JP5411538B2 - Optical multicarrier generation apparatus and method, and optical multicarrier transmission apparatus using optical multicarrier generation apparatus - Google Patents

Description

  The present invention relates to an optical multicarrier generation apparatus and method used as a light source of an optical communication system, and an optical multicarrier transmission apparatus using the optical multicarrier generation apparatus, and in particular, one single wavelength light source and one optical modulator. The present invention relates to an optical multicarrier generation apparatus and method capable of generating optical multicarriers of three waves or five waves, and an optical multicarrier transmission apparatus using the optical multicarrier generation apparatus.

  Up to now, the speed of optical fiber transmission has been increased by time division multiplexing, but the problem that the transmission distance is limited by the chromatic dispersion of the optical fiber has become apparent. As one means for solving this problem, it is conceivable to use a dispersion compensation device such as a dispersion compensation fiber. However, it is desirable to avoid the use if possible from the viewpoint of device size, device cost, and additional loss. As one of the solutions, a method of developing a high-speed signal in parallel and transmitting it with a plurality of optical carriers is being studied.

  In the transmission system using a plurality of optical carriers, a system using a plurality of independent light sources is the most general, but from the viewpoint of the apparatus size and the apparatus cost, a multi-wavelength which uses a light modulator to increase the wavelength of continuous light from one light source. The carrier light source is attractive. FIG. 14 shows a configuration example of a multicarrier light source that generates four optical carriers from a single wavelength light source.

In the configuration shown in FIG. 14, continuous (CW) light generated from a laser diode (LD) 11 is input to two Mach-Zehnder (MZ) type optical modulators 12 and 14 that are cascade-connected. The front-stage MZ optical modulator 12 is driven by a radio frequency (RF) signal having a frequency f ₀ , and the rear-stage MZ optical modulator 14 is driven by an RF signal having a frequency 2f ₀ (see, for example, Non-Patent Document 1). ). As shown in FIG. 15, by driving the MZ type optical modulator by push-pull, the carrier component of CW light is suppressed at the output of the preceding stage MZ type optical modulator 12 and is twice the drive signal frequency f ₀ . Two optical carriers separated by a frequency 2f ₀ can be generated. FIG. 15A shows the spectrum of the output light from the preceding stage MZ type optical modulator 12. This signal is further input to the subsequent MZ type optical modulator 14. The MZ optical modulator 14 at the subsequent stage generates optical carriers separated from the two optical carriers by a frequency 4f _{0 that is} twice the drive signal frequency 2f ₀ . In other words, the optical frequency omega _c -f ₀ is converted into light of the light and the frequency omega _c + _{f 0} of the frequency omega _c -3f _0, the frequency omega _c + light _{f 0} is light and the frequency of the frequency omega _c -f ₀ omega _c + 3f converted into ₀ light. As a result, four optical carriers are generated as shown in FIG.

A. Chowdfury, Z. Jia, G.-K. Chang, and R. Younce, "Novel 100Gbps Ethernet System for Next-generation Metro Transport and Wide-area Access Networks using Optical carrier suppression and separation Technique," Proceedings of LEOS Summer Topical Meeting 2007, Paper TuE1.2, 2007.

  However, in the configuration in which the optical modulators are cascade-connected, an increase in optical loss is inevitable, and it is difficult to ensure a high optical signal-to-noise ratio (OSNR). Further, in the configuration in which the optical modulators are cascade-connected, it is difficult to realize a compact device size and low device cost.

  The present invention has been made in view of the above points, and an object thereof is to provide an optical multicarrier generation apparatus and method with low loss, small size, and low cost, and an optical multicarrier transmission apparatus using the optical multicarrier generation apparatus. To do.

  FIG. 1 is a first principle configuration diagram of the present invention.

In order to achieve the above object, the invention described in claim 1 includes continuous light generation means 104 for generating continuous light,
Mach-Zehnder light intensity modulation means 106 capable of zero chirp operation;
RF signal generating means 101 for generating a radio frequency (RF) signal of frequency f ₀ ;
Drive amplitude varying means 103 for changing the amplitude of the drive signal of the Mach-Zehnder type light intensity modulating means 106;
A bias voltage variable means 105 for changing a bias voltage applied to the Mach-Zehnder type light intensity modulation means 106;
The bias voltage variable means 105 uses Vπ as the half-wave voltage of the Mach-Zehnder light intensity modulation means 106, sets the bias voltage that minimizes the light output from the Mach-Zehnder light intensity modulation means 106 to the extinction voltage, and maximizes the bias voltage. The peak voltage is set to the peak voltage, the bias voltage between the minimum and maximum is set to the intermediate voltage, the peak-to-peak voltage of the RF signal is set to Vπ, and the bias voltage applied to the Mach-Zehnder light intensity modulation unit 106 is set to the intermediate have a means for setting between the voltage and the extinction voltage, an optical multicarrier generation apparatus characterized by generating light multicarrier three-wave having a uniform power level.

The invention according to claim 2 is a continuous light generating means for generating continuous light;
Mach-Zehnder light intensity modulation means capable of zero chirp operation;
RF signal generating means for generating a radio frequency (RF) signal of frequency f ₀ ;
Drive amplitude variable means for changing the amplitude of the drive signal of the Mach-Zehnder light intensity modulation means;
A bias voltage variable means for changing a bias voltage applied to the Mach-Zehnder type light intensity modulation means,
The bias voltage varying means uses Vπ as the half-wave voltage of the Mach-Zehnder light intensity modulation means, the bias voltage at which the light output from the Mach-Zehnder light intensity modulator is minimized, the extinction voltage, and the maximum bias voltage. Is set to a peak voltage, a bias voltage that is between the minimum and maximum is an intermediate voltage, and the peak-to-peak voltage of the RF signal is set between 2 Vπ and 2.5 Vπ,
The bias voltage applied to the Mach-Zehnder type optical intensity modulating means, have a means for setting between the quenching voltage and a peak voltage, and wherein the generating light multicarrier five waves with uniform power level An optical multicarrier generator.

The invention according to claim 3 is an optical multicarrier generation method for generating three-wave optical multicarriers with uniform power levels ,
The continuous light generating means generates continuous light,
RF signal generating means generates a radio frequency (RF) signal of frequency f ₀ ,
The drive amplitude variable means changes the amplitude of the drive signal of the Mach-Zehnder light intensity modulation means capable of zero chirp operation,
The bias voltage varying means uses Vπ as the half-wave voltage of the Mach-Zehnder light intensity modulating means, the bias voltage at which the light output from the Mach-Zehnder light intensity modulating means is minimized, the extinction voltage, and the maximum bias voltage. Is a peak voltage, a bias voltage that is intermediate between the minimum and maximum is set as an intermediate voltage, the peak-to-peak voltage of the RF signal is set to Vπ, and the bias voltage applied to the Mach-Zehnder light intensity modulation means by setting between the voltage, by changing the bias voltage applied to the Mach-Zehnder type optical intensity modulating means, characterized by Rukoto to generate light multicarrier three-wave having a uniform power level.

The invention of claim 4 is an optical multi-carrier generation method for generating optical multi-carriers of five waves with uniform power levels ,
The continuous light generating means generates continuous light,
RF signal generating means generates a radio frequency (RF) signal of frequency f ₀ ,
The drive amplitude variable means changes the amplitude of the drive signal of the Mach-Zehnder light intensity modulation means capable of zero chirp operation,
The bias voltage varying means uses Vπ as the half-wave voltage of the Mach-Zehnder light intensity modulating means, the bias voltage at which the light output from the Mach-Zehnder light intensity modulator is minimized, the extinction voltage, and the maximum bias voltage. Is a peak voltage, a bias voltage that is between the minimum and maximum is an intermediate voltage, and the peak-to-peak voltage of the RF signal is set between 2 Vπ and 2.5 Vπ,
By setting the bias voltage applied to the Mach-Zehnder light intensity modulating means between the extinction voltage and the peak voltage, the bias voltage applied to the Mach-Zehnder light intensity modulating means is changed, and the power level to generate 5 waves of light multicarrier with uniform and said Rukoto.

  FIG. 2 is a second principle configuration diagram of the present invention.

The invention according to claim 5 is an optical multicarrier generator 100 according to claim 1 or 2,
Optical demultiplexing means 301 for demultiplexing n (where n is 3 or 5) optical multicarriers output from the optical multicarrier generator for each optical carrier;
N optical modulators 302 for modulating n optical carriers output from the optical demultiplexer 301,
An optical multicarrier transmission apparatus comprising: an optical multiplexing unit 303 that multiplexes n optical modulation signals output from the n optical modulation units 302.

  According to a sixth aspect of the present invention, in the optical multicarrier transmission apparatus according to the fifth aspect, among the at least n optical modulator driving units of the n optical modulation units, the unused optical modulator driving unit is driven. There is further provided means for cutting off at least part of the electric power.

  According to the present invention, an optical multicarrier can be generated by one single wavelength light source and one optical modulator, and can be generated by changing the driving condition of the optical modulator. The number of optical multicarriers generated can be changed by changing the driving conditions of the modulator. Accordingly, it is possible to provide a low loss, small size, low cost optical multicarrier generation apparatus and method, and an optical multicarrier transmission apparatus using the optical multicarrier generation apparatus.

It is a 1st principle block diagram of this invention. It is a 2nd principle block diagram of this invention. It is a structural example (the 1) of the optical multicarrier generator in the 1st Embodiment of this invention. It is a structural example (the 2) of the optical multicarrier generator in the 1st Embodiment of this invention. It is a structural example (the 3) of the optical multicarrier generator in the 1st Embodiment of this invention. It is a figure for demonstrating the operation | movement in the case of generating 3 waves in the 1st Embodiment of this invention. It is a figure for demonstrating the operation | movement in the case of generating 5 waves in the 1st Embodiment of this invention. Simulation results of setting the drive signal frequency f ₀ in the first embodiment of the present invention to 10GHz (Part 1). The driving signal frequency f ₀ in the first embodiment of the present invention is a simulation result when set to 10 GHz (Part 2). It is a block diagram (the 1) of the optical multicarrier transmission apparatus in the 2nd Embodiment of this invention. It is a block diagram (the 2) of the optical multicarrier transmission apparatus in the 2nd Embodiment of this invention. It is a block diagram (the 3) of the optical multicarrier transmission apparatus in the 2nd Embodiment of this invention. It is a structural example of the optical carrier receiver which makes a pair with the optical carrier transmitter of this invention. It is a structural example of the conventional optical multicarrier generator. It is a figure which shows operation | movement of the conventional optical multicarrier generator.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[First Embodiment]
FIG. 3 is a configuration example (No. 1) of the optical multicarrier generating apparatus according to the first embodiment of the present invention. In this configuration example, an RF oscillator 101 that generates a radio frequency (RF) signal having a frequency f ₀ , an attenuator 102 for adjusting the amplitude of the RF signal, a continuous light oscillation light source (LD) 104 that generates continuous light, and a zero chirp Operable zero chirp Mach-Zehnder type optical intensity modulator (hereinafter referred to as “MZ type optical modulator”) 106, modulator driver 103 that changes the amplitude of the drive signal of the MZ type optical modulator 106, MZ type The voltage source 105 changes the bias voltage applied to the optical modulator 106.

The configuration example of the first optical multicarrier generator 100A shown in the figure generates three or five optical multicarriers using a single wavelength light source that generates one continuous light and one optical modulator. It is a configuration that can. An RF signal for driving the MZ type optical modulator 106 includes an RF oscillator 101 for generating an RF signal having a frequency f ₀ , an attenuator 102 for adjusting the amplitude of the RF signal, and the RF signal as an optical modulator. Is generated by a modulator driver 103 that amplifies the signal to a predetermined amplitude that can be driven. The attenuator 102 may be either fixed or variable as long as it is set to a predetermined value. The continuous light output from the continuous light oscillation light source (CW light source) 104 is input to the MZ type optical modulator 106. In the MZ type optical modulator 106, the CW light is modulated and output by the RF signal described above. The driving condition of the MZ type optical modulator 106, specifically, the amplitude of the driving signal and the bias voltage from the voltage source 105 are different between the case where three waves are generated and the case where five waves are generated.

  FIG. 4 is a configuration example (No. 2) of the optical multicarrier generating apparatus according to the first embodiment of the present invention.

  In the figure, the same components as those in FIG. 3 are denoted by the same reference numerals, and the description thereof is omitted. The difference from the first configuration example is that the attenuator 102 disposed in the preceding stage of the modulator driver 103 in the first configuration example is disposed in the subsequent stage of the modulator driver 103. Other operations are the same as those in the first configuration example.

  FIG. 5 is a configuration example (No. 3) of the optical multicarrier generating apparatus according to the first embodiment of the present invention.

  In the figure, the difference from the first and second configuration examples is that a gain setting means 201 is provided in the modulator driver 103 instead of the attenuator 102. Other operations are the same as those in the first embodiment. Eventually, the drive signal amplitude of the MZ type optical modulator 106 only needs to be a predetermined value. If the signal from the RF transmitter 101 satisfies the predetermined amplitude as it is, the attenuator 102 also has gain setting means. 201 is not necessary.

  The multicarrier wave generating operation in the configuration example of the optical carrier generating device of the present invention shown in FIGS. 3 to 5 will be described below with reference to FIGS. Hereinafter, it is assumed that the half-wave voltage of the MZ optical modulator 106 is Vπ, the voltage at which the optical output from the MZ optical modulator 106 is maximum is the peak voltage, and the minimum voltage is the extinction voltage.

FIG. 6 shows the operation when three waves are generated. FIG. 6A shows the spectrum of the three-wave optical carrier generated experimentally, and FIG. 6B shows the operating conditions. The amplitude voltage of the RF signal of frequency f ₀ is Vπ, and the bias voltage is the midpoint between the peak voltage and the extinction voltage of the MZ type optical modulator 106 (“M” in FIG. 6B) and the extinction voltage (FIG. 6B). Middle “N”). In a state where the bias voltage is set to the point “M”, the output optical signal waveform is a zero feedback (RZ) pulse with a duty ratio of 50%, and therefore the component of the optical carrier frequency ω ₀ (center wavelength) is the frequency ω on both sides. _The power is increased by about 3 dB compared to the ₀ ± f ₀ component. When the bias voltage is shifted from this state toward the point “N”, the power of the optical carrier frequency component decreases and the power of the frequency components on both sides increases. When the bias voltage reaches the point “N”, the optical carrier component is not suppressed, and there is a state in which the three optical frequency components have the same power before that.

FIG. 7 shows the operation when five waves are generated. FIG. 7A shows the spectrum of five optical carriers generated experimentally, and FIG. 7B shows the operating conditions. The amplitude of the RF signal of frequency f ₀ is set to about 2.3 Vπ, and the bias voltage is set between the peak voltage (“P” in FIG. 7) and the extinction voltage (“N” in FIG. 7) of the MZ type optical modulator 106. .

A procedure for finding conditions for generating five waves at the same power level will be specifically described with reference to FIGS. 8 and 9 are simulation results when the drive signal frequency f ₀ is set to 10 GHz. FIG. 8A shows the relationship between the driving voltage and power transmittance of the MZ type optical modulator 106. The half-wave voltage Vπ is set to 2.5V, the peak voltage is set to + 5.0V, and the extinction voltage is set to + 2.5V. In FIG. 8B, the vertical axis of the graph of FIG. 8A is drawn not as power transmittance but as amplitude transmittance that can take a negative value in terms of phase inversion. This indicates that the optical phase of the output light of the zero-chirp MZ type optical modulator 106 is inverted at the extinction point.

FIG. 9 shows the output light spectrum. FIG. 9A shows an output light spectrum when the modulator driving amplitude of the RF signal is set to 2Vπ and the bias voltage is set to the peak voltage (“P” in FIG. 9). Since driving is performed with a voltage twice the half-wave voltage, the component (ω _c ± f ₀ ) separated from the optical carrier component (ω _c ) by the drive signal frequency f ₀ is suppressed, and is twice the drive signal frequency. It can be seen that a component (ω _c ± 2f ₀ ) separated by the frequency 2f ₀ is greatly generated. When the amplitude of the RF signal is increased from this state, the turning point of the modulator drive signal spreads outside the two extinction points in FIG. 8A or FIG. 8B. As can be seen from FIG. 8 (b), when the amplitude of the modulator drive signal is increased, a component whose phase is inverted with respect to the optical carrier frequency is generated on the optical carrier frequency and works to cancel the optical carrier frequency component. . On the other hand, the component (ωc ± 2f ₀ ) that is separated from the optical carrier component (ω _c ) by the frequency 2f _{0 that is} twice the drive signal frequency is shown in FIG. Since the peak of the amplitude transmittance passing through is increased, it works in the direction of strengthening, and becomes maximum when the amplitude of the modulator drive signal becomes 4Vπ. Thus, the drive voltage is set so that the power of the optical carrier component and the power of the component (ω _c ± 4f ₀ ) separated from the optical carrier component (ω _c ) by a frequency 2f _{0 that is} twice the drive signal frequency are equal. . FIG. 9B shows the optical spectrum at that time. In this simulation, the drive voltage that satisfies this condition is 5.85 V (2.34 × Vπ), but this value is generally considered to vary slightly depending on various conditions such as the frequency response characteristics of the optical modulator.

Next, the bias voltage is shifted in either the high or low direction from this state. When shifting the bias voltage from a peak voltage (in FIG. 9 "P"), power and only the frequency 2f ₀ of the 2 times away component of the driving signal frequency from the optical carrier component (omega _c) of optical carrier components (omega _c) The power of (ωc ± 2f ₀ ) decreases, and instead, the power of the component (ω _c ± f ₀ ) separated from the optical carrier component (ω _c ) by the drive signal frequency f ₀ increases. When the bias voltage comes completely extinction point (in FIG. 9 "N"), away from the power and optical carrier component of the optical carrier component (ω _c) (ω _c) by twice the frequency 2f ₀ of the driving signal frequency The power of the component (ω _c ± 2f ₀ ) is completely suppressed in principle. This is because the characteristic of FIG. 8B is oddly symmetric with respect to the extinction point (“N” in FIG. 9). Therefore, there is a point where the power of the five optical frequency components is equal between the extinction voltage (“N” in FIG. 9) and the peak voltage (“P” in FIG. 9). Set to. In this simulation, the bias voltage that satisfies this condition is 4.225 V (peak voltage −0.31 × Vπ), but this value is generally considered to vary slightly depending on various conditions such as the frequency response characteristics of the optical modulator. .

[Second Embodiment]
The optical multicarrier transmission apparatus will be described below.

  FIG. 10 is a configuration example (No. 1) of the optical multicarrier transmission apparatus according to the second embodiment of the present invention. This configuration example is arranged in parallel with the optical multicarrier generator (three-carrier generation light source) 100-3 described in the first embodiment, and the optical demultiplexer 301 that demultiplexes each of the optical multicarriers. It comprises three optical modulators 302 and an optical multiplexer 303 that multiplexes the modulated optical signals.

  In this configuration example, it is assumed that the optical modulator 302 is an optical vector modulation having a two-row Mach-Zehnder configuration, but any other type of optical modulator may be used. The optical vector modulator 302 can be used as either a differential quaternary phase modulator (DQPSK) or a differential binary phase modulator (DPSK) by changing the driving method. When operating as a DPSK modulator, the bit rate is the same as the signal port rate, and when operating as a DQPSK modulator, the bit rate is twice the signal port rate. This configuration example is a case where both the optical multicarrier interval and the optical modulation clock rate are 10 GHz. The optical modulator 302 has six 10 Gbit / s data input ports and can accommodate a maximum 60 Gbit / s signal.

  FIG. 11 is a configuration example (No. 2) of the optical multicarrier transmission apparatus according to the second embodiment of the present invention. While the configuration shown in FIG. 10 is a case of 3 carriers, this example shows a case of 5 carriers. This configuration example is a case where both the optical multicarrier interval and the optical modulation clock rate are 10 GHz. The optical modulator 402 has ten 10 Gbit / s data input ports and can accommodate a maximum of 100 Gbit / s signals.

  FIG. 12 is a configuration example (part 3) of the optical multicarrier transmission apparatus according to the second embodiment of the present invention. In this configuration example, a power on / off means is provided in the modulator driver 505 of each optical modulator 502 for data modulation arranged in parallel. By turning on / off the power supply of the modulator driver 505, the bit rate of the optical multicarrier transmission apparatus can be made variable as necessary. Further, since only the minimum necessary modulator driver is operated, useless power consumption can be reduced. This configuration example is an example in which a 5-carrier multi-carrier generating apparatus 100 is used, and 10 Gbit / s is changed from 10 Gbit / s to 100 Gbit / s by switching a combination of operation modes of modulators of each carrier by DPSK / DQPSK. The bit rate can be changed in units. The same can be done even in the case of three carriers. In this case, the bit rate can be changed in units of 10 Gbit / s from 10 Gbit / s to 60 Gbit / s.

  FIG. 13 shows a configuration example of an optical multicarrier receiving apparatus paired with the optical multicarrier transmitting apparatus shown in FIG. 11 or FIG. The received signal is demultiplexed into multicarriers by a demultiplexer 601 and input to a DQPSK demodulator 602, respectively. The DQPSK demodulator 602 is often composed of two asymmetric Mach-Zehnder interferometers, and in that case, it can be used as a DPSK demodulator by using only one demodulation circuit.

  The present invention is not limited to the above-described embodiment, and various modifications and applications can be made within the scope of the claims.

DESCRIPTION OF SYMBOLS 100 Optical multicarrier generator 100-3 3 carrier generation light source 100-5 5 carrier generation light source 101 RF signal generation means, RF oscillator 102 Attenuator 103 Drive amplitude variable means, modulator driver 104 Continuous light generation means, Continuous light oscillation light source 105 Bias voltage variable means, voltage source 106 Mach-Zehnder type light intensity modulation means, zero chirp Mach-Zehnder type modulator 201 gain setting means 300 3 parallel multicarrier modulator 301 optical demultiplexing means, optical demultiplexer 302 optical modulation Means, optical modulator 303 Optical multiplexing means, optical multiplexer 500 5-parallel multicarrier modulator 501 Optical demultiplexer 502 Optical modulator 503 Optical multiplexer 505 Modulator driver 600 5-parallel multicarrier demodulator 601 Demultiplexer 602 Demodulation vessel

Claims (6)

Continuous light generating means for generating continuous light;
Mach-Zehnder light intensity modulation means capable of zero chirp operation;
RF signal generating means for generating a radio frequency (RF) signal of frequency f ₀ ;
Drive amplitude variable means for changing the amplitude of the drive signal of the Mach-Zehnder light intensity modulation means;
A bias voltage variable means for changing a bias voltage applied to the Mach-Zehnder type light intensity modulating means,
The bias voltage varying means uses Vπ as the half-wave voltage of the Mach-Zehnder light intensity modulating means, and sets the bias voltage that minimizes the light output from the Mach-Zehnder light intensity modulating means to the extinction voltage and maximizes the bias voltage. The bias voltage is set to the peak voltage, the bias voltage between the minimum and maximum is set to the intermediate voltage, the peak-to-peak voltage of the RF signal is set to Vπ, and the bias voltage applied to the Mach-Zehnder light intensity modulation means is set to the intermediate have a means for setting between the voltage and the extinction voltage, light multicarrier generator and wherein the generating light multicarrier three-wave having a uniform power level. Continuous light generating means for generating continuous light;
Mach-Zehnder light intensity modulation means capable of zero chirp operation;
RF signal generating means for generating a radio frequency (RF) signal of frequency f ₀ ;
Drive amplitude variable means for changing the amplitude of the drive signal of the Mach-Zehnder light intensity modulation means;
A bias voltage variable means for changing a bias voltage applied to the Mach-Zehnder type light intensity modulating means,
The bias voltage varying means uses Vπ as the half-wave voltage of the Mach-Zehnder light intensity modulating means, and sets the bias voltage that minimizes the light output from the Mach-Zehnder light intensity modulator to the extinction voltage and maximizes the bias voltage. The bias voltage is set to the peak voltage, the bias voltage that is between the minimum and maximum is set to the intermediate voltage, the peak-to-peak voltage of the RF signal is set between 2Vπ and 2.5Vπ,
And wherein the bias voltage applied to the Mach-Zehnder type optical intensity modulating means, have a means for setting between the quenching voltage and a peak voltage, thereby generating light multicarrier five waves with uniform power level Optical multi-carrier generator. An optical multicarrier generation method for generating three-wave optical multicarriers with uniform power levels ,
The continuous light generating means generates continuous light,
RF signal generating means generates a radio frequency (RF) signal of frequency f ₀ ,
The drive amplitude variable means changes the amplitude of the drive signal of the Mach-Zehnder light intensity modulation means capable of zero chirp operation,
Bias voltage varying means, the half-wave voltage of the Mach-Zehnder type optical intensity modulating means of V [pi, comprising a bias voltage to the light output from the Mach-Zehnder type optical intensity modulating means is minimized extinction voltage, maximum The bias voltage is set to the peak voltage, the bias voltage between the minimum and maximum is set to the intermediate voltage, the peak-to-peak voltage of the RF signal is set to Vπ, and the bias voltage applied to the Mach-Zehnder light intensity modulation means is set to the intermediate By setting the voltage between the voltage and the extinction voltage, the bias voltage applied to the Mach-Zehnder type light intensity modulation means is changed, and three-wave optical multicarriers with uniform power levels are generated. An optical multicarrier generation method characterized by the above. An optical multicarrier generation method for generating optical multicarriers of five waves with uniform power levels ,
The continuous light generating means generates continuous light,
RF signal generating means generates a radio frequency (RF) signal of frequency f ₀ ,
The drive amplitude variable means changes the amplitude of the drive signal of the Mach-Zehnder light intensity modulation means capable of zero chirp operation,
Bias voltage varying means, the half-wave voltage of the Mach-Zehnder type optical intensity modulating means of V [pi, comprising a bias voltage to the light output from the Mach-Zehnder type optical intensity modulator is minimized extinction voltage, maximum The bias voltage is set to the peak voltage, the bias voltage that is between the minimum and maximum is set to the intermediate voltage, the peak-to-peak voltage of the RF signal is set between 2Vπ and 2.5Vπ,
By setting the bias voltage applied to the Mach-Zehnder light intensity modulation means between the extinction voltage and the peak voltage, the bias voltage applied to the Mach-Zehnder light intensity modulation means is changed, and the power An optical multicarrier generation method, characterized by generating five-wave optical multicarriers with uniform levels . An optical multicarrier generator according to claim 1 or 2,
Optical demultiplexing means for demultiplexing n (where n is 3 or 5) optical multicarriers output from the optical multicarrier generator for each optical carrier;
N light modulation means for modulating each of the n optical carriers output from the light demultiplexing means;
Optical multiplexing means for multiplexing n optical modulation signals output from the n optical modulation means;
An optical multicarrier transmission apparatus comprising: 6. The optical multicarrier transmission according to claim 5, further comprising means for cutting off at least a part of drive power of an unused optical modulator driving means among at least n optical modulator driving means of the n optical modulating means. apparatus.

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