JP2003329938A - Variable wavelength optical filter and wavelength varying method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a wavelength selective optical filter which can switch wavelengths at a high speed and has high performance, and a wavelength varying method. <P>SOLUTION: A variable wavelength optical filter has a plurality of wavelength selective optical filters 13 arranged along the optical axis 11 of collimated light connecting ends of input and output optical fibers, selects at least one wavelength selective filter 13 by independently moving each of the wavelength selective optical filters 13 by a driving mechanism, and putting it in and taking it out from the optical path of the collimated light to select a wavelength. The driving mechanism is equipped with a rotary motor 12 having a rotary shaft perpendicular or parallel to the optical axis 11 of the collimated light and a rotor substrate 15 fixed to the rotary shaft, and the wavelength selective optical filter 13 is arranged on the rotor substrate surface by a fitting fixture 14 at a position displaced from the center of the rotor substrate 15 and provided with a stopper mechanism 17 to which the rotor substrate 15 butt to stop at a position where the wavelength selective filter 13 enters the optical path of the collimated light and a position where it completely leaves the optical path. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wavelength tunable optical filter and a wavelength tunable method. For example, it is useful when applied to a wavelength tunable filter, especially a dielectric multilayer optical filter.

[0002]

2. Description of the Related Art In order to realize an optical communication network using wavelength routing, a wavelength tunable optical filter capable of switching passing wavelengths at high speed is required. The dielectric multilayer optical filter has excellent characteristics such as low temperature dependence and low aging property, and the wavelength can be easily switched by a simple mechanical switching mechanism. It has been generalized as an applicable one in the past.

FIG. 5 shows a conventional example of a switching mechanism. As shown in FIG. 5, the dielectric multilayer optical filter rotor substrate 1 in which the dielectric 1b is integrated on the rotor substrate 1a is rotated to change the incident angle of light to the filter layer and change the transmission center wavelength. It has a structure. Further, another conventional example is shown in FIG. As shown in FIG. 6, when the resonator layer of the filter uses a wedge-shaped dielectric multilayer optical filter rotor substrate 2, the rotor substrate 2 is directly moved as shown by an arrow in the figure to transmit light. It is equipped with a mechanism for changing the transmission center wavelength by changing the position.

In the filter, since the incident angle is always constant, it is possible to suppress the polarization dependent loss if the vertical incidence is maintained.

[0005]

In the wavelength tunable optical filter according to the above-mentioned prior art, it is necessary to move the optical filter to perform optimum position control in order to determine the target wavelength. Since the position accuracy directly affects the accuracy of the selected wavelength, a moving positioning mechanism using a closed loop control circuit is required to realize highly accurate wavelength switching. However, in the closed loop control method, generally, when trying to increase the response speed, it is necessary to increase the driving force and also a damping mechanism for suppressing mechanical resonance.

For this reason, the drive mechanism becomes extremely large, which has been a factor that impedes its application to optical communication systems.
Further, in the wavelength tunable optical filter having the wedge-shaped resonator layer, since the wide band is included, the lower limit of the size of the filter rotor substrate is limited, and therefore, the reduction of the inertial mass required for realizing the high speed operation is reduced. It was difficult.

Further, in a mechanism for retracting and inserting the wavelength selection filter in the optical path by using a linear motion mechanism or a rotary motion mechanism that simply takes a binary value, the performance is greatly affected by the mounting state of the wavelength selection filter. When using a rotary motor that has a rotary axis that is perpendicular to the optical axis of the collimated light, the required performance may not be ensured if the wavelength selection filter is installed tilted with respect to the optical axis. There was a problem.

Further, for example, when a rotary motor having a rotary shaft in a direction parallel to the optical axis of the collimated light is used, the positions of the respective wavelength selection filters are not perfectly aligned, so that the collimated light is eclipsed. However, the decrease in insertion loss has been a problem. The present invention has been made to solve the above-mentioned problems, and an object thereof is to provide a high-performance wavelength selective optical filter and a wavelength tunable method capable of switching a selective wavelength at high speed.

[0009]

A tunable optical filter according to claim 1 of the present invention comprises a plurality of wavelength selective optical filters along an optical axis of collimated light connecting ends of input and output optical fibers. A wavelength tunable optical filter that performs wavelength selection by moving each wavelength selective optical filter independently by a driving mechanism, selecting at least one wavelength selective filter, and putting the optical fiber in and out of the optical path of the collimated light. The drive mechanism includes a rotation motor having a rotation axis in a direction perpendicular or parallel to the optical axis of the collimated light and a rotor substrate fixed to the rotation axis, and the wavelength selection optical filter is deviated from the center of the rotor substrate. Are placed on the surface of the rotor substrate by a mounting jig at the above positions, and the wavelength selection filter is placed at a position where it enters the optical path of collimated light and a position where it is completely retracted. And having a structure in which the stopper mechanism is provided to stop abutment is over data board.

A tunable optical filter according to a second aspect of the present invention is the tunable optical filter according to the first aspect, wherein a slit for a rotary encoder for position detection is provided on the rotor substrate and the slit is provided. It is characterized by having a structure in which an optical encoder is arranged so as to sandwich it. With this configuration, it is possible to switch arbitrary wavelength selection optical filters. Further, by dispersing the drive mechanism, the moment of inertia of the driven object can be reduced to a desired value. Furthermore, since the moment of inertia of the driven object is small, the reduction mechanism is not needed.

A wavelength tunable method according to claim 3 of the present invention comprises:
In the wavelength tunable method using the wavelength tunable optical filter according to claim 1, for a wavelength selection filter other than a target among a plurality of wavelength selection filters, a wavelength selection filter that is not in a retracted position is rotated by a rotary motor to rotate a rotor substrate. To move all of the wavelength selection filters to the retracted position and the relationship information between the drive input and the rotor substrate rotation position written in the memory of the control device in advance, and the target wavelength selection filter of the plurality of wavelength selection filters is retracted. From a state where the rotor substrate is rotated to a target position in the optical path of the collimated light, the rotor substrate rotates and the rotor substrate is stopped by the stopper. With this configuration, it is possible to perform positioning from the origin position for all rotary motors regardless of the current position of each rotary motor.

A wavelength tunable method according to claim 4 of the present invention comprises:
The wavelength tunable method using the wavelength tunable optical filter according to claim 2, wherein a wavelength selection filter other than the target wavelength selection filter among the plurality of wavelength selection filters is rotated by rotating the rotor substrate with a rotation motor. By referring to the first step of moving all of them to the retracted position and the relationship information between the drive input and the rotor substrate rotation position written in the memory of the control device in advance, the target wavelength selection filter among the plurality of wavelength selection filters is selected. From the retracted state to the target position that enters the optical path of the collimated light, the rotation motor rotates and the rotor substrate is stopped by the stopper.
And the step of finely adjusting to the optimum position of the wavelength selection filter by the slit for the rotary encoder for position detection on the rotor substrate and the position detection signal from the optical encoder.
And the process of

With this configuration, when the rotary motor having the rotary shaft in the direction perpendicular to the optical axis of the collimated light is used, the inclination of the wavelength selective optical filter from the optical axis of the collimated light is corrected. Further, when the rotary motor having the rotary shaft in the direction parallel to the optical axis of the collimated light is used, the position of the wavelength selection filter can be aligned with the optimum position with respect to the optical axis.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will now be described in detail with reference to the embodiments shown in the drawings. [Embodiment 1] A first embodiment of the present invention is shown in FIGS. FIG. 1 is a configuration diagram of a wavelength tunable optical filter according to this embodiment. FIG. 2 is an explanatory diagram showing steps of a wavelength selection method using the wavelength tunable optical filter according to this embodiment.

As shown in FIG. 1, the wavelength tunable optical filter of the present invention has an optical axis 11 of collimated light that connects the ends of a collimator 10 installed in an input / output optical fiber.
The wavelength selection optical filter (dielectric multilayer film optical filter) 13 mounted on a plurality of driving mechanisms is arranged. As the drive mechanism, an ultrasonic motor 12 having a rotation axis in a direction parallel to the optical axis 11 of the collimated light was used, and the rotor substrate 15 was fixed to the rotation axis.

At a position deviated from the center of the rotor substrate 15, a wavelength selection optical filter 13 is arranged on the substrate surface by a mounting jig 14. A hole for attaching the filter is opened in the mounting jig 14, and the wavelength selection optical filter 13 is inserted and fixed in the hole. Further, a stopper mechanism 17 is arranged to stop the rotor substrate 15 from abutting at the position where the wavelength selection optical filter 13 enters the optical path of the collimated light and the position where it is completely retracted.

FIG. 2 shows a wavelength tuning method using the wavelength tuning filter according to this embodiment (hereinafter referred to as a wavelength selection method). First, as shown in FIG. 2A, regarding a wavelength selection filter other than the target among the plurality of wavelength selection filters,
The wavelength selection filter 20 that is not in the retracted position is attached to the rotary motor 2
The rotor substrate 15 is rotated by 2 to move all to the retracted position. Next, as shown in FIG. 2B, reference is made to the relationship information between the drive input and the rotor substrate rotational position, which has been written in advance in the memory of the control device, and the target wavelength selection filter of the plurality of wavelength selection filters is selected. The rotor substrate is rotated by the rotary motor from the retracted state of 21 to the target position where it enters the optical path of the collimated light 23, and the attachment jig 14 causes the stopper 1 to move.
It stops by hitting 7.

The target wavelength selection filter 21 is not limited to being selected as one filter, but may be selected as a plurality of filters. Since the wavelength selection optical filter 21 is within the optical axis of the collimated light 23 at the stop position, wavelength selection is performed.

Based on the configuration and the selection method described above, the wavelength selection filter is constructed and the selection switching operation is confirmed. As a result, the wavelength selection set by the wavelength tunable optical filter of the present invention can be executed. confirmed. Further, as a result of constructing the wavelength selection filter by using a commercially available ultra-small ultrasonic motor (diameter 5 mm), it was confirmed that the size was significantly reduced from the conventional one. Regarding the switching time, it was confirmed that the time required for one wavelength selective optical filter to retract from the optical path of the collimated light was about 20 ms or less.

In the above embodiment, the optical axis 11 of the collimated light is used.
Although the mode in which the rotary motor having the rotary axis in the direction parallel to the optical axis is used has been described, the same effect is obtained even in the mode in which the wavelength selective filter is retracted and inserted by the rotary motor having the rotary axis in the direction perpendicular to the optical axis 11. It was confirmed that
It should be noted that the present invention is not limited to the forms described in the above embodiments, and for example, a direct drive (linear) motor can be used for the drive mechanism, and the drive mechanism is not limited to the ultrasonic motor, and the electromagnetic drive can be used. Type servo motors, electrostatic drive motors and the like can be used, and it is needless to say that various modifications can be made without departing from the spirit of the invention.

[Embodiment 2] A second embodiment of the present invention is shown in FIG.
And shown in FIG. FIG. 3 is a configuration diagram of the wavelength tunable optical filter according to the present embodiment. FIG. 4 is an explanatory diagram showing steps of a wavelength selection method using the wavelength tunable optical filter according to the present embodiment. As shown in FIG. 3, the wavelength tunable optical filter of the present invention is mounted on a plurality of drive mechanisms along an optical axis 31 of collimated light that connects the ends of the collimator 30 installed in the input and output optical fibers. The wavelength selection optical filter (dielectric multilayer film optical filter) 33 is arranged.

The drive mechanism used was an electromagnetically driven servomotor (not shown) having a rotary shaft in a direction perpendicular to the optical axis 31 of the collimated light, and the rotor substrate 32 was fixed to the rotary shaft. At a position deviated from the center of the rotor substrate 32, a wavelength selection optical filter 33 is arranged on the substrate surface by a mounting jig 34. Further, a slit 35 for a rotary encoder for position detection is provided on the rotor substrate 32, and an optical encoder 36 is arranged so as to sandwich the slit of the rotor substrate 32. Further, a stopper mechanism 37 is provided so that the rotor substrate 32 abuts and stops at the position where the wavelength selection optical filter 33 enters the optical path of the collimated light and the position where it is completely retracted.

FIG. 4 shows a wavelength tuning method (hereinafter referred to as a wavelength selection method) using the wavelength tunable filter according to this embodiment. First, as shown in FIG. 4A, regarding a wavelength selection filter other than the purpose among the plurality of wavelength selection filters,
The wavelength selection filter 40 that is not in the retracted position is moved to the retracted position by rotating the rotor substrate 32 by an electromagnetically driven servomotor. Next, as shown in FIG. 4 (b), referring to the relationship information between the drive input and the rotor substrate rotation position, which is written in the memory of the control device in advance, the target wavelength selection filter of the plurality of wavelength selection filters is selected. The rotor substrate is rotated by the rotary motor from the retracted state of 41 to a position where it enters the optical path of the collimated light 31, and the mounting jig 34 comes into contact with the stopper 37 to stop.

The target wavelength selection filter 41 is not limited to being selected as one filter, but may be selected as a plurality of filters. Finally, as shown in FIG. 4C, the slit 35 provided on the rotor substrate 32.
Feedback control is performed by the position detection signal from the optical encoder 36, and the wavelength selection optical filter 41 is finely adjusted to the optimum position.

Based on the configuration and the selection method described above, the wavelength selection filter is configured and the selection switching operation is confirmed. As a result, the wavelength selection set by the wavelength tunable optical filter of the present invention can be executed. confirmed. Further, as a result of constructing the wavelength selection filter using a commercially available ultra-compact motor (diameter: 5 mm), it was confirmed that the size of the wavelength was significantly reduced. Regarding the switching time, it was confirmed that the time required for one wavelength selective optical filter to retract from the optical path of the collimated light was about 20 ms or less. Also, after moving the wavelength selective optical filter from the retracted position to the stopper position and feeding back the position detection amount by the encoder after stopping, calibration is performed so that the surface of the wavelength selective optical filter is perpendicular to the optical axis of the collimated light. It was possible and confirmed to have high performance.

In the above embodiment, the optical axis 31 of the collimated light is used.
Although the form applied to the rotary motor having the rotary shaft in the direction perpendicular to the direction has been described, the insertion loss is reduced even in the form in which the wavelength selective filter is retracted and inserted by the rotary motor having the rotary shaft in the direction parallel to the optical axis 31. The wavelength selection optical filter can be miniaturized. It should be noted that the present invention is not limited to the form described in the above embodiment, and for example, a direct drive (linear) motor can be used for the drive mechanism, and the drive mechanism is not limited to the electromagnetic drive type servo motor. It is needless to say that a sonic motor, an electrostatic drive motor, or the like can be used, and various modifications can be made without departing from the spirit of the invention.

As described above, the present invention relates to a wavelength tunable optical filter having the basic features shown in FIGS. 1 to 4 and a wavelength conversion method in the filter,
It is equipped with a plurality of rotary drive mechanisms (such as ultrasonic motors), a filter installed on the rotor substrate of the drive mechanism, and a stopper that regulates the movement position when the filters are moved by the rotary drive. Since the selected wavelength is converted by inserting / removing at least one filter, it is possible to realize a highly tunable wavelength tunable optical filter which is small in size and can perform the selective wavelength conversion at high speed.

[0028]

As described above, according to the wavelength tunable optical filter of the present invention, industrially remarkable effects can be obtained as shown below. The drive mechanism includes a rotary motor having a rotary shaft in a direction perpendicular or parallel to the optical axis of the collimated light and a rotor substrate fixed to the rotary shaft, and the wavelength selective optical filter is deviated from the center of the rotor substrate. At a position, which is arranged by a mounting jig on the surface of the rotor substrate, a structure is provided with a stopper mechanism that stops the rotor substrate from abutting at the position where the wavelength selection filter enters the optical path of collimated light and the position where it is completely retracted, Further, a slit for a rotary encoder for position detection is provided on the rotor substrate, and an optical encoder is arranged so as to sandwich the slit, so that the inertial moment of the object to be driven by dispersing the drive mechanism Can be reduced to a desired value, and the desired switching time can be achieved with a small drive mechanism, greatly reducing the size of the device. Reduction became possible. Further, since the moment of inertia of the object to be driven is small, a reduction mechanism is not required, and the cost of the device itself can be reduced.

Further, in the wavelength tunable method using the tunable optical filter, for the wavelength selection filters other than the intended one among the plurality of wavelength selection filters, the wavelength selection filter not in the retracted position is rotated by the rotation motor to rotate the rotor substrate. Of the target wavelength selection filter among the plurality of wavelength selection filters by referring to the relationship information between the drive input and the rotor substrate rotation position, which is stored in advance in the memory of the control device, and the step of moving all the wavelength selection filters to the retracted position. Rotation is performed by the rotation motor to stop the rotor substrate from the stopped state to the target position where it enters the optical path of the collimated light. Since the feedback control for positioning over the entire circumference of the motor is not performed, any wavelength selective optical filter can be used. High-speed switching of it has become possible.
It is possible to position from the origin position without fail.
It is possible to achieve high reliability of switching of arbitrary wavelength selection optical filters.

In addition to the above steps, a wavelength tunable selection is added by adding a third step of finely adjusting to the optimum position of the wavelength selection filter by a slit for a rotary encoder for position detection on the rotor substrate and a position detection signal from an optical encoder. By adopting the method, the feedback control for positioning over the entire circumference of the rotary motor is not performed, so that it is possible to switch any wavelength selective optical filter at high speed. When using a rotary motor that has a rotary axis that is perpendicular to the optical axis of the collimated light, the tilt of the wavelength selective optical filter from the optical axis of the collimated light can be corrected, and the desired performance can be secured. Became possible.

Further, when the rotary motor having the rotary shaft in the direction parallel to the optical axis of the collimated light is used, the positions of the wavelength selection filters can be aligned so that the insertion loss can be reduced and the wavelength selection can be performed. The optical filter can be downsized, and the entire size can be downsized.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a wavelength tunable optical filter according to a first embodiment of the present invention.

FIG. 2 is an explanatory diagram showing steps of the wavelength selection method in the first embodiment of the present invention.

FIG. 3 is a configuration diagram of a wavelength tunable optical filter according to a second embodiment of the present invention.

FIG. 4 is an explanatory diagram showing a step of a wavelength selection method according to a second embodiment of the present invention.

FIG. 5 is an explanatory view conceptually showing a wavelength tunable optical filter according to a conventional technique.

FIG. 6 is an explanatory view conceptually showing another wavelength tunable optical filter according to the prior art.

[Explanation of symbols]

1a rotor substrate 1b Dielectric 1 Dielectric multilayer film optical filter rotor substrate 2 Dielectric multilayer optical filter rotor substrate 10 Collimator 11 optical axis 12 rotation motor 13 Dielectric multilayer film optical filter 14 Mounting jig 17 Stopper 20 wavelength selective optical filter 21 Wavelength selective optical filter 22 rotary motor 23 Collimated light 30 collimator 31 Collimating optical axis 32 rotation motor 33 Dielectric multilayer film optical filter 34 Mounting jig 35 slits 36 Optical encoder 37 Stopper 40 wavelength selective optical filter 41 wavelength selective optical filter

Continued front page    (72) Inventor Eiji Yoshida             2-3-1, Otemachi, Chiyoda-ku, Tokyo             Inside Telegraph and Telephone Corporation (72) Inventor Kunihiko Mori             2-3-1, Otemachi, Chiyoda-ku, Tokyo             Inside Telegraph and Telephone Corporation F-term (reference) 2H041 AA21 AB10 AC01 AZ02 AZ06                 2H048 GA23 GA25 GA62 GA66

Claims (4)

[Claims] 1. A plurality of wavelength selection optical filters are arranged along an optical axis of collimated light connecting end portions of input and output optical fibers, and each wavelength selection optical filter is independently moved by a driving mechanism. A wavelength tunable optical filter that performs wavelength selection by selecting at least one wavelength selection filter and putting it in and out of the optical path of the collimated light,
The drive mechanism includes a rotation motor having a rotation axis in a direction perpendicular or parallel to the optical axis of the collimated light and a rotor substrate fixed to the rotation axis, and the wavelength selection optical filter is deviated from the center of the rotor substrate. A structure is provided in which a stopper mechanism is provided on the surface of the rotor substrate at a predetermined position by a mounting jig, and the rotor substrate abuts and stops at a position where the wavelength selection filter enters the optical path of collimated light and a position where the wavelength selection filter is completely retracted. A tunable optical filter characterized by having. 2. The variable wavelength optical filter according to claim 1, wherein a slit for a rotary encoder for position detection is provided on the rotor substrate, and an optical encoder is arranged so as to sandwich the slit. Tunable optical filter characterized by. 3. A wavelength tunable method using the wavelength tunable optical filter according to claim 1, wherein a wavelength selection filter which is not in a retracted position is selected from a plurality of wavelength selection filters by a rotary motor. By referring to the process of rotating the rotor substrate to move it all to the retracted position and the relationship information between the drive input and the rotor substrate rotational position written in the memory of the controller in advance, the target wavelength of the plurality of wavelength selection filters is selected. A wavelength tunable method comprising: a step of rotating a selection filter from a retracted state to a target position entering the optical path of collimated light by a rotation motor and stopping a rotor substrate by a stopper. 4. The wavelength tunable method using the wavelength tunable optical filter according to claim 2, wherein a wavelength selection filter which is not in the retracted position is selected from a plurality of wavelength selection filters other than the target by a rotary motor. Of the plurality of wavelength selection filters, the first step of rotating the rotor substrate to move all to the retracted position and the relational information between the drive input and the rotor substrate rotational position written in the memory of the control device in advance are referred to. From the retracted state of the target wavelength selection filter to the target position where it enters the optical path of the collimated light, the second step in which the rotor substrate is rotated by the rotation motor and the rotor substrate is stopped by the stopper, and the position detection on the rotor substrate is performed. The slit for the rotary encoder and the position detection signal from the optical encoder finely adjust to the optimum position of the wavelength selection filter. A wavelength tunable method comprising the steps of: