JPS61248490A - Measurement apparatus for semiconductor laser - Google Patents

Abstract

PURPOSE:To select a semiconductor laser which has a high coupling efficiency with an optical fiber with a high yield only by measuring a light power transmitted through a Gaussian distribution filter inserted between the semiconductor laser and a detector. CONSTITUTION:Only a Gaussian component of a laser beam of a semiconductor laser is taken out by inserting a Gaussian distribution filter into a measurement apparatus. For instance, the apparatus consists of a semiconductor laser 1, a Gaussian distribution filter 2 and a detector 3. If necessary, a lens 4 may be inserted between (1) and (2) or between (2) and (3). The Gaussian distribution filter is produced in such a manner that a portion 6 whose refractive index is 1.4702 and radius is 28.8mum is formed at the center part of a glass plate 5 whose refractive index is 1.4701 by ion exchange. Then, in order to make the numerical aperture of the Gaussian filter agree with the numerical aperture of an optical fiber (NA=0.1), a metal film 7 is evaporated on the surface of the filter and a circular window which forms concentric circles with the center part 6 of the glass and has a radius of 50mum is formed in the metal film 7. The distance from the semiconductor laser 1 to the surface of the Gaussian distribution filter 2 is 500mum.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a semiconductor laser measurement device for optical fiber communication, and more particularly to a semiconductor laser measurement device suitable for measuring the characteristics of a Gaussian distribution component of a semiconductor laser beam. .

[Background of the invention]

Semiconductor lasers are used as light sources for optical communications by coupling with optical fibers, but higher coupling efficiency with optical fibers is desired in terms of transmission characteristics, device life, and the like. Conventional.

A method of tapering the tip of a fiber (H. Kawamura et al.; [Effective coupling of a semiconductor laser and a single mode fiber using a tapered hemispherical end] Applied Optics Vol. 19, p. 2578, 1980 (H. Hawam
ura et al.: “Efficiency Coupling
fro+nSem1conductor La5ers
1nto Single-mode fibersw
ith tapered he+5ispherica
l ends” Appl,,OPt,+Vo1.],
9. p2578.1980 )) Another method for easily selecting semiconductor lasers with good coupling efficiency before shipping is to use a far-field pattern of the laser beam, or to attach a detector to one end face of the semiconductor laser to match the NA of the optical fiber. A method of pre-selecting the laser by moving it further away and measuring its optical characteristics was used. However, if the far-field pattern of the semiconductor laser has a complicated shape, it cannot be sorted with sufficient accuracy. In order to improve the accuracy of sorting.

It is necessary to measure the amount of light components that are likely to couple with an optical fiber in a semiconductor laser and to select their characteristics. The electric field distribution of light transmitted through an optical fiber is
It has a nearly Gaussian distribution with parameters of the refractive index difference between the core and cladding, and the core diameter, and only the Gaussian distribution component in the semiconductor laser beam is coupled to the optical fiber. Therefore, there is a need for a device that can measure how many Gaussian components exist.

[Purpose of the invention]

The object of the present invention is to obtain a semiconductor laser beam from a semiconductor laser beam 11.

An object of the present invention is to provide a semiconductor laser measuring device using a filter that transmits only light components coupled to an optical fiber.

[Summary of the invention]

Conventionally, the optical characteristics of a semiconductor laser have been determined by detecting the laser beam with a photodetector through a lens or the like to obtain opto-electrical characteristics and a far-field image. but.

Since only the Gaussian distribution component of the semiconductor laser beam is coupled to the optical fiber, the optical characteristics measured by the conventional method cannot be said to be sufficient information on the device as a light source for optical fiber communication. The present invention inserts a Gaussian mode filter that allows only Gaussian distribution components to pass between the semiconductor laser and the detector of a conventional measurement device, and simply measures the optical power passing through the filter. A 7 Gaussian mode filter, which is related to a measuring device that can select based on yield, is a filter that transmits only Gaussian components from the electric field distribution of light.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to FIGS. 1 and 2. The apparatus comprises a semiconductor laser 1, a Gaussian distribution filter 2, and a detector 3. Between 1 and 2, if necessary.
Or insert lens 4 between 2 and 3. Here, the structure of Gaussian distribution filter No. 2 is shown in FIG. This has a curvature of 1
．． The refractive index is 1.4702 at the center of the glass plate 5 of 4701.
A portion 6 having a radius of 28.8 μm was formed by an ion exchange method.

In this state, light with a wavelength of 1.3 μm was incident, and the intensity distribution of the transmitted light was measured, and it was found to be a Gaussian beam.

Next, the numerical aperture of the Gaussian filter is the numerical aperture of the optical fiber (N
A=0.1), a metal film 7 is vapor-deposited on the surface of the same filter, and a window with a radius of 50 μm is provided on this so as to be concentric with the glass part 6, so that the surface of the semiconductor laser 1 and Gaussian distribution filter 2 is The distance to the center was set to 500 μm.

According to this example, the efficiency measured by the detector 3 was in good agreement with the coupling efficiency with a single mode optical fiber having a numerical aperture of 0.1, and the device was effective as a semiconductor laser evaluation device.

〔Effect of the invention〕

According to the present invention, by inserting a Gaussian distribution filter into the measuring device, only the Gaussian component of the laser beam of the semiconductor laser can be extracted, resulting in the following effects. In other words, if the far-field pattern of the semiconductor laser is shaped into a Gaussian distribution and the full angle at half maximum is θ, the coupling efficiency between the optical fiber and the laser beam is expressed with θ as a parameter, and the coupling efficiency is The maximum value is determined by the fiber core diameter and the difference in refractive index between the cladding and the core, and the fiber output is determined by the I-L characteristics and coupling efficiency.

If you have data such as the core diameter and refractive index difference of an optical fiber, you can calculate the coupling efficiency for each semiconductor laser without directly coupling it to that optical fiber.

Since the fiber output can be estimated and selection is easy and highly accurate, it is possible to improve the reliability of semiconductor lasers and systems using the same.

[Brief explanation of drawings]

Figure 1 is a diagram showing an example of a nine-semiconductor laser measurement device.
FIG. 2 is a diagram showing the structure of a Gaussian distribution filter.

Claims (1)

[Claims] 1. A semiconductor laser measuring device comprising a semiconductor laser and a detector, characterized in that a Gaussian distribution filter is inserted between the semiconductor laser and the detector. 2. The semiconductor laser measuring device according to claim 1, wherein the Gaussian distribution filter has a numerical aperture (NA) that allows effective optical coupling with a semiconductor laser and an optical fiber.