JP2006330523A - Frequency comb light generator and multiwavelength light source for high density wavelength multiplex transmission - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To generate frequency comb light in a wide band having frequency intervals twice as that of the lower modulation frequency output using a modulation drive circuit with low modulation frequency. <P>SOLUTION: The frequency comb light generator has an optical waveguide circuit 11 constituted by connecting a first MZ type waveguide 111 and a second MZ type waveguide 112 in series, a modulation electrode group 12 consisting of a first sine wave modulation electrode 121 which modulates propagation light of two optical paths of the first MZ type waveguide with sine waves of phases opposite to each other, a second sine wave modulation electrode 122 which modulates propagation light of two optical paths of the second MZ type waveguide with sine waves of phases opposite to each other and a modulation signal generation circuit 13 which drives the first sine wave modulation electrode by a modulation signal with amplitude of ψ1, angle frequency of Ω and drives the second sine wave modulation electrode with a modulation signal with amplitude of ψ2, angle frequency of Ω. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a frequency comb light generator and high-density wavelength division multiplex transmission that can generate a wideband frequency comb light having a frequency interval twice that of the low modulation frequency output using a modulation drive circuit having a low modulation frequency. The present invention relates to a multi-wavelength light source.

Conventionally, a frequency comb light generator as shown in FIG. 13A is known.
In FIG. 13A, the frequency comb light generator 9 includes a phase modulator 91, an intensity modulator 92, a modulation drive circuit 93, and a mirror 94.

  The phase modulator 91 includes electrodes 911, 912, and 90, and the intensity modulator 92 includes electrodes 921, 922, and 90. The electrode 90 is shared by the phase modulator 91 and the intensity modulator 92.

The modulation drive circuit 93 includes a power supply 931, amplifiers 932 and 933, ground resistors 934 and 935, and a delay circuit 936.
The waveguide 95 includes a single optical path 951 and an MZ type (Mach-Zehnder) waveguide 952.
Incident light B ₀ (angular frequency ω ₀ ) from a laser light source (not shown) enters the single optical path 951 and is phase-modulated by the phase modulator 91. A modulation signal φ ₁ sinΩt is given by the modulation drive circuit 93 between the electrode 911 and the electrodes 912 and 90 serving as the ground. The light modulated by the phase modulator 91 is folded by the mirror 94 and is incident on the intensity modulator 92.

The light incident on the intensity modulator 92 is given a modulation signal φ ₂ sin (Ωt + θ) by the modulation drive circuit 93 between the electrode 921 and the electrodes 922 and 90 serving as the ground. One of the two optical paths of the MZ waveguide 952 is supplied with a modulation signal φ ₂ sin (Ωt + θ). θ is a phase difference with respect to the modulation signal φ ₁ sinΩt generated by the delay circuit 936. The outgoing light of the MZ type waveguide 952 is frequency comb light having an interval Ω as shown in FIG.

  By the way, since the angular frequency interval of the frequency comb light is generally proportional to the modulation angular frequency, if the modulation angular frequency Ω is increased, frequency comb light having a larger angular frequency interval can be obtained.

  However, at present, for example, a modulation drive circuit with an angular frequency output of 25 GHz can be obtained easily and inexpensively, but it is difficult to obtain a 50 GHz modulation drive circuit that is twice that of the modulation drive circuit. For this reason, if a 50 GHz modulation drive circuit is to be used, a special order production must be requested from the circuit maker, and the device price is naturally high.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a frequency comb light generating apparatus and high density capable of generating broadband frequency comb light having an angular frequency interval twice the modulation angular frequency using a modulation driving circuit having a low modulation angular frequency. It is to provide a multi-wavelength light source for wavelength division multiplexing transmission.

The frequency comb light generator of the present invention is summarized as (1) to (9).
"(1) 1st to nth (n is 2 or more) MZ-type waveguides, or further 1st to mth (m is 1 or more) phase adjusting optical paths connected in series and parallel;
First to nth sine wave modulation electrodes for modulating propagating light in two optical paths of the first to nth MZ type waveguides with sine waves having opposite phases, or further, the first to mth phase adjustments A modulation electrode group comprising first to m-th DC modulation electrodes for modulating propagating light in the optical path with direct current;
Modulation in which at least two of the sine wave modulation electrodes are driven by sine waves having different amplitudes φk and the same angular frequency Ω (not φ1 = φ2 =... = Φn), and the DC modulation electrodes are driven by DC. A signal generation circuit;
Have
A laser beam having an angular frequency ω ₀ is incident from one end of the optical waveguide circuit, and a broadband frequency comb light having a central angular frequency ω ₀ and an angular frequency interval of 2Ω is emitted from the other end.
The frequency comb light generator characterized by the above-mentioned. "

“(2) an optical waveguide circuit in which a first MZ-type waveguide and a second MZ-type waveguide are connected in series;
The first sine wave modulation electrode that modulates the propagation light in the two optical paths of the first MZ-type waveguide with sine waves having opposite phases to each other, and the propagation light in the two optical paths of the second MZ-type waveguide are opposite to each other. A modulation electrode group comprising a second sine wave modulation electrode that modulates with a phase sine wave;
A modulation signal generating circuit for driving the first sine wave modulation electrode with a modulation signal having an amplitude φ1 and an angular frequency Ω, and driving the second sine wave modulation electrode with a modulation signal having an amplitude φ2 and an angular frequency Ω;
The frequency comb light generator according to (1), comprising: "

(3) “an optical waveguide circuit in which a first MZ-type waveguide and a parallel-connected waveguide of a second MZ-type waveguide and a phase adjustment optical path are connected in series;
The first sine wave modulation electrode that modulates the propagation light in the two optical paths of the first MZ-type waveguide with sine waves having opposite phases to each other, and the propagation light in the two optical paths of the second MZ-type waveguide are opposite to each other. A second sine wave modulation electrode that modulates with a phase sine wave; a DC modulation electrode that modulates the propagation light of the phase adjusting optical path with a direct current;
A modulation electrode group comprising:
The first sine wave modulation electrode is driven with a modulation signal having an amplitude φ1 and an angular frequency Ω, the second sine wave modulation electrode is driven with a modulation signal having an amplitude φ2 and an angular frequency Ω, and the DC modulation electrode is driven with a direct current A modulation signal generating circuit for
The frequency comb light generator according to (1), comprising: "

(4) An optical waveguide circuit in which a first MZ type waveguide and a series connection waveguide of a second MZ type waveguide and a phase adjusting optical path are connected in parallel;
The first sine wave modulation electrode that modulates the propagation light in the two optical paths of the first MZ-type waveguide with sine waves having opposite phases to each other, and the propagation light in the two optical paths of the second MZ-type waveguide are opposite to each other. A modulation electrode group consisting of a second sine wave modulation electrode that modulates with a phase sine wave, and a DC modulation electrode that modulates the propagation light of the phase adjusting optical path with a direct current;
The first sine wave modulation electrode is driven with a modulation signal having an amplitude φ1 and an angular frequency Ω, the second sine wave modulation electrode is driven with a modulation signal having an amplitude φ2 and an angular frequency Ω, and the DC modulation electrode is driven with a direct current A modulation signal generating circuit for
The frequency comb light generator according to (1), comprising: "

(5) “A series connection waveguide of a third MZ type waveguide and a phase adjustment optical path is connected in parallel to a series connection waveguide of a first MZ type waveguide and a second MZ type waveguide. An optical waveguide circuit;
First to third modulation electrodes for modulating propagating light in the two optical paths of the first to third MZ type waveguides with sine waves having opposite phases, and direct current for modulating propagating light in the phase adjusting optical path with direct current A modulation electrode group comprising modulation electrodes;
The first, second, and third sinusoidal modulation electrodes are driven by modulation signals of angular frequency Ω having amplitudes φ1, φ2, and φ3 (where φ1 = φ2 =... A modulation signal generating circuit for driving the modulation electrode with a direct current;
(4) The frequency comb light generator according to (4). "

(6) “The frequency comb light generator according to any one of (1) to (5), wherein the waveguide and the optical path are formed on an LN substrate or a semiconductor substrate.”

(7) A frequency comb light generator having a configuration in which the waveguide and the optical path are formed on an LN substrate, and at least two MZ-type waveguides are connected in series,
The frequency comb light generator according to (1), (2), (3), or (5), wherein the optical path is folded by a curved optical fiber or a mirror at a connection point between the MZ type waveguides. "

(8) The modulation signal generation circuit outputs a sine wave modulation signal mutually incoherent to at least two of the first to nth sine wave modulation electrodes. Frequency comb light generator according to any one of the above. "

(9) “The frequency comb light generating device according to any one of (1) to (8), wherein mirrors are provided at an entrance and an exit of the optical waveguide circuit.”

The multi-wavelength light source for high-density wavelength multiplex transmission of the present invention is
"Laser light source,
The frequency comb light generator according to any one of (1) to (8), in which light from the laser light source is incident;
An optical equivalent / optical amplifier that makes the light of the frequency comb light generator incident, equalizes the light intensity, and performs amplification,
An arrayed waveguide grating (AWG) that outputs light emitted from the optical equivalent / amplifier performing the amplification to a plurality of optical paths at different wavelengths;
A multi-wavelength light source for high-density wavelength division multiplexing transmissions. "
Is the gist.

  In the present invention, since frequency comb light having an angular frequency interval twice that of the prior art can be generated, it is possible to use a modulation drive circuit (with a low angular frequency output) that is easily available and inexpensive.

The frequency comb light generator of the present invention will be described below with reference to the drawings. In each figure, the optical path width, the optical path length, the optical path interval of the MZ (Mach-Zehnder) type waveguide, the substrate thickness, the electrode size, the electrode thickness, etc. are different from the actual design values.
FIG. 1A is an explanatory diagram showing a first embodiment of the frequency comb light generator of the present invention. In FIG. 1A, a frequency comb light generator 1 generates an optical waveguide circuit 11 and a modulation electrode group 12 formed on a substrate SUB made of an LN crystal or a compound semiconductor crystal, and a modulation signal generation for driving the modulation electrode group 12. The circuit 13 is formed.

The optical waveguide circuit 11 is configured by connecting a first MZ type waveguide 111 and a second MZ type waveguide 112 in series.
The modulation electrode group 12 includes a first sine wave modulation electrode 121 and a second sine wave modulation electrode 122.
The first sine wave modulation electrode 121 modulates the propagating light of the two optical paths of the first MZ type waveguide 111 with sine waves of opposite phases, and the second sine wave modulation electrode 122 is the second MZ wave. The propagating light in the two optical paths of the type waveguide 112 is modulated with sine waves having opposite phases. The modulation signal generating circuit 13 drives the first sine wave modulation electrode 121 with a modulation signal of φ ₁ sinΩt, and drives the second sine wave modulation electrode with a modulation signal of amplitude φ ₂ sinΩt.

The frequency comb light generator 1 receives the laser beam B ₀ of the angular frequency ω ₀ generated by the laser light source 19 from one end IN of the optical waveguide circuit 11, and the central angular frequency ω ₀ , angle from the other end OUT. Broadband frequency comb light B ₁ (2Ω) having a frequency interval of 2Ω is emitted.
Here, the outgoing light B ₁ of the optical waveguide circuit 11 is expressed by the equation (1).

となる。ここで、Ｊ_2mは、ベッセル関数である。

It becomes. Here, J _2m is a Bessel function.

FIG. 2 shows a state in which frequency comb light having a 2Ω interval is generated at the central angular frequency ω ₀ .
As shown in FIG. 1B, an optical resonator structure in which mirrors M1 and M2 are provided at the entrance and exit of the optical waveguide circuit 11 can be obtained. In this case, the laser light reflected by the mirrors M1 and M2 out of the laser light B _{0 having} the angular frequency ω ₀ generated by the laser light source 19 is repeatedly modulated in the optical waveguide circuit 11, and thus has a wide bandwidth of 2Ω. Frequency comb light can be obtained. In the frequency comb light generators 2, 3, and 4 in the first to fourth embodiments described later and the frequency comb light generator 52 in the multi-wavelength light source for high-density wavelength division multiplex transmission (DWDM), similar mirrors M1 and M2 are used. Can be provided.

  FIG. 3 is an explanatory view showing a second embodiment of the frequency comb light generator of the present invention. In FIG. 3, the frequency comb light generator 2 includes an optical waveguide circuit 21, a modulation electrode group 22, and a modulation signal generation circuit 23 that drives the modulation electrode group 22 formed on the LN substrate SUB.

The optical waveguide circuit 21 is configured by connecting a first MZ type waveguide 211 and a parallel connection waveguide of a second MZ type waveguide 212 and a phase adjusting optical path 213 in series.
The modulation electrode group 22 includes a first sine wave modulation electrode 221 that modulates propagating light in two optical paths of the first MZ type waveguide 211 with sine waves having opposite phases, and a second MZ type waveguide 212. It consists of a second sine wave modulation electrode 222 that modulates the propagation light in the two optical paths with sine waves of opposite phases, and a DC modulation electrode 223 that modulates the propagation light in the phase adjustment optical path 213 with direct current.

  The modulation signal generating circuit 23 drives the first sine wave modulation electrode 221 with a modulation signal having an amplitude φ1 and an angular frequency Ω, and drives the second sine wave modulation electrode 222 with a modulation signal having an amplitude φ2 and an angular frequency Ω. The direct current modulation electrode 223 is driven with direct current. The phase difference θ (see formula (2)) of the light propagating through the two optical paths can be adjusted by the DC bias applied to the DC modulation electrode 223.

The frequency comb light generator 2 receives the laser beam B ₀ of the angular frequency ω ₀ generated by the laser light source 29 from one end IN of the optical waveguide circuit 21, and the central angular frequency ω ₀ , angle from the other end OUT. Broadband frequency comb light B ₁ (2Ω) having a frequency interval of 2Ω is emitted.
Here, the outgoing light B ₁ of the optical waveguide circuit 21 is expressed by the equation (2).

となる。
図４は本発明の周波数コム光発生装置の第３実施形態を示す説明図である。図４において、周波数コム光発生装置３は、ＬＮ基板ＳＵＢに形成された光導波回路３１および変調電極群３２ならびに変調電極群３２を駆動する変調信号発生回路３３からなる。

It becomes.
FIG. 4 is an explanatory view showing a third embodiment of the frequency comb light generator of the present invention. In FIG. 4, the frequency comb light generating device 3 includes an optical waveguide circuit 31, a modulation electrode group 32, and a modulation signal generation circuit 33 that drives the modulation electrode group 32 formed on the LN substrate SUB.

The optical waveguide circuit 31 is configured by connecting a first MZ type waveguide 311 and a series connection waveguide of the second MZ type waveguide 312 and the phase adjusting optical path 313 in parallel.
The modulation electrode group 32 includes a first sine wave modulation electrode 321 that modulates propagating light in two optical paths of the first MZ type waveguide 311 with sine waves having opposite phases, and a second MZ type waveguide 312. It consists of a second sine wave modulation electrode 322 that modulates the propagation light in the two optical paths with sine waves of opposite phases, and a DC modulation electrode 323 that modulates the propagation light in the phase adjustment optical path 313 with direct current.

  The modulation signal generating circuit 33 drives the first sine wave modulation electrode 321 with a modulation signal having an amplitude φ1 and an angular frequency Ω, and drives the second sine wave modulation electrode 322 with a modulation signal having an amplitude φ2 and an angular frequency Ω. The direct current modulation electrode 323 is driven by direct current. The phase difference θ (see formula (3)) of the light propagating through the two optical paths can be adjusted by the DC bias applied to the DC modulation electrode 323.

The frequency comb light generator 3 receives the laser light B ₀ having the angular frequency ω ₀ generated by the laser light source 39 from one end IN of the optical waveguide circuit 31, so that the central angular frequency ω ₀ , angle from the other end OUT is incident. Broadband frequency comb light B ₁ (2Ω) having a frequency interval of 2Ω is emitted.
Here, the outgoing light B ₁ of the optical waveguide circuit 31 is expressed by the equation (3).

図５は本発明の周波数コム光発生装置の第４実施形態を示す説明図である。図５において、周波数コム光発生装置４は、ＬＮ基板ＳＵＢに形成された光導波回路４１および変調電極群４２ならびに変調電極群４２を駆動する変調信号発生回路４３からなる。

FIG. 5 is an explanatory view showing a fourth embodiment of the frequency comb light generator of the present invention. In FIG. 5, the frequency comb light generator 4 includes an optical waveguide circuit 41 formed on the LN substrate SUB, a modulation electrode group 42, and a modulation signal generation circuit 43 that drives the modulation electrode group 42.

  The optical waveguide circuit 41 is formed by connecting a first MZ-type waveguide 411 and a second MZ-type waveguide 412 in series to a series-connected waveguide of a third MZ-type waveguide 413 and a phase adjusting optical path 414. Are connected in parallel.

  The modulation electrode group 42 includes a first modulation electrode 421 that modulates propagating light in the two optical paths of the first MZ-type waveguide 411 with sine waves having opposite phases, and two optical paths of the second MZ-type waveguide 412. A second modulation electrode 422 that modulates the propagating light with a sine wave having a phase opposite to each other, and a third modulation electrode 423 that modulates the propagating light in the two optical paths of the third MZ type waveguide 413 with a sine wave having an opposite phase to each other And a direct current modulation electrode 424 that modulates the propagation light of the phase adjustment optical path 414 with direct current. The phase difference θ (see formula (4)) of the light propagating through the two optical paths can be adjusted by the DC bias applied to the DC modulation electrode 424.

The modulation signal generation circuit 43 uses the first, second, and third sine wave modulation electrodes 421, 422, and 423 to have angular frequencies of amplitude φ1, φ2, and φ3 (where φ1, φ2, and φ3 are different from each other). Drive with Ω modulation signal and drive DC modulation electrode with DC.
Here, the outgoing light B ₁ of the optical waveguide circuit 41 is expressed by the equation (4).

以下、第１実施形態の周波数コム光発生装置１を例に、ＸカットＬＮ基板を用いた場合の変調電極群１２の電極パターンの具体構成を示す。

Hereinafter, a specific configuration of the electrode pattern of the modulation electrode group 12 when an X-cut LN substrate is used will be described using the frequency comb light generator 1 of the first embodiment as an example.

  FIG. 6 shows an example in which an X-cut LN substrate is used for the substrate SUB of the frequency comb light generating apparatus 1, and FIGS. 7A and 7B are cross-sectional explanatory views of the substrate SUB in FIG. FIG.

In FIG. 6, the phase adjustment electrode PCE is provided on one of the two optical paths of the MZ type waveguides 111 and 112. The phase adjusting electrode PCE is provided to correct a phase difference caused by a slightly different distance between the coupling point and the branch point. 6 and 7A, in the X-cut LN substrate, φ ₁ sinΩt and φ ₂ sinΩt are generated from the modulation signal generation circuit 13, so that the propagating lights in the two optical paths are sine waves having opposite phases to each other. Can be modulated.

  FIG. 8 shows an example in which a Z-cut LN substrate is used as the substrate SUB of the frequency comb light generating device 1, and FIGS. 9A and 9B are cross-sectional explanatory views of the substrate SUB in FIG. FIG.

Also in FIG. 8, the phase adjustment electrode PCE is provided on one of the two optical paths of the MZ type waveguides 111 and 112. As can be seen from FIGS. 8 and 9A and 9B, in the Z-cut LN substrate, φ ₁ sinΩt, −φ ₁ sinΩt, φ ₂ sinΩt, and −φ ₂ sinΩt must be generated from the modulation signal generation circuit 13. In addition, the number of electrode pieces increases as compared with the case where an X-cut LN substrate (FIG. 6, FIG. 7 (A), (B)) is used. As can be seen from the comparison of the electric field lines 7 (A) (the electric field lines of the X-cut LN substrate), when the Z-cut LN substrate is used, the modulation efficiency is much higher than that of the X-cut LN substrate. Can be expensive.

  By the way, in a frequency comb light generator (for example, refer to the first, second, and fourth embodiments described above) in which MZ type waveguides using LN crystals are connected in series, the total length becomes long enough to become a practical obstacle (several numbers). 10 cm). For this reason, in the configuration in which the MZ waveguides are connected in series, the optical path can be folded at the connection point between the MZ waveguides.

Hereinafter, a specific example of turning back the optical path in the frequency comb light generator 1 of the first embodiment will be described.
In FIG. 10, the MZ type waveguide 111 and the MZ type waveguide 112 are connected by the single mode optical fiber 7. In FIG. 10, an X-cut LN substrate is used as the substrate SUB. By folding, part of the first sine wave modulation electrode 121 and part of the second sine wave modulation electrode 122 of the MZ type waveguide 111 and MZ type waveguide 112 can be shared, and the first sine wave modulation electrode A part of the phase adjustment electrode PCE 121 and a part of the phase adjustment electrode PCE of the second sine wave modulation electrode 122 can be shared. In FIG. 10, the optical fiber is folded by a curved optical fiber, but may be folded by a mirror.

  In the above embodiment, the modulation signal generation circuits 13, 23, 33, and 43 are configured to transmit mutually coherent sine wave modulation signals to the respective sine wave modulation electrodes, but transmit incoherent sine wave modulation signals. You can also In this case, it is possible to obtain frequency comb light having a wide band and an interval of 2Ω.

For example, in the frequency comb light generator 1 of FIG. 6, when the sinusoidal modulation electrodes 321 and 322 are driven by one oscillator G as shown in FIG. 11A, each modulation signal φ ₁ sinΩt, φ The phase difference of ₂ sinΩt is always constant. In this case, the modulation signal generation circuit 33 sends a coherent sine wave modulation signal to 321 and 322.

  In the frequency comb light generator 1 of FIG. 6, when the sine wave modulation electrode 321 is driven by the oscillator G1 and the sine wave modulation electrode 322 is driven by the oscillator G2, as shown in FIG. The phase difference of the signal changes randomly with time. In this case, the modulation signal generation circuit 33 sends incoherent sine wave modulation signals to 321 and 322.

FIG. 12 is an explanatory diagram of a multi-wavelength light source for high-density wavelength division multiplexing (DWDM) according to the present invention.
In FIG. 12, the multi-wavelength light source 5 includes a laser light source 51, a frequency comb light generator 52, an optical equivalent / optical amplifier 53, and an arrayed waveguide grating (AWG) 54.

  The laser light source 51 includes a power source 511, an LD (laser diode) 512, and a wavelength locker 513, and corresponds to the laser light sources 19, 29, 39, and 49 described in the first to fourth embodiments. The frequency comb light generator 52 is the frequency comb light generator 1, 2, 3, 4 described in the first to fourth embodiments. The frequency comb light generator 52 receives the light from the laser light source 51 and generates the frequency comb light. The optical equivalent / optical amplifier 53 receives light from the frequency comb light generation device 52, amplifies the light intensity, and performs equalization. In this embodiment, the optical equivalent / optical amplifier 53 includes a front-stage optical amplifier 532 and a rear-stage optical equalizer 531. It is configured. The arrayed waveguide grating (AWG) 54 outputs the frequency comb light emitted from the optical equivalent / optical amplifier through a plurality of optical paths.

  In one of the standards of the high-density wavelength multiplex transmission system, it is determined that each frequency interval of a large number of optical carriers is set to 50 GHz. In the present invention, a frequency comb light of 50 GHz can be generated by using a modulation drive circuit with an angular frequency output of 25 GHz that can be easily (cheaply) acquired. Therefore, a multi-wavelength light source for high-density wavelength division multiplexing (DWDM) or a frequency The comb light generators 1, 2, 3, 4, 52 can be manufactured easily and at a low price.

(A) is explanatory drawing which shows 1st Embodiment of the frequency comb light generator of this invention, (B) is a figure which equips the entrance and output port of an optical waveguide circuit with the mirror, and shows the modification of 1st Embodiment. is there. It is a figure which shows the frequency characteristic of the frequency comb light of the angular frequency (omega | ohm) space | interval produced | generated by the frequency comb light generator of this invention. It is explanatory drawing which shows 2nd Embodiment of the frequency comb light generator of this invention. It is explanatory drawing which shows 3rd Embodiment of the frequency comb light generator of this invention. It is explanatory drawing which shows 4th Embodiment of the frequency comb light generator of this invention. It is a figure which shows the example which used the X cut LN board | substrate for the board | substrate SUB of the frequency comb light generator. (A) is a cross-sectional explanatory drawing of the board | substrate in FIG. 6, (B) is bb cross-sectional explanatory drawing similarly. It is a figure which shows the example which used the Z cut LN board | substrate for the board | substrate SUB of the frequency comb light generator. (A) is a sectional view taken along the line aa of the substrate in FIG. 8, and (B) is a sectional view taken along the line bb. It is a figure which shows the Example which connected two MZ type | mold waveguides and MZ type | mold waveguides with the U-shaped optical fiber. (A) is explanatory drawing which shows the frequency comb light generator which sends out a coherent sine wave modulation signal, (B) is explanatory drawing which shows the frequency comb light generator which sends out an incoherent sine wave modulation signal. It is explanatory drawing which shows the conventional wavelength multiplexing multiwavelength light source. (A) is explanatory drawing which shows the conventional frequency comb light generator, (B) is a figure which shows the frequency characteristic of the frequency comb light of an angular frequency (omega | ohm) space | interval.

Explanation of symbols

1 to 4, 52 Frequency comb light generator 11 Optical waveguide circuit 12 Modulation electrode group 13 Modulation signal generation circuit 111 First MZ type waveguide 112 Second MZ type waveguide 121 First sine wave modulation electrode 122 Second Sine wave modulation electrode 5 (for DWDM) multi-wavelength light source

Claims (10)

An optical waveguide circuit in which first to n-th (n is 2 or more) MZ-type waveguides, or further, first to m-th (m is 1 or more) phase adjustment optical paths are connected in series and parallel;
First to nth sine wave modulation electrodes for modulating propagating light in two optical paths of the first to nth MZ type waveguides with sine waves having opposite phases, or further, the first to mth phase adjustments A modulation electrode group comprising first to m-th DC modulation electrodes for modulating propagating light in the optical path with direct current;
Modulation in which at least two of the sine wave modulation electrodes are driven by sine waves having different amplitudes φk and the same angular frequency Ω (not φ1 = φ2 =... = Φn), and the DC modulation electrodes are driven by DC. A signal generation circuit;
Have
A laser beam having an angular frequency ω ₀ is incident from one end of the optical waveguide circuit, and a broadband frequency comb light having a central angular frequency ω ₀ and an angular frequency interval of 2Ω is emitted from the other end.
The frequency comb light generator characterized by the above-mentioned. An optical waveguide circuit in which a first MZ-type waveguide and a second MZ-type waveguide are connected in series;
The first sine wave modulation electrode that modulates the propagation light in the two optical paths of the first MZ-type waveguide with sine waves having opposite phases to each other, and the propagation light in the two optical paths of the second MZ-type waveguide are opposite to each other. A modulation electrode group comprising a second sine wave modulation electrode that modulates with a phase sine wave;
A modulation signal generating circuit for driving the first sine wave modulation electrode with a modulation signal having an amplitude φ1 and an angular frequency Ω, and driving the second sine wave modulation electrode with a modulation signal having an amplitude φ2 and an angular frequency Ω;
The frequency comb light generator according to claim 1, further comprising: An optical waveguide circuit in which a first MZ type waveguide and a parallel connection waveguide of a second MZ type waveguide and a phase adjustment optical path are connected in series;
The first sine wave modulation electrode that modulates the propagation light in the two optical paths of the first MZ-type waveguide with sine waves having opposite phases to each other, and the propagation light in the two optical paths of the second MZ-type waveguide are opposite to each other. A second sine wave modulation electrode that modulates with a phase sine wave; a DC modulation electrode that modulates the propagation light of the phase adjusting optical path with a direct current;
A modulation electrode group comprising:
The first sine wave modulation electrode is driven with a modulation signal having an amplitude φ1 and an angular frequency Ω, the second sine wave modulation electrode is driven with a modulation signal having an amplitude φ2 and an angular frequency Ω, and the DC modulation electrode is driven with a direct current A modulation signal generating circuit for
The frequency comb light generator according to claim 1, further comprising: An optical waveguide circuit in which a first MZ type waveguide and a series connection waveguide of a second MZ type waveguide and a phase adjustment optical path are connected in parallel;
The first sine wave modulation electrode that modulates the propagation light in the two optical paths of the first MZ-type waveguide with sine waves having opposite phases to each other, and the propagation light in the two optical paths of the second MZ-type waveguide are opposite to each other. A modulation electrode group consisting of a second sine wave modulation electrode that modulates with a phase sine wave, and a DC modulation electrode that modulates the propagation light of the phase adjusting optical path with a direct current;
The first sine wave modulation electrode is driven with a modulation signal having an amplitude φ1 and an angular frequency Ω, the second sine wave modulation electrode is driven with a modulation signal having an amplitude φ2 and an angular frequency Ω, and the DC modulation electrode is driven with a direct current A modulation signal generating circuit for
The frequency comb light generator according to claim 1, further comprising: An optical waveguide circuit in which a series connection waveguide of a third MZ type waveguide and a phase adjustment optical path is connected in parallel to a series connection waveguide of a first MZ type waveguide and a second MZ type waveguide; ,
First to third modulation electrodes for modulating propagating light in the two optical paths of the first to third MZ type waveguides with sine waves having opposite phases, and direct current for modulating propagating light in the phase adjusting optical path with direct current A modulation electrode group comprising modulation electrodes;
The first, second, and third sinusoidal modulation electrodes are driven by modulation signals of angular frequency Ω having amplitudes φ1, φ2, and φ3 (where φ1 = φ2 =... A modulation signal generating circuit for driving the modulation electrode with a direct current;
The frequency comb light generator according to claim 4, further comprising:   6. The frequency comb light generator according to claim 1, wherein the waveguide and the optical path are formed on an LN substrate or a semiconductor substrate. A frequency comb light generator comprising a configuration in which the waveguide and the optical path are formed on an LN substrate, and at least two MZ type waveguides are connected in series,
6. The frequency comb light generating apparatus according to claim 1, wherein the optical path is folded by a curved optical fiber or a mirror at a connection point between the MZ type waveguides.   8. The frequency according to claim 1, wherein the modulation signal generation circuit sends a sine wave modulation signal mutually incoherent to at least two of the first to n th sine wave modulation electrodes. 9. Com light generator.   9. The frequency comb light generating apparatus according to claim 1, wherein mirrors are provided at an entrance and an exit of the optical waveguide circuit. A laser light source;
The frequency comb light generator according to any one of claims 1 to 8, wherein light from the laser light source is incident;
An optical equivalent / optical amplifier that makes the light of the frequency comb light generator incident, equalizes the light intensity, and performs amplification,
An arrayed waveguide grating for outputting light emitted from the optical equivalent / amplifier for performing amplification at different wavelengths to a plurality of optical paths;
A multi-wavelength light source for high-density wavelength division multiplexing transmissions.

Images