JPH0520016U - Optical device - Google Patents

Abstract

(57) [Summary] [Object] To obtain an optical device in which constituent members are easily arranged and fixed and the amount of light rays incident on a condenser lens is not reduced. The optical device 11 includes a light source 12 in which a tip end surface 12a is inclined with respect to a vertical surface V1 by a predetermined angle θ1, and a principal ray L of the light source 12 that focuses light from the light source 12. A condenser lens 13 arranged so as to pass through the center O, and an incident surface 14 arranged in parallel with the optical axis of the condenser lens 13 and corresponding to the focal position of the focused light.
An optical fiber 1 in which a is inclined by an angle θ3
4 and.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to an optical device in an optical communication device or the like, which converges light emitted from a light source through a condenser lens and makes it enter an optical fiber.

[0002]

[Prior Art]

 2. Description of the Related Art Conventionally, there is known an optical device that converges light emitted from a laser diode or the like through a condenser lens and condenses it on an optical fiber. This optical device collects the light from the laser diode with a condenser lens and makes it enter from the end face of the optical fiber. However, when the laser diode, the condenser lens and the optical fiber are arranged coaxially, the laser diode A part of the light emitted from the laser is reflected from the vertical incidence end face of the optical fiber and returns to the laser diode, and this return light causes the problems of destabilizing the oscillation characteristics of the laser diode and increasing noise.

Therefore, a structure has been considered in which the incident surface of the optical fiber is cut obliquely with respect to the center axis of the fiber to prevent the reflected return light from the incident surface from returning to the laser diode. An example of this improvement is shown in FIGS. 2 and 3 are schematic configuration diagrams showing an optical device using a conventional optical fiber. The optical device 1 shown in FIG. 2 includes a light source 2 including a laser diode, a condenser lens 3 that focuses the light emitted from the light source 2, and an optical fiber 4 on which the focused light enters. Although the fiber 4 is configured, the incident surface 4a of the fiber 4 is inclined by an angle θ (which means the scraped angle) so that the reflected light does not return to the light source 2. In addition, the principal ray of the incident light (the ray having the strongest intensity) L has an angle θ 0 with respect to the fiber central axis D so that the phase matching with the fiber 4 is good and the coupling efficiency is high. The light is incident on the incident surface 4a.

[0004]

In the optical device shown in FIG. 2, the chief ray L of the light source 2 and the central axis of the condenser lens 3 are arranged coaxially with each other, but the central axis D of the optical fiber 4 is The structure has an angle of θ0 with respect to the central axis of the condenser lens 3. In this type of device, the light source 2 and the condenser lens 3 are positioned and fixed to each other, for example, in the same holder, and since the optical fiber 4 is long, its end is held by an adapter, and the holder and this adapter are It is designed to be connector-bonded to each other. However, in the structure of FIG. 2, since the central axis of the condensing lens 3 and the central axis of the optical fiber 4 have an angle θ0, it is necessary to accurately position both central axes in accordance with this angle for connector joining. Becomes very difficult.

Therefore, in order to configure an actual device, as shown in FIG. 3, it is necessary to connect the central axis of the condenser lens 3 and the central axis of the fiber 4 in parallel. By making the central axis of the condenser lens 3 and the central axis of the optical fiber 4 parallel to each other, a holder holding the light source 2 and the condenser lens 3 and a plug holding the end portion of the optical fiber 4 are provided. Since the connecting portions of are parallel to each other, the connector can be easily configured, and the holder and the plug can be accurately positioned and joined.

However, in the structure of FIG. 3, when the direction of the chief ray L emitted from the light source 2 and the central axis of the condenser lens 3 are arranged in parallel, the light from the light source 2 is incident on the incident surface of the optical fiber 4. 4a, the principal ray needs to be incident along the central axis D of the optical fiber 4 at an angle θ0 capable of phase matching, and therefore, the light emitting point of the light source 2 and the incident surface 4a of the optical fiber 4 are required. The center line O1 connecting the center points must pass through the center O of the condenser lens 3. As a result, the principal ray L of the light emitted from the light source 2 is incident with an axial offset from the central axis of the condenser lens 3. Therefore, the divergent light from the light source 2 is incident on the condenser lens 3 in a biased manner, and for example, the ambient light indicated by L1 cannot be taken in by the condenser lens 3 and the light utilization efficiency decreases. become.

The present invention has been made to solve the above problems, and provides an optical device in which a connector between a condenser lens and an optical fiber can be easily connected and light from a light source can be efficiently used. The purpose is to

[0008]

[Means for Solving the Problems]

 The structure of the present invention for achieving the above object is to provide an optical fiber whose incident surface is formed obliquely to the central axis, a light source, and collect light from this light source on the incident surface of the optical fiber. In an optical device having a condenser lens, the central axis of the optical fiber and the central axis of the condenser lens are arranged in parallel, and the direction of the main light ray of the light emitted from the light source is the center of the condenser lens. It is characterized in that it is set so as to pass through and be refracted at the incident surface to the optical fiber and enter along the central axis thereof.

[0009]

[Action]

 In the above means, since the central axis of the condenser lens and the central axis of the optical fiber are parallel to each other, the holder holding the condenser lens and the plug holding the end of the optical fiber are The connector is easily connected and the positioning of the condenser lens and the optical fiber is easy. Moreover, since only the direction of the light source is changed so that the chief ray goes toward the center of the condenser lens, the utilization efficiency of light from the light source is not reduced. Further, if the light source and the condenser lens are fixed in the same holder, the positioning of the light source and the condenser lens is not so difficult, and the positioning and fixing of both can be performed with high accuracy.

[0010]

【Example】

 An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic configuration diagram showing an optical device according to an embodiment of the present invention. An optical device 11 shown in the figure is a light source 12 in which a chip end surface 12a of a light emitting element is arranged at an angle of a predetermined angle θ1 with respect to a vertical surface V1, and a light source 12 that focuses light from the light source 12 And the optical axis of the condenser lens 13 (the center O of the lens and the apex of the spherical surface or aspherical surface of the lens are connected to each other). (Straight line) O2 and the optical fiber 14 arranged in parallel. The incident surface 14a of the optical fiber 14 is arranged in a direction orthogonal to the vertical line of the fiber center axis D by θ 3. The light emitting point P of the light source 12 and the center Q of the incident surface 14 a are arranged at the focal position of the condenser lens 13.

In this embodiment, the chief ray L from the light source 12 needs to pass through the center O of the condenser lens 13 and be incident on the optical fiber 14 in a phase-matchable manner. For this phase matching, it is a condition that the chief ray L is incident along the central axis D of the optical fiber 14. Hereinafter, the conditions for setting the tilt angle θ1 will be described.

The incident angle of the principal ray L on the incident surface 14a of the fiber 14 is θ2, and the outgoing angle of the chief ray L into the fiber 14 is θ3. In order for the principal ray L to enter along the central axis D of the fiber 14, the exit angle θ3 is the same as the inclination angle of the entrance surface 14a of the fiber 14. Assuming that the refractive index of the fiber 14 is n, the refractive index of air is “1”, so the above condition is sin θ2 = n · sin θ3.

Here, as shown in FIG. 1, the light emitting point of the light source 12 is P, the input point of the fiber 14 is Q, the extension line of the central axis D is H2, and the light passing through the light emitting point P A parallel line parallel to the extension line H2 is defined as H1. When an arbitrary point of the extension line H2 is X and an arbitrary point of the parallel line H1 is Y, the angle YPO = the angle XQO = the angle θ1 Therefore, the inclination angle θ1 of the light source 12 is the angle θ1 = The relationship of angle θ2-angle θ3 is established.

This relationship is, for example, if the fiber tilt angle θ3 = 8 ° and the refractive index n = 1.45 of the fiber 14, the tilt angle θ1 = 3.6 °.

If the light source 12, the condenser lens 13, and the fiber 14 are arranged in the above-described positional relationship, the central axis O2 of the condenser lens 13 and the central axis D of the fiber 14 can be made parallel to each other. Since the principal ray L from 12 enters the center O of the condenser lens 13, divergent light from the light source can be symmetrically taken in with respect to the principal ray L, and the light utilization efficiency is improved.

Furthermore, since the holder for holding the condenser lens 13 and the adapter for holding the end portion of the fiber 14 are connected in parallel, the structure of the connector is simplified, and the condenser lens 13 and the fiber The mutual alignment with 14 can also be performed with high precision. Further, if the light source 12 and the condenser lens 13 are fixed in the same holder, it is easy to assemble the light source 12 and the condenser lens 13 by setting the relation of the angle θ1 with high accuracy.

The present invention is not limited to the above-described embodiments, and various modifications can be made within the scope of the invention. For example, in the above embodiment, the case where each one of the light source 12, the condenser lens 13 and the fiber 14 is used has been described, but it may be applied to an optical device in which a plurality of each of them is integrated.

[0018]

[Effect of the device]

 As described above, according to the present invention, it is possible to provide an optical device in which the components are easily arranged and fixed and the amount of light rays incident on the condenser lens is not reduced.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing an optical device according to an embodiment of the present invention.

FIG. 2 is a schematic configuration diagram showing a conventional optical device.

FIG. 3 is a schematic configuration diagram showing another example of a conventional optical device.

[Explanation of symbols]

 11 optical device 12 light source 12a irradiation end face 13 condensing lens 14 optical fiber L chief ray

Claims (1)

[Scope of utility model registration request] 1. An optical device comprising: an optical fiber having an incident surface formed obliquely to a central axis; a light source; and a condenser lens for condensing light from the light source onto the incident surface of the optical fiber. The central axis of the optical fiber and the central axis of the condenser lens are arranged in parallel, and the direction of the chief ray of the light emitted from the light source passes through the center of the condenser lens and is incident on the optical fiber at the incident surface. An optical device, which is set so as to be refracted and incident along the central axis thereof.