JP4858827B2 - Alignment method - Google Patents

Description

  The present invention relates to an alignment method for irradiating two photodiodes with light emitted from two optical fibers (two-core ferrule fiber), and more particularly to an alignment method capable of performing alignment efficiently.

  Prior art documents related to the alignment method such as irradiating two photodiodes with light emitted from two conventional optical fibers (ferrule fibers) include the following.

JP 2001-154147 A JP 2002-202440 A JP 2003-124559 A

  9 and 10 are a plan view and a perspective view showing an example of such a conventional alignment method. 9 and 10, reference numerals 1 and 2 denote optical fibers, 3 denotes an emission end (ferrule), 4 denotes a lens, and 5 denotes a photodiode unit having two light receiving surfaces indicated by “PD01” and “PD02”. 1, 2 and 3 constitute a two-core ferrule fiber.

  The light propagating through the optical fiber 1 is emitted from the emission end 3, passes through the lens 4 like a light beam indicated by “BM01” in FIGS. 9 and 10, and “PD01” in FIGS. 9 and 10 of the photodiode unit 5. It is incident on one light receiving surface shown in FIG.

  Similarly, the light propagated through the optical fiber 2 is emitted from the emission end 3, passes through the lens 4 as shown by “BM02” in FIGS. 9 and 10 and passes through the lens 4 in FIGS. 9 and 10. The light is incident on the other light receiving surface indicated by “PD02”.

  Here, a conventional alignment method shown in FIGS. 9 and 10 will be described. When the distance between the emitting end 3 indicated by “l” in FIG. 10 and the lens 4 is changed, the light beams indicated by “BM01” and “BM02” in FIG. The distance to be squeezed changes.

  On the other hand, when the distance between the lens 4 indicated by “L” in FIG. 10 and the photodiode unit 5 is changed, the distance between the light beams indicated by “BM01” and “BM02” in FIG. The distance of changes.

  Therefore, the distance indicated by “L” in FIG. 10 is changed so that the distance between the light beams indicated by “BM01” and “BM02” in FIG. 10 on the light receiving surface of the photodiode unit 5 is “PD01” in FIG. Adjustment is made so that the distance between the light receiving surfaces indicated by “PD02” matches the distance (strictly speaking, the distance between the center points of the light beams matches the distance between the center points of the light receiving surfaces).

  At the same time, by changing the distance indicated by “l” in FIG. 10 and adjusting the distance until the light beam diameter is reduced to coincide with the light receiving surface of the photodiode unit 5, “PD01” and It becomes possible to irradiate the light receiving surface of the photodiode unit 5 indicated by “PD02” with the light beams indicated by “BM01” and “BM02” in FIG.

  As a result, the distance between the emitting end 3 and the lens 4 and the distance between the lens 4 and the photodiode unit 5 are appropriately changed, and the distance until the light beam diameter is reduced is the light receiving surface of the photodiode unit 5. By adjusting the distance between the center points of the light beams to match the distance between the center points of the light receiving surface, the light beam can be irradiated onto the light receiving surface of the photodiode unit 5 with a reduced light beam diameter. It becomes possible. In other words, alignment is completed.

  However, in the conventional example shown in FIGS. 9 and 10, the axis passing through the center point of the two light receiving surfaces indicated by “PD01” and “PD02” in FIG. 10 is the same as the axis passing through the center point of the two light beams. In many cases, I have not done it.

  When alignment is performed in such a state, one light beam irradiates one light receiving surface of the photodiode unit 5, but the light beam is mistakenly received due to the mismatch of the axes described above. The surface may be irradiated.

  For example, the light beam indicated by “BM01” in FIG. 10 should be originally irradiated on the light receiving surface indicated by “PD01” in FIG. 10, but may be applied to the light receiving surface indicated by “PD02” in FIG. Is done.

  In this case, there is a problem that the alignment work becomes very complicated, and the alignment work time becomes very long.

That is, in the actual alignment work, the light beam “BM01” emitted from the optical fiber 1 and the light beam “BM02” emitted from the optical fiber 2 are clearly distinguished as shown in the perspective view of FIG. There was a problem that it was difficult to eliminate the possibility of performing misalignment.
Therefore, the problem to be solved by the present invention is to realize an alignment method capable of performing alignment efficiently.

In order to solve such a problem, the invention according to claim 1 of the present invention,
An alignment method of irradiating two light receiving surfaces of a photodiode unit with two light beams from an emission end to which two optical fibers are fixed, respectively,
Two polarization plane holding optical fibers are fixed to the exit end so that the respective polarization planes are 90 degrees with each other, and a polarizing plate inserted between the exit end and the lens is rotated to emit light beams one by one. While passing through and incident on the light receiving surface of the photodiode unit, the position of the photodiode unit is moved, and the XY coordinates of the surface on which the light receiving surface of the photodiode unit is formed are measured from the position of the photodiode unit , The photodiode unit is rotated about the origin where the center point of the light beam coincides with the center point of the light receiving surface on the XY coordinate plane by the first correction angle obtained from the measurement coordinates of the two light beams . a shaft passing through the center point of the light-receiving surface, by matching the axis passing through the center point of the two light beams, so can be performed efficiently alignment That.

The invention according to claim 2
An alignment method of irradiating two light receiving surfaces of a photodiode unit with two light beams from an emission end to which two optical fibers are fixed, respectively ,
An etalon is inserted between the exit end and the lens, and light having a wavelength different by ½ of the free spectral region of the etalon is propagated to the two optical fibers, and the angle, temperature, or refractive index of the etalon. The wavelength of light that can be transmitted is selected by changing the wavelength, and the light beam is allowed to pass one by one to be incident on the light receiving surface of the photodiode unit, and the position of the photodiode unit is moved so that the photo diode is moved from the position of the photodiode unit. The XY coordinate of the surface on which the light receiving surface of the diode unit is formed is measured, and the photodiode unit is moved to the center of the light beam on the XY coordinate plane by the first correction angle obtained from the measurement coordinates of the two light beams. Rotate around the origin where the center points of the light-receiving surfaces coincide with each other, and rotate the axes passing through the center points of the two light-receiving surfaces and the two light beams. By matching the axis passing through the center point, it is possible to perform efficiently alignment.

The invention described in claim 3
An alignment method of irradiating two light receiving surfaces of a photodiode unit with two light beams from an emission end to which two optical fibers are fixed, respectively ,
The light propagating through the two optical fibers is optically modulated at different modulation frequencies, and the light beam of the two optical fibers is determined based on the optical modulation frequency of the light received when detected by the photodiode unit. Judging and making the two light beams enter the photodiode unit, moving the position of the photodiode unit, and measuring the XY coordinates of the surface on which the light receiving surface of the photodiode unit is formed from the position of the photodiode unit And rotating the photodiode unit by the first correction angle obtained from the measurement coordinates of the two light beams about the origin where the center point of the light beam coincides with the center point of the light receiving surface on the XY coordinate plane, a shaft passing through the center points of the two light receiving surfaces, by matching the axis passing through the center point of the two light beams, efficiency Ku it is possible to perform centering.

The invention according to claim 4
An alignment method according to any one of claims 1 to 3, comprising:
Two light beams are incident on the photodiode unit, the position of the photodiode unit is moved, and the Z coordinate in the direction perpendicular to the surface on which the light receiving surface of the photodiode unit is formed is measured from the position of the photodiode unit. and, from the two light beams measured coordinates of the determined second correction angle, the second correction angle by the photodiode unit, a point bisecting the interval of the light receiving surface of the photodiode unit in the XZ coordinate plane By rotating as the center of rotation and aligning the axis passing through the center point of the two light receiving surfaces and the axis passing through the center point of the two light beams, alignment can be performed efficiently.

The present invention has the following effects.
According to the first and fourth aspects of the present invention, the optical fiber holding the polarization plane and the output end 8 are fixed so that the respective polarization planes are 90 degrees from each other at the output end, and the distance between the light beams is set to the photodiode. Adjust the distance between the light-receiving surfaces of the unit, rotate the polarizing plate, pass the light beam one by one, and measure the XY coordinates of the incident position on the photodiode unit. By rotating on the coordinate plane, alignment can be performed efficiently.

  According to the second and fourth aspects of the present invention, an ordinary single mode fiber is used as the two optical fibers instead of the polarization-maintaining optical fiber, and an etalon FSR (for each optical fiber) is used. Only one of the two optical fibers can be selected by propagating light having a different wavelength by half of the free spectral range) and changing the etalon angle, temperature, or refractive index to select the wavelength of light that can be transmitted. Efficiently by rotating the photodiode unit on the XY coordinate plane by the correction angle obtained by irradiating the photodiode unit, passing the light beam one by one and measuring the XY coordinate of the incident position on the photodiode unit. Alignment can be performed.

  According to the invention of claim 3 and claim 4, the light propagating through the two optical fibers is optically modulated at different modulation frequencies, and the two light modulation frequencies of the light received when the light is detected by the photodiode unit are used. By determining which light beam is in the optical fiber and rotating the photodiode unit on the coordinate plane by the correction angle obtained by measuring the coordinates of the incident positions of the two light beams on the photodiode unit, the efficiency is improved. It becomes possible to align well.

  Hereinafter, the present invention will be described in detail with reference to the drawings. 1 and 3 are plan views showing an embodiment of the alignment method according to the present invention, and FIGS. 2 and 4 are perspective views showing an embodiment of the alignment method according to the present invention.

  1 to 4, reference numerals 6 and 7 denote optical fibers holding the polarization plane, 8 denotes an output end (ferrule), 9 denotes a polarizing plate, 10 denotes a lens, and 11 denotes two light receiving surfaces indicated by “PD11” and “PD12”. This is a photodiode unit. 6, 7 and 8 constitute a two-core ferrule fiber.

  The light propagating through the optical fiber 6 is emitted from the emission end 8, passes through the polarizing plate 9 and the lens 10 like the light beam indicated by “BM 11” in FIGS. 1 and 2, and shows the photodiode unit 11 in FIGS. 2 is incident on one light receiving surface indicated by “PD11”.

  Similarly, the light propagating through the optical fiber 7 is emitted from the emission end 8 and passes through the polarizing plate 9 and the lens 10 as shown by “BM12” in FIG. 3 and FIG. And it injects into the other light-receiving surface shown by "PD12" in FIG.

  The operation of the embodiment shown in FIGS. 1 to 4 will be described with reference to FIG. FIG. 5 is an explanatory diagram showing the relationship between each light receiving surface of the photodiode unit 11 and two light beams to be irradiated.

  First of all, the optical fibers 6 and 7 are polarization-maintaining optical fibers, and the optical fibers 6 and 7 are fixed to the output end 8 so that the respective polarization planes are “90 degrees” at the output end 8. Is done.

  Secondly, the distance between the emission end 8 and the lens 10 and the distance between the lens 10 and the photodiode unit 11 are appropriately changed, and the interval between the light beams (strictly speaking, the two light beams). Is adjusted so that the distance between the light receiving surfaces of the photodiode unit 11 (strictly speaking, the distance between the center points of the two light receiving surfaces).

  Further, a surface on which the light receiving surface of the photodiode unit 11 is formed is defined as an “XY coordinate plane”.

  In such a state, the polarizing plate 9 is rotated by a driving unit (not shown), and only one of the light beams is allowed to pass through, and the light receiving surface of the photodiode unit 11 is irradiated through the lens 10.

  For example, the polarizing plate 9 is rotated to block the light beam indicated by “BM12” in FIGS. 1 and 2, and only the light propagating through the optical fiber 6 is transmitted as indicated by “BM11” in FIGS.

  The light beam indicated by “BM11” in FIGS. 1 and 2 is incident on the light receiving surface indicated by “PD11” in FIGS. 1 and 2 of the photodiode unit 11 through the lens 10, and the position of the photodiode unit 11 is also determined. To XY coordinates of the light beam on the incident surface.

  As an XY coordinate measuring method, the position of the photodiode unit 11 is moved by moving the position of the photodiode unit 11 so that the beam diameter of the light beam indicated by “BM11” in FIGS. To XY coordinates on the light receiving surface of the light beam indicated by “BM11” in FIGS.

  Similarly, for example, the polarizing plate 9 is rotated to block the light beam indicated by “BM11” in FIGS. 3 and 4, and only the light propagating through the optical fiber 6 is indicated as indicated by “BM12” in FIGS. Make it transparent.

  The light beam indicated by “BM12” in FIGS. 3 and 4 is incident on the light receiving surface indicated by “PD12” in FIGS. 1 and 2 of the photodiode unit 11 through the lens 10, and the position of the photodiode unit 11 is also determined. To XY coordinates of the light beam on the incident surface.

  As the measurement method of the XY coordinates, the position of the photodiode unit 11 is moved so that the beam diameter on the light receiving surface of the light beam indicated by “BM12” in FIG. 3 and FIG. From the position of the unit 11, XY coordinates on the light receiving surface of the light beam indicated by “BM12” in FIGS. 3 and 4 are measured.

  In FIG. 5, “BM31” is the measured XY coordinate of the light beam indicated by “BM11” in FIGS. 1 and 2, and “BM32” is the measured XY coordinate of the light beam indicated by “BM12” in FIGS. , “PD31” is the XY coordinate of the light receiving surface indicated by “PD11” in FIGS. 1 and 2 of the photodiode unit 11, and “PD32” is the light receiving surface indicated by “PD12” in FIGS. 3 and 4 of the photodiode unit 11. Let it be XY coordinates.

  Then, the center point of the light beam indicated by “BM31” in FIG. 5 is matched with the center point of the light receiving surface indicated by “PD31” in FIG.

となる。 Further, the interval between the light receiving surfaces of the photodiode unit 11 (strictly speaking, the interval between the center points of the two light receiving surfaces) is “W”, and the center point and the origin of the light beam indicated by “BM32” in FIG. And the difference between the center point of the light beam indicated by “BM32” in FIG. 5 in the X-axis direction and the center point of the light receiving surface indicated by “PD32” in FIG. The angle “θ” is

It becomes.

  That is, the photodiode unit 11 (or the correction angle “θ” around the origin (the center point of the light beam indicated by “BM31” in FIG. 5 or the center point of the light receiving surface indicated by “PD31” in FIG. 3)) By rotating the emission end 8) in the “XY coordinate plane”, the center point of the light beam indicated by “BM32” in FIG. 5 coincides with the center point of the light receiving surface indicated by “FD32” in FIG.

  FIG. 6 is an explanatory view showing an example of a conventional incorrect alignment method. In FIG. 6, “BM31”, “BM32”, “PD31”, and “PD32” are denoted by the same reference numerals as in FIG.

  In the conventional wrong alignment method, “BM31” and “BM32” in FIG. 6 are irradiated at the same time. Therefore, the light beam “BM31” emitted from the optical fiber 6 and the light beam emitted from the optical fiber 7 are used. “BM32” cannot be clearly distinguished.

  For this reason, the light beam indicated by “BM32” in FIG. 6 that should originally be applied to the light receiving surface indicated by “PD32” in FIG. 6 may be applied to the light receiving surface indicated by “PD31” in FIG. In this case, a very large amount of alignment work is required, but in the present invention, the light beam “BM32” emitted from the fiber 7 can be clearly distinguished. It is possible to prevent the alignment method from being performed.

  As a result, the polarization-maintaining optical fibers 6 and 7 are fixed to the emission end 8 so that the respective polarization planes at the emission end 8 are “90 degrees”, and the interval between the light beams is the light receiving surface of the photodiode unit 11. , The polarizing plate 9 is rotated, the light beam is allowed to pass one by one, and the XY coordinates of the incident position on the photodiode unit 11 are measured to obtain the correction angle “θ” by the correction angle “θ”. Is rotated on the “XY coordinate plane”, thereby enabling efficient alignment.

  In the description of the embodiment shown in FIGS. 1 to 4, the XY coordinates on the light receiving surfaces of the two light beams are measured to obtain the correction angle, but the XYZ coordinates on the light receiving surfaces of the two light beams are measured. Then, alignment may be performed so as to correct the difference in the Z-axis direction.

  FIG. 7 is an explanatory diagram for explaining an alignment method in consideration of the difference in the Z-axis direction. In FIG. 7, 11, “BM11”, “BM12”, “PD11” and “FD12” have the same reference numerals as in FIG. It is attached. Further, the plan view and the perspective view are the same as those in FIGS. 1 to 4, and the difference is that the XYZ coordinates on the light receiving surface of the light beam are measured.

  Here, the surface on which the light receiving surface of the photodiode unit 11 is formed is defined as an “XY coordinate plane”, and the direction perpendicular to the light receiving surface of the photodiode unit 11 is defined as the Z axis.

  As can be seen from FIG. 7, the Z-axis direction corresponds to the deviation of the optical axis method at the position where the beam diameter of the light beam is minimized, and the measurement method of the XYZ coordinates is the same as described above. The position of the photodiode unit 11 is moved so as to minimize the beam diameter, and the XYZ coordinates on the light receiving surface of the light beam are measured from the position of the photodiode unit 11.

  For example, when the position at which the beam diameter of the light beam indicated by “BM11” in FIG. 7 is the minimum is “FP41” in FIG. 7, the polarizing plate 9 is rotated so that only the light beam indicated by “BM11” in FIG. The photodiode unit 11 is irradiated, and the position indicated by “FP41” in FIG. 7 is aligned with the light receiving surface of the photodiode unit 11 indicated by “PD11” in FIG. 7, and the XYZ coordinates of the position indicated by “FP41” in FIG. taking measurement.

  Similarly, for example, when the position at which the beam diameter of the light beam indicated by “BM12” in FIG. 7 is the minimum is “FP42” in FIG. 7, the polarizing plate 9 is rotated and the light indicated by “BM12” in FIG. Only the beam is irradiated to the photodiode unit 11, and the position indicated by “FP42” in FIG. 7 is aligned with the light receiving surface of the photodiode unit 11 indicated by “PD12” in FIG. Measure XYZ coordinates.

  FIG. 8 is an explanatory diagram for explaining a method of correcting a difference in the Z-axis direction. In FIG. 8, 11, “BM11”, “BM12”, “PD11”, and “FD12” are assigned the same reference numerals as in FIG. “FP41” and “FP42” have the same reference numerals as those in FIG.

  A point that bisects the interval between the light receiving surfaces of the photodiode unit 11 shown in “RT51” in FIG. 8 (strictly, the interval between the center points of the two light receiving surfaces) is the rotation center, and the rotation center is the Z-axis direction. The difference “ΔZ” is shifted to a half position and rotated by “φ” on the “XZ coordinate plane” around the rotation center, so that “FP41” and “PD11” are changed to “FP42”. “PD12” can be matched.

となる。 That is, as described above, when “ΔX” and “ΔY” are obtained from the difference between two XYZ coordinates and the difference in the Z-axis direction is “ΔZ”, the correction angle “φ ′” of the “XZ coordinate plane” is ,

It becomes.

となる。 Also, the correction angle “θ” of the “XY coordinate plane” is

It becomes.

  As a result, the optical fibers 6 and 7 holding the wavefronts are fixed to the output end 8 so that the polarization planes of the output end 8 are “90 degrees”, and the interval between the light beams is the light receiving surface of the photodiode unit 11. , The polarizing plate 9 is rotated, the light beam is allowed to pass one by one, and the XYZ coordinates of the incident position on the photodiode unit 11 are measured to obtain the correction angle “θ” by the correction angle “θ”. Rotate in the “XY coordinate plane” and rotate the photodiode unit 11 in the “XZ coordinate plane” by the correction angle “φ” for correcting the difference in the Z-axis direction. Become.

  In the embodiment shown in FIG. 1 and the like, a polarizing plate is used to separate two light beams, but an etalon may be used instead of the polarizing plate.

  In this case, the two optical fibers are not single polarization-maintaining optical fibers but normal single mode optical fibers (Single Mode Fibers), and each optical fiber has a wavelength that is ½ of the etalon FSR (free spectral region). The wavelength of light that can be transmitted is selected by changing the angle, temperature, or refractive index of the etalon, and only one of the two optical fibers is irradiated to the photodiode unit. What is necessary is just to measure the coordinates of the light beam.

  In the embodiment shown in FIG. 1 and the like, a polarizing plate is used to separate two light beams. However, light that propagates through two optical fibers can be modulated with different modulation frequencies without using a polarizing plate. In addition, based on the light modulation frequency of the light received at the time of detection by the photodiode unit, it may be determined which of the two optical fibers is a light beam, and the coordinates of each light beam may be measured.

  In this case, the number of components is reduced, and a mechanism for rotating the polarizing plate and a mechanism for controlling the angle of the etalon are not necessary.

It is a top view which shows one Example of the alignment method which concerns on this invention. It is a perspective view which shows one Example of the alignment method which concerns on this invention. It is a top view which shows one Example of the alignment method which concerns on this invention. It is a perspective view which shows one Example of the alignment method which concerns on this invention. It is explanatory drawing which shows the relationship between each light-receiving surface and two light beams irradiated. It is explanatory drawing which shows an example of the conventional incorrect alignment method. It is explanatory drawing explaining the alignment method which considered the difference of a Z-axis direction. It is explanatory drawing explaining the correction method of the difference of a Z-axis direction. It is a top view which shows an example of the conventional alignment method. It is a perspective view which shows an example of the conventional alignment method.

Explanation of symbols

1, 2, 6, 7 Optical fiber 3, 8 Output end 4, 9 Lens 5, 11 Photodiode unit 10 Polarizing plate

Claims (4)

An alignment method of irradiating two light receiving surfaces of a photodiode unit with two light beams from an emission end to which two optical fibers are fixed, respectively,
Two polarization plane holding optical fibers are fixed to the exit end so that the respective polarization planes are 90 degrees each other ,
A polarizing plate inserted between the emitting end and the lens is rotated to allow a light beam to pass one by one to be incident on the light receiving surface of the photodiode unit and to move the position of the photodiode unit. XY coordinates of the surface where the light receiving surface of the photodiode unit is formed from the position of
The photodiode unit is rotated about the origin where the center point of the light beam coincides with the center point of the light receiving surface on the XY coordinate plane by the first correction angle obtained from the measurement coordinates of the two light beams . An alignment method, characterized in that an axis passing through the center point of the light receiving surface coincides with an axis passing through the center point of the two light beams . An alignment method of irradiating two light receiving surfaces of a photodiode unit with two light beams from an emission end to which two optical fibers are fixed, respectively ,
Insert an etalon between the exit end and the lens,
Propagating light having different wavelengths by half of the free spectral region of the etalon to the two optical fibers;
The wavelength of light that can be transmitted is selected by changing the angle, temperature, or refractive index of the etalon, the light beam is allowed to pass one by one to enter the light receiving surface of the photodiode unit, and the position of the photodiode unit is set. Move , measure the XY coordinates of the surface on which the light receiving surface of the photodiode unit is formed from the position of the photodiode unit ,
The photodiode unit is rotated about the origin where the center point of the light beam coincides with the center point of the light receiving surface on the XY coordinate plane by the first correction angle obtained from the measurement coordinates of the two light beams . An alignment method, characterized in that an axis passing through the center point of the light receiving surface coincides with an axis passing through the center point of the two light beams . An alignment method of irradiating two light receiving surfaces of a photodiode unit with two light beams from an emission end to which two optical fibers are fixed, respectively ,
Applying light modulation at different modulation frequencies to the light propagating through the two optical fibers;
Determine which light beam of the two optical fibers based on the light modulation frequency of the light received when detecting with the photodiode unit,
The two light beams are incident on the photodiode unit, the position of the photodiode unit is moved, and the XY coordinates of the surface on which the light receiving surface of the photodiode unit is formed are measured from the position of the photodiode unit ,
The photodiode unit is rotated about the origin where the center point of the light beam coincides with the center point of the light receiving surface on the XY coordinate plane by the first correction angle obtained from the measurement coordinates of the two light beams . An alignment method, characterized in that an axis passing through the center point of the light receiving surface coincides with an axis passing through the center point of the two light beams . Two light beams are incident on the photodiode unit, the position of the photodiode unit is moved, and the Z coordinate in the direction perpendicular to the surface on which the light receiving surface of the photodiode unit is formed is measured from the position of the photodiode unit. And
The second correction angle is obtained from the measurement coordinates of the two light beams ,
The photodiode unit is rotated about a point that bisects the interval between the light receiving surfaces of the photodiode unit on the XZ coordinate plane by the second correction angle, and an axis that passes through the center point of the two light receiving surfaces; The alignment method according to any one of claims 1 to 3, wherein an axis passing through a center point of the light beam of the book is made coincident .

Images