JP2005317819A - Laser system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a laser system wherein emitted laser light is prevented from being changed in its direction and position even when an angle of a grating is adjusted. <P>SOLUTION: An external resonator type semiconductor laser is constituted by a semiconductor laser 2, a lens 3, and the grating 5. The grating 5 is rotated by rotating a grating base 7 around a predetermined rotational axis, and receives laser light from the semiconductor laser 2 at a predetermined position. Further, although emitted light to the outside is changed in its direction owing to the rotation of the grating 5, an entire table 13 for holding the grating base 7 is turned on a drive 15 around the predetermined rotational axis so as to cancel the change of the direction of the emitted light. The rotational axis is on a plane involving a plane of incidence of the grating 5, and is orthogonal to a plane involving an entrance optical path and an exit optical path to the grating 5, and is further an axis that passes through an intersecting point between the center of the laser light incident on the grating 5 and the foregoing plane of incidence. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a laser system including an external cavity semiconductor laser, and more particularly to a laser system that switches wavelengths without changing the direction of emission of laser light.

  In recent years, semiconductor lasers have been widely used in information equipment because of their small size and low power consumption. For example, a single mode laser is used for holographic data storage (HDS). In the HDS, one laser beam is divided into two by a beam spiriter, and then combined again on a recording medium, and data is stored by the interference.

  Since interference does not occur in multimode, the use of a single mode laser is a condition. At present, the second harmonic (532 nm) of YAG is often used as a laser for such applications.

  By the way, a semiconductor laser such as a laser diode (LD) has multi-mode oscillation and cannot be used for the above-mentioned applications, but can be realized in a single mode by being combined with an external resonator.

  Here, the configuration of a laser system including a typical Littrow type external resonance semiconductor laser that has been commercially available will be described with reference to FIGS. 7 and 8 simultaneously. 7 is a plan view of the laser system 200, and FIG. 8 is a front view of the laser system 200 as viewed along the direction of the arrow F shown in FIG. The configuration of the laser system 200 is the same as the configuration of the laser system described in Non-Patent Document 1.

L. Ricci, et al .: "A compact grating-stabilized diode laser system for atomic physics", Optics Communications, 117 1995, pp541-549

  In the laser system 200, longitudinal multimode laser light (oscillation light) emitted from a semiconductor laser element such as a laser diode 201 is collected in parallel by a lens 202 and is incident on a grating (diffraction grating) 203. The grating 203 outputs first-order diffracted light of incident light. Depending on the arrangement angle of the grating 203, the first-order diffracted light having a specific wavelength is back-injected into the laser diode 201 through the lens 202. As a result, the laser diode 201 resonates with the injected first-order diffracted light and emits single-mode light (0th-order light represented by the arrow G). The wavelength of the light is from the grating 203. It becomes the same as the wavelength of the returned light.

  As shown in FIGS. 7 and 8, the laser system 200 includes a laser diode 201, a lens 202, a grating 203, a first support portion 204, a first screw 205, a first groove 206, a second support portion 207, a first support portion 207, and a second support portion 207. The laser unit 220 includes two screws 208 and a second groove 209, and the temperature control unit 230 includes a Peltier element 210 and a heat sink 211.

  In the laser system 200, optical components (lens 202, grating 203, etc.) are arranged on the second support portion 207 so that the optical path of the laser light is substantially horizontal with respect to the upper surface of the second support portion 207. . Further, a temperature control unit 230 is disposed on the lower side of the laser unit 220, thereby mainly controlling the temperatures of the laser diode 201, the lens 202 and the like. The temperature controller 230 keeps the temperature of the laser diode 201 constant, thereby stabilizing the light source. Furthermore, by suppressing thermal expansion, the size of the external resonator including the grating 203 and the first support portion 204 can be kept constant, and the position and angle of the emitted laser light can be kept constant.

  The laser system 200 adjusts the wavelength of the oscillation light of the laser diode 201 by changing the arrangement angle of the grating 203. The grating 203 is held by the first support portion 204. The first support portion 204 is provided with a first groove 206. By rotating the first screw 205 provided in the first support portion 204, the interval between the first grooves 206 is widened (or narrowed). As a result, the horizontal arrangement angle of the grating 203 slightly changes.

  A similar mechanism is also provided for adjusting the vertical angle of the grating 203. The first support portion 204 that holds the grating 203 is held by the second support portion 207, and the second support portion 207 is provided with a second screw 208 and a second groove 209. By rotating the second screw 208, the interval between the second grooves 209 provided in the second support portion 207 is partially expanded (or narrowed) similarly to the first support portion 204 described above, whereby the grating 203 and The vertical arrangement angle of the first support portion 204 slightly changes.

  However, in the configuration such as the laser system 200 described above, not only the horizontal and vertical angles of the grating 203 change, but also the position of the grating 203 (more specifically, the position at which the grating 203 receives laser light, And the position of reflection) also change. This also changes the direction and position of the zero-order light emitted from the grating 203 to the outside, and again adjusts the positions of the optical components arranged in the periphery in order to use the emitted light from the laser system 200. There is a need.

  That is, even if the positional relationship between the laser system 200 and peripheral optical components is accurately adjusted, if the angle of the grating 203 is readjusted for reasons such as switching the wavelength of the laser light to be used, the peripheral optical All the positions and angles of parts must be readjusted, and the burden on the user becomes very large.

  Accordingly, an object of the present invention is to provide a laser system capable of emitting a plurality of laser beams having different wavelengths without readjusting the position of peripheral optical equipment.

  A further object of the present invention is to provide a laser system in which the direction and position of emitted laser light does not change even when the angle of the grating is adjusted.

  The invention according to the first embodiment includes a grating that enters laser light emitted from a semiconductor laser and emits laser light of a predetermined wavelength to the outside, a grating table that holds the grating, a grating table, and a semiconductor laser. The grating table and the entire table are configured to rotate on the same rotation axis, and the rotation axis is on a plane including the incident surface of the grating on which the laser beam is incident and is incident on the grating. The axis is perpendicular to the plane including the incident optical path of the laser beam and the exit optical path of the laser beam emitted from the grating, and the axis passes through the point where the center of the laser beam incident on the grating intersects the incident plane This is a laser system configured as follows.

  The invention according to the second embodiment is the laser system according to the first embodiment, wherein the grating table rotated by a predetermined first angle about the rotation axis is fixed to the entire table. The entire platform rotated about a rotation axis by a predetermined second angle on the drive holding the entire platform is a laser system configured to be fixed to the drive.

  The invention according to the third embodiment is the laser system according to the second embodiment, wherein the second angle is changed by the rotation of the first angle of the grating stage, and the direction of the laser light emitted from the grating Is a laser system configured to be adjusted to return to the direction of the laser light before rotation.

  The invention according to the fourth embodiment is the laser system according to the second embodiment, wherein the rotation of the grating stage is performed using an eccentric driver.

  The invention according to the fifth embodiment is the laser system according to the fourth embodiment, wherein the grating base has an eccentric driver hole penetrating in the thickness direction, and the entire base is a protrusion of the eccentric driver. The rotation of the grating table is performed in a state where the eccentric driver passes through the eccentric driver hole of the grating table and the protruding part of the eccentric driver is inserted into the hole of the entire table. A laser system configured to be performed by rotating a lead driver.

  The invention according to a sixth embodiment is the laser system according to the second embodiment, wherein the rotation of the entire platform is performed using an eccentric driver.

  The invention according to a seventh embodiment is the laser system according to the sixth embodiment, wherein the whole base has a hole for an eccentric driver penetrating in the thickness direction, and the drive is a protrusion of the eccentric driver. The eccentric driver is inserted in the state where the eccentric driver passes through the eccentric driver hole of the entire unit and the protrusion of the eccentric driver is inserted into the hole of the drive. Is a laser system configured to be performed by being rotated.

  The invention according to the eighth embodiment is the laser system according to the first embodiment, wherein a lens is disposed between the semiconductor laser and the grating, and an external resonator type semiconductor laser is formed by the semiconductor laser, the lens, and the grating. It is a configured laser system.

  The invention according to a ninth embodiment is the laser system according to the eighth embodiment, wherein the external cavity semiconductor laser is configured to be a Littrow type.

  The invention according to the tenth embodiment is the laser system according to the first embodiment, wherein the grating base and the overall base are connected by a first pin, the first pin functions as a rotating shaft, and the overall base and the drive Are connected by a second pin, the second pin functions as a rotation axis, the first pin and the second pin are arranged apart from each other, and are configured to protrude in the thickness direction of the entire table, and the grating table is The drive is a laser system configured to have a hole for receiving the first pin and the drive having a hole for receiving the second pin.

  The present invention provides a laser system in which the direction and position of emitted laser light does not change even when the angle of the grating is adjusted. In addition, since the direction and position of the emitted laser light do not change in this way, even if the angle of the grating is adjusted, it is not necessary to readjust the position of the peripheral optical equipment, and the burden on the user Can be reduced.

  First, the configuration of a laser system according to an embodiment of the present invention will be described with reference to FIG. FIG. 1 shows a top view of a laser system 1 including a Littlow-type external cavity semiconductor laser. The laser system 1 includes a laser support table 4 and a grating table 7 on an entire table 13 (the entire laser table). The laser support base 4 is fixed to the overall base 13 by, for example, bonding or the like, but the grating base 7 can be rotated around the first pin as will be described later, and finally the overall base 13 by screws. Fixed to. The screw holes 10a and 10b in FIG. 1 are holes through which these screws pass, and these can be configured to have a larger shape than an ordinary screw hole, for example, an oval shape or an oval shape. An eccentric driver hole 8 is provided to adjust the rotation angle of the grating base 7.

  The whole base 13 is further fixed to a drive such as a holographic drive with screws or the like. The screw holes 12a to 12d in FIG. 1 are holes through which these screws pass. As will be described later, the entire base 13 can be rotated on the drive. For this reason, the screw holes 12a to 12d can be configured to have a larger shape than an ordinary screw hole, for example, an oval shape or an oval shape. In addition, an eccentric driver hole 11 is provided to adjust the rotation angle of the entire base 13.

  A semiconductor laser 2 and a lens 3 are fixedly attached to the laser support 4. Laser light emitted from the semiconductor laser 2 is collected by the lens 3 and provided in the direction of the grating stage 7. The grating support 6 is fixed on the grating table 7 by, for example, adhesion. The grating 5 is held by the grating support 6 and returns the light emitted from the semiconductor laser 2 to the semiconductor laser 2 (first-order diffracted light), and resonates with the first-order diffracted light and emits zero-order diffracted light.

  FIG. 2 is a front view of the laser system 1 viewed along the direction of the arrow A shown in FIG. As shown in FIG. 2, the grating base 7 is held on the whole base 13 in a rotatable state by the first pin 9, and the whole base 13 is further rotated by the second pin 14 to the drive 15. Is retained. Here, the first pin 9 and the second pin 14 can be configured as a single pin, but can be a medium for conducting heat, such as the semiconductor laser 2, and therefore, carefully configured in consideration of this point. There is a need to. The first pins 9 and the second pins 14 extend from the overall base 13 and are formed integrally with the overall base 13. In this case, the grating base 7 is provided with a pin hole for receiving the first pin 9, while the drive 15 is provided with a pin hole for receiving the second pin 14.

  As can be seen from FIG. 1, the position of the rotation axis formed by the first pin 9 (and the second pin 14) is on the incident surface of the grating 5 and the center of the laser light emitted from the semiconductor laser 2. Intersect. To express this more precisely, the rotation axis is on a (virtual) plane including the incident surface of the grating 5 on which the laser beam from the semiconductor laser 2 is incident, and the incident optical path of the laser beam incident on the grating 5 And an axis that is orthogonal to the (virtual) plane including the optical path of the laser beam emitted from the grating 5 and passes through the point where the center of the laser beam incident on the grating 5 intersects the incident surface. be able to.

  Thus, no matter how the grating 5 is rotated about the first pin 9 as the rotation axis, the virtual laser emission position on the grating 5 does not change.

  Next, the configuration related to the rotation of the grating stage 7 and how the laser light emitted from the semiconductor laser 2 will be explained by the rotation will be described with reference to FIGS.

  FIG. 3 shows a state in which zero-order diffracted light (laser light B) is emitted from the grating 5 to the outside by the laser light emitted from the semiconductor laser 2. Here, it is considered that the grating stage 7 is slightly rotated in the direction of the arrow D in order to adjust the wavelength of the laser beam B or switch to another wavelength. For this purpose, the eccentric driver 16 is inserted into the eccentric driver hole 8 and rotated in the direction of arrow E. The eccentric driver 16 has a structure in which the rotation axis is not provided at the center of a cross section orthogonal to the rotation axis. Therefore, the side of the eccentric driver 16 comes into contact with the inner side surface of the eccentric driver hole 8 due to the rotation of the eccentric driver 16, and the grating table 7 is slightly moved in the direction of the arrow D by pressing this side surface. Rotate to. As described above, the rotation of the grating table 7 is centered on the first pin 9.

  FIG. 4 shows a state after the grating table 7 is rotated by the rotation of the eccentric driver 16. The grating table 7 is slightly rotated. In FIG. 3, it can be seen that the laser support table 4 and the grating table 7 that are arranged substantially in parallel are no longer in such a positional relationship. However, even if the grating stage 7 rotates in this way, the laser light from the semiconductor laser 2 enters the same position as the light receiving portion of the grating 5 shown in FIG. However, at this stage, the 0th-order diffracted light (laser light C) emitted from the grating 5 to the outside is emitted in a direction different from the laser light B in FIG.

  Next, the relationship between the eccentric driver 16 and the eccentric driver hole 8 will be described with reference to FIG. As shown in FIG. 5, the eccentric driver 16 has a protruding portion 16 a and a side portion 16 b, and the protruding portion 16 a is formed at one end of the eccentric driver 16. It is arranged at a position shifted from the center.

  Further, the eccentric driver hole 8 has a side portion 8 b, and the hole 8 a is provided on the entire base 13. The protrusion 16a of the eccentric driver 16 is inserted into the hole 8a. In this state, when the eccentric driver 16 is rotated along the protruding portion 16a, the side portion 16b of the eccentric driver 16 comes into contact with the side portion 8b of the eccentric driver hole 8 and pushes the side portion 8b in a certain direction. . That is, the grating table 7 is displaced in a fixed direction relative to the entire table 13.

  However, since the grating table 7 and the entire table 13 are rotatably held around the first pin 9 as described above, the displacement of the grating table 7 with respect to the entire table 13 is centered on the first pin 9. Rotation. By such rotation, the arrangement angle of the grating 5 is changed, and finally the wavelength of the laser light emitted from the laser system 1 is changed.

  Actually, in order to adjust the rotation angle of the grating table 7 at a fine level, the grating table 7 is lightly screwed through the screw holes 10a and 10b provided in the grating table 7, respectively. The core driver 16 is inserted into the eccentric driver hole 8 and slightly rotated. Then, the grating table 7 is rotated by a very small angle due to resistance by screwing. This is continued, and when the desired wavelength is obtained, the screws passed through the screw holes 10 a and 10 b are tightened, and the grating table 7 is fixed to the entire table 13.

  As described above, the position where the first pin 9 is disposed is exactly the same as the position where the grating 5 receives the laser beam emitted from the semiconductor laser 2 (that is, the rotation axis of the first pin 9 is Therefore, even if the angle of the grating 5 is changed in the above-described manner, the grating 5 is not connected to the semiconductor laser 2 because the grating 5 is on the incident surface of the grating 5 and intersects the center of the laser beam emitted from the semiconductor laser 2. There is no change in the position of the laser beam received from.

  However, as shown in FIG. 4, the emission angle (direction) of laser light emitted from the laser system 1 to the outside changes from the state of FIG. 3 due to the movement of the grating 5.

  In order to solve such a problem, the laser system 1 according to the present invention changes the direction of the laser beam shifted by rotating the grating table 7 to the original direction using a mechanism as shown in FIG. return. For example, it is assumed that the laser beam direction (laser beam B direction) shown in FIG. 3 is shifted to the laser beam direction (laser beam C direction) in FIG. In that case, the entire base 13 is rotated relative to the drive 15 in a certain direction (for example, the direction opposite to the rotational direction of the grating base 7) so as to cancel out the deviation between the directions of the laser light B and the laser light C. . The mechanism for rotating the entire table 13 on the drive 15 is the same as the mechanism for rotating the grating table 7 on the entire table 13. The whole base 13 rotates around a second pin 14 (see FIG. 2) on the same rotation axis as the first pin 9. In FIG. 6, the original position of the overall platform 13 is indicated by a dotted line 13 ′.

  By such rotation of the entire base 13, the laser beam F emitted to the outside is obtained, and this is the same as the direction of the laser beam B shown in FIG.

  Similarly to the eccentric driver hole 8 of the grating base 7, an eccentric driver hole 11 is provided in the overall base 13, and the overall base 13 is mounted on the drive 15 by an eccentric driver (not shown). Rotate. After the adjustment, the entire base 13 is fixed by screws that pass through the screw holes 12a to 12d.

  Further, the rotation of the entire table 13 on the drive 15 is in the opposite direction (or the same direction) as the rotation of the grating table 7 on the entire table 13, but the angle is not necessarily the same. This is because the rotation of the entire table 13 does not cancel the rotation of the grating table 7 itself, but cancels and compensates for the change in the angle of the emitted laser beam due to the rotation of the grating table 7.

  So far, the screw holes 10a and 10b, 12a to 12d have been illustrated as having an elliptical shape, but it is not necessary to limit to such a shape. It is sufficient that each of the possible rotations of the grating table 7 or the entire table 13 is formed so that it can be screwed.

  In addition, the first pin 9 and the second pin 14 have been described as extending from the entire base 13, but conversely, the first pin 9 and the second pin 14 are configured to extend from the grating base 7 and the drive 15 side, and corresponding holes are formed in the entire base 13. It may be provided on the side.

  Furthermore, a Peltier element or the like for temperature control may be provided between the overall base 13 and the drive 15. As the Peltier element, for example, one having a hole in the center is commercially available. As long as such a Peltier element is used, the above-described configuration of the present invention is not hindered.

  The laser system 1 of the present invention is configured to emit laser beams having different wavelengths in the same direction by using a two-stage rotation mechanism. In the above description, a pair of an eccentric driver and an eccentric driver hole is used as means for finely adjusting such two-stage rotation. However, the present invention is not limited to this means. The laser system of the present invention can be constructed using other means capable of finely adjusting the rotation of the grating table and the entire table.

1 is a schematic diagram showing a configuration of a laser system according to an embodiment of the present invention. It is a front view of the laser system shown in FIG. It is an approximate line figure showing the mode of rotation of the grating stand of the laser system concerning one embodiment of this invention. It is an approximate line figure showing a mode of rotation of a grating stand of a laser system concerning one embodiment of this invention. It is a basic diagram for demonstrating the relationship between the eccentric driver and the hole for eccentric drivers in the laser system which concerns on one Embodiment of this invention. It is an approximate line figure showing the mode of rotation in the whole stand of a laser system concerning one embodiment of this invention. It is a basic diagram showing the structure of the conventional laser system. FIG. 8 is a front view of the laser system shown in FIG. 7.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Laser system, 2 ... Semiconductor laser, 3 ... Lens, 4 ... Laser support stand, 5 ... Grating, 6 ... Grating support part, 7 ... Grating stand, 8 ... eccentric driver hole, 9 ... first pin, 10a, 10b ... screw hole, 11 ... eccentric driver hole, 12a, 12b, 12c, 12d ... screw hole, 13 ... Whole stand, 14 ... Second pin, 15 ... Driver, 16 ... Eccentric driver

Claims (10)

A grating that enters laser light emitted from a semiconductor laser and emits laser light of a predetermined wavelength to the outside,
A grating table for holding the grating;
The grating stage and an overall stage for holding the semiconductor laser;
The grating table and the entire table are configured to rotate on the same rotation axis,
The rotation axis is
On a plane including an incident surface of the grating on which the laser beam is incident;
Orthogonal to a plane including an incident optical path of laser light incident on the grating and an optical path of laser light emitted from the grating to the outside, and
A laser system characterized in that the center of the laser beam incident on the grating is an axis passing through a point intersecting the incident surface. The laser system according to claim 1, wherein
The grating table rotated by a predetermined first angle on the entire table about the rotation axis is fixed to the entire table,
2. The laser system according to claim 1, wherein the whole base rotated by a predetermined second angle on the drive holding the whole base about the rotation axis is fixed to the drive. The laser system according to claim 2, wherein
The second angle is adjusted so as to return the direction of the laser light emitted from the grating, which has been changed by the rotation of the first angle of the grating base, to the direction of the laser light before the rotation. Featured laser system. The laser system according to claim 2, wherein
The laser system according to claim 1, wherein the rotation of the grating stage is performed using an eccentric driver. The laser system according to claim 4, wherein
The grating table has an eccentric driver hole penetrating in the thickness direction,
The whole platform has a hole into which the protrusion of the eccentric driver is inserted,
The rotation of the grating table is
The eccentric driver passes through the hole for the eccentric driver of the grating table,
In a state where the protrusion of the eccentric driver is inserted into the hole of the overall platform,
The laser system is performed by rotating the eccentric driver. The laser system according to claim 2, wherein
The laser system is characterized in that the rotation of the whole base is performed using an eccentric driver. The laser system according to claim 6.
The whole base has an eccentric driver hole penetrating in the thickness direction,
The drive has a hole into which the protrusion of the eccentric driver is inserted;
The rotation of the whole base is
The eccentric driver passes through the eccentric driver hole of the whole base,
With the protruding part of the eccentric driver inserted into the hole of the drive,
The laser system is performed by rotating the eccentric driver. The laser system according to claim 1, wherein
A lens is disposed between the semiconductor laser and the grating;
An external cavity type semiconductor laser is constituted by the semiconductor laser, the lens, and the grating. The laser system of claim 8, wherein
2. The laser system according to claim 1, wherein the external cavity semiconductor laser is a Littrow type. The laser system according to claim 1, wherein
The grating table and the entire table are connected by a first pin, and the first pin functions as the rotating shaft,
The whole platform and the drive are connected by a second pin, and the second pin functions as the rotating shaft,
The first pin and the second pin are arranged apart from each other, and are configured to protrude in the thickness direction of the entire base,
Furthermore, the grating table has a hole for accommodating the first pin,
The laser system, wherein the drive has a hole for receiving the second pin.

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