JPH05346603A - Fiber type light wavelength conversion device - Google Patents

Abstract

PURPOSE:To easily adjust the optical axis of a fiber type light wavelength conversion element and the optical axis of an Axicon lens only by moving the Axicon lens along the flat surface of a supporting body when the axial centers thereof are aligned and to simplify an adjustment mechanism in accordance with the facilitation of the adjustment. CONSTITUTION:At least a fiber type light wavelength conversion element 5, the Axicon lens 8 collimating light emitted from the element 5, a groove 10 guiding the element 5 in freely movably in the optical axis direction thereof and the supporting body 9 obtained by integrally forming the flat surface 11 guiding the lens 8 in freely movably in a direction vertical to the shaft direction of the groove 10 are provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fiber type optical wavelength conversion device using Cherenkov radiation type phase matching, and more particularly to an optical system for converting second harmonic light emitted from an optical fiber into aberration-free parallel light. The present invention relates to a fiber type optical wavelength conversion device having a feature in an element adjusting mechanism.

[0002]

2. Description of the Related Art An optical pickup capable of writing and reading information on an optical disc at a higher density by converting the wavelength of a laser light beam emitted from a laser light source into half by using an optical wavelength conversion element. Is known (see Japanese Patent Laid-Open No. 61-50122).

As such an optical wavelength conversion element, a fiber type SHG (Second Harmo) using a second-order nonlinear optical effect is used.
nics Generator; second harmonic generation element), and this fiber type SHG adopts Cherenkov radiation phase matching. According to this method, it is possible to generate the second harmonic (hereinafter, abbreviated as SH wave) whose phase is matched almost automatically.

In the fiber type SHG using the Cherenkov phase matching, the SH wave to be emitted has a ring-shaped intensity distribution, and the equiphase surface is conical. This S
In order to focus the H wave on the diffraction limit, the emitted light emitted from the laser light source 1 such as a semiconductor laser as shown in FIGS. 1 (a) and 1 (b) is collimated by the collimator 2, the shaping prism 3, and the cup. Fiber type SH via lens system such as ring lens 4
It is guided to G5, guided to the axicon lens 6 (or Fresnel type axicon lens) that converts the SH wave wavelength-converted by the fiber type SHG5 into aberration-free parallel light, and the parallel light 7 converted here is further guided. An optical system in which light is condensed by a condenser lens (not shown) is generally applied.

The axicon lens 6 used here is
In general, it is made of glass or plastic, and when it is arranged in the above optical system, it is supported by a separate supporting member. Therefore, the optical axis of the fiber type SHG 5 and the optical axis of the axicon lens 6 are precisely aligned. Need to be adjusted. However, such adjustment requires angle adjustment of the optical axis (angle deviation adjustment) and position adjustment of the optical axis (position deviation adjustment), and both the adjustment mechanism and the adjustment procedure are complicated and difficult, resulting in a waste of adjustment. There was a problem that it took a long time.

[0006]

In view of the above-mentioned problems of the prior art, it is an object of the present invention to provide a fiber type optical wavelength conversion element (fiber type SHG) and an SH wave radiated from such an element into parallel light. (EN) An optical system having at least an axicon lens for converting the optical axis into a fiber type optical wavelength conversion device having means for easily aligning the optical axes of the both.

[0007]

A fiber-type optical wavelength conversion device according to the present invention comprises a fiber-type optical wavelength conversion element (fiber-type SHG) and radiated light emitted from the fiber-type optical wavelength conversion element into parallel light. An axicon lens, a groove for movably guiding the fiber-type optical wavelength conversion element in its optical axis direction, and a flat surface for movably guiding the axicon lens in a direction perpendicular to the axial direction of the groove. And a support that is formed in a specific manner.

[0008]

Since the groove for guiding the fiber type optical wavelength conversion element in the one-dimensional direction and the plane for guiding the axicon lens in the two-dimensional direction are integrally formed in a perpendicular relationship, As long as the light wavelength conversion element is supported in the groove and moved only in the groove axis direction, and the axicon lens is supported in contact with the plane and moved only in the plane, the fiber type optical The optical axis of the wavelength conversion element and the optical axis of the axicon lens are always kept parallel.

Therefore, when the optical axes of the two are deviated from each other, the optical axes of the both can be made coincident only by moving and adjusting only the axicon lens in the plane. When adjusting the distance between the fiber type optical wavelength conversion element and the axicon lens in order to obtain parallel light SH waves having a circular intensity distribution, only the fiber type optical wavelength conversion element is provided in the groove. It only has to be moved along and placed in the optimum position.

[0010]

EXAMPLE FIG. 2 shows a fiber type optical wavelength conversion element 5 with a V
An embodiment of the fiber type optical wavelength conversion device according to the present invention, which is supported by the V-shaped groove 10 of the block-shaped support 9 and the axicon lens 8 is abutted and supported by the flat surface 11 located at the end of the support 9. It is a schematic perspective view showing an example.

As shown in the figure, the support 9 has a V-block shape and is formed by machining so that the groove axis of the V-groove 10 and the plane 11 located at the end of the groove are perpendicular to each other. ing. Then, the fiber type optical wavelength conversion element 5 is placed in the V groove 10, guided movably in the groove axis direction C, that is, the optical axis direction, and at a desired position by a predetermined fixing member (not shown). It is supposed to be fixed.

On the other hand, on the flat surface 11, an adjusting screw 13 is screwed into a screw supporting projection 14 which is mounted so as to be rotatable in the plane R and is pivotally pinned to the holding frame 12 by an adjusting screw 13. A holding frame 12 is movably arranged in the plane 11, and the axicon lens 8 is arranged between the holding frame 12 and the plane 11. As a result, the axicon lens 8 is moved following the movement of the holding frame 12 within the plane 11.

Now, an adjusting method for aligning the optical axis of the fiber type optical wavelength conversion element 5 and the optical axis of the axicon lens 8 will be described. First, polarized light is applied to the fiber type optical wavelength conversion element 5 and the axicon lens 8 from the light incident direction of the fiber type optical wavelength conversion element 5.
On the other hand, the position of the axicon lens 8 can be adjusted while observing both fiber type optical wavelength conversion elements 5 and the axicon lens 8 through an analyzer that allows only polarized light orthogonal to the polarized light emitted from the axicon lens 8 side to pass. By doing so, the core portion 5a of the fiber-type optical wavelength conversion element 5 can be clearly seen due to the birefringence, and therefore the center of the axicon lens 8 and the core portion 5a can be easily aligned.

As described above, when aligning the optical axes of the two, the angle adjustment of the axicon lens 8 is omitted and the position is adjusted only within the plane 11 (the adjusting screw 13 is moved in the A and B directions). Since the adjustment mechanism can be simplified, the adjustment time can be shortened, and since it can be firmly fixed, the change over time can be suppressed as much as possible and a stable function can be guaranteed.

The axicon lens 8 used here is a plane 1
The state of contact with the first lens will be described in detail. As shown in FIGS. 3 (a) to 3 (c), it may be in a surface contact state or a line (circle) contact state, and further, a Fresnel type axicon lens. Is preferred. In the present embodiment, the adjusting screw and the holding frame are shown as the holding means and the adjusting means of the axicon lens 8. However, the holding means and the holding frame are not limited to these, and the axicon lens can be held. Any means can be applied as long as it is an adjustable mechanism.

Although the V-block-shaped support is shown as the support in the above-mentioned embodiments, the support is not limited to this, and the fiber type optical wavelength conversion element can be moved in the optical axis direction. Any groove may be used as long as the groove for guiding to and the plane for sliding the axicon lens are integrally formed in a vertical relationship. Another embodiment of the support according to the present invention is shown in FIG. In the support 15 shown in the figure, the flat surface 11 is formed integrally so that the flat surface 11 is positioned perpendicular to the groove axis direction of the V groove 10, and the end portion of the V groove 10 is also formed. Since the SH wave radiated from the fiber-type optical wavelength conversion element has a conical shape because there is a predetermined distance L between it and the plane 11, the distance between the two should be positioned so as to be in an optimum state. You can

[0017]

As described above, according to the fiber type optical wavelength conversion device of the present invention, the fiber type optical wavelength conversion element is supported so as to be movable only in the optical axis direction thereof, and the axicon lens is described above. Since it is supported so as to be movable only in a plane perpendicular to the optical axis direction of the element, when the optical axis of the element and the optical axis of the axicon lens are aligned, the axicon lens It is only necessary to adjust the position (move in the plane), and the adjustment can be facilitated.

Therefore, the adjusting mechanism can be simplified because the angle adjustment is not necessary, and it can be firmly fixed and the stable function can be guaranteed by suppressing the change with time as much as possible.

[Brief description of drawings]

1 shows a schematic configuration diagram of a conventional fiber type optical wavelength conversion device, FIG. 1 (a) is a plan view thereof, and FIG.
Is a front view thereof.

FIG. 2 is a fiber-type optical wavelength conversion element according to the present invention,
It is a schematic perspective view showing the positional relationship between an axicon lens and a support.

FIG. 3 shows an aspect in which an axicon lens is brought into contact with and supported by a flat surface of a support according to the present invention, and FIG.
3C and 3C show a state in which they are brought into contact with each other by surface contact, and FIG.

FIG. 4 is a schematic perspective view showing another embodiment of the support according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 light source 2 collimator 3 shaping prism 4 coupling lens 5 fiber type light wavelength conversion element 5a core part 6,8 axicon lens 7 parallel light 9,15 support body 10 groove 11 plane 12 holding frame 13 adjustment screw 14 screw support protrusion

Claims (1)

[Claims] 1. A fiber-type optical wavelength conversion element, an axicon lens for converting emitted light emitted from the fiber-type optical wavelength conversion element into parallel light, and moving the fiber-type optical wavelength conversion element in its optical axis direction. At least a groove for freely guiding and a support integrally formed with a flat surface for movably guiding the axicon lens in a direction perpendicular to the axial direction of the groove are provided. Wavelength converter.