JP2002299751A - Semiconductor laser device and optical transmitter using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve faults of a front-to-back ratio linearity of the essentiality of a semiconductor field absorption type modulator integrated laser of one of the important components of a main line optical transmission. SOLUTION: A monitoring current Ip, of the rear output of an EA(electroabsorption) modulator integrated laser 106, is electrically corrected by a nonlinear amplifier 402 to a current output, such as after passing the EA modulator similarly to the forward output, and a laser drive current source 103 is controlled, to suppress the current dependence of the front-to-back ratio. Accordingly, the rear monitoring current is converted into the nonlinear type, and this electrical signal is output as the laser drive current. Since the current is corrected by the semiconductor laser module and the optical transmission module mounting the nonlinear type, the optical output stability and reliability of the laser module and the transmission module are improved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor laser device and an optical transmission device using the same, and more particularly, to a semiconductor electro-absorption modulator integrated laser. The present invention relates to an optical transmission device using a semiconductor electro-absorption modulator integrated light source that controls a driving current of a semiconductor laser and controls an optical output of the semiconductor laser.

[0002]

2. Description of the Related Art Conventionally, a semiconductor electroabsorption modulator integrated light source used in an optical communication system has an optical transmission module structure shown in FIG. 1 when the transmission speed is about 10 Gbit / s. . The optical transmission module 101 includes a laser module 102, a laser drive current source 103, a modulator drive unit 104, a bias amplitude control unit 105, and a temperature control circuit 116 provided inside a package. A main part of the laser module 102 includes a semiconductor electro-absorption modulator integrated laser (hereinafter referred to as EA (electro-absorpti).
on) modulator integrated laser) 106 is mounted on a Peltier substrate 112. EA modulator integrated laser 10
6 is a distributed feedback laser (Dist) driven by a constant current.
rib 107, and an EA modulator 10 operated by a modulation voltage.
8. The EA modulator turns on / off the light of the DFB laser by shifting the absorption edge of the active layer of the EA modulator by utilizing the quantum confinement Stark effect generated by applying a voltage to the EA modulator. Modulator. References describing EA modulators include: MAoki, et.al., “High-speed (10 Gbit / s)
and low-drive-voltage (1V peak to peak) InGaAs / InG
aAsP MQW electroabsorption modulator integrated DF
B laser with semi-insulating buried heterostructur
e, ”Electron. Lett., vol. 28, pp. 1157-1158, 1992.
There is.

[0003] A terminating resistor 110 is mounted in parallel with the EA modulator 108 to achieve impedance matching. In front of the EA modulator integrated laser 106, optical means for coupling light c from the laser to the optical fiber 117 via the lens 113, the isolator 115 and the lens 114 is provided. Further, a photodiode 109 for monitoring an optical output is mounted behind the EA modulator integrated laser. A monitor current Im photoelectrically (O / E) -converted by the photodiode 109 passes through the laser drive current source 103 to control the DFB laser 107 to keep the optical output of the laser 107 constant, so-called auto power control (APC). ) A loop is formed. Here, each of the laser drive current sources 103 outputs linearly with respect to the input current.

[0004]

SUMMARY OF THE INVENTION In addition to an optical transmitter equipped with an EA modulator integrated laser and having a transmission distance of 40 km currently being commercialized, 80 km and 100 km will be used in the future.
The long-distance transmission described above is progressing. When the transmission over a long distance is advanced, the EA modulator integrated laser is required to have characteristics of high light output, low chirp, and high extinction ratio.
When these characteristics are improved in the EA modulator integrated laser, the characteristics that deteriorate with the characteristics are the front / rear specific linearity ΔPf / ΔIm described below. This is because even when any of the characteristics is improved, the light absorption in the EA modulator integrated laser EA modulator section increases, and the linearity of the EA modulator integrated laser forward optical output becomes non-linear with respect to the laser drive current. This is because of the influence, the linearity between the front and rear of the element itself is deteriorated. This will be described in more detail. EA modulator integrated laser 1 of EA modulator integrated light source
06 is an EA modulator 108 in front of the DFB laser 107.
Are integrated. Due to its properties, the EA modulator absorbs light from the DFB laser 107 even when no voltage is applied. Therefore, the output of the light c from the front of the EA modulator integrated laser 106 is extracted as the optical output of the DFB laser 107 with the light absorption of the EA modulator section subtracted. On the other hand, light from behind the EA modulator integrated laser 106
As for the output of b, since there is no EA modulator behind, the optical output of the DFB laser is extracted as it is.

In order to stably operate the EA modulator integrated light source under APC control, the ratio of the monitored EA modulator integrated laser rear light output b to the front light output c must be within the laser drive current range. Must be kept constant. Because, for example, when the rear light output doubles for a certain current increase amount, if the front light output becomes only 1.5 times, the front light output is stabilized by APC control by the rear light output monitor. This is because it is impossible to control them.

In the conventional EA modulator integrated light source, the relationship between the output signal from the photodiode 109 and the light output of the lens 114 is as shown in FIG.
Is indicated by a dotted line, and the optical output Io of the lens 114 is indicated by a solid line. Here, the output signals Ip and Io are normalized by the output of the laser drive current; If = 150 mA, so the vertical axis is not an absolute value.

In FIG. 2, the output Io of the light c from the front of the EA modulator 108 does not completely coincide with the output Ip from the rear even though it is standardized.
Is about 80 mA from the threshold current Ith, and the output Io
(Solid line) is smaller. This is because the EA modulator 108 is integrated in front of the EA modulator integrated laser 107. Light a from the front of the laser 107
After passing through the EA modulator 108, the output of the lens 11
3, 114, and the optical fiber 1 via the isolator 115.
17, the light of the DFB laser 107 is
It is absorbed by the EA modulator 108 integrated on the same element. This absorption occurs at a photocurrent of about 10 mA even when the EA modulator 108 is not driven, that is, when the EA modulator is not biased, and the laser drive current is increased from the threshold current (Ith) to 80 mA. It occurs remarkably in the region of. On the other hand, since no absorber is integrated behind the EA modulator integrated laser, a coupling loss occurs between the EA modulator integrated laser and the photodiode 109.
A value proportional to the output of the laser 107 is the output of the photodiode 106.

The laser module 106 controls the forward light output to be constant by monitoring the backward output.
Therefore, even when the laser drive current If changes, if the ratio of the front output to the rear output is not constant within a certain range, the front output cannot be controlled to the same as before the laser drive current If changes. .

In this regard, FIG. 3 shows the current dependence of an actual EA modulator integrated laser, where the ratio of the rear output Im to the front output Pf is defined as the front-back ratio. In the figure, it can be seen that the front-to-back ratio fluctuates due to the drive current If, as shown by the solid line A in the conventional current dependency. This is shown in FIG.
This is due to the difference between the rear light output Ip and the front light output Io. In the laser drive current If region where the EA modulator generates a light output such that the light absorption is remarkable, that is, in the region where the laser drive current If is 80 mA from the threshold current, the front-to-back ratio is not constant and the laser drive current If is not constant. Drive current I
f tends to increase as f increases. On the other hand, in a laser drive current region that generates an optical output in which the light absorption of the EA modulator section is at a saturation level, the front-to-back ratio is substantially constant with respect to the laser drive current If.

Normally, the laser drive current is If = 60 to 8
Although it is 0 mA, in order to guarantee long-term reliability, it is necessary to guarantee a value of 50% increase, that is, If = 90 to 120 mA. Therefore, for example, If = 70m at the beginning
The module operating at A has a current above a threshold value Ith, which is a drive current range, for example, 30 mA to 105 mA.
Although the operation up to mA must be guaranteed, as shown in FIG. 3, when the front-to-back ratio is If = 30 mA and 105 mA, the front-back ratio fluctuates by about 20%, and when this fluctuation exceeds 20%, the light output It is difficult to operate the signal constantly. As an index of this allowable value, the current fluctuation of the front-rear output ratio is represented by ΔPf / ΔIm = [{Pf (105 mA) / Pf (30 mA)} / {Im (105 m
A) / Im (30 mA)}]-1, if this value is not less than ± 20%, reliability cannot be guaranteed for a long time as described above. In addition, the EA modulator has a tendency to saturate at a certain light input level, so that the ratio between the rear light output and the front light output further fluctuates. Therefore, when the rear light output is linearly converted by a monitor photodiode to control the laser drive current, if the ratio between the rear light output and the front light output fluctuates, the light output in front of the laser is controlled to be constant. It becomes difficult to do.

For this reason, conventionally, the operating current is increased to If = 65 m
By performing at A, the value of the front-back ratio linearity is
The high reliability of the present optical transmission module is realized by selecting the laser elements at ± 20% or less with respect to + 22%. Therefore, the product yield is low and uneconomical,
It can be used over a wide range of operating current and cannot extend the product life. It has been found that this variation depends on the characteristics of the EA modulator, for example, the extinction characteristic. In an optical transmission device using a semiconductor EA modulator integrated laser designed for long-distance transmission, this variation is more remarkable. There are problems that arise.

SUMMARY OF THE INVENTION Accordingly, it is a main object of the present invention to provide an electro-absorption modulator integrated laser device in which the driving current of a semiconductor laser has a small variation in the ratio between the rear light output and the front light output over a wide range, and optical transmission using the same. The realization of the device.

[0013]

SUMMARY OF THE INVENTION To achieve the above object, the present invention provides an optical means for optically coupling forward output light of a semiconductor electro-absorption modulator integrated laser to an optical fiber; Laser device having a monitor photodiode for monitoring the backward output light of the integrated laser, and a laser drive power source controlled by the monitor photodiode and generating a drive current for the semiconductor laser of the semiconductor electro-absorption modulator integrated laser Wherein a non-linear amplifier is provided between the monitor photodiode and the laser drive power supply, the monitor amplifier having a monitor photodiode output monitor current whose amplification factor changes with respect to the value of the laser drive current. Here, the semiconductor laser device includes a laser module, an optical transmitting module, and an optical transmitting and receiving module described in the embodiments.

According to the present invention, the rear monitor current is converted by a non-linear amplifier by the control means, and the converted current is output as a laser drive current. Bug solved. The above-described non-linear amplifier has a function of correcting a variation in the drive current between the forward-backward linearity of the semiconductor EA modulator integrated laser and the drive current.

[0015]

<First Embodiment> FIG. 4 is a block diagram showing an embodiment of an optical transmission device (optical transmission module) according to the present invention. In this embodiment, an EA modulator integrated laser having a transmission speed of 10 Gbit / s is mounted. The basic configuration of the optical transmission module 401 is almost the same as the description of the related art with reference to FIG. Components that are substantially the same as those in FIG. 1 are denoted by the same reference numerals and symbols as in FIG. 1, and detailed descriptions thereof are omitted. The difference in configuration from that of FIG.
The point is that the E-converted output current Ip is input to the laser light output stabilizing circuit via the non-linear amplifier 402.

The non-linear amplifier 402 receives the monitor current Ip, converts it into a non-linear signal, and outputs it. The output current Iq of the non-linear amplifier 402 is input to the semiconductor laser 107 via the laser drive current source 103. The non-linear conversion means a conversion in which the amplification factor changes with respect to the level of the input monitor current Ip. Specifically, E
The forward light output of the A modulator integrated laser 106 is small,
EA modulator 10 integrated in front of modulator integrated laser
In the case where the light absorption at 8 does not reach the saturation level and the light absorption is remarkable, the amplification factor of the nonlinear amplifier at this time is set to N1. On the other hand, in the case of the EA modulator integrated laser front optical output level in which the light absorption of the laser input integrated in the EA modulator 108 reaches the saturation region, in other words, the EA modulator section photocurrent is In the case where the saturation level has been reached with respect to the laser light input, the amplification factor of the nonlinear amplifier 402 at this time is set to N2. A non-linear conversion is defined as a conversion that gives the amplification factor of the non-linear amplifier in each region a relationship of N1 <N2.

As can be seen from the above description, the nonlinear conversion means that the amplification factor should be changed depending on the optical input level to the EA modulator section of the EA modulator integrated laser. Since the input has a one-to-one correspondence with the input level of the monitor current, the effect of the present invention can be obtained by a conversion in which the amplification factor changes with respect to the input level of the monitor current Ip. Further, since the optical input to the EA modulator 108 has a one-to-one correspondence with the drive current of the EA modulator integrated laser, the non-linear conversion is also defined as a conversion in which the amplification factor changes in the region of the laser drive current. can do. An example of the characteristics of the nonlinear amplifier 402 will be described with reference to FIGS.

FIG. 5 is a graph showing the nonlinear amplifier output with respect to the laser driving current If, and FIG. 6 is a graph showing the amplification factor of the nonlinear amplifier with respect to the laser driving current If.
Two non-linear amplifiers A and B are shown.

The amplification operation in the case shown in FIGS. 5 and 6 will be described. The first example of a non-linear amplifier A is E
The threshold value Ith in which light absorption in the A modulator 108 does not reach the saturation level and remarkable light absorption is observed.
In the laser drive current region of about 80 mA from FIG.
And the amplification factor is N1 as shown in FIG. Meanwhile, EA
Assuming that the amplification factor in the laser driving current If region where the photocurrent of the modulator reaches the saturation level with respect to the laser light input and is 70 mA or more is N2, the amplification factor N1 <N2.

FIG. 5 shows a non-linear amplifier B as another example.
6 and FIG. The characteristic of the non-linear amplifier B is that the amplification factor N3 is a function of If in the region from the threshold value Ith to 70 mA, but also in this case, the amplification factor N3 is equal to the amplification factor N4 in the region where the laser driving current is 70 mA or more. Is N3
(If) <N4. In practical use, the nonlinear amplifier 402 is used for the A / A modulator integrated laser depending on the characteristics of the laser.
It is possible to use different types and B types. Such a non-linear amplifier 402 can be realized by forming a circuit by combining active elements and passive elements, or by programming a microcomputer with a desired amplification factor.

FIG. 7 is a block diagram of a configuration example of the above-mentioned nonlinear amplifier. The nonlinear amplifier 402 converts the monitor current Ip into a voltage, a current / voltage conversion circuit 403, a memory (ROM) 404 in which forward output information is written in advance, and an output voltage of the current / voltage conversion circuit 403 by using the forward output information. It comprises a front and rear correction circuit 405 composed of a small processor that executes a program for correction based on the correction.

FIG. 8 is a characteristic diagram of the nonlinear amplifier 402. The operation of the nonlinear amplifier 402 will be specifically described with reference to the laser drive current If. The monitor current Ip input to the non-linear amplifier 402 is as shown in the non-linear amplifier input Ip in FIG.
q is converted to a monitor current indicated by a characteristic Iq in FIG.
Here, the currents Ip and Iq in FIG.
Since the output is normalized at 150 mA, the vertical axis is not an absolute value. The current dependency of the ratio between the monitor current Iq via the non-linear amplifier 402 and the optical output Io in front of the laser is obtained as shown by the dotted line B in FIG. You can see that it is small. Therefore, even when the laser drive current If changes, the ratio of the front output to the rear output is substantially constant, so that the front output can be controlled to the same as before the laser drive current If changes.

For example, a module which is initially operated with a drive current If = 70 mA must guarantee operation in a drive current range of a minimum current value; 30 mA to a maximum current value; 105 mA, as shown in FIG. Street, front-back ratio B
However, since the fluctuation at If = 30 mA and 105 mA is smaller than that of the conventional A, the optical output signal can be operated constantly within a range of about ± 10% even when the current fluctuates.
The index of the current fluctuation ΔPf / ΔIm (refer to the prior art) of the front-back ratio linearity indicates that the value of the front-rear ratio linearity is +15
The distribution can be improved from + 22% to ± 10% distribution centering on 0%. This improvement effect can be obtained by converting the monitor current into the same drive current dependency as the forward light output of the laser by the non-linear amplifier. In addition, the characteristics of the non-linear amplifier determine the dependence of the monitor current after conversion by the non-linear amplifier on the drive current, and the current dependence of the front-to-back ratio linearity. Therefore, a highly reliable optical transmission device can be realized by designing a nonlinear amplifier so as to obtain desired front-to-back ratio linearity characteristics as an optical transmission module.

FIG. 4 shows the EA.
Components for controlling the modulator integrated laser at a constant temperature,
Although the Peltier 112, the thermistor 113, and the temperature control circuit 116 are described, the effect of the present invention does not change even in the case of a semiconductor laser module that does not require these components and does not require temperature control. Further, in FIG. 4 of the embodiment, it is needless to say that the present invention can provide the same effect even in a so-called simple package having no aspherical lens 113, selfoc lens 114, and isolator 115. . <Embodiment 2> FIG. 9 shows the configuration of another embodiment of the optical transmission module according to the present invention. In this embodiment, the transmission speed is 10 Gbit / s
EA modulator integrated laser. The basic configuration of the optical transmission module 601 in FIG. 9 is almost the same as the optical transmission module 106 in FIG. 4 described in the first embodiment.
4 are denoted by the same reference numerals and symbols, and detailed description thereof will be omitted. The difference between the configuration in FIG. 9 and the configuration in FIG. 4 is that the nonlinear amplifier 802 is mounted in the semiconductor laser module 601. The output current Ip O / E-converted by the photodiode 109 is output to the monitor current output Iq of the semiconductor laser module via the non-linear amplifier 802 mounted in the semiconductor laser module.
Becomes

The operation of the nonlinear amplifier 802 is the same as that described in the first embodiment, whereby the ratio of the optical output to the optical fiber 117 of the semiconductor laser module 601 to the monitor current output Iq via the nonlinear amplifier 802 is reduced. 3, the laser drive current dependency as shown by the dotted line B in FIG. 3 and the fiber light output can be controlled to be constant even when the laser drive current changes.

In the embodiment shown in FIG. 9, components for controlling the EA modulator integrated laser 601 at a constant temperature,
Although Peltier 112 and thermistor 111 are described,
Even in the case of a semiconductor laser module that does not need these components and does not require temperature control, the effect of the present invention does not change. Further, in the embodiment shown in FIG. 9, it is needless to say that the same effect can be obtained in a so-called simple package having no aspheric lens 113, selfoc lens 114, and isolator 115.

Also, in a semiconductor laser module with a built-in wavelength locker equipped with a wavelength locking mechanism for wavelength multiplex transmission, if the semiconductor laser is a laser in which an EA modulator is integrated, the present invention is used. In addition, a highly reliable semiconductor laser module with a built-in wavelength locker that can control the fiber light output to be constant with respect to the fluctuation of the driving current can be manufactured. <Embodiment 3> For the embodiment of the present invention, a transmission speed of 10 Gbit
The / s optical transmission device will be described. By mounting the optical transmission module described in the first embodiment and configuring the optical transmission device, the optical output is controlled to be constant irrespective of the change in the drive current of the semiconductor EA modulator integrated laser due to aging and environmental changes. It is possible to realize an optical transmission device having high long-term reliability. By constructing an optical transmission system using this optical transmission device, a highly reliable optical transmission system can be realized. <Embodiment 4> FIG. 10 shows an optical transmission apparatus (optical transmission module) equipped with an EA modulator integrated wavelength tunable laser according to the present invention.
2 shows a configuration of another embodiment. The basic configuration of the transmitting module 901 is almost the same as that described in the first embodiment (FIG. 4), except that the EA modulator integrated tunable laser 902 is mounted in FIG. . The EA modulator integrated tunable laser 902 is characterized in that the semiconductor laser unit is constituted by the tunable laser 903 and the EA modulator unit 108.

Also in the case of a wavelength tunable laser, the EA modulator is integrated in front of the wavelength tunable laser,
In the A modulator integrated wavelength tunable laser device itself, the front-to-back ratio linearity has laser drive current dependence as described in the first embodiment. Furthermore, since the wavelength is changed, the absorption characteristics of the EA modulator portion change, so that the current dependency of the front-to-back ratio linearity may increase compared to the transmission module of the first embodiment in which the wavelength does not change. sell. Therefore, by configuring the optical transmission module by mounting the nonlinear amplifier in the same manner as in the first embodiment, it is possible to control the optical output to be constant even when the semiconductor laser drive current fluctuates. <Embodiment 5> FIG. 11 shows an optical transmission apparatus (optical transmission module) equipped with an EA modulator integrated wavelength tunable laser according to the present invention.
The configuration of still another embodiment is shown. The basic configuration of the semiconductor laser module 1001 is almost the same as that described in the second embodiment, except that the EA modulator integrated wavelength tunable laser 902 is mounted in FIG. E
The A-modulator integrated tunable laser 902 is different from the first embodiment in that the semiconductor laser unit includes the tunable laser 903 and the EA modulator. Also in this case, the same effect as that of the second embodiment can be obtained as the EA modulator integrated wavelength tunable laser module.

Although the embodiment of the present invention has been described above, the present invention is not limited to the above embodiment. Furthermore, as the optical transmission device of the present invention, the optical transmission module has been described, but is not limited to the optical transmission module, an optical transmission device equipped with the optical transmission module, a wavelength multiplexed optical transmission device equipped with the optical transmission module, The present invention is also applied to an optical communication system using these optical transmission devices.
In wavelength-division multiplexed optical transmission at a transmission rate of about 10 Gbit / s, since each module consists of a different optical transmission module for each wavelength, individual differences between modules and the wavelength of components such as filters and wavelength multiplexers in optical transmission equipment are considered. Depending on the dependence, the light output level may be different. However, in the optical transmission device, it is necessary to control the optical output levels of the respective wavelengths to be uniform in view of the configuration of the optical transmission system. For this optical output level control, the optical transmission module described in the first embodiment is mounted,
By configuring the wavelength division multiplexing optical transmission device, optical output control suitable for the wavelength division multiplexing optical transmission device becomes possible, and a wavelength division multiplexing optical transmission device having high long-term reliability is realized.

Further, by constructing a wavelength optical transmission system using the wavelength division multiplexing optical transmission device, the wavelength dependent components constituting the system, such as an optical fiber, an optical amplifier, an optical switch, etc. Optical output control becomes possible, and a highly reliable wavelength optical transmission system can be realized.

[0031]

According to the present invention, the deterioration of the front-to-back ratio linearity, which is one of the important components of the trunk line optical transmission, which is the essence of the semiconductor electro-absorption modulator integrated laser, is achieved by introducing a non-linear amplifier. A semiconductor laser module equipped with this,
In addition, since the correction is performed by the optical transmission module, the optical output stability and reliability of the semiconductor laser module and the optical transmission module are improved. Further, by using these optical transmission modules, it is possible to control the optical output to be constant irrespective of the fluctuation of the driving current of the laser integrated with the semiconductor EA modulator due to the change with time and the environmental change, so that the optical transmission device with high reliability can be obtained. , And construction of a trunk optical transmission system.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing the structure of a conventional optical transmission module.

FIG. 2 is a characteristic diagram for explaining the operation of a conventional optical transmission module.

FIG. 3 is a comparison diagram of characteristics of an optical transmission module according to the related art and the present invention.

FIG. 4 is a circuit diagram of a first embodiment of a semiconductor laser device according to the present invention;

FIG. 5 is an output characteristic diagram of a nonlinear amplifier in the semiconductor laser device according to the present invention.

FIG. 6 is an amplification characteristic diagram of a nonlinear amplifier in the semiconductor laser device according to the present invention.

FIG. 7 is a configuration diagram of an embodiment of a nonlinear amplifier in a semiconductor laser device according to the present invention.

FIG. 8 is an input / output characteristic diagram of a nonlinear amplifier in a semiconductor laser device according to the present invention.

FIG. 9 is a circuit diagram of a second embodiment of the semiconductor laser device according to the present invention.

FIG. 10 is a circuit diagram of a fourth embodiment of the semiconductor laser device according to the present invention.

FIG. 11 is a circuit diagram of a fifth embodiment of the semiconductor laser device according to the present invention.

[Explanation of symbols]

101: Optical transmission module, 102: Semiconductor laser module, 103: Laser drive current source, 10
4. Modulator driver 105 Bias amplitude controller 106 Electroabsorption (EA) modulator integrated DFB
Laser, 107: Electroabsorption modulator (EA modulator), 108: DFB laser, 109: Monitor photodiode, 110: Terminator, 111
..Mister, 112 ........ Peltier board, 113.
..Surface lenses, 114 ... Selfoc lenses,
115: isolator, 116: temperature control circuit, 117: optical fiber, 401: optical transmission module according to the first embodiment, 402: nonlinear amplifier, 8
01 ... the semiconductor laser module according to the second embodiment, 9
01 ... the optical transmission module according to the fifth embodiment;
..EA-modulator integrated tunable laser, 903... Tunable laser unit, 1001... Optical transmission module according to embodiment 6,

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H04B 10/04 10/06 10/152 10/142 (72) Inventor Akihisa Higashiguchi Totsuka-ku, Totsuka-ku, Yokohama-shi, Kanagawa Prefecture 216-cho, Hitachi, Ltd., Communication Division, Hitachi, Ltd. FA05 GA03 GA12 GA14 GA22 GA23 GA24 5K002 AA02 BA13 CA09 FA01

Claims (6)

[Claims] An optical means for optically coupling forward output light of a semiconductor electro-absorption modulator integrated laser to an optical fiber; a monitor photodiode for monitoring rear output light of the conductor electro-absorption modulator integrated laser; A semiconductor laser device having a laser drive power supply controlled by the monitor photodiode and generating a drive current for the semiconductor laser of the semiconductor electro-absorption modulator integrated laser, wherein a laser drive power supply is provided between the monitor photodiode and the laser drive power supply; A semiconductor laser device, comprising: a non-linear amplifier in which the monitor photodiode output monitor current changes in amplification factor with respect to the value of the laser drive current. 2. The semiconductor laser device according to claim 1, wherein the semiconductor laser of the semiconductor electro-absorption modulator integrated laser is a tunable laser. 3. The semiconductor laser module according to claim 1, wherein said semiconductor electro-absorption modulator integrated laser, said optical means, said monitor photodiode, and said nonlinear amplifier are mounted. . 4. The semiconductor laser module according to claim 3, further comprising a modulator driving section for driving an electro-absorption modulator in said semiconductor electro-absorption modulator integrated laser. 5. The semiconductor electro-absorption modulator integrated laser of the semiconductor laser device according to claim 1, wherein said optical means, said monitor photodiode, said laser drive power supply, said nonlinear amplifier, and An optical transmission module including a modulator driving unit for driving an electro-absorption modulator of a semiconductor electro-absorption modulator integrated laser. 6. An optical transmitter comprising the semiconductor laser device according to claim 1 and a modulator driving unit for driving an electro-absorption modulator in the semiconductor electro-absorption modulator integrated laser.