 1630 are defined as a first modulation unit and a second modulation unit, respectively. Assume that the incident wavelengths to the respective modulators are shifted from each other by 8 times the interval of the output multi-wavelength light.

  FIG. 24A schematically shows a relationship between both incident wavelengths when 9-channel flat multi-wavelength light is generated by the multi-wavelength collective generators 1620 and 1630 and is incident on the first and second modulators. It shows. As is clear from this figure, the wavelength at the right end to the first modulation unit and the wavelength at the left end to the second modulation unit overlap each other, so that wavelength is wasted.

  Therefore, in this application example, the multi-wavelength light is incident on the first modulation section so that 9-channel flat multi-wavelength light is incident, while the second modulation section is incident on the 7-channel flat multi-wavelength light. The batch generators 1620 and 1630 are operated independently. This operation can be realized by setting the applied voltages to the first and second modulation units to different values. Specifically, by setting the voltage applied to the second modulation unit to a value lower than the voltage applied to the first modulation unit, waste of wavelength can be eliminated and the signal voltage can be reduced. Can do. Even if the operations of the first and second modulators are reversed, the same effect can be obtained.

It is a principle block diagram of the multi-wavelength collective generator which concerns on this invention. BRIEF DESCRIPTION OF THE DRAWINGS It is a block diagram which shows 1st Embodiment of the multi-wavelength collective generator which concerns on this invention. It is a wave form diagram explaining that the flattening of an optical spectrum is realizable with 1st Embodiment of the multi-wavelength collective generator which concerns on this invention. It is a wave form diagram explaining that the flattening of an optical spectrum is realizable with 1st Embodiment of the multi-wavelength collective generator which concerns on this invention. It is a block diagram which shows the modification of 1st Embodiment of the multi-wavelength batch generation apparatus which concerns on this invention. It is a characteristic view which shows the example which changed the power deviation between channels in the modification of 1st Embodiment of the multi-wavelength collective generator which concerns on this invention. It is a wave form diagram explaining that flattening of an optical spectrum is realizable by the modification of 1st Embodiment of the multi-wavelength collective generator which concerns on this invention. It is a block diagram which shows 2nd Embodiment of the multi-wavelength batch generation apparatus which concerns on this invention. It is a block diagram which shows 3rd Embodiment of the multi-wavelength collective generator which concerns on this invention. It is a block diagram which shows 4th Embodiment of the multi-wavelength collective generator which concerns on this invention. It is a block diagram which shows 5th Embodiment of the multi-wavelength collective generator which concerns on this invention. It is a wave form diagram which shows the experimental result by 5th Embodiment of the multi-wavelength collective generator which concerns on this invention. It is a block diagram which shows 6th Embodiment of the multi-wavelength batch generation apparatus which concerns on this invention. It is a block diagram which shows 7th Embodiment of the multi-wavelength batch generator which concerns on this invention. It is a wave form diagram which shows the experimental result by 7th Embodiment of the multi-wavelength collective generator which concerns on this invention. It is a block diagram which shows 8th Embodiment of the multi-wavelength batch generator which concerns on this invention. It is a block diagram which shows 9th Embodiment of the multi-wavelength batch generator which concerns on this invention. It is a block diagram which shows 10th Embodiment of the multi-wavelength batch generator which concerns on this invention. It is a block diagram which shows 11th Embodiment of the multi-wavelength batch generator which concerns on this invention. It is a block diagram which shows 12th Embodiment of the multi-wavelength batch generator which concerns on this invention. It is a wave form diagram which shows the experimental result by 12th Embodiment of the multi-wavelength batch generator which concerns on this invention. It is a wave form diagram explaining the operation | movement of the experimental result by 12th Embodiment of the multi-wavelength batch generator which concerns on this invention, and the operation | movement of the modification example. It is a wave form diagram which shows the experimental result by 12th Embodiment of the multi-wavelength batch generator which concerns on this invention. It is a schematic diagram explaining the applied operation | movement of 12th Embodiment of the multi-wavelength batch generator which concerns on this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Light source 2,2a, 2e, 2c Optical modulator group 3,1640,1650 Oscillator 3a Sine wave oscillator 4 Power regulator 5 Power variable direct-current power supply 6 Phase regulator 7 Multiplier 8,9 Optical branching device 10,10a, 10b Photoelectric converter 11 Calculator 12 Controller 16 ₁ , 16 ₂ , 16 ₃ , 16 ₄ ,... 16 _2n−1 , 16 _2n Laser light emitting elements 17 ₁ ,... 178 ₈ Frequency region to be deleted 20 Mach-Zehnder intensity modulator 25 Amplitude Modulator 28 Phase modulator 50 Optical amplifier 200 Electro-absorption-type intensity modulator 1600, 1610 Optical multiplexer (optical coupler)
1620, 1630 Multi-wavelength batch generator (IM / PM)
1660, 1670 splitter 1680, 1690 multiplexer 1700 optical coupler

Claims (5)

A multi-wavelength collective device that modulates incident light having a single center wavelength using a repetitive signal voltage of a predetermined period, and collectively generates and outputs multi-wavelength light having a plurality of center wavelengths,
A plurality of optical paths each having an optical modulation means are coupled in series, the first-stage optical modulation means is an amplitude modulator to which the incident light is input, and the remaining-stage optical modulation means are the modulation modulators. A modulation unit that is a single-stage or multiple-stage phase modulator connected in series with the detector;
A plurality of voltage applying means for adjusting the amplitude of the signal voltage and applying it to an input port of the light modulating means of the modulating unit;
A plurality of incident lights, each having a different single center wavelength, are arranged at a predetermined frequency.
Further, a first multiplexing unit that multiplexes the plurality of incident lights on the frequency axis by being incident on the first-stage light modulation unit of the modulation unit, and the rest of the plurality of incident lights is alternated. A multiplexing unit including a second multiplexing unit that enters and multiplexes the first-stage light modulation unit of the modulation unit;
The modulation unit includes a first modulation unit that modulates multiplexed light from the first multiplexing unit, and a second modulation unit that modulates multiplexed light from the second multiplexing unit,
And first multiplexing / demultiplexing means for demultiplexing and multiplexing the output light from the first modulation unit for each of the different single center wavelengths,
Second multiplexing / demultiplexing means for demultiplexing and multiplexing the output light from the second modulation unit for each of the different single center wavelengths;
Means for multiplexing the multiplexed light having the alternate components by the first multiplexing / demultiplexing means and the multiplexed light having the remaining alternate components by the second multiplexing / demultiplexing means. ,
The modulation unit linearly modulates the phase of the incident light having a single wavelength with respect to the signal voltage waveform applied to the input port of the light modulation unit to obtain a phase modulation function,
The predetermined period includes an increasing period in which the signal voltage increases monotonously in a half of the continuous period, and a decreasing period in which the signal voltage decreases symmetrically with the monotonous increase in the increasing period in the remaining half of the continuous period. ,
The amplitude modulator gates the amplitude of the modulated incident light in a part of the increase period, and gates the amplitude in a part of the decrease period that is not continuous with the part. Multi-wavelength batch generator. A multi-wavelength collective device that modulates incident light having a single center wavelength using a repetitive signal voltage of a predetermined period, and collectively generates and outputs multi-wavelength light having a plurality of center wavelengths,
A plurality of optical paths each having an optical modulation means are coupled in series, the first-stage optical modulation means is an amplitude modulator to which the incident light is input, and the remaining-stage optical modulation means are the modulation modulators. A modulation unit that is a single-stage or multiple-stage phase modulator connected in series with the detector;
A plurality of voltage applying means for adjusting the amplitude of the signal voltage and applying it to an input port of the light modulating means of the modulating unit;
A plurality of incident lights, each having a different single center wavelength, are arranged at a predetermined frequency.
Further, a first multiplexing unit that multiplexes the plurality of incident lights on the frequency axis by being incident on the first-stage light modulation unit of the modulation unit, and the rest of the plurality of incident lights is alternated. A multiplexing unit including a second multiplexing unit that enters and multiplexes the first-stage light modulation unit of the modulation unit;
The modulation unit includes a first modulation unit that modulates multiplexed light from the first multiplexing unit, and a second modulation unit that modulates multiplexed light from the second multiplexing unit,
And first multiplexing / demultiplexing means for demultiplexing and multiplexing the output light from the first modulation unit for each of the different single center wavelengths,
Second multiplexing / demultiplexing means for demultiplexing and multiplexing the output light from the second modulation unit for each of the different single center wavelengths;
Means for multiplexing the multiplexed light having the alternate components by the first multiplexing / demultiplexing means and the multiplexed light having the remaining alternate components by the second multiplexing / demultiplexing means. ,
The modulation unit linearly modulates the phase of the incident light having a single wavelength with respect to the signal voltage waveform applied to the input port of the light modulation unit to obtain a phase modulation function,
The predetermined period includes an increasing period in which the signal voltage increases monotonously in a half of the continuous period, and a decreasing period in which the signal voltage decreases symmetrically with the monotonous increase in the increasing period in the remaining half of the continuous period. ,
The amplitude modulator gates the amplitude of the modulated incident light in a predetermined period spanning a portion of the increase period that is closer to the decrease period and a portion of the decrease period that is continuous with the portion. Multi-wavelength batch generator. In the multi-wavelength collective generator according to claim 1 or 2,
The first modulation unit generates (2N + m) wavelength side modes (N is a natural number, m is an integer) at the output thereof, and the fluctuation range of the optical power between the side modes is within a predetermined value. The output is flattened,
The second modulation unit generates (2N−m) wavelength side modes (N is a natural number, m is an integer) at its output, and the fluctuation range of the optical power between the side modes is within a certain value. The multi-wavelength collective apparatus characterized in that the output is flattened as described above. In the multi-wavelength collective generator according to any one of claims 1 to 3,
A multi-wavelength collective apparatus comprising an optical amplifier in an optical path through which at least a multi-wavelength signal is output. In the multi-wavelength collective generator according to any one of claims 1 to 3,
The multi-wavelength simultaneous generation apparatus, wherein the amplitude modulator operates as a phase modulator at the same time.

Images