JPH0359619A - Optical amplifier - Google Patents

Abstract

PURPOSE:To easily eliminate polarization dependency by setting the direction of polarized light wherein the maximum gain of a 1st and a 2nd semiconductor laser is obtained to the direction of polarized light that light beams projected from a 3rd a 4th optical waveguide given after passing through Faraday rotators. CONSTITUTION:A semiconductor laser 8-1 is rotated around the optical axis by 45 deg. and arranged so that the active layer of the semiconductor laser 8-1 coincides with the electric field direction of TE polarized light projected from the 3rd optical waveguide 3-3 since the electric field direction rotates by 45 deg. after passing through the Faraday rotator 6-1. A semiconductor laser 8-2 is rotated around the optical axis by -45 deg. and arranged so that the active layer of the semiconductor laser coincides with the electric field direction of TM polarized light projected from the 4th optical waveguide 3-4 since the electric field direction rotates by 45 deg. after passing through a Faraday rotator 6-2. Thus, input light is split into two specific polarized light beams, whose polarization directions are made coincident with the direction of the polarization where the maximum gain of the semiconductor lasers is obtained through the Faraday rotator 6-2 to easily eliminate the polarization dependency.

Description

DETAILED DESCRIPTION OF THE INVENTION "Field of Industrial Application" The present invention relates to an optical amplifier using a semiconductor laser.

``Prior art and problems to be solved by the invention'' Conventional optical amplifiers usually have a configuration in which both end faces of a semiconductor laser with anti-reflection feet provided on both end faces are coupled to a power fiber and an output fiber, respectively. However, assembly was difficult because it required precise position adjustment and fixing in three directions on the input end and output side, respectively. Furthermore, since the gain of a normal semiconductor laser depends on the polarization direction, a special semiconductor laser element structure is required to construct an optical amplifier that is independent of polarization.

An object of the present invention is to provide an optical amplifier that is polarization independent and easy to assemble.

"Means for Solving the Problems" The optical amplifier of the present invention has a T of light incident on a first optical waveguide.
The E acid component and the TM acid component are separated into third and fourth optical waveguides, and the TM acid component and TE acid component of the light incident on the second optical waveguide are separated into third and fourth optical waveguides, respectively. a waveguide trace-shaped polarization separation element having a waveguiding function; first and second semiconductor lasers each having an anti-reflection coating applied to one side of the light emitting end face; the third and fourth optical waveguides; a Faraday rotator having a Faraday rotation angle of 45 degrees provided between the third and fourth optical waveguides and the first and second semiconductor lasers; after each light emitted from the third and fourth optical waveguides passes through the Faraday rotator, a first
The second semiconductor laser is characterized in that the directions of polarization in which the maximum gain is obtained are made to coincide with each other.

"Operation" In the optical amplifier of the present invention, input light is converted into TE acid component TM.
By separating the acid components into two specified polarized lights, and by using a Faraday rotator to match the direction of polarization to the direction of polarization that provides the maximum gain of the semiconductor laser, the maximum gain can be achieved for both TE and 7M polarized lights. These signals are combined and output.

"Embodiment" Hereinafter, an embodiment of the optical amplifier of the present invention will be described with reference to the drawings.

In the figure, 1 is a waveguide trace type polarization separation element, 2 is a waveguide substrate on which a waveguide trace type polarization separation element l is formed, 3-1 to 3-4
is an optical waveguide constituting the waveguide trace polarization separation element 1, and 3-
1 is a first optical waveguide, 3-2 is a second optical waveguide, 3-3
- is the third optical waveguide, and 3-4 is the fourth optical waveguide.

4-1.1-2 is a first and second 3 dB coupler that constitutes the waveguide trace type polarization separation element 1; 5-1.5-2 is a stress applying waveguide that constitutes the waveguide trace type polarization separation element 1; 61.6
-2 is a Faraday rotator with a Faraday rotation angle of 45 degrees, '! -1.7-2 is the lens, 81.8-2 is the first
and a second semiconductor laser, 9-1.9-2 is an end face with anti-reflection coating of semiconductor laser 8-1.8-2;
-1.10-2 is the other end face of the semiconductor laser 8-1.8-2. And third and fourth optical waveguides 3-3
゜3-4 and the first and second semiconductor lasers 9-1゜9-
A lens '11.7-2 and a Faraday rotator 6-1.6-2 are arranged between the two.

The operation of this embodiment will be explained below according to the figures.

TE acid component of the light incident from the first optical waveguide 3-1:
The component whose direction is parallel to the waveguide substrate 2) is divided into two equal parts by the 3 dB coupler 4-1, and the stress-applying waveguide 5-1.
After propagating, they are coupled by a 3 dB coupler 4-2 and guided to a third optical waveguide 3-3. Further, the TM acid component magnetic field of the light incident from the first optical waveguide 3-1 (component whose direction is parallel to the waveguide substrate 2) is guided to the fourth optical waveguide 3-4.

Claims (1)

[Claims] The TE component and TM component of the light incident on the first optical waveguide are separated into third and fourth optical waveguides, respectively, and the TM component and TE component of the light incident on the second optical waveguide are separated, respectively. a waveguide-type polarization splitting element having a function of separating and guiding waves into third and fourth optical waveguides; first and second semiconductor lasers each having a non-reflection coating applied to one side of the light emitting end face; and the third and fourth semiconductor lasers. the fourth optical waveguide and the first and second optical waveguides;
and a Faraday rotator having a Faraday rotation angle of 45 degrees provided between the third and fourth optical waveguides and the first and second semiconductor lasers. and the direction of polarization in which the maximum gain of the first and second semiconductor lasers is obtained is determined in the direction of polarization after each light emitted from the third and fourth optical waveguides passes through the Faraday rotator. An optical amplifier characterized by matching.