JPH03282512A - Polarization nondependent optical device - Google Patents

Abstract

PURPOSE:To enable an optical device which has polarization dependency upon insertion loss to easily operate as the polarization nondependent optical device by equalizing incident light and out going light in polarized component ratio by using a polarizing filter. CONSTITUTION:While an input port 2 and an output port 3 are connected, the light which is made incident from the port 2 passes through an optical switch 1 which has the polarization dependency on the insertion loss, so the light becomes equal in polarized component ratio to the incident light and the insertion loss characteristics of the optical switch 1 appear as they are. When, however, the optical switch 1 is switched to connect output ports 3 and 4, the port 3 operates as an input port, so the light which is made incident from the port 3 is made incident on the polarizing filter 5 through the optical switch 1. When the light projected from the filter 5 is so adjusted that its polar ized component ratio becomes equal to that of the light made incident on the optical switch 1, the light projected from the port 4 is observed without being affected by the switch 11 and the incident light from the port 2 and the projec tion light from the port 4 function as the polarization nondependent optical device.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Separation] The present invention relates to a polarization-independent optical device used for optical fiber communication, optical measurement, optical information processing, etc.

[Conventional technology]

Conventionally, in optical fiber communication and optical measurement, it is necessary to prevent insertion loss from depending on the polarization state so that the optical output from an optical device inserted in the middle of an optical transmission line or optical circuit does not vary depending on the polarization state of the optical input. Specially designed polarization-independent source devices have been used.

[Problem to be solved by the invention]

However, in the above-mentioned conventional polarization-independent optical devices, the design of the optical device is limited due to too much consideration given to polarization independence.
The drawbacks were that it had limited power and was expensive. This is particularly noticeable when the optical device is formed of an optical waveguide because the polarization independence conditions are limited.

The purpose of the present invention is, apart from polarization independence of insertion loss, to
An object of the present invention is to provide a polarization-independent optical device that can equalize the polarization component ratio of incident light and output light.

[Means to solve the problem]

The polarization-independent optical device of the present invention includes an optical device having at least one input port and at least one output port and having polarization dependence in insertion loss, and an optical device that inputs and outputs light from the output port of the optical device. and a polarizing filter adjusted so that the polarization component ratio of the light is equal to the polarization component ratio of the light incident on the optical device.

〔Example〕

Next, the present invention will be explained with reference to the drawings.

FIG. 1 is a block diagram showing one embodiment of the present invention, and shows an example of an optical switch.

The embodiment shown in FIG. 1 has one input port 2 and two output ports 3, 4f: an optical switch 1 whose insertion loss is polarization dependent, and a polarization filter 5 inserted into the output port 4. It is composed of.

In this embodiment, in the state shown in FIG. 1, input port 2 and output port 3 are connected, but optical switch 1
Output port 3 and output port 4 can be connected by switching. In that case, output port 3 becomes the input port.

Next, the operation of this embodiment will be explained.

When input port 2 and output port 3 are connected,
The light incident from the input port 2 passes through the original switch l whose insertion loss is polarization dependent, and then passes through the optical switch 1 whose polarization component ratio of the output light is the polarization component ratio whose insertion loss is polarization dependent. Therefore, it is not equal to the polarization component ratio of the incident light, and the insertion loss characteristic of the optical switch 1 appears as it is.

However, when the optical switch 1 is switched next and the output ports 3 and 4 are connected, the output port 3 works as an input port, so the insertion loss of the light incident from the output port 3 has polarization dependence. The light passes through the optical switch l and enters the polarizing filter 5.

Here, if the polarization component ratio of the light emitted from the polarizing filter 5 is adjusted to be equal to the polarization component ratio of the light incident on the optical switch 1, the light emitted from the output port 4 will depend on the polarization dependence of the optical switch 1. It seems that he was not affected in any way by
/CIl! be measured. In this way, this embodiment functions as a polarization-independent optical device, although there is IIi only between the light incident on the input port 2 and the light emitted from the output port 4.

The embodiment shown in FIG. 1 is an optical pulse tester (OTI) R:
0ptical 'l'ime Domain Re
An example of application to a reflectometer is shown in FIG. In FIG. 2, a semiconductor laser 6 is connected to the input port 2, and a (Ii11 constant fiber 7) is connected to the output port 3.
, a light receiving element 8 is connected to the output port 4, respectively.

Pulse-modulated light from the semiconductor laser 6 enters the input port 2. Here, when the input port 2 and the output port 3 are connected in the optical switch 1, the pulsed light incident on the 1 input port 2 passes through the output port 3 and enters the fiber 7 to be measured. The input pulsed light is transmitted to the constant fiber 7 which is damaged.
As a result of this, the light returns to the optical switch 1 through the output port 3 again. At this time, when the optical switch 1 is switched to connect the output ports 3 and 4, the reflected light incident on the optical switch 1 is incident on the polarizing filter 5.

Here, since the polarization component ratio of the light emitted from the polarizing filter 5 is adjusted to be equal to the polarization component ratio of the light incident on the optical switch 1, the light emitted from the output port 4 is , the theater is watched as if it had not been affected by the polarization dependence of the original switch 1. This enables stable and high nyt measurement.

Although the embodiment as an optical switch has been described above, the present invention can also be applied to optical devices other than optical switches.

〔Effect of the invention〕

As explained above, in the present invention, by using a polarizing filter to equalize the polarization component ratio of the incident light and the output light, it is possible to easily create an optical device whose insertion loss is polarization-dependent.
In addition, there is an effect that the device can be operated as a polarization-independent optical device at low cost.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing an embodiment of the present invention, and FIG. 2 is a block diagram showing an example of how the embodiment shown in FIG. 1 is used. 1... Optical switch whose insertion loss has polarization dependence, 2
...Input port, 3, 4...Output port, 5...
polarizing filter.

Claims (1)

[Claims] An optical device that has at least one input port and at least one output port and has polarization dependence in insertion loss; and an optical device that inputs light from the output port of the optical device, and that outputs light with a polarization component ratio to the optical device. A polarization-independent optical device comprising: a polarization filter adjusted to be equal to the polarization component ratio of incident light.