KR100700478B1 - Tunable group delay controller for optical telecommunication system - Google Patents

Abstract

A variable time delay controller for an optical communication system is provided to precisely regulate the time delay characteristic of waves by controlling tensile force, contractive force, and dispersion slope induced to a chirped fiber grating according to the moving distance of movable plates, which are rectilinearly move in the opposite directions. A variable time delay controller for an optical communication system is composed of a base(1); first and second movable plates(22,24) horizontally arranged in parallel on the base and rectilinearly moved; a first movable plate moving unit; a second movable plate relative moving unit, which has a saw-toothed wheel rotatably installed on the base, a first linear gear(12) engaged with the saw-toothed wheel, and disposed in the movement direction and combined with the first movable plate, and a second linear gear(14) engaged with the other side of the saw-toothed wheel opposite to the first linear gear, and disposed in the movement direction and combined with the second movable plate, and relatively moving the second movable plate in the opposite direction of the first movable plate in moving the first movable plate; an elastic plate(40) arranged on the first and second movable plates at right angle to the movement direction and attached with optical fibers including a chirped fiber grating, on one side; and a unit for bending the elastic plate and the optical fiber symmetrically to the longitudinal center of the elastic plate in relatively moving the first and second movable plates. Contractive force is induced to one half part of the chirped fiber grating symmetrically bent and tensile force is induced to the other half part.

Description

Variable Time Delay Controller for Optical Communication Systems {TUNABLE GROUP DELAY CONTROLLER FOR OPTICAL TELECOMMUNICATION SYSTEM}

1 is a perspective view showing a variable time delay controller for an optical communication system according to the present invention;

2 is a perspective view showing an operation example of a variable time delay controller for an optical communication system according to the present invention;

3 is a plan view showing an operation example of a variable time delay controller for an optical communication system according to the present invention;

4 is a graph showing the reflectance of a chirped optical fiber grating measured as the elastic plate is bent in a variable time delay controller for an optical communication system according to the present invention;

5 is a graph showing a change in time delay characteristics measured as the elastic plate is bent in a variable time delay controller for an optical communication system according to the present invention.

<Explanation of symbols for the main parts of the drawings>

10: gear

12: first linear gear

14: second straight gear

22: first movable plate

24: second movable plate

26: first fixing pin

28: second fixing pin

30: support plate

32: first support frame

34: second support frame

40: elastic plate

50: optical fiber

52: concubine fiber grating

The present invention relates to a variable time delay controller for use in an optical communication system, and more particularly, to an apparatus capable of adjusting a time delay characteristic of an optical signal by bending a chirped fiber grating to induce an appropriate deformation.

Optical communication technology is rapidly developing as the amount of information required by the popularization of the Internet is rapidly increasing. In particular, a wavelength division multiplexing (WDM) optical transmission technology for transmitting optical signals of different wavelength bands through a single optical fiber is becoming a core technology in the optical communication field. The wavelength band used most in the WDM system is 1530-1565nm, and since the refractive index of the optical fiber is changed according to each wavelength of the optical signal, the optical signals having different wavelengths have different time delay characteristics. Therefore, an interference signal increases or a dispersion phenomenon in which a signal bandwidth is widened occurs. In addition, since the time delay characteristics of the optical signals increase as the transmission distance increases, it is difficult to distinguish the received optical signals from the receiving end of the optical communication system because the adjacent optical signals overlap each other.

In order to control such time delay characteristics, optical fibers in which chirped fiber gratings have been recently used are mainly used. When a change in period occurs in a chirped optical fiber grating, a change in the reflection point of optical signals of different wavelengths causes a change in the optical path and a change in the time delay characteristic (the change in the grating period is called a chirping rate). . That is, in the optical fiber grating, optical signals of different wavelengths are different from each other depending on the ratio of the optical fiber gratings, and the overall optical path is different, so that the time delay characteristics of the optical signals are changed.

Representative methods for controlling the time delay characteristics using a chirped optical fiber grating include temperature and bending. First, in the method using temperature, the chirp optical fiber grating is divided into several to several dozen sections, and each section is heated and cooled to different temperatures to change the refractive index of the optical fiber grating to induce a change in the splice rate by This method adjusts the time delay characteristics of the signal. However, in the temperature-based method, the refractive index change of each of the optical fiber gratings is discontinuous due to repeated heating and cooling of the optical fiber gratings, and unintentional change of refractive index occurs due to heat conduction in the adjacent areas. There is a problem such that the resonant wavelength of the chirped optical fiber grating is shifted.

On the other hand, the method of controlling the time delay characteristics by using bending, after attaching the chirp optical fiber grating on the surface of the elastic plate and bending the elastic plate to induce tensile force and contractile force to resonate the chirp optical fiber grating It is a way to change the time delay characteristics by changing the period of the chirped optical fiber grating without causing a change in wavelength. However, since the elastic plate is bent by changing only the position of one end of both ends of the elastic plate, there is a problem that the center wavelength of the optical signal entering and reflecting into the optical fiber grating may be changed by the changed grating period of the optical fiber grating. have. In addition, it is difficult to accurately adjust the time delay characteristics, and there is a disadvantage in that accurate bending and low reproducibility are realized.

The present invention is to solve the problems of the prior art, an object of the present invention is to provide a variable time delay controller for an optical communication system that can suppress the distortion of the optical signal by simply and continuously adjusting the time delay characteristics of the optical fiber grating To provide.

A variable time delay adjuster for an optical communication system according to the present invention for achieving the above object is a base; A first movable plate and a second movable plate which are horizontally parallel and linearly movable on the base; Means for moving the first movable plate; Means for relatively moving the second movable plate in a direction opposite to the moving direction of the first movable plate when the first movable plate moves; An elastic plate disposed on the first movable plate and the second movable plate at a right angle to the moving direction; An optical fiber attached to one surface of an elastic plate and including an optical fiber grating; And means for bending the elastic plate and the optical fiber symmetrically about the longitudinal center of the elastic plate during relative movement of the first movable plate and the second movable plate.

One side half of the symmetrically bent chirp optical fiber grating induces a contractive force and the other half induces a tensile force.

Preferably, the means for moving the first movable plate is a micrometer coupled to one surface of the first movable plate.

Preferably, the means for relatively moving the second movable plate is a gear wheel rotatably installed on the base, and the first linear gear is coupled to the cog wheel and disposed in the movement direction to the first movable plate and coupled; And a second straight gear which is separated from the side of the first straight gear of the cog wheel and is arranged to be coupled to the second movable plate in a moving direction.

Preferably, the means for bending the elastic plate and the optical fiber is installed in the base and the holder for fixing both ends of the elastic plate, and the upper surface of the first movable plate and the second movable plate in contact with the two opposite surfaces of the elastic plate, respectively It includes a first fixing pin and a second fixing pin provided.

On the upper surfaces of the first movable plate and the second movable plate, a plurality of pinholes in which the first fixing pin and the second fixing pin are selectively inserted are formed. The plurality of pinholes are arranged at right angles to the moving directions of the first movable plate and the second movable plate, and the spacing between the adjacent pinholes is constant.

Hereinafter, with reference to the accompanying drawings will be described in detail a preferred embodiment of the present invention.

1 is a perspective view showing a variable time delay adjuster for an optical communication system according to the present invention, Figures 2 and 3 are a perspective view and a plan view showing an operation example of the variable time delay adjuster for an optical communication system according to the present invention.

As shown therein, a toothed wheel 10 is rotatably installed at the center of the upper surface of the base 1 of the plate, and the teeth of the gear 10 are bitten off around the gear 10. The first linear gear 12 and the second linear gear 14 are installed to be linearly movable in opposite directions. An approximately rectangular parallelepiped first movable plate 22 is coupled to an upper surface of the first linear gear 12. Similarly, the second movable plate 24 having a substantially rectangular parallelepiped shape is horizontally coupled to the first movable plate 22 on the upper surface of the second linear gear 14.

Means for moving the first movable plate 22 by applying an external force to the first movable plate 22 are provided in the base 1. Preferably, the means is micrometer 16. The micrometer 16 includes a rotating part 16a and a moving bar 16b which extends from the rotating part 16a and whose front end is coupled to one side of the first movable plate 22 toward the moving direction. Since the micrometer 16 configured to move the reciprocating bar 16b in a linear reciprocating motion according to the forward and reverse rotation of the rotating part 16a is already well known, a description thereof will be omitted. Reference numeral 18 is a bracket installed on the base 1 to fix the micrometer 16.

Between the inner surfaces of which the first movable plate 22 and the second movable plate 24 face each other, a substantially rectangular parallelepiped shape for supporting the first and second movable plates 22 and 24 and guiding the movement at the same time. The support plate 30 is fixedly installed on the base 1. In addition, a first support frame for supporting the first and second movable plates 22 and 24 and guiding movement by contacting the outer surfaces of the first movable plate 22 and the second movable plate 24, respectively. 32 and the second support frame 34 are fixedly installed on the base 1.

An elastic plate 40 having a length from the first support frame 32 to the first support plate 22, the support plate 30, the second movable plate 24 and the second support frame 34 is shown in FIG. 2. ) Is installed upright on their upper surfaces. Preferably, the elastic plate 40 is formed of a material having high elastic restoring force (for example, metal, rubber, synthetic resin, etc.), and in this embodiment, spring steel having a length of 120 mm, a width of 30 mm, and a thickness of 0.2 mm. (spring steel) was used. First and second holders 36 and 38 for supporting both ends of the elastic plate 40 are formed on the upper surfaces of the first support frame 32 and the second support frame 34, respectively. The installation positions of the holders 36 and 38 are determined so that the first and second movable plates 22 and 24 can be disposed at right angles to the moving directions of the first and second movable plates 22 and 24. An optical fiber 50 including a plurality of concave optical fiber gratings 52 is horizontally attached to any one of the front surface 42 and the rear surface 44 of the elastic plate 40. In this embodiment, the optical fiber 50 is attached to the rear surface 44 of the elastic plate 40. The chirped optical fiber grating 52 has a linear grating period in accordance with a predetermined ratio. In the center 50a of the optical fiber 50 located at the longitudinal center point 40a of the elastic plate 40, an optical signal pulse having a center wavelength among optical signals introduced into the optical fiber 50 is reflected to compensate for dispersion. The grid with the center period is located.

The first fixing pin 26, which is in contact with the front surface 42 of the elastic plate 40, is installed on the upper surface of the first movable plate 22, and the elastic plate 40 is disposed on the upper surface of the second movable plate 24. The second fixing pin 28 in contact with the back 44 of the is installed upright. In order to install the first and second fixing pins 26 and 28, a plurality of pinholes 27 into which fixing pins 26 and 28 are inserted into upper surfaces of the first movable plate 22 and the second movable plate 24. , 29) are formed respectively. The plurality of pinholes 27 and 29 are arranged at right angles to the moving direction of the movable plates 22 and 24, and the spacing between the adjacent pinholes is constant. According to the desired bending position or degree of bending of the elastic plate 40, the user selects an appropriate pinhole among the plurality of pinholes 27 and 29 formed in the first movable plate 22 and the second movable plate 24, and then the first. The fixing pin 26 and the second fixing pin 28 may be inserted and fixed.

Hereinafter, the operation and effect of the variable time delay controller for the optical communication system according to the present invention configured as described above will be described.

In the non-operational state as shown in FIG. 1, when both ends of the elastic plate 40 to which the optical fiber 50 is attached are fixed to the first and second holders 36 and 38, respectively, the elastic plate 40 is fixed. The first and second movable plates 22 and 24 are arranged at right angles to the moving directions. The first fixing pin 26 and the second fixing pin 28 are inserted to be symmetrical to the desired pin holes 27 and 29 so as to be in contact with the front 42 and the rear 44 of the elastic plate 40.

When the worker rotates the rotating part 16a of the micrometer 16 in one direction, the moving bar 16b and the first movable plate 22 coupled thereto according to the amount of rotation are predetermined in the direction shown by the arrow X in FIG. Move straight distance. At this time, the movement of the first movable plate 22 is accurately guided in a straight line by the first support frame 32 and the support plate 30 which are in contact with both side surfaces of the first movable plate 22.

The first linear gear 12 coupled to the lower surface together with the first movable plate 22 also moves linearly, and the first linear gear 12 and the toothed tooth 10 are rotated. Therefore, the second linear gear 14 which is provided by being separated from the cogwheel 10 in the opposite direction of the first linear gear 12 moves the first linear gear 12 by the rotation of the cogwheel 10. It moves linearly in the direction opposite to the direction (the arrow Y direction in Fig. 2). At the same time, the second movable plate 24 coupled to the upper surface of the second linear gear 14 is also accurately moved in the direction of arrow Y by the support plate 30 and the second support frame 34 which are in contact with both sides thereof. do.

In addition, the first fixing pin 26 and the second fixing pin 28 are linearly moved in opposite directions by the relative movement of the first movable plate 22 and the second movable plate 24 as described above. . As a result, the elastic plate 40 has a first fixing pin 26 and a second fixing pin in a state where both ends thereof are fixed by holders 36 and 38 formed on the first and second support frames 32 and 34. As the contact portion with (28) is pressed in opposite directions according to the relative movement of the two fixing pins (26, 28), the elastic plate 40 is symmetrically deformed approximately S-shape as a whole based on its center point (40a). . At this time, the optical fiber 50 horizontally attached to the rear surface 44 of the elastic plate 40 is also deformed to be substantially S-shaped like the elastic plate 40 so that the period of the patch optical fiber grating 52 is changed.

As shown in FIG. 3, the chief optical fiber grating 52 located at the first half A from the first holder 36 to the center point 40a of the elastic plate 40 has a predetermined size. While the tensile force is induced, contraction force symmetrical to the tensile force is induced in the optical fiber grating 52 located at the second half portion B from the center point 40a of the elastic plate 40 to the second holder 38. . The period of the chirp optical fiber grating 52 of the first half portion A in which the tensile force is induced is increased, and the period of the chirp optical fiber grating 52 of the second half B in which the retraction force is induced is reduced, thereby reducing the Change is induced, and since the time delay characteristic of the optical signal changes, the dispersion characteristic can also be changed. The resonant wavelength of the chirp optical fiber grating 52 does not change since the magnitudes of the tensile force and the contraction force are symmetrically induced in the chirp optical fiber gratings 52 of the first and second half parts A and B, respectively. Instead, the movement of the center wavelength constituting the optical signal pulse introduced into the optical fiber 50 can be suppressed.

For convenience of description, an embodiment of the present invention has been described taking an example of attaching one optical fiber 50 having an optical fiber grating 52 to the elastic plate 40 as an example, but a plurality of optical fibers are attached to the elastic plate 40. When attached, the time delay characteristic can be adjusted for multi-channel optical signals.

4 and 5 show the movement of the moving bar 16b of the micrometer 16 in the variable time delay controller for the optical communication system according to the present invention (0 mm, 5 mm, 8 mm, 12 mm, 14 mm, 16 mm). This is a graph showing the change in reflectance and time delay characteristics of the spliced fiber grating measured by ADVENTEST's Optical Network Analyzer (model name: Q7750 OPTSCOPE).

The measurement results show that the time delay characteristics of the optical fiber grating are effectively controlled using the variable time delay controller for the optical communication system according to the present invention, and that the slope can be varied in the range of (+) 266.14 to (+) 35.97 ㎰ / nm. Can be. Here, the slope represents the dispersion characteristic of the chirped optical fiber grating, and the time delay characteristic of the optical fiber grating can be varied by using the adjusting device of the present invention, and the dispersion characteristic can be effectively adjusted.

The present invention is not limited to the above embodiments, and various modifications may be made by those skilled in the art without departing from the gist of the present invention as claimed in the claims.

As described in detail above, in the variable time delay controller for the optical communication system according to the present invention, by controlling the tensile force, the contraction force and the dispersion slope induced in the chirp optical fiber grating according to the moving distance of the movable plate linearly moving in the opposite direction In addition, dispersion compensation is performed by precisely adjusting the time delay characteristics of wavelengths constituting the optical signal pulse introduced into the optical fiber grating.

In addition, not only the dispersion inclination of the optical fiber grating can be continuously controlled, but also the structure and the operation are simple, and the effect is excellent in reproducibility.

Claims (6)

A base; A first movable plate and a second movable plate which are horizontally parallel and linearly movable on the base; Means for moving the first movable plate; A cog wheel rotatably installed on the base, a first straight gear which is engaged with the cog wheel and is disposed and coupled to the first movable plate in a moving direction, and opposite to the first straight gear of the cog wheel; A second linear gear that is bitten and disposed in the movement direction and coupled to the second movable plate, and relatively moves the second movable plate in a direction opposite to the movement direction of the first movable plate when the first movable plate is moved. Means for making; An elastic plate disposed on the first movable plate and the second movable plate at a right angle to the moving direction, and having an optical fiber including a superposed optical fiber grating on one surface thereof; Means for bending the elastic plate and the optical fiber symmetrically with respect to the longitudinal center of the elastic plate during relative movement of the first movable plate and the second movable plate; A variable time delay controller for an optical communication system, characterized in that a contractive force is induced at one half of the chirped optical fiber grating, and a tensile force is induced at the other half. 2. The variable time delay adjuster for optical communication system as claimed in claim 1, wherein the means for moving the first movable plate is a micrometer coupled to one surface of the first movable plate. delete According to claim 1, The means for bending the elastic plate and the optical fiber is installed on the base and the holder for fixing both ends of the elastic plate, and the elastic on the upper surface of the first movable plate and the second movable plate And a first fixing pin and a second fixing pin provided in contact with two opposite surfaces of the plate, respectively. 5. The variable optical communication system according to claim 4, wherein a plurality of pin holes are formed on upper surfaces of the first movable plate and the second movable plate to selectively insert the first fixing pin and the second fixing pin. Time delay adjuster. 6. The variable time delay adjuster of claim 5, wherein the plurality of pinholes are disposed at right angles to the moving directions of the first movable plate and the second movable plate, and the spacing between adjacent pinholes is constant. .

Images