JP2004347813A - Optical modulator with control box - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical modulator with a control box preventing complication of electric connection to the optical modulator and enlargement of a total optical device including the optical modulator and reducing propagation loss of a microwave signal. <P>SOLUTION: In the optical modulator with the control box wherein a casing 1 incorporating an optical modulating element generating an optical signal modulated corresponding to an electric signal and the control box 2 incorporating a controlling means controlling the optical modulating element are freely attachably and detachably bonded, the casing 1 is mechanically bonded to the control box 2 and electric connection between both sides of the casing and the control box is performed by the bonding. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an optical modulator with a control box, and more particularly, to an optical modulator that generates an optical signal modulated in response to an electric signal, and a housing that incorporates an optical modulator and a control unit that controls the optical modulator. The present invention relates to an optical modulator with a control box which is detachably connected to a control box.
[0002]
[Prior art]
2. Description of the Related Art In the field of optical communication and optical measurement, optical modulators that convert an electric signal into an optical signal are often used. As an optical modulator, an external modulator such as a direct modulator using a laser diode, an electroabsorption modulator, or an optical waveguide type optical modulator in which an optical waveguide is formed on a substrate having an electro-optic effect such as lithium niobate. It has been known.
In response to the growing demand for high-speed, large-capacity information communication in recent years, in particular, optical waveguide type optical modulators have no optical wavelength dependency and easy control of the amount of chirp. It is widely used as an optical modulator suitable for optical communication at a frequency.
In addition, high-density wavelength division multiplexing (DWDM) optical communication suitable for high-speed, large-capacity information communication has been developed, and many optical elements such as optical modulators are used in combination. For this reason, complicated connection of the optical modulator to the optical modulator and enlargement of the entire optical device have become major issues.
[0003]
In an optical waveguide type optical modulator, in order to apply an appropriate electric field to the optical waveguide, it is necessary to precisely control the phase and intensity of the microwave applied to the modulation electrode. However, since the frequency of the microwave signal applied to the optical modulator increases as the optical modulation frequency becomes wider, the distance that the microwave propagates from the microwave oscillator to the modulation electrode must be strictly adjusted. Thus, the difficulty of assembling and adjusting the optical device is increasing.
Further, when a coaxial cable is used for microwave transmission, microwave loss occurs at a cable connection portion, which causes an increase in drive voltage and deterioration of frequency characteristics. In addition, there are many fluctuation factors such as the connection state of the cable, bending, vibration, and temperature, which causes a problem that stable driving of the optical modulator is difficult.
Furthermore, workability at the time of replacing the optical modulator is poor, and it is difficult to ensure reproducibility.
[0004]
[Problems to be solved by the invention]
SUMMARY OF THE INVENTION The present invention solves the above-described problems, prevents the electrical connection to the optical modulator from being complicated, prevents the entire optical device including the optical modulator from being enlarged, and reduces the propagation loss of the microwave signal. An object of the present invention is to provide an optical modulator with a control box.
[0005]
[Means for Solving the Problems]
As means for solving the above-mentioned problems, the invention according to claim 1 controls a housing including a light modulation element that generates an optical signal modulated in response to an electric signal, and controls the light modulation element. In an optical modulator with a control box in which a control box containing control means is detachably connected, the housing is mechanically connected to the control box, and the connection allows the housing to be connected to the control box. Electrical connection with the side.
[0006]
According to the first aspect of the present invention, an electrical connection between the housing and the control box containing the control means can be made by mechanically connecting the housing containing the light modulation element and the control box containing the control means. In addition, complicated wiring work can be omitted, and manufacturing and assembly work can be performed efficiently.
[0007]
According to a second aspect of the present invention, in the optical modulator with the control box according to the first aspect, the housing is mechanically supported and fixed by the control box.
[0008]
According to the second aspect of the present invention, since the housing incorporating the light modulation element is mechanically supported and fixed by the control box, the housing and the base plate of the optical device in which the control box is housed. Can be made non-contact. This makes it difficult for the light modulation element to be affected by heat fluctuations, vibrations, and the like of the base plate, thereby enabling stable driving.
[0009]
Further, in the invention according to claim 3, in the optical modulator with the control box according to claim 1 or 2, all the electrical connections required by the housing side are made through coupling with the control box. It is characterized by being.
[0010]
According to the third aspect of the present invention, it is possible to make all electrical connections between the two by simply mechanically coupling the housing containing the light modulation element and the control box containing the control means. Therefore, complicated wiring work is not required at all, and the manufacturing and assembly work can be performed efficiently.
[0011]
According to a fourth aspect of the present invention, in the optical modulator with the control box according to any one of the first to third aspects, the electric signal includes a microwave signal.
[0012]
According to the fourth aspect of the present invention, in particular, a microwave signal transmission system having a large influence on the optical modulation characteristics is also propagated because the electrical connection is made by mechanical coupling between the housing and the control box. It is possible to always transmit a stable microwave signal without being affected by the connection state of the coaxial cable, bending, vibration, temperature, and the like, and to maintain excellent optical modulation characteristics.
[0013]
According to a fifth aspect of the present invention, in the optical modulator with the control box according to any one of the first to fourth aspects, the housing has a built-in photodetector and the control means includes the photodetector. It operates based on a detection signal from
[0014]
According to the invention according to claim 5, a light detecting element is provided in a housing containing a light modulation element, and control means for controlling the light modulation element is built in a control box. Is configured to introduce a detection signal from the light detection element to the control means by an electrical connection provided between the light detection elements.
Therefore, it is possible to adjust the positional relationship between the light modulation element and the light detection element when the light modulation element and the light detection element are incorporated in the housing, and the light detection element can be accurately arranged with respect to the light modulation element. In addition, electrical wiring from the photodetector to the control means can be easily performed by mechanical connection between the housing and the control box, thereby improving work efficiency.
[0015]
BEST MODE FOR CARRYING OUT THE INVENTION
An optical modulator with a control box according to the present invention will be described.
FIG. 1 is a schematic diagram showing a joint state between a housing 1 having a built-in light modulation element and a control box 2 having a control means for controlling the light modulation element.
The housing 1 and the control box 2 are mechanically joined and fixed, and electrical components such as a light modulation element and a light detection element incorporated in the housing and electric components such as control means incorporated in the control box. It is configured to make an electrical connection with the component.
[0016]
The mechanical connection between the housing 1 and the control box 2 can be performed by a screwing method (for example, a method of fixing with a screw 30 as shown in FIG. 2) or a fitting claw provided on one side is engaged with the other hole. It is possible to use mechanical joining means known in the art, such as a fixing method.
However, it is desirable that the housing 1 and the control box 2 are configured to be detachable in accordance with the exchange of the light modulation element and the control circuit.
When the housing 1 containing the light modulation element is lightweight and no physical shock such as tension or pressing force is applied to the housing, connection pins for electrically connecting the housing and the control box are provided. (Including a coaxial terminal for microwave transmission) can also be used for the function of mechanical joining.
[0017]
Further, as shown in FIG. 1, the housing 1 is mechanically supported and fixed by the control box 2, so that the housing 1 is attached to the base plate 3 of the optical device that houses the housing and the control box. Non-contact can be achieved.
This makes it difficult for the light modulation element in the housing 1 to be affected by heat fluctuation, vibration, and the like from the base plate 3, so that more stable driving is possible. Further, since the housing 1 and the control box 2 are not fixed to the same base, it is possible to prevent the occurrence of bending due to thermal expansion or the like.
[0018]
The light modulating element incorporated in the housing 1 is formed on a substrate made of lithium niobate (LiNbO ₃ ), lithium tantalate (LiTaO ₃ ), PLZT (lanthanum lead titanate zirconate) or the like and having an electro-optical effect. An external modulator in which an optical waveguide and a modulation electrode are formed, a direct modulator using a laser diode, an electroabsorption modulator, and the like can be used. In particular, it is more preferable to apply the present invention to an external modulator using a microwave signal, from the viewpoint of reducing the load of connection work of a microwave connection cable, a connection terminal, and the like, and reducing signal loss.
[0019]
Further, in addition to the above-described light modulation element, a light detection element for detecting an operation state of the light modulation element can be incorporated in the housing 1.
For example, as shown in FIG. 2, the light detection element 11 is disposed in the housing 1, and the light emitted from the end of the light modulation element 10 is guided by the auxiliary member ( The light can be reflected in the direction of the light detection element 11 by a capillary 15 or the like, and the reflected radiation 16 can be detected by the light detection element 11.
In this manner, by incorporating the light modulation element and the light detection element in the same housing 1, the light detection element can be accurately arranged and fixed to the light modulation element.
FIG. 2 schematically shows the inside of the housing 1 and the control box 2.
[0020]
As shown in FIG. 2, as an electrical connection terminal to the light modulation element 10, a coaxial terminal 12 for inputting an RF signal such as a modulation signal, a terminal 13 for supplying various electric signals such as application of a DC bias, and the like. There is.
Further, a terminal 14 for outputting a detection signal from the light detection element 11 is also provided in the housing 1.
Further, an electric circuit such as a control circuit can be incorporated in the housing 1 as needed.
[0021]
In the control box 2, as shown in FIG. 2, a drive circuit 22 for a modulation signal, a control circuit 21, and a power supply unit 23 for supplying power to the drive circuit 22 and the control circuit 21 are provided. .
As shown in FIG. 2, the drive circuit 22 is configured to receive an RF signal from the outside, amplify the RF signal, and propagate the amplified RF signal toward the light modulation element 10. When adjusting the DC bias, the drive circuit 22 may be configured to receive a low-frequency signal from the control circuit 21 and superimpose the low-frequency signal on the modulation signal.
Note that it is also possible to incorporate an RF signal generation unit in the control box 2 without inputting an RF signal from the outside. In addition, it is also possible to connect the coaxial terminal 27 and the coaxial terminal 24 with a coaxial cable without providing the drive circuit 22, and to directly transmit the modulation signal generated outside the control box to the light modulation element 10. is there.
[0022]
The control circuit 21 has a function of supplying a DC bias to the light modulation element 10 via the terminal 25 and adjusting the DC bias to always have an appropriate value according to the state of the light modulation element. ing.
Further, the detection signal from the light detection element 11 is introduced into the control circuit 21 via the terminal 26, and the detection signal is used for DC bias control or the like.
[0023]
The control circuit 21 is connected to a terminal 28 for exchanging electric signals with the outside of the control box. For example, when a signal is externally input to the control circuit 21 such as changing the amplification factor of the modulation signal, switching the modulation frequency, and setting the timing and frequency of DC bias control, It can be used when transmitting data indicating the modulation state.
[0024]
As shown in FIG. 1, the control box 2 is not limited to the one that can hold the housing 1. For example, the control box 2 is configured to be approximately the same size as the housing 1, The arrangement and fixing of the casing 1 and the control box 2 to the base plate of the apparatus can be performed by using other joining / attaching means.
When the control box is made compact, only circuits that can be built compactly inside the box, such as a modulation signal drive circuit and a DC bias control circuit, are provided, and the power supply unit and RF signal generator are outside the control box. It is constituted so that it may be provided. Then, a required electric signal can be externally introduced into the control box via an external connection terminal such as the terminal 27 in FIG.
[0025]
【The invention's effect】
As described above, according to the present invention, it is possible to prevent the electrical connection to the optical modulator from being complicated, to prevent the entire optical device including the optical modulator from being enlarged, and to reduce the propagation loss of the microwave signal. An optical modulator with a control box can be provided.
[Brief description of the drawings]
FIG. 1 is a schematic diagram showing an entire optical modulator with a control box according to the present invention.
FIG. 2 is a schematic diagram of a housing and a control box according to the present invention.
[Explanation of symbols]
1 housing 2 control box 3 base plate 4 optical fiber

Claims (5)

Optical modulation with a control box in which a housing containing an optical modulation element for generating an optical signal modulated in accordance with an electric signal and a control box containing control means for controlling the optical modulation element are detachably connected. In the vessel,
The optical modulator with a control box, wherein the housing is mechanically connected to the control box, and the connection electrically connects the housing side to the control box side. The optical modulator with a control box according to claim 1, wherein the housing is mechanically supported and fixed by the control box. 3. An optical modulator with a control box according to claim 1, wherein all electrical connections required by the housing are made through coupling with the control box. With light modulator. The optical modulator with a control box according to any one of claims 1 to 3, wherein the electric signal includes a microwave signal. The optical modulator with a control box according to any one of claims 1 to 4, wherein the housing includes a photodetector, and the control unit operates based on a detection signal from the photodetector. Features a light modulator with a control box.

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