JP2004228546A - Laser beam output method for semiconductor laser and equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a laser beam output method for semiconductor laser and equipment that are not affected by an intensity change caused by a beam shift, and stabilize beam output for a long time. <P>SOLUTION: In a laser beam output method in which a laser beam with a specified wavelength is extracted from semiconductor laser that oscillates laser beams with multiple wavelengths and then, part of the laser beam with the specified wavelength is reflected to feed back optically to semiconductor laser, part of the laser beam is reflected such that the area of the laser beam optically fed back is different from that of the laser beam with the specified wavelength before being reflected. The present invention includes laser beam output equipment for the semiconductor laser based on the laser output method. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a laser light output method for a semiconductor laser, and more particularly to a laser light output method and apparatus for a semiconductor laser that outputs high-power laser light with a very narrow wavelength.
[0002]
[Prior art]
2. Description of the Related Art A laser is used when performing spectroscopic analysis using the generation and increase / decrease of light based on a light emission phenomenon, a light absorption phenomenon, and the like. In this spectroscopic analysis, even a difference in wavelength on the order of pm has a great influence on the analysis accuracy, and high accuracy is required. The same applies to the case where a laser is used as a light source, and there is a demand for improving the stability of various parameters including the wavelength and intensity of the laser.
[0003]
Under such circumstances, semiconductor lasers are widely used as inexpensive small-sized lasers having an extremely narrow line width and outputting high-power light. Particularly in recent years, lasers capable of high-power oscillation even in a low-wavelength (blue) region have been developed, for example, blue semiconductor lasers. However, the output wavelength of the laser light output from this semiconductor laser is pm (picometer: 10 ^-12 m) On the order, there is not a single wavelength but a plurality of wavelengths at intervals determined by the size and frequency of the semiconductor. Therefore, the output intensity of the target wavelength extracted from the plurality of wavelengths is small, and 20% of the total output of the semiconductor laser is steady. It is difficult to exceed.
[0004]
For example, the blue semiconductor laser has an oscillation line with an extremely small line width (1 pm or less) in a state of standing at about 5 to 20 lines at a wavelength interval of about 35 pm as a minimum unit, and has an appropriate resolution. By using a spectroscope or an etalon or other spectroscopic means, it is possible to extract a single target line (wavelength). However, the proportion occupied by the target wavelength is about 20% when the wavelength is large, and is 10% or less in most cases.
[0005]
In order to solve the above problem, there is a "reflection amplification method" as a method for constantly securing the intensity at a target wavelength. In this method, only the light of a specific wavelength is fed back to the laser, that is, optical feedback is applied to amplify only the target wavelength in the laser light to increase the intensity. For this reflection amplification method, for example, a semiconductor laser, a wavelength selection element, and a reflection unit for applying optical feedback to the semiconductor laser are provided, and the oscillation wavelength of the semiconductor laser is stabilized within the wavelength tolerance of the wavelength conversion element. There is a document that discloses a stabilized light source (see, for example, Patent Document 1). Further, for example, there is a semiconductor light emitting device in which light emitted from a semiconductor optical amplifier is wavelength-selected and returned to the semiconductor optical amplifier to control the emission wavelength to a desired value (for example, see Patent Document 2).
[0006]
As a method other than the reflection amplification method, there are a method of synthesizing a plurality of beams for the purpose of improving the intensity and an arrangement of various optical components for beam shaping.
[0007]
[Patent Document 1]
JP-A-8-21686
[0008]
[Patent Document 2]
JP-A-10-190105
[0009]
[Problems to be solved by the invention]
However, although any of the above techniques has a temporary or short-term effect, there is a problem that it is difficult to maintain the strength for a long time. In other words, thermal fluctuations due to subtle changes in ambient temperature and deterioration over time of the semiconductor laser due to long-term oscillation, and physical fluctuations due to slight misalignment of various optical components for performing feedback. As a result, a beam shift (optical axis shift) appears, and the intensity is reduced due to the deterioration of the amplification state.
[0010]
The present invention has been made to solve the above-described problems, and is intended to stabilize laser light in a state where a predetermined wavelength is reflected and amplified, for a long time without being affected by intensity fluctuation due to beam shift. An object of the present invention is to provide a laser light output method and device of a semiconductor laser.
[0011]
[Means for Solving the Problems]
The present inventors have studied to solve the above problems, and as a result, have obtained the following knowledge. That is, the area of the laser light to be optically fed back (the cross-sectional area of the laser light in a direction orthogonal to the direction of travel of the laser light) is equal to the area of the laser light of a predetermined wavelength before reflection. By differently reflecting the laser light, the influence of the shift of the laser light which is optically fed back to the laser light oscillated from the semiconductor laser becomes extremely small, and the deterioration of the amplification state (= intensity decrease) and It was found that it was hardly affected by intensity fluctuation.
[0012]
In addition, by measuring the intensity of light after reflection amplification and adjusting the reflection angle at the time of optical feedback based on the obtained light intensity, it is possible to maintain the reflection amplification state for a long time. I found that.
[0013]
The present invention has been made based on the above findings, and has the following configuration.
[0014]
[1] Laser light of a predetermined wavelength is extracted from a semiconductor laser that oscillates laser light of a plurality of wavelengths, and then a laser light output that reflects a part of the laser light of a predetermined wavelength and provides optical feedback to the semiconductor laser. A method for outputting a laser beam from a semiconductor laser, wherein a part of the laser beam is reflected such that the area of the laser beam to be optically fed back is different from the area of the laser beam of a predetermined wavelength before reflection.
[0015]
[2] The laser light output method for a semiconductor laser according to the above [1], wherein the area of the laser light to be optically fed back is larger than the area of the laser light of a predetermined wavelength before reflection.
[0016]
[3] The method of [1], wherein the area of the laser light to be optically fed back is 2.25 to 100 times the area of the laser light of a predetermined wavelength before reflection. .
[0017]
[4] The semiconductor laser according to [1] to [3], wherein a part of the laser light having a predetermined wavelength is reflected by using a concave or convex lens and optically fed back to the semiconductor laser. Laser light output method.
[0018]
[5] A semiconductor laser that oscillates laser light of a plurality of wavelengths, a collimating means for converting the laser light oscillated from the semiconductor laser into parallel light, and a laser collimated by the parallelizing means A wavelength selection unit that transmits only a predetermined wavelength of light, and a reflection unit that reflects a part of the predetermined wavelength transmitted by the wavelength selection unit and applies optical feedback to the semiconductor laser, the reflection unit including: A laser beam output device for a semiconductor laser, comprising means for reflecting the laser beam to be fed back so that the area of the laser beam to be fed back differs from the area of the laser beam having a predetermined wavelength before reflection.
[0019]
[6] In the above [5], further, an intensity measuring means for measuring the intensity of the light after the reflection amplification, and a reflection for adjusting a reflection angle in the reflecting means based on the light intensity obtained by the intensity measuring means. A laser light output device for a semiconductor laser, comprising: an angle adjusting unit.
[0020]
[7] The semiconductor laser according to [6], further comprising an angle adjusting unit that adjusts an angle in the wavelength selecting unit based on the light intensity obtained by the intensity measuring unit. Laser light output device.
[0021]
[8] A laser light output is performed using the laser light output device of the semiconductor laser according to the above [7], and the angle adjusting means for adjusting the angle in the wavelength selecting means adjusts the reflection angle in the reflecting means. A laser light output method for a semiconductor laser, wherein a reflection amplification state is corrected by making fine adjustments by a reflection angle adjusting means to be adjusted.
[0022]
BEST MODE FOR CARRYING OUT THE INVENTION
First, a laser light output device for a semiconductor laser according to the present invention will be specifically described.
[0023]
FIG. 1 is an explanatory diagram showing one embodiment of a laser light output device in a semiconductor laser of the present invention. As shown in FIG. 1, this laser light output device includes a semiconductor laser 1 that oscillates laser light, an optical component 2 that converts the laser light oscillated by the semiconductor laser 1 into parallel light, and a parallel light that is formed by the optical component 2. An etalon 3 for extracting only a target wavelength from the laser light thus obtained, and an optical component 4 for reflecting a part of the target wavelength extracted by the etalon 3 and providing optical feedback to a semiconductor laser.
[0024]
The semiconductor laser 1 is obtained by oscillating a blue semiconductor laser with a standard driver (having a semiconductor laser driving current supply and temperature control function) recommended by a manufacturer. A laser having a total output of about 30 mW may be used. it can.
[0025]
The optical component 2 is a lens for collimating (parallelizing) a beam oscillated from a semiconductor laser, and has an appropriate size and shape according to the required intensity and beam diameter after passing through the lens. I do. For example, in FIG. 1, since the beam divergence angle of the used element is large and the beam diameter after passing through the lens needs to be within several mm, efficient collimation is performed using an aspherical lens, and the lens transmission is performed. The latter beam had an elliptical shape of about 2 mm × 3 mm. Considering the necessity of disposing a wavelength selection jig such as an etalon plate after that, it is desirable that the beam transmitted through the lens be as parallel as possible to increase the transmission efficiency.
[0026]
The etalon 3 only needs to have a function capable of extracting only the target wavelength from the laser light of a plurality of wavelengths oscillated from the semiconductor laser 1 with extremely high resolution (about 10 pm in half width of the transmission profile). Usually used ones are used.
[0027]
When the optical component 4 optically feeds back a part of the target wavelength extracted by the etalon 3, the area of the laser light to be optically fed back (the cross-sectional area of the laser light in a direction orthogonal to the direction in which the laser light travels). Is different from the area of the laser light of a predetermined wavelength before reflection. The optical component 4 is preferably made of a material that absorbs little because the finally used laser is a transmitted beam. Although it depends on the wavelength region, glass or quartz generally used for optical components can be used. Also, it is simple and appropriate to use a concave or convex lens because of the availability and the variety of beam shaping means based on the shape and focal length. In particular, a plano-convex / plano-concave / biconvex / biconcave type lens is preferable from the viewpoint of easiness in adjusting the beam shape after passing through the lens. In FIG. 1, a plano-concave lens is used, and an optical component 6 having the same focal length is disposed immediately after the lens for the purpose of re-collimating the reduced parallelism. Further, in order to further improve the transmittance, means for applying a coating according to the wavelength to the surface of the optical component can be considered. However, there is a danger that the coating material may cause interference fringes and the like, leading to deterioration of output stability due to unevenness of light density. Therefore, coating is unnecessary unless particularly necessary.
[0028]
It is desirable that the center position of the laser light to be fed back optically coincides with the center position of the laser light before reflection as much as possible, and that a state where the deviation of the optical axis appears in any direction can be mitigated. , The center position and the optical axis are preferably adjustable.
[0029]
Further, the performance of the optical components of the semiconductor laser 1, the optical component 2, the etalon 3, and the optical component 4 and the distance (= disposition) between the components need to be combined so as to be within an optimum condition range. That is, if, for example, the distance between the semiconductor laser light source 1 and the reflecting optical component 4 is too large with respect to the divergence angle of the reflected beam, the light amount necessary to amplify the target wavelength cannot be secured at the position of the semiconductor laser 1. Conversely, if the divergence angle of the reflected beam is too small, the effect of the present invention will be diminished. However, for the former problem, for example, measures can be considered to increase the intensity of the reflected light itself by applying an appropriate coating to the reflecting end face of the reflecting optical component, and in view of the required function, It is necessary to design in consideration of the balance of the entire system.
[0030]
Next, a laser light output method for a semiconductor laser according to the present invention will be described with reference to FIG.
Laser light oscillated from the semiconductor laser 1 is converted into parallel light by the optical component 2 and enters the etalon 3. The etalon 3 is designed such that the gap between the etalons is designed according to the target wavelength, and the target wavelength can be extracted by finely adjusting the incident angle. The laser beam incident on the etalon 3 is extracted only at the target wavelength. And sent to the optical component 4. The optical component 4 reflects a part of the extracted light of the target wavelength, for example, after increasing its diameter, and returns it to the semiconductor laser. As described above, the (temporal) maintenance of the amplification state of the target wavelength in the semiconductor laser light is significantly improved.
[0031]
As described above, the laser light output method for a semiconductor laser of the present invention extracts a laser light of a predetermined wavelength from a semiconductor laser that oscillates a plurality of wavelengths of laser light, and then reflects a part of the laser light of the predetermined wavelength. The output intensity at a predetermined wavelength is increased by optically feeding back the semiconductor laser.
[0032]
In the present invention, when a part of the laser light having the predetermined wavelength is reflected and optically fed back to the semiconductor laser, the area of the laser light to be optically fed back is different from the area of the laser light having the predetermined wavelength before the reflection. Is characterized by being reflected. As described above, the laser beam to be optically fed back is reflected so that the area of the laser beam of a predetermined wavelength before the reflection is different from that of the laser beam. Is eliminated.
[0033]
FIG. 2 shows the degree of deviation of laser light which is fed back optically to laser light oscillated from a semiconductor laser. As shown in FIG. 2A, when the light is reflected using a flat plate (conventional method), the shape (area) of the laser light to be optically fed back is the same as the shape (area) of the laser light before reflection. For this reason, when a beam shift occurs, the laser beams of the laser beams do not easily overlap each other, and it is difficult to maintain a long-term amplification state. On the other hand, as shown in FIG. 2B, when the light is reflected using the concave plate (the method of the present invention), the shape (area) of the laser light to be optically fed back is made smaller than the shape (area) of the laser light before reflection. Since the laser beam is enlarged, even if a beam shift (shift) of the same amount as in the conventional method occurs, the laser beam that performs optical feedback covers the laser beam before the reflection, and the laser beam before the reflection. The laser light that optically feeds back to the laser light overlaps, and the reflection amplification state is easily maintained.
[0034]
In particular, in the present invention, it is preferable that the area of the laser light to be fed back optically is larger than the area of the laser light of a predetermined wavelength before reflection. This generally means that the laser emission point is a few μm ² When the area of the reflected beam is small compared to the original beam, optical adjustment is required to return the reflected beam to the emission point for amplification of the target wavelength. This is because of the difficulty. Furthermore, comparing the allowable beam shift (deviation) when the diameter of the reflected beam is increased and the allowable beam shift when the reflected beam is reduced, the former is larger, and the former is larger regardless of the size of the light emitting point. Is clearly advantageous.
The area of the laser light to be fed back optically is preferably within a certain range. The reason is that if the area of the laser light to be optically fed back is not too large with respect to the area of the laser light before reflection, the effect of relaxation is reduced, and if it is too large, the light density is insufficient and the amplification itself is not performed. This is because it may not happen. Therefore, the area of the laser light to be optically fed back is preferably 2.25 to 100 times, more preferably 9 to 25 times the area of the laser light before reflection.
[0035]
As for the method of reflecting the laser light so that the area of the laser light to be optically fed back is different from the area of the laser light before the reflection, the light is reflected so that the area of the laser light to be fed back is different from the area of the laser light before the reflection. Any method may be used, and there is no particular limitation.
[0036]
FIG. 8 is an explanatory view showing another embodiment of the laser light output device in the semiconductor laser of the present invention. 8, a semiconductor laser 1 that oscillates laser light, a Peltier device 7 that controls the temperature of the semiconductor laser 1, a laser housing 8 that incorporates the semiconductor laser 1 and the Peltier device 7, and a drive current supply for the semiconductor laser 1. A control circuit 9 for controlling temperature and temperature, an optical component 2 for converting laser light oscillated by the semiconductor laser 1 into parallel light, and an etalon plate for extracting only a target wavelength from the laser light collimated by the optical component 2 10, an etalon controller 20 for adjusting the angle of the etalon plate 10, a reflector 11 for reflecting (optical feedback) a part of the light of the wavelength extracted by the etalon plate 10, and fixing the reflector 11 A controller 12 for adjusting the angle, a sampling mirror 13 for sampling a part of the reflected and amplified laser light, and a sampling mirror 13 And a half mirror 14 for dividing the sampled light by 13. Further, an intensity monitor 15 for measuring the intensity of the reflected and amplified light split by the half mirror 14, and the angle of the reflection plate 11 through the controller 12 as necessary based on the measured intensity value measured by the intensity monitor 15. An adjustment personal computer 16, a condenser lens 17 for condensing the reflected and amplified light split by the half mirror 14, an optical fiber 18 for measuring the wavelength of the light condensed by the condenser lens 17, and a wavelength meter 19 It has.
[0037]
As the semiconductor laser 1 and the optical component 2, those similar to those in FIG. 1 can be used.
[0038]
The control circuit 9 may have any function as long as it has a drive current supply and temperature control function for the semiconductor laser, and a commonly used one is used.
[0039]
The etalon plate 10 is provided on the optical path with respect to the laser housing 8 and has a very high resolution (about 10 pm in half width of the transmission profile) from a plurality of wavelengths of laser light oscillated from the semiconductor laser 1. It has a function that can take out only There is no particular limitation, and those commonly used are used.
[0040]
The etalon controller 20 adjusts the angle of the etalon plate 10 when the state of the reflection amplification is deteriorated and needs to be corrected.
[0041]
The reflecting plate 11 only needs to have a function of returning the amount of light necessary for amplification to the light emitting point, similarly to the optical component 4 in FIG. Although it depends on the type and wavelength of the laser, the reflectance is usually about 5%, and a quartz plate or the like can be used.
[0042]
The controller 12 holds the reflection plate and adjusts the angle of the reflection plate when the state of the reflection amplification deteriorates and correction is required.
[0043]
The sampling mirror 13 and the half mirror 14 are respectively inclined at 45 degrees with respect to the traveling direction of the laser light in order to guide a part of the oscillated laser light to the intensity monitor 15 and the wavelength meter 19. The sampling mirror 13 and the half mirror 14 may have a function capable of branching a part of the laser light.
[0044]
The intensity monitor 15 measures the intensity of the laser light guided by the sampling mirror 13 and the half mirror 14, and outputs the measured value. The condenser lens 17 collects light. The optical fiber 18 guides the collected light to a wavelength measuring device. The wavelength meter 19 measures the wavelength of the laser light condensed by the condenser lens 17 and guided by the optical fiber 18. The intensity monitor 15, the condenser lens 17, the optical fiber 18, and the wavelength meter 19 are not particularly limited and may have the above functions.
[0045]
The personal computer 16 has a built-in sequence in advance, and adjusts the angle of the reflection plate 11 through the controller 12 as necessary by transmitting the measured intensity value.
[0046]
According to FIG. 8, laser light having the intensity and wavelength set by the control circuit 9 is oscillated by the semiconductor laser 1. The laser light oscillated from the semiconductor laser 1 becomes parallel light by the optical component 2, and only the target wavelength is extracted by the etalon plate 10. Next, a part of the laser beam extracted only at the target wavelength is reflected by the reflector plate surface by the reflector 11, and this light is fed back to the light emitting point of the semiconductor laser 1 so that only the target wavelength is reflected and amplified. It becomes. The reflected and amplified laser light is partially sampled by the sampling mirror 13 for wavelength and intensity measurement, and the sampled laser light is further branched by the half mirror 14. Part of the branched laser light is guided to an intensity monitor 15 and the intensity is measured. The intensity measurement value obtained by the intensity monitor 15 is transmitted to the personal computer 16 as an intensity signal, and the personal computer 16 compares the threshold value with the intensity measurement value at a preset timing. When the intensity measurement value falls below the threshold value, The output is adjusted by adjusting the angle of the etalon plate 11 by the etalon controller 20 and the angle of the reflector 11 by the controller 12 (for example, the angles α and β along the X axis and the Y axis on a plane orthogonal to the beam). Control is performed so as to be maximum. On the other hand, the other laser light branched by the half mirror 14 is condensed by the condenser lens 17, passes through the optical fiber 18, and the wavelength is measured by the wavelength meter 19.
[0047]
As described above, by controlling and adjusting the angles of the etalon plate 11 and the reflection plate 11, the deterioration of the reflection amplification state is periodically corrected, and the output of the semiconductor laser can be stabilized for a long time. In performing the control to maximize the output, the etalon control controller 20 first adjusts the angle of the etalon plate 11 and then finely adjusts the angle of the reflection plate 11 by the controller 12. Is preferred.
[0048]
In addition, in order to stabilize the output wavelength simultaneously with the output for a long time, the drift amount between the target wavelength and the measured wavelength is obtained based on the data of the wavelength measured by the wavelength meter 19, and the drift amount is determined in advance according to the drift amount. The temperature change of the Peltier element 7 is determined based on the obtained wavelength change coefficient per unit temperature, and the output wavelength can be stabilized through the temperature control of the Peltier element 7. In this case, the above functions can be incorporated in the personal computer 16.
[0049]
Furthermore, if the position of the oscillated beam changes (beam shifts) due to various factors such as subtle room temperature fluctuations and deterioration of the laser light emitting element itself in the process of performing long-time oscillation, the oscillation may initially be oscillated. Even if the amount of light required for reflection amplification is returned to the light emitting point, the amount of light returned to the light emitting point gradually decreases with the degree of this beam shift, and eventually the threshold of the light amount required for optical feedback is reduced. If it falls below this level, amplification may not be performed. In such a case, in order to maintain the reflection amplification state for a long period of time, it is necessary to monitor and correct the influence of the beam shift with time, and the embodiment of FIG. 8 is an effective means in this respect.
[0050]
【Example】
(Example 1)
A laser diode manufactured by Nichia Corporation was used as a semiconductor laser, and laser light having a plurality of wavelengths was oscillated by a laser light output device shown in FIG. Here, FIG. 3 shows another embodiment of a laser light output device in a semiconductor laser, in which 5 is a reflected light diameter confirming means for confirming the reflected light diameter of the laser light fed back by optical feedback, and 6 is a laser light reproducing device. It is an optical component for making parallel light. Since other structures are the same as those in FIG. 1, the same reference numerals are given and the detailed description is omitted.
[0051]
At this time, as shown in FIG. 4, the output center wavelength of the laser was 403 nm, and a plurality of oscillation lines were output at intervals having a minimum unit of 35 pm. The total light intensity of the laser output light at all wavelengths was 30 mW, and the light intensity at the target wavelength of 403.000 nm was 18%, which was 5.4 mW. Next, the laser light oscillated from the semiconductor laser is converted into parallel light using an aspherical lens, and the parallel light is passed through an etalon having a gap of 0.2 mm to emit light having a target wavelength of 403.000 nm and a full width at half maximum of 0.001 nm or less. Only permeate. FIG. 5 shows the wavelength profile at this time. At this time, the efficiency of the etalon was 60%, and the intensity at the target wavelength was 3.2 mW.
[0052]
Next, a part of the light transmitted through the etalon is reflected by an optical component (concave lens), and the angle is adjusted so that the area of the laser light to be optically fed back is larger than the area of the laser light before reflection. The reflected light was adjusted so as to return to the semiconductor laser. In addition, the center position of the reflected light beam was matched as much as possible with the center position of the original beam. As a result, the area of the laser light optically fed back by the reflected light diameter confirming means 5 was 9 times and 25 times the area of the laser light before reflection. Also. No surface coating was performed to avoid unevenness in the intensity of reflected light due to interference fringes and the like. At this time, the reflectivity was about 5% (transmittance 95%). At this time, the distance from the laser emission point to the incident side end face of the reflection surface was set to about 60 cm. In addition, the beam shape and spread after transmission can be corrected, if necessary, by disposing an appropriate optical component, for example, the optical component 6.
[0053]
From the above, the output intensity of the target wavelength finally obtained was 8.0 mW. This was the same amplification factor as the result of the comparative example performed by the same method as described above, except that a planar substrate (the area of the reflected light was maintained) was used as an optical component for reflection.
[0054]
6 and 7 show the relationship between the elapsed time from the start of laser light oscillation and the output intensity of laser light with respect to the continuity of the amplification state of the target wavelength. FIG. 6 shows a case where a concave lens is used as an optical component of the present invention, and FIG. 7 shows a case where a planar lens is used as an optical component as a comparative example. In FIGS. 6 and 7, the output intensity of the laser light with respect to the elapsed time from the start of the laser light oscillation is relative intensity (normalized to a relative value at the start of laser oscillation, that is, when the intensity at t = 0 is set to 1). ), And up to a 20% reduction in intensity (= 0.8) was taken as the allowable range of the amplification state (output maintenance). From FIGS. 6 and 7, when the planar lens of the comparative example was used, the amplification state was maintained for only about 1 hour, whereas the concave lens of the present invention was used to provide optical feedback. When the area of the light is 9 times and 25 times the area of the laser light before reflection, the amplification state is maintained for about one week or more (9 times: 7.5 days, 25 times: 8.2 days). . From the above, it can be seen that when the area of the laser light to be optically fed back is 9 to 25 times the area of the laser light before reflection, it is extremely effective in maintaining the amplified output. In addition, in FIG. 6, when the area is 25 times, the specified output is maintained for a longer time than when the area is 9 times.
[0055]
(Example 2)
A laser diode manufactured by Nichia Corporation was used as a semiconductor laser, and laser light having a plurality of wavelengths was oscillated by a laser light output device shown in FIG.
[0056]
At this time, as in Example 1, as shown in FIG. 4, the output center wavelength of the laser was 403 nm, and a plurality of oscillation lines were output at intervals of 35 pm as a minimum unit. The total light intensity of the laser output light at all wavelengths was 30 mW, and the light intensity at the target wavelength of 403.000 nm was 18%, which was 5.4 mW. Next, the laser light oscillated from the semiconductor laser is converted into parallel light using an aspherical lens, and the parallel light is passed through an etalon having a gap of 0.2 mm to emit light having a target wavelength of 403.000 nm and a full width at half maximum of 0.001 nm or less. Only permeate. FIG. 5 shows the wavelength profile at this time. At this time, the efficiency of the etalon was about 60%, and the intensity at the target wavelength was about 3.2 mW.
[0057]
Next, a part of the light transmitted through the etalon was reflected by a quartz plate having a reflectance of about 5% with respect to this wavelength, and adjustment was made so that the reflected light returned to the semiconductor laser. At this time, the distance from the laser emission point to the incident side end face of the reflection surface was set to about 60 cm.
[0058]
As described above, the output intensity at the target wavelength finally obtained by the reflection amplification was 8.0 mW. With respect to the initial value of the output, the threshold value is set to 80%, and the output intensity is measured by the intensity monitor every one minute. When the measured value is lower than 6.4 mW, the quartz for reflection is transmitted through the controller. The light intensity after the reflection amplification was controlled by adjusting the plate angle.
[0059]
FIG. 9 shows the relationship between the elapsed time from the start of laser light oscillation and the output intensity of laser light with respect to the continuity of the amplification state of the target wavelength. In FIG. 9, the change over time of the output intensity is represented by a relative intensity (normalized to a relative value at the start of laser oscillation, that is, when the intensity at t = 0 is set to 1).
[0060]
FIG. 9 shows that in the example of the present invention in which the light intensity control is performed, the amplification state is maintained for about 30.0 days, and it is understood that the control method of the present invention is extremely effective in maintaining the amplified output.
[0061]
【The invention's effect】
As described above, according to the present invention, it is possible to stably output a laser beam having a predetermined wavelength for a long period of time while maintaining a large output and its intensity. In addition, since the laser device of the present invention has a good amplification state and greatly improves the (temporal) maintenance of the amplification state of the target wavelength, the laser device is used as a light source to stabilize the light intensity for a long time. It is effective for various necessary technologies and devices.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram showing one embodiment of a laser light output device in a semiconductor laser of the present invention.
FIG. 2 is a diagram showing a positional relationship between laser beams before and after reflection.
FIG. 3 is an explanatory view showing another embodiment of the laser light output device in the semiconductor laser of the present invention.
FIG. 4 is a diagram showing a wavelength profile before transmission through an etalon.
FIG. 5 is a diagram showing a wavelength profile after transmission through an etalon.
FIG. 6 is a diagram showing the relationship between the elapsed time from the start of laser light oscillation and the laser light output intensity.
FIG. 7 is a diagram illustrating a relationship between an elapsed time from the start of laser light oscillation and a laser light output intensity in a comparative example.
FIG. 8 is an explanatory view showing another embodiment of the laser light output device in the semiconductor laser of the present invention.
FIG. 9 is a diagram showing a relationship between an elapsed time from the start of laser light oscillation and a laser light output intensity.
[Explanation of symbols]
1 Semiconductor laser
2 Optical components
3 etalons
4 Optical components
5 Reflected light diameter confirmation means
6 Optical components
7 Peltier element
8 Laser housing
9 Control circuit
10 Etalon board
11 Reflector
12 Controller
13 Sampling mirror
14 Half mirror
15 Strength monitor
16 PC
17 Condensing lens
18 Optical fiber
19 Wavelength meter
20 Etalon control controller

Claims (8)

A laser light output method for extracting laser light of a predetermined wavelength from a semiconductor laser that oscillates laser light of a plurality of wavelengths, and then reflecting a part of the laser light of the predetermined wavelength and optically feeding back the laser light to the semiconductor laser. A laser light output method for a semiconductor laser, wherein a part of the laser light is reflected so that the area of the laser light to be optically fed back is different from the area of the laser light of a predetermined wavelength before reflection. 2. The laser light output method for a semiconductor laser according to claim 1, wherein the area of the laser light to be optically fed back is larger than the area of the laser light of a predetermined wavelength before reflection. 2. The method according to claim 1, wherein the area of the laser light to be optically fed back is 2.25 to 100 times the area of the laser light of a predetermined wavelength before reflection. 4. The laser light output method for a semiconductor laser according to claim 1, wherein a part of the laser light having a predetermined wavelength is reflected by using a concave or convex lens and optically fed back to the semiconductor laser. A semiconductor laser that oscillates a plurality of wavelengths of laser light, a collimating means for collimating the laser light oscillated from the semiconductor laser, and a laser light collimated by the collimating means. A wavelength selection unit that transmits only a predetermined wavelength; and a reflection unit that reflects a part of the predetermined wavelength transmitted by the wavelength selection unit and applies optical feedback to the semiconductor laser. A laser light output device for a semiconductor laser, comprising: means for reflecting the laser light to be fed back so that the area of the laser light is different from the area of the laser light of a predetermined wavelength before reflection. Further, it is provided with an intensity measuring means for measuring the intensity of the light after the reflection amplification, and a reflection angle adjusting means for adjusting a reflection angle in the reflecting means based on the light intensity obtained by the intensity measuring means. 6. The laser light output device for a semiconductor laser according to claim 5, wherein: 7. The laser light output of a semiconductor laser according to claim 6, further comprising an angle adjusting means for adjusting an angle in said wavelength selecting means based on the light intensity obtained by said intensity measuring means. apparatus. 8. A laser light output device using the laser light output device for a semiconductor laser according to claim 7, wherein the angle adjustment means adjusts the angle in the wavelength selection means, and the reflection angle adjusts the reflection angle in the reflection means. A laser light output method for a semiconductor laser, wherein a reflection amplification state is corrected by performing fine adjustment by a preparation unit.

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