JPS62174623A - Polarized wave ratio measuring instrument for semiconductor laser - Google Patents

Abstract

PURPOSE:To obtain an instrument whose measuring operation is easy by providing a polarizer which rotates continuously and a device which detects the output signal of a photodetector varying with it. CONSTITUTION:A semiconductor laser 1 to be measured is driven by a DC power source 2. Its output light enters the photodetector 5 through the polarizer 4. The polarizer 4 rotates at a constant speed in a plane perpendicular to the traveling direction of the light. A DC power source 6 is a bias power source for the photodetector 5 and the signal output of a resistance 7 as a resistance for signal detection is measured on an oscilloscope 8. The polarizer 4 rotates, so the light passed through it varies in polarized wave component ratio with time and the quantity of the light incident on the photodetector 5 also varies. Therefore, the signal output of the resistance 7 also varies, which is observed on the oscilloscope 8.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a device for measuring polarization ratio among the characteristics of semiconductor lasers.

[Conventional technology]

Output light from a semiconductor laser is usually divided into TE waves and TM waves, and is generally polarized into TE waves with almost no TM waves. By the way, when the source is propagated through a fiber, there is a slight difference in the propagation constant and group velocity between the two polarized components, which can cause problems in the source fiber communication.

Therefore, it is necessary to measure the ratio of the TE wave component to the TM wave component, that is, the polarization ratio.

In conventional polarization ratio measuring equipment, a polarizer is placed between the semiconductor laser to be measured and a light receiver for detecting its optical output, and the TE wave component and TM wave component are detected while adjusting the angle of the polarizer. was measuring.

[Problem that the invention seeks to solve]

The conventional polarization ratio measuring device described above needs to measure both side wave components after adjusting the angle of the polarizer. Therefore, the measurement process requires adjusting the polarizer to obtain each polarized wave, which has the disadvantage of lengthening the measurement time.

SUMMARY OF THE INVENTION In view of the above drawbacks, the present invention provides an apparatus that is easy to operate for measurement.

[Means to resolve the issue]

To achieve this objective, the measuring device of the invention has a continuously rotating polarizer and a device for detecting the changing output signal of the receiver.

[Next example]

FIG. 1 shows an embodiment of the invention.

1 is a semiconductor laser to be measured, and 2 is a @current power source for driving it. This output light passes through a polarizer 4 and enters a light receiver 5. The polarizer 4 rotates at a constant rotational speed in a plane perpendicular to the direction in which the light travels. Reference numeral 6 is a bias power source for the photoreceiver 5, and resistor 7 is a signal detection resistor, the signal output of which is determined by an oscilloscope 8. Since the polarizer 4 is rotating, the polarization component ratio of the light passing through it changes over time, and the amount of light incident on the light receiver 5 also changes. Accordingly, the signal output of the detection resistor 7 changes accordingly, and this situation is observed with the oscilloscope 8. FIG. 2 shows changes in the signal output, and a maximum value P MAX and a minimum value P MIN can be seen periodically.

In this figure, the horizontal axis shows time t, and the vertical axis shows the signal output of the resistor 7, that is, the amount of light incident on the light receiver 5.

Here, the maximum value PMAX is proportional to the TE wave component of the semiconductor laser to be measured f+u1, and the minimum value PMIN is a value proportional to the TM wave component.

Therefore, by setting PMAx and P MIN to 4111 on the oscilloscope 8, the polarization ratio T
E/TM is calculated TE/TM=PvAx/Pm+* +++++++++++
+++ (1) [Effects of the Invention] As explained above, according to the present invention, it is possible to simplify the operation of the secondary leg without having to adjust the polarizer.

Note that as shown in the embodiment of FIG.
Any measuring device that can measure IN is fine.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention, and FIG. 2 is a graph showing an output signal of a light receiver. l...Semiconductor laser to be measured, 2, 6...
...DC 111X, 3. 7...Resistance, 4...
...Polarizer, 5...Receiver, 8...
···oscilloscope. /-N\ Agent Patent Attorney Uchihara 8 ・Nogawa 1

Claims (1)

[Claims] A polarization ratio measuring device for a semiconductor laser, characterized in that a rotating polarizer is positioned between a semiconductor laser to be measured and a light receiver, and the polarization ratio of the semiconductor laser is measured.