JPS63269131A - Parallel light forming device - Google Patents

Abstract

PURPOSE:To convert projected light from a waveguide type nonlinear optical device into parallel light by using a convex cylindrical lens continuously changing its curvature. CONSTITUTION:Light radiated from a light source 100 is made incident upon the waveguide type nonlinear optical device 101. The device 101 generates and projects higher harmonic of the light radiated from the light source 100, one of the projected light 103 is converted into parallel light and the other is projected as dispersed light. A light emitting point of secondary higher harmonic radiated from the incident end of the waveguide is different from that of secondary higher harmonic radiated from its projection end. A convex cylindrical lens 103 is arranged vertically to an optical axis so that the dispersed light out of the projected light are converted into parallel light. The curvature of the lens 102 is changed in accordance with the incident position of light and continuously changed so that its focus is fitted to the whole waveguide formed on the device 101. Consequently, the projected light from the device 101 can be converted into parallel light.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a parallel light generating device using a laser light source used in optical discs and laser printers.

Conventional technology In recent years, among laser light sources, laser light sources using semiconductor lasers have superior characteristics such as being smaller, lighter, and easier to modulate than those using gas lasers such as He-Ne. It is widely used in optical disks, laser printers, etc. On the other hand, since the recording capacity of an optical disk is inversely proportional to the area of the bit, research is underway to shorten the wavelength of semiconductor lasers to form smaller bits. Nonlinear optical elements are one such device, and by converting incident primary light into its secondary harmonic, it is possible to obtain light with a wavelength half that of the original light source.

In a waveguide-type nonlinear optical element, when light emitted from a semiconductor laser or the like enters a waveguide formed on the nonlinear optical element,
This is an element that emits the second harmonic at a certain angle (approximately 16° in the case of a semiconductor laser) with respect to the waveguide. In order to use the light emitted from these light sources to form bits on the disk or read out the bits on the disk, the light must be placed on the disk at a diffraction-limited spot (semiconductor). If it is a laser, it must be focused on a diameter of about 1.4μ ring). For this purpose, it is desirable to make parallel light incident on the condenser lens. Since the emitted light of a semiconductor laser is a diverging light, it must be converted into parallel light once, and the semiconductor laser light sources used in optical discs etc. are also supplied in a form that emits parallel light. many. An example of a semiconductor laser light source for optical pickup used in a conventional optical disc will be described below with reference to the drawings.

FIG. 3 is an explanatory diagram of a semiconductor laser light source used in conventional optical pickup. In Figure 3, 301
is a semiconductor laser, 302 is a collimating lens, and 303 is a semiconductor laser beam.

Laser light 303 emitted from semiconductor laser 301 is
It is a spherical wave and spreads with a certain spread angle in both the vertical and horizontal directions. By aligning the focal point of the collimating lens 302 with the emission center of the semiconductor laser beam 303, the divergent light is converted into parallel light. (For example, Latter Day; "Usage and precautions for optical components", PP, 87, Neptronics Co., Ltd. (1985)).

Problems to be Solved by the Invention However, with the above configuration, although the emitted light of the semiconductor laser can be converted, the emitted light of the waveguide type valve linear optical element cannot be converted into parallel light, and the laser that emits parallel light cannot be converted into parallel light. It does not serve as a light source. The problems will be explained below with reference to FIG.

Figure 4 is an explanatory diagram of the second harmonic output light generated from the waveguide type valve linear optical element, and Figure 4 (a) shows the waveguide type valve linear optical element on the surface where the waveguide is formed. FIG. 4(b) is a view viewed from the lateral direction, and FIG. 4(b) is a view viewed from the direction in which the waveguide is formed. In both figures, 101 is a waveguide type valve linear optical element, 401, 403, and 404 are the output lights of 101, and 402 is a spherical lens.

(1) The light emitted from the waveguide type valve linear optical element 101 is not a diverging light in both the vertical and horizontal directions like the light emitted from a semiconductor laser (one is parallel light 401 and the other is diverging light that spreads at a certain angle). 403.404. Therefore,
The spherical lens 402 alone cannot convert both into parallel light at once.

(2) As shown in Figure 4(b), the spread angle of the second harmonic 403 radiated from the input end of the primary light of the waveguide and the second harmonic 404 radiated from the output end is constant. However, the light emitting point is different. Therefore, if you try to convert into parallel light with one lens, even if the light is divergent in the same plane, 405 and 4
As shown in 06, one becomes parallel light and the other becomes divergent light.

Means for Solving the Problems In order to solve the above problems, the apparatus of the present invention includes a light source;
A waveguide type valve linear optical element that receives the light emitted from the light source and emits harmonics of the light source, and a convex cylindrical lens whose curvature changes continuously that converts the light emitted from the nonlinear optical element into parallel light. It uses

Function: Since the present invention uses a convex cylindrical lens with the above-described configuration, only the diverging light is converted into parallel light, and the other parallel light is preserved as is. Furthermore, since the focal length depends on the location where the diverging light is incident, even if the light emitting points are different, all of them can be converted into parallel light. Therefore, a laser light source that emits parallel light can be formed.

EXAMPLE Hereinafter, a laser light source according to a first example of the present invention will be described with reference to the drawings.

Figure 1 is an explanatory diagram of a laser light source, Figure 1 (a) is a diagram of a waveguide type valve linear optical element viewed from the direction in which the waveguide is formed, and Figure 1 (b) is a diagram of it viewed from the side. This is the view. In both figures, 100 is a light source such as a semiconductor laser, and 101 is a light source such as a semiconductor laser.
102 is a convex cylindrical lens whose curvature changes continuously, 103 is the output light of the nonlinear optical element, and 104 is the converted parallel light.

The laser light source configured as above will be explained using FIG. 1 and FIG. 2.

The light emitted from the light source 100 is transmitted to the waveguide type valve linear optical element 1.
01. The waveguide type valve linear optical element 101 generates and emits harmonics of the light source 100, and as explained in FIG. 4, one of the output lights 103 is parallel light and the other is diverging light. Further, the second harmonics emitted from the input end of the waveguide and the second harmonics emitted from the output end have different light emission points. The emitted light 103 is arranged so that the divergent light is converted into parallel light as shown in FIG. 1(a), and the parallel light is transmitted as it is as shown in FIG. 1(b).
and a convex cylindrical lens 102 perpendicular to the optical axis.
Place. The convex cylindrical lens 102 has a different curvature depending on the incident position of light. Its curvature changes continuously so that the focal point matches the entire waveguide formed on the nonlinear optical element 101. FIG. 2 shows a design example of this convex cylindrical lens. This convex cylindrical lens is designed to focus on the waveguide within the element when placed at a distance of 5.3-m from the element at a temperature of io+e-. The curvature is 10 on the input end side as shown in Figure 2.
．． The fog is as large as 15+e, and is as small as 7.08 sv on the exit end side, and changes in between as a linear function of distance as shown by equation (1).

r = 0.512d + 7.08 "" (1) r: curvature, d: distance from the output end to the light emitting point (S-) Also, the thickness of this cylindrical lens and the distance between the elements are determined according to the given conditions. It is possible to reset the settings by

As described above, by designing a convex cylindrical lens, it is possible to convert the light emitted from the waveguide type valve linear optical element into parallel light. Therefore, it becomes a laser light source that emits parallel light.

Effects of the Invention As described above, according to the present invention, the light emitted from the waveguide type valve linear optical element can be converted into parallel light using one convex cylindrical lens. Therefore, a laser light source that emits the harmonics of a light source such as a semiconductor laser as parallel light can be obtained, and since it has the same emission form as current semiconductor laser light sources, it can be incorporated into current equipment in the same way as semiconductor laser light sources. becomes possible.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of a laser light source showing a first embodiment of the present invention, FIG. 2 is an explanatory diagram showing a design example of a convex cylindrical lens, and FIG. 3 is an explanatory diagram showing a conventional semiconductor laser light source.
FIG. 4 is an explanatory diagram of the emission state of the second harmonic generated from the waveguide type valve linear optical element. 100... Light source, 101... Waveguide type valve linear optical element, 102... Convex cylindrical lens, 103...
- Outgoing light of the nonlinear optical element, 104...Parallel light. Name of agent: Patent attorney Toshio Nakao and one other person Im---
Light source 1st y4/(12-
-One-convex cylindrical lens Fig. 2/θ2. 311)/--One and a half one! ! Figure 33 - Collimating lens No. 3 of the salary laser
Zuku 301 302. 1) 3 Figure 4 Xiong 1

Claims (1)

[Claims] a light source; a waveguide-type nonlinear optical element that receives light emitted from the light source and emits harmonics of the light source; A parallel light generating device characterized by comprising a variable convex cylindrical lens.