JP4148837B2 - Light modulator with control box - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an optical modulator with a control box, and in particular, includes a housing containing an optical modulation element that generates an optical signal modulated in response to an electrical signal, and a control means for controlling the optical modulation element. The present invention relates to an optical modulator with a control box that is detachably coupled to a control box.
[0002]
[Prior art]
In the fields of optical communication and optical measurement, an optical modulator that converts an electrical signal into an optical signal is 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 optical modulator in which an optical waveguide is formed on a substrate having an electrooptic effect such as lithium niobate. It has been known.
In response to the increasing demand for high-speed, large-capacity information communication in recent years, in particular, optical waveguide type optical modulators have no dependence on optical wavelength, and the chirp amount can be easily controlled. 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 and large-capacity information communication is progressing, and many optical elements such as optical modulators are used in combination. For this reason, complication of electrical connection to the optical modulator and enlargement of the entire optical device are major issues.
[0003]
In the optical waveguide type optical modulator, it is necessary to accurately control the phase and intensity of the microwave applied to the modulation electrode in order to apply an appropriate electric field to the optical waveguide. However, as the optical modulation frequency becomes wider, the frequency of the microwave signal applied to the optical modulator becomes higher. Therefore, it is necessary to strictly adjust the distance that the microwave propagates from the microwave oscillator to the modulation electrode. In addition, the difficulty of assembling and adjusting the optical device is increasing.
In addition, when a coaxial cable is used for microwave transmission, microwave loss occurs in the cable connection portion, which causes an increase in driving voltage and deterioration in frequency characteristics. In addition, there are many fluctuation factors such as the cable connection status, bending, vibration, temperature, and the like, causing a problem that it is difficult to stably drive the optical modulator.
Furthermore, workability at the time of replacement of the optical modulator is poor, and it is difficult to ensure reproducibility.
[0004]
[Problems to be solved by the invention]
The present invention solves the above-described problems, prevents complication of electrical connection to the optical modulator, enlargement of the entire optical device including the optical modulator, and reduces propagation loss of the microwave signal. An optical modulator with a control box is provided.
[0005]
[Means for Solving the Problems]
As a means for solving the above-mentioned problems, the invention according to claim 1 controls the light modulation element and a housing containing a light modulation element that generates an optical signal modulated in response to an electric signal. In an optical modulator with a control box, which is detachably coupled to a control box incorporating a control means, the casing is mechanically coupled to the control box, and the casing side and the control box are coupled by the coupling. Electrical connection with the side is performed.
[0006]
According to the first aspect of the present invention, it is possible to make electrical connection between the two by mechanically coupling the housing containing the light modulation element and the control box containing the control means. Thus, 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 a 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 accommodated Can be made non-contact. This makes it difficult for the light modulation element to be affected by thermal fluctuations, vibrations, and the like of the base plate, thus enabling stable driving.
[0009]
According to a third aspect of the present invention, in the optical modulator with a control box according to the first or second aspect, all electrical connections required on the housing side are made through coupling with the control box. It is characterized by being.
[0010]
According to the invention of claim 3, it is possible to perform 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 manufacturing and assembly work can be performed efficiently.
[0011]
According to a fourth aspect of the present invention, in the optical modulator with a control box according to any one of the first to third aspects, the electrical signal includes a microwave signal.
[0012]
According to the invention of claim 4, in particular, a microwave signal transmission system that has a great influence on the light modulation characteristics is transmitted by microwaves because 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 fluctuations due to the connection state of the coaxial cable, bending, vibration, temperature, etc., and to maintain excellent light modulation characteristics.
[0013]
According to a fifth aspect of the present invention, in the optical modulator with a control box according to any one of the first to fourth aspects, the housing includes a light detection element, and the control means includes the light detection element. It operates based on the detection signal from
[0014]
According to the fifth aspect of the present invention, the photodetecting element is provided in the housing containing the light modulating element, and the control means for controlling the light modulating element is built in the control box, and the housing, the control box, The detection signal from the photodetecting element is introduced into the control means by electrical connection provided between the control means.
For this reason, it becomes 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, the electrical wiring from the light detection element to the control means can be easily performed by mechanical connection between the housing and the control box, and the working efficiency is improved.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
An optical modulator with a control box according to the present invention will be described.
FIG. 1 is a schematic view showing a joining state of a housing 1 containing a light modulation element and a control box 2 containing control means for controlling the light modulation element.
The casing 1 and the control box 2 are mechanically bonded and fixed, and electric parts such as a light modulation element and a light detection element incorporated in the casing, and an electric such as a control means incorporated in the control box. It is configured to make an electrical connection with a component.
[0016]
The mechanical connection between the housing 1 and the control box 2 is achieved by screwing (for example, fixing with a screw 30 as shown in FIG. 2) or by engaging a fitting nail provided on one side with the other hole. It is possible to use a mechanical joining means known in the art, such as a method of fixing and fixing.
However, it is desirable that the housing 1 and the control box 2 are configured to be detachable in accordance with the replacement of the light modulation element and the control circuit.
Further, when the housing 1 incorporating the light modulation element is lightweight and physical impact such as tension or pressing force is not applied to the housing, a connection pin for electrically connecting the housing and the control box. It is also possible to combine the function of mechanical joining with (including a coaxial terminal for microwave transmission).
[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 placed against the base plate 3 of the optical device in which the housing and the control box are accommodated. It becomes possible to be non-contact.
This makes it difficult for the light modulation element in the housing 1 to be affected by thermal fluctuations, vibrations, and the like from the base plate 3, so that more stable driving is possible. Moreover, since the housing | casing 1 and the control box 2 are not being fixed to the same base, it becomes possible to prevent that bending arises by thermal expansion etc.
[0018]
The light modulation element built in the housing 1 is made of lithium niobate (LiNbO ₃ ), lithium tantalate (LiTaO ₃ ), PLZT (lead lanthanum zirconate titanate), etc. An external modulator having an optical waveguide and a modulation electrode, 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 connection loss of a microwave connection cable, a connection terminal, and the like, and reducing signal loss.
[0019]
In addition to the light modulation element, the housing 1 can incorporate a light detection element for detecting the operating state of the light modulation element.
For example, as shown in FIG. 2, a light detection element 11 is arranged in the housing 1, and an auxiliary member for guiding and joining the optical fiber 4 with radiated light emitted from the end of the light modulation element 10 ( It can be configured such that the reflected light 16 is reflected by the light detection element 11 by being reflected in the direction of the light detection element 11 by a capillary 15 or the like.
As described above, by incorporating the light modulation element and the light detection element in the same housing 1, the light detection element can be arranged and fixed with respect to the light modulation element with high accuracy.
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 for 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 necessary.
[0021]
As shown in FIG. 2, the control box 2 includes a modulation signal drive circuit 22, a control circuit 21, and a power supply unit 23 for supplying power to the drive circuit 22 and the control circuit 21. .
As shown in FIG. 2, the drive circuit 22 is configured to input an RF signal from the outside, amplify the RF signal, and propagate the amplified RF signal toward the optical modulation element 10. The drive circuit 22 can also be configured to receive a low frequency signal from the control circuit 21 and superimpose the low frequency signal on the modulation signal when adjusting the DC bias.
Note that the RF signal generator can also be incorporated into the control box 2 without inputting an RF signal from the outside. Further, it is 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 propagate 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]
Further, the control circuit 21 is connected to the terminal 28 in order to exchange electric signals with the outside of the control box. For example, when the signal is input to the control circuit 21 from the outside, such as changing the amplification factor of the modulation signal, switching the modulation frequency, setting the timing and frequency of the DC bias control, or from the control circuit to the outside, It can be used when data indicating a modulation state is transmitted.
[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 have the same size as the housing 1, and the optical Arrangement and fixing of the housing 1 and the control box 2 to the base plate of the apparatus can also be performed using other joining / attaching means.
When configuring the control box compactly, provide only a circuit that can be compactly incorporated inside the box, such as a modulation signal drive circuit and a DC bias control circuit, and the power supply unit and RF signal generator are outside the control box. It is comprised so that it may be provided. And it can comprise so that a required electrical signal may be introduced into a control box from the outside via an external connection terminal like the terminal 27 of FIG.
[0025]
【The invention's effect】
As described above, according to the present invention, it is possible to prevent complication of electrical connection to the optical modulator, enlargement of the entire optical device including the optical modulator, and reduce 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 view showing an entire optical modulator with a control box according to the present invention.
FIG. 2 is a schematic view 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 that generates an optical signal modulated in response to an electrical signal and a control box containing a control means for controlling the optical modulation element are detachably coupled In the vessel
An optical modulator with a control box, wherein the housing is mechanically coupled to the control box and electrically connects the housing side and the control box side by the coupling. 2. The optical modulator with a control box according to claim 1, wherein the casing is mechanically supported and fixed by the control box. 3. The optical modulator with a control box according to claim 1, wherein all electrical connections required by the housing side are made through coupling with the control box. With optical modulator. 4. The optical modulator with a control box according to claim 1, wherein the electrical signal includes a microwave signal. 5. The optical modulator with a control box according to claim 1, wherein the housing includes a light detection element, and the control means operates based on a detection signal from the light detection element. An optical modulator with a control box.

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