JP2014060251A - Optical power monitoring device, optical power monitoring method, and laser generator using optical power monitoring device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical power monitor in which failure of a laser diode module can be detected, excessive insertion loss is not generated, risk or failure due to bending of an optical fiber can be suppressed, and the amount of laser light outputted from the laser diode module can be monitored.SOLUTION: An optical power monitor 50 comprises a photodetector 52 disposed on the side face of a connection 33 of an optical fiber 22 for outputting pumping light, as an optical fiber for outputting laser light of a laser diode module 20, and an optical instrument utilizing the pumping light as the laser light outputted from the laser diode module 20. The amount of pumping light outputted from the laser diode module 20 is measured by measuring the amount of the pumping light leaking from the side face of the connection 33 by means of the photodetector 52.

Description

  The present invention relates to an optical power monitoring device, an optical power monitoring method, and a laser generator using the optical power monitoring device, and more particularly, for example, an optical fiber amplifier using an optical fiber output laser diode for laser medium excitation and optical fiber laser excitation. Optical power monitoring device for measuring the amount of laser light in laser light sources for laser markers, laser light sources for laser processing machines, illumination light sources, and optical sensor light sources using laser diodes such as light, and optical fiber output laser diodes, optical power The present invention relates to a monitoring method and a laser generator using an optical power monitoring device.

  Optical fiber amplifiers and optical fiber lasers using rare earth element-doped optical fibers in which rare earth elements such as erbium (Er) and ytterbium (Yb) are added to optical fibers are rapidly spreading. Since the beginning of the 1990s, optical fiber amplifiers using erbium-doped optical fibers have been widely used in optical communication applications, and output power has been increasing year by year. In addition, since around 1995, development of high-power optical fiber amplifiers using ytterbium-doped optical fibers and high-power optical fiber lasers using the same has progressed, and now optical fiber lasers whose output power exceeds several kW. (R. Paschotta et al., “Yterbium-doped fiber amplifiers,” IEEE J. Quantum Electron., Vol. 33, no. 7, pp. 1049, 1097). And Non-Patent Document 2 (HM Park et al., “Yterbium-doped silica fiber lasers: Versatile sources for the 1-1. 2 μm region, IEEE J. Sel. Topics in Quantum Electron., Vol. 1, no. 1, pp. 2-13, 1995) reference).

A conventional basic optical fiber amplifier is, for example, a laser diode module having a rare earth element-doped optical fiber that performs direct optical amplification and a laser diode that outputs laser light such as pump light for exciting the rare earth element-doped optical fiber. And a multiplexing device that multiplexes the pumping light and the amplified signal light and injects them into the rare earth element-doped optical fiber.
In such a conventional optical fiber amplifier, the pumping light output optical fiber for extracting the pumping light output from the laser diode of the laser diode module is connected to the pumping light input optical fiber of the multiplexer, thereby providing pumping light. Is injected into the rare earth-doped optical fiber via a multiplexer.

It is necessary to measure the output light amount of the laser diode module for the purpose of monitoring the operation state and stabilizing control of the conventional optical fiber amplifier and optical fiber laser.
In general, many methods are used to measure the amount of light emitted in the direction opposite to the port where the laser diode of the laser diode module and the optical fiber for pumping light output are coupled to each other. For example, a photodiode is placed in a laser diode module, and the output from the laser diode is directly measured.
For example, as disclosed in Non-Patent Document 1 (http://www.furukawa.co.jp/tukuro/pdf/optsogo/optsogo_7_04.pdf), etc. A method of extracting power by extracting a part of the power of an optical signal to be monitored using a coupler is generally used.
Furthermore, for example, as disclosed in Patent Document 1 (Japanese Patent No. 3966287) and the like, by bending an optical fiber with a small bending radius, light propagating inside the optical fiber as a bending loss is intentionally made outside. A method of taking out has been proposed.

Japanese Patent No. 3966287

R. Paschotta et al. "Yterbium-doped fiber amplifiers," IEEE J. Quantum Electron. , Vol. 33, no. 7, pp. 1049-1056, 1997 H. M.M. Park et al. , “Yterbium-doped silica fiber lasers: Versatile sources for the 1-1.2 μm region,” IEEE J. Sel. Topics in Quantum Electron. , Vol. 1, no. 1, pp. 2-13, 1995 http: // www. furukawa. co. jp / tukuro / pdf / optsogo / optsogo — 7 — 04. pdf

However, in the method of directly measuring the output from the laser diode, the amount of light output from the pumping light output optical fiber to which the laser diode is coupled is not measured. Therefore, when the coupling loss between the laser diode and the pumping light output optical fiber varies, the amount of light output from the pumping light output optical fiber changes. This change cannot be detected. Actually, many of the failures of the laser diode module are not caused by the failure of the laser diode itself, but by the failure of the coupling portion between the laser diode and the optical fiber for laser light output such as the optical fiber for pumping light output.
Also, in the method using an optical fiber coupler, since such an optical fiber coupler has an insertion loss, when the amount of pumping light is high, optical loss or heat is generated, and the output of the optical fiber amplifier is reduced. Causes problems such as reduced reliability.
Furthermore, when bending an optical fiber with a small bending radius, there is a risk in the bend of the optical fiber operating at a high output, and if an excessive bending loss occurs, heating due to leaked light or the optical fiber There is a possibility of causing major obstacles such as damage.

  Therefore, the main object of the present invention is to detect the failure of the laser diode module due to the failure of the coupling portion between the laser diode of the laser diode module and the optical fiber for laser light output, resulting in excessive insertion loss. In addition, an optical power monitoring device, an optical power monitoring method, and an optical power monitoring device capable of suppressing the danger and failure due to bending of the optical fiber and measuring the amount of laser light output from the laser diode module, and A laser generator using an optical power monitoring device is provided.

An optical power monitoring device according to the present invention is output from a laser diode module having a laser diode that outputs laser light and a laser light output optical fiber that is coupled to the laser diode and outputs laser light output from the laser diode. An optical power monitoring device for measuring the amount of laser light emitted from a laser diode output optical fiber of a laser diode module and an optical device using laser light output from the laser diode module. An optical power monitoring device that measures the amount of laser light output from the laser diode module by measuring the amount of laser light that leaks from the side surface of the connecting portion with the photodetector. is there.
In the optical power monitoring device according to the present invention, for example, an optical device is combined by a combining device for combining a laser beam output from a laser diode module and a signal light to be amplified, and a combining device. An optical fiber amplifier including a laser diode module, a multiplexing device, and a rare earth element-doped optical fiber, including a rare earth element-doped optical fiber that is injected with laser light and signal light to be amplified and excited by the laser light and performs optical direct amplification Used for.
In the optical power monitoring device according to the present invention, for example, the optical device includes a laser light output optical fiber of the laser diode module and a laser light input optical fiber connected between the multiplexing devices, and the photodetector is The optical fiber for laser light output and the side surface of the connecting portion of the optical fiber for laser light input are disposed.
In the optical power monitoring apparatus according to the present invention, for example, the optical device includes a condensing optical system for condensing laser light output from the laser diode module, an optical fiber for outputting laser light from the laser diode module, and condensing. The optical detector includes a laser light input optical fiber provided between the optical systems, and the photodetector is disposed on a side surface of the laser light output optical fiber and the connecting portion of the laser light input optical fiber.
In the optical power monitoring apparatus according to the present invention, for example, the optical device includes a diffusion optical system for diffusing laser light output from the laser diode module, an optical fiber for laser light output from the laser diode module, and diffusion optics. The optical detector includes a laser light input optical fiber provided between the systems, and the photodetector is disposed on a side surface of the laser light output optical fiber and the connection portion of the laser light input optical fiber.
Furthermore, in the optical power monitoring device according to the present invention, for example, the photodetector is provided on the cover, which covers the side surface of the laser light output optical fiber and the connection portion of the laser light input optical fiber, and outputs the laser light. And a photodiode facing the side surface of the connecting portion of the optical fiber for laser and the optical fiber for laser light input.
A laser generator according to the present invention includes a laser diode for outputting laser light, a laser diode module having a laser light output optical fiber coupled to the laser diode and outputting laser light output from the laser diode, and a laser diode A laser generator including an optical device that uses laser light output from a module and an optical power monitoring device according to the present invention that measures the amount of laser light output from a laser diode module.
An optical power monitoring method according to the present invention is output from a laser diode module having a laser diode that outputs laser light and a laser light output optical fiber that is coupled to the laser diode and outputs laser light output from the laser diode. An optical power monitoring method for measuring the amount of laser light to be used, and using the optical power monitoring device according to the present invention, the laser light output optical fiber of the laser diode module and the laser light output from the laser diode module are used. This is an optical power monitoring method in which the amount of laser light output from the laser diode module is measured by measuring the amount of laser light that leaks from the side surface of the connecting portion with the optical device.
In the optical power monitoring method according to the present invention, for example, the light amount of the laser light output from the laser diode module is measured by multiplying a certain light amount of the measured laser light by a certain coefficient.
In the optical power monitoring method according to the present invention, for example, an optical device that uses laser light output from a laser diode module by multiplying a certain amount of the measured laser light by another constant coefficient. The amount of laser light to be injected is measured.

According to the present invention, the amount of laser light that leaks from the side surface of the connecting portion between the optical fiber for laser light output of the laser diode module and the optical device that uses the laser light output from the laser diode module is measured. Thus, the amount of laser light output from the laser diode module is measured.
Therefore, according to the present invention, it is possible to detect a failure of the laser diode module due to a failure of the coupling portion between the laser diode of the laser diode module and the laser light output optical fiber.
Further, according to the present invention, it is not necessary to use an optical fiber coupler, so that excessive insertion loss does not occur. Therefore, even if the amount of laser light is high, light loss and heat are suppressed, and it is difficult to cause problems such as a decrease in output and reliability of the optical amplifier.
Furthermore, according to the present invention, since there is no need to bend the optical fiber, it is possible to suppress a major obstacle such as danger due to bending of the optical fiber, heating due to leaked light, or breakage of the optical fiber.

  According to the present invention, it is possible to detect a failure of the laser diode module due to a failure of the coupling portion between the laser diode of the laser diode module and the optical fiber for laser light output, and no excessive insertion loss occurs. An optical power monitoring device, an optical power monitoring method, and an optical power monitoring device capable of suppressing danger and failure due to bending of an optical fiber and monitoring the amount of laser light output from a laser diode module Can be obtained.

  The above-described object, other objects, features, and advantages of the present invention will become more apparent from the following description of embodiments for carrying out the invention with reference to the drawings.

It is an illustration figure which shows an example of the laser generator using the optical power monitoring apparatus concerning this invention. It is the disassembled perspective view seen from the one side of the photodetector used for the optical power monitoring apparatus shown in FIG. It is the disassembled perspective view seen from the other side of the photodetector used for the optical power monitoring apparatus shown in FIG. It is a graph which shows the relationship between the voltage (V) of the signal output from the photodetector of Experimental example 1, and the output light quantity (W) of the excitation light output from the laser diode module. It is a graph which shows the relationship between the voltage (V) of the signal output from the photodetector of Experimental example 1, and the input light quantity (W) of the excitation light injected into the optical fiber for excitation light input. It is a schematic diagram which shows the connection part which the optical fiber for excitation light outputs, and the optical fiber for excitation light input were fuse | melted. It is a graph which shows the relationship between the output light quantity (W) of the excitation light output from the laser diode module of Experimental example 2, and the voltage (V) of the signal output from a photodetector. It is an illustration figure which shows the other example of the laser generator using the optical power monitoring apparatus concerning this invention. It is an illustration figure which shows the further another example of the laser generator using the optical power monitoring apparatus concerning this invention.

  A laser generator 10 shown in FIG. 1 has a basic structure of a basic optical fiber amplifier and includes a laser diode module 20. The laser diode module 20 outputs a laser diode (not shown) called a semiconductor laser that outputs excitation light as laser light, and excitation light as laser light coupled to the laser diode and output from the laser diode. And a pumping light output optical fiber 22 as a laser light output optical fiber.

  The excitation light is for exciting a rare earth element-doped optical fiber 40 described later. For example, an ytterbium-doped optical fiber is used as the rare earth element-doped optical fiber 40. In an ytterbium-doped optical fiber amplifier used as an optical fiber amplifier with a wavelength of 1 μm, a laser diode that oscillates in the vicinity of wavelengths 915 nm, 940 nm, and 976 nm as pumping light. Is used.

  The amount of pumping light is currently increasing from several watts to one hundred watts, for example, and in accordance with this, the pumping light output optical fiber 22 attached to the laser diode module 20 is also a multimode whose core diameter exceeds 100 μm, for example. An optical fiber is used.

  The laser generator 10 further includes an optical device that uses the excitation light output from the laser diode module 20. The optical apparatus includes, for example, a multiplexing device 30 and a rare earth element-doped optical fiber 40.

The multiplexing device 30 is for multiplexing the excitation light output from the laser diode module 20 and the signal light amplified from the outside. Examples of the multiplexing device 30 that combines the excitation light and the signal light include, for example, optical fiber couplers (wavelength division multiplexing (WDM) couplers) having different coupling ratios for each wavelength band and optical fiber combiners that use optical fiber cladding modes. (For example, see US Pat. No. 5,459,804).
Further, the multiplexing device 30 is for injecting the pumping light and the signal light combined by the multiplexing device 30 into the rare earth element-doped optical fiber 40.
Therefore, the multiplexing device 30 includes an excitation light input optical fiber 32, a signal light input optical fiber 34, and a combined light output optical fiber 36 as laser light input optical fibers. The excitation light input optical fiber 32 is for inputting excitation light as laser light output from the laser diode module 20 to the multiplexing device 30. The signal light input optical fiber 34 is for inputting signal light amplified from the outside to the multiplexer 30. The multiplexed light output optical fiber 36 is for outputting the excitation light and the signal light multiplexed by the multiplexing device 30 from the multiplexing device 30 to the rare earth element-doped optical fiber 40.
Here, by connecting the pumping light output optical fiber 22 for extracting the pumping light output from the laser diode of the laser diode module 20 to the pumping light input optical fiber 32 of the multiplexer 30, the laser diode module 20 The pumping light that is output can be injected into the rare earth element-doped optical fiber 40 via the multiplexing device 30.
The connection portion 33 to which the pumping light output optical fiber 22 and the pumping light input optical fiber 32 are connected is mainly subjected to optical fiber fusion in order to connect them. May be used.

  The rare earth element-doped optical fiber 40 is injected with pumping light combined by the combining device 30 and signal light to be amplified. The rare earth element-doped optical fiber 40 is excited by pumping light and is used for direct optical amplification. That is, in the rare earth element-doped optical fiber 40, the amplitude of the signal light is amplified.

  The laser generator 10 further includes an optical power monitoring device 50. The optical power monitoring device 50 is used for an optical fiber amplifier including the laser diode module 20, the multiplexing device 30, and the rare earth element-doped optical fiber 40, that is, an optical fiber amplifier using the rare earth element doped optical fiber. The optical power monitoring device 50 is for measuring the amount of excitation light output from the laser diode module 20.

The optical power monitoring device 50 includes a photodetector 52. The photodetector 52 is disposed on the side surface of the connection portion 33 between the optical fiber 22 for pumping light output of the laser diode module 20 and an optical device that uses the pumping light output from the laser diode module 20. The light quantity of the excitation light output from the laser diode module 20 is measured by measuring the light quantity of a part of the excitation light leaking from the side surface of the connection portion 33 by the photodetector 52.
Here, the optical apparatus includes a pumping light input optical fiber 22 of the laser diode module 20 and a pumping light input optical fiber 32 connected between the multiplexing device 30. Therefore, the photodetector 52 is arranged on the side surface of the connection portion 33 between the excitation light output optical fiber 22 and the excitation light input optical fiber 32.

  The photodetector 52 includes, for example, a base cover 54 and a main body cover 56 made of a metal having good thermal conductivity as covers that cover the side surfaces of the connection portion 33 of the excitation light output optical fiber 22 and the excitation light input optical fiber 32. . The base cover 54 and the main body cover 56 are arranged on both sides of the side surface of the connection portion 33 so as to sandwich the side surface of the connection portion 33. In this case, in order for the base cover 54 and the main body cover 56 to block the surrounding light from other than the connection portion 33 with respect to the connection portion 33 of the optical fibers 22 and 32, Covered and shaded.

  The main body cover 56 is formed with a linear groove 58 having a width wider than the width of the optical fibers 22 and 32 from one end to the other end of the main surface facing the connection portion 33. Cushion materials 60 and 60 made of a relatively soft material are provided on both side portions in the groove 58 of the main body cover 56, respectively. The cushion members 60 and 60 are for preventing the optical fibers 22 and 32 from being damaged when the connecting portion 33 of the optical fibers 22 and 32 is sandwiched between the covers 54 and 56. Further, the main body cover 56 is formed with, for example, a circular through hole 62 in the center portion in the groove 58. The through hole 62 is a hole for arranging a photodiode 66 described later.

  A substrate 64 is provided outside the main body cover 56 of the photodetector 52. The substrate 64 is fixed to the main body cover 56 with a fixing tool such as a screw, and the main body cover 56 is also fixed to the base cover 54 with a fixing tool such as a screw.

  The photodetector 52 further includes a photodiode 66. The photodiode 66 is attached to the substrate 64 and is disposed in the through hole 62 of the main body cover 56. In this case, the photodiode 66 is disposed so as to face the side surface of the connection portion 33 of the excitation light output optical fiber 22 and the excitation light input optical fiber 32. Therefore, the light quantity of the leakage light of the excitation light from the connection part 33 of the optical fibers 22 and 32 can be measured by the photodiode 66 as a light detection signal. In this case, since the light from the outside is blocked by the covers 54 and 56, the connection portion 33 and the photodiode 66 can accurately measure the amount of leakage light of the excitation light from the connection portion 33.

  The substrate 64 is mounted with an electronic circuit (not shown) for performing signal processing such as amplification or noise removal of the light detection signal from the photodiode 66, and the electronic circuit is connected to the connection wiring 68. Electrically connected. Therefore, the light detection sensitivity and accuracy of the light detection signal from the photodiode 66 can be improved. In this manner, a light detection signal corresponding to the light power incident on the photodiode 66 can be output from the light detector 52. The output signal from the photodetector 52 is expressed as a voltage magnitude, for example. In measuring the amount of light, the device is not limited to the photodiode 66, and an optical device that reacts to the optical power may be used instead of the photodiode 66.

  The photodetector 52 is electrically connected to the control unit 70 via the connection wiring 68. The control unit 70 is for calculating the amount of excitation light output from the laser diode module 20 based on the signal output from the photodetector 52. Further, the control unit 70 has a display unit for displaying the calculated light amount or a display unit (not shown) for displaying a signal output from the photodetector 52.

  The control unit 70 calculates the amount of excitation light output from the laser diode module 20 by, for example, multiplying a signal output from the photodetector 52 by a certain coefficient. For example, when the output light amount from the laser diode module 20 is 100 times the light amount of the excitation light measured by the photodetector 52, the excitation light output from the laser diode module 20 is multiplied by 100 as a constant coefficient. Is calculated.

  In addition, the control unit 70 multiplies the signal output from the photodetector 52 by another constant coefficient, so that the control unit 70 applies an optical fiber that uses the pump light output from the laser diode module 20, that is, an optical fiber for pump light input. The amount of excitation light injected into 32 is calculated. For example, when the input light amount of the excitation light injected into the excitation light input optical fiber 32 is 98 times the light amount of the excitation light measured by the photodetector 52, by multiplying by 98 as another constant coefficient, The amount of excitation light injected into the excitation light input optical fiber 32 is calculated.

  In this laser generator 10, a part of the pumping light leaking from the side surface of the connection portion 33 between the optical fiber 22 for pumping light output of the laser diode module 20 and the optical device using the pumping light output from the laser diode module 20. By measuring the amount of light, the amount of excitation light output from the laser diode module 20 can be measured. Therefore, in this laser generator 10, it is possible to detect a failure of the laser diode module 20 due to a failure of the coupling portion between the laser diode of the laser diode module 20 and the pumping light output optical fiber 22.

  Further, according to the laser generator 10, there is no need to use an additional optical component such as an optical fiber coupler, so that excessive insertion loss does not occur. Therefore, even if the amount of excitation light is high, light loss and heat are suppressed, and problems such as a decrease in output and a decrease in reliability of the optical amplifier are hardly caused.

  Furthermore, according to this laser generator 10, since there is no need to bend the optical fiber, there is no risk of bending due to bending of the optical fiber and leakage light without mechanical deformation as in the case where excessive loss is produced by bending. Large obstacles such as heating by heating and optical fiber breakage can be suppressed, and it is safe.

  Further, in this laser generator 10, since the covers 54 and 56 are provided around the connection portion 33, not only disturbance is prevented, but also leakage light from the connection portion 33 does not leak to the outside, so that safety is improved. .

  Furthermore, in this laser generator 10, since the covers 54 and 56 are made of a metal having good thermal conductivity, even if the connection portion 33 should generate heat, the covers 54 and 56 function as a radiator. Increases nature.

(Experimental example 1)
Experimental example 1 in which the graphs shown in FIGS. 4 and 5 are obtained will be described using the laser generator 10 shown in FIG.
The laser diode module 20 of the laser generator 10 shown in FIG. 1 used in Experimental Example 1 oscillates at a wavelength of 976 nm, uses a multimode optical fiber having a core diameter of 105 μm and a cladding diameter of 125 μm as an optical fiber for pumping light output. 22, the excitation light is output. This pumping light output optical fiber 22 was fused and connected to a multiplexing device 30 having the same type of multi-mode optical fiber as an input end, and an optical power monitoring device 50 was attached around the fused connection portion 33. At this time, they were arranged so that the position of the connecting portion 33 was almost in front of the photodiode 66 of the optical power monitoring device 50.

  FIG. 4 shows the voltage (V) of the signal output from the photodetector 52 and the excitation output from the laser diode module 20 when the output light amount is changed by changing the excitation current flowing through the laser diode module 20. It is a graph which shows the relationship with the output light quantity (W) of light. From the graph shown in FIG. 4, a good linear relationship is obtained, and the voltage (V) of the signal output from the photodetector 52 is output from the laser diode module 20 by multiplying it by a coefficient of 6.49. The output light amount (W) of the excitation light can be measured.

  Similarly, FIG. 5 shows an optical device that uses the voltage (V) of the signal output from the photodetector 52 and the pumping light output from the laser diode module 20, that is, is injected into the optical fiber 32 for pumping light input. It is a graph which shows the relationship with the input light quantity (W) of the excitation light to be performed. Also in the graph shown in FIG. 5, a good linear relationship is obtained, and the excitation light input optical fiber 32 is obtained by multiplying the voltage (V) of the signal output from the photodetector 52 by the coefficient 5.98. The input light amount (W) of the excitation light injected into the can be measured.

(Experimental example 2)
In Experimental Example 2, the sensitivity of the laser generator 10 shown in FIG. 1 according to the position of the photodiode 66 with respect to the connection portion 33 of the optical fibers 22 and 32 was examined.
In the laser generator 10 shown in FIG. 1, when fusion splicing is used as a method of connecting the connection portions 33 of the optical fibers 22 and 32, the position of the photodiode 66 is not directly below the connection location, but is the excitation light input light. By arranging in the vicinity of the coated end on the fiber 32 side, the leaked light from the connection portion 33 can be efficiently guided to the photodiode 66. For this reason, even when the amount of leakage light is small, it becomes possible to measure with high sensitivity.

  FIG. 6 is a schematic diagram showing the fused connection portion 33 between the pumping light output optical fiber 22 and the pumping light output optical fiber 32. Both the pumping light output fiber 22 connected to the laser diode module 20 and the optical device that uses the pumping light, that is, the pumping light input optical fiber 32, are UV curable resin for mechanically protecting the fiber. In order to connect, a part of the coating is peeled off and fused to be connected. The length to peel off the coating is usually about 3 to 9 mm. In such a structure, a part of the excitation light from the laser diode module 20 is scattered at the fusion point (connection portion 33). At that time, the leakage light generated at the fusion point does not leak directly to the outside of the clad but directly propagates through the inside while being reflected by the clad surface so as to be used for excitation light input. It is scattered by the coating on the optical fiber 32 side and leaks to the outside. For this reason, the light amount of the leaked light is larger than the light amount of the leaked light from the connecting portion 33 in the vicinity of the coating end on the excitation light input optical fiber 32 side.

FIG. 7 is a graph showing the relationship between the output light amount (W) of the excitation light output from the laser diode module and the voltage (V) of the signal output from the photodetector, obtained in Experimental Example 2. In the graph of FIG. 7, the relationship when the photodiode 66 of the optical power monitoring device 50 is arranged near the front surface of the connection portion 33 and the photodiode 66 of the optical power monitoring device 50 are connected to the excitation light input optical fiber 32. And their relationship when arranged in the vicinity of the front surface of the side covering end.
From the graph shown in FIG. 7, the voltage of the signal output from the photodetector 52 with respect to the output light amount of the equal laser diode module 20 is near the front of the coating end of the photodiode 66 on the side of the optical fiber 32 for pumping light input. In the case where the photodiode 66 is disposed, the sensitivity is 50 times better than that in the case where the photodiode 66 is disposed near the front surface of the connection portion 33, that is, the sensitivity is 50 times better.

FIG. 8 is an illustrative view showing another example of a laser generator using the optical power monitoring device according to the present invention. The laser generator 10 shown in FIG. 8 is a method called backward pumping in which excitation light is injected into the multiplexing device 30 in the opposite direction to the signal light, as compared with the laser generator 10 shown in FIG.
The laser generator 10 shown in FIG. 1 is a method called forward pumping in which excitation light is injected into the multiplexing device 30 in the same direction as the signal light. The laser generator according to the present invention is a laser generator shown in FIG. Like the device 10, a method called backward pumping in which pumping light is injected into the multiplexing device 30 in a direction opposite to the signal light may be used.
In the laser generator 10 shown in FIG. 8, the pumping light input optical fiber 34 is connected to the multiplexer 30 via the rare earth element-doped optical fiber 40, as compared with the laser generator 10 shown in FIG. .

  Further, the laser generator according to the present invention may be a method called bidirectional excitation in which excitation light is injected into the multiplexing device 30 from both directions.

  Although the above laser generator has a basic structure of a basic optical fiber amplifier, the present invention can also be applied to a laser generator having a basic structure of a basic optical fiber laser.

  FIG. 9 is an illustrative view showing still another example of a laser generator using the optical power monitoring device according to the present invention. Compared with the laser generator 10 shown in FIG. 1, the laser generator 10 shown in FIG. 9 includes a laser diode module 20 that is coupled to the laser diode (not shown) that outputs laser light and the laser diode. A laser light output optical fiber 22 ′ for outputting laser light output from the diode.

  The laser generator 10 shown in FIG. 9 further includes an optical device that uses the laser light output from the laser diode module 20. The optical apparatus includes, for example, a condensing optical system 31 as an optical system. The condensing optical system 31 is for condensing the laser beam output from the laser diode module 20, and for example, an optical element such as a plurality or a single mirror or a plurality or a single lens is used. Therefore, a laser light input optical fiber 32 ′ is provided between the laser light output optical fiber 22 ′ and the condensing optical system 31 of the laser diode module 20. The laser light input optical fiber 32 ′ is for guiding the laser light output from the laser diode module 20 to the condensing optical system 31 side. The connecting portion 33 connecting the laser light output optical fiber 22 ′ and the laser light input optical fiber 32 ′ is mainly subjected to optical fiber fusion in order to connect them. An optical connector may be used.

  In the laser generator 10 shown in FIG. 9, the photodetector 52 of the optical power monitoring device 50 is disposed on the side surface of the connecting portion 33 between the laser light output optical fiber 22 ′ and the laser light input optical fiber 32 ′. Is done.

  In the laser generator 10 shown in FIG. 9, the laser light output from the laser diode module 20 is guided to the condensing optical system 31 side by the laser light input optical fiber 32 ′ and condensed by the condensing optical system 31. , Output to outside and use it. Examples of this application include many devices such as a laser marker that performs marking using laser light, a laser processing machine that performs processing, a lighting fixture, and a light source for an optical sensor.

  In the laser generator 10 shown in FIG. 9, a diffusion optical system using optical elements such as a plurality or a single mirror or a plurality or a single lens is used as an optical system instead of the condensing optical system 31. May be. In this way, the laser light output from the laser diode module 20 is guided to the diffusion optical system side by the laser light input optical fiber 32 ′, diffused by the diffusion optical system, and output to the outside for use. . As this application, for example, an application in which a beam of laser light is spread and used, for example, illumination can be cited.

  Further, in the laser generator 10 shown in FIG. 9, similarly to the laser generator 10 shown in FIG. 1, the connecting portion between the laser light output optical fiber 22 ′ and the laser light input optical fiber 32 ′ of the laser diode module 20. By arranging the photodetector 52 of the optical power monitoring device 50 in the vicinity of 33, the amount of laser light output from the laser diode module 20 and the amount of laser light output from the laser light input optical fiber 32 'are measured. can do.

  The power monitoring apparatus according to the present invention is particularly suitably used for laser generators such as optical fiber amplifiers, optical fiber lasers, laser markers, laser processing machines, lighting fixtures, and light sources for optical sensors.

DESCRIPTION OF SYMBOLS 10 Laser generator 20 Laser diode module 22 Optical fiber for excitation light output 22 'Optical fiber for laser light output 30 Multiplexer 31 Condensing optical system 32 Optical fiber for excitation light input 32' Optical fiber for laser light input 33 Connection part 34 Optical fiber for signal light input 36 Optical fiber for optical output of multiplexed light 40 Optical fiber for rare earth element 50 Optical power monitoring device 52 Photo detector 54 Base cover 56 Main body cover 58 Groove 60 Cushion material 62 Hole 64 Substrate 66 Photodiode 68 Connection wiring 70 Control unit

Claims (10)

A laser diode that outputs a laser beam and a laser beam output from a laser diode module that is coupled to the laser diode and outputs a laser beam that is output from the laser diode are measured. An optical power monitoring device,
A photodetector disposed on a side surface of a connection portion between the optical fiber for laser beam output of the laser diode module and an optical device that utilizes laser light output from the laser diode module; An optical power monitoring device that measures the amount of laser light output from the laser diode module by measuring the amount of laser light that leaks from the side surface of the connecting portion. The optical instrument is:
A multiplexing device for combining the laser beam output from the laser diode module and the amplified signal beam; and the laser beam combined by the multiplexing device and the amplified signal beam are injected, and the laser Including rare earth-doped optical fibers excited by light and performing direct optical amplification,
The optical power monitoring apparatus according to claim 1, wherein the optical power monitoring apparatus is used in an optical fiber amplifier including the laser diode module, the multiplexer, and the rare earth element-doped optical fiber. The optical device includes a laser light input optical fiber connected between the laser light output optical fiber of the laser diode module and the multiplexer,
The optical power monitoring device according to claim 2, wherein the photodetector is disposed on a side surface of a connection portion between the laser light output optical fiber and the laser light input optical fiber. The optical instrument is:
A condensing optical system for condensing the laser light output from the laser diode module, and the laser light output optical fiber of the laser diode module and a laser light input optical fiber provided between the condensing optical systems Including
2. The optical power monitoring device according to claim 1, wherein the photodetector is disposed on a side surface of a connection portion between the laser light output optical fiber and the laser light input optical fiber. The optical instrument is:
A diffusion optical system for diffusing the laser light output from the laser diode module; and the laser light output optical fiber of the laser diode module and a laser light input optical fiber provided between the diffusion optical systems,
2. The optical power monitoring device according to claim 1, wherein the photodetector is disposed on a side surface of a connection portion between the laser light output optical fiber and the laser light input optical fiber. The photodetector is
A cover that covers a side surface of the connection portion between the laser light output optical fiber and the laser light input optical fiber; and a cover provided on the cover, the laser light output optical fiber and the connection portion between the laser light input optical fiber The optical power monitoring device according to claim 3, comprising a photodiode facing the side surface. A laser diode module having a laser diode for outputting laser light and a laser light output optical fiber coupled to the laser diode for outputting laser light outputted from the laser diode;
The optical power monitoring apparatus according to any one of claims 1 to 6, wherein an optical device using laser light output from the laser diode module, and an amount of laser light output from the laser diode module are measured. Including a laser generator. A laser diode that outputs a laser beam and a laser beam output from a laser diode module that is coupled to the laser diode and outputs a laser beam that is output from the laser diode are measured. An optical power monitoring method,
An optical device using the laser light output optical fiber of the laser diode module and an optical device using the laser light output from the laser diode module using the optical power monitoring device according to any one of claims 1 to 6. An optical power monitoring method for measuring a light amount of a laser beam output from the laser diode module by measuring a light amount of a part of the laser beam leaking from a side surface of the connecting portion.   The optical power monitoring method according to claim 8, wherein the light amount of the laser light output from the laser diode module is measured by multiplying a certain amount of the measured light amount of the laser light by a constant coefficient.   Measuring the amount of laser light injected into an optical device that uses the laser light output from the laser diode module by multiplying the measured light amount of the laser light by some other constant, The optical power monitoring method according to claim 8 or 9.

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