CN104332823B - It is a kind of to improve the method for wide bar shaped high power semiconductor lasers beam quality - Google Patents

Abstract

The invention discloses a method for improving the beam quality of a wide-strip high-power semiconductor laser, belonging to the technical field of lasers. Known technologies in this field are difficult to effectively improve the beam quality of wide-strip high-power semiconductor lasers, which greatly limits the application of wide-strip high-power semiconductor lasers. The invention adopts the method of applying the tensile stress of the convex intensity distribution in the wide strip waveguide area, weakens the convex refractive index distribution caused by the convex temperature distribution in the waveguide area, and suppresses the thermal lens effect of the laser waveguide, thereby improving the wide strip shape. Beam quality of power semiconductor lasers. The method can be applied to the manufacture of various wide-strip high-power semiconductor lasers.

Description

A Method for Improving the Beam Quality of Wide Strip High Power Semiconductor Laser

technical field

The invention relates to a method for improving the beam quality of a wide-strip high-power semiconductor laser, belonging to the technical field of lasers.

Background technique

Wide-strip high-power semiconductor lasers have the advantages of high output power, simple thermal management, and simple power combination. Usually, the wide-strip high-power semiconductor laser chip is flip-chip-bonded on a transitional heat sink with high thermal conductivity. Since the large operating current is concentrated in the light-emitting waveguide area, the waste heat generated by the non-radiative recombination of carriers leads to the temperature distribution in the waveguide area as follows: The convex distribution makes the effective refractive index of the light-emitting waveguide region also present a convex distribution, which increases the instability of the waveguide structure and the beam divergence angle when the laser is working. Usually, it is mainly through improving the epitaxial growth quality of laser materials, reducing defects in the light-emitting waveguide region, and suppressing the convex refractive index distribution caused by waste heat. Due to the limitations of the laser structure epitaxial growth source material and the purity of the atmosphere, there are still certain material defects that lead to wide The beam quality of the bar-shaped high-power semiconductor laser becomes significantly worse under the high-current working condition.

Contents of the invention

The present invention is realized in this way, as shown in accompanying drawing 1, the laser chip (mainly made up of chip substrate 1, light-emitting waveguide region 2, current confinement layer 3) is welded on the laser transition heat sink 4 by solder 6, through Welding pads 5 are introduced on both sides of the welding surface and pressure is applied to the middle of the laser chip during the welding process. Due to the solidification of the solder, the welded laser chip is bent, and a convex tension distribution is introduced in the light-emitting waveguide region 1 .

The technical effect of the present invention is that the introduction of a convex tension distribution in the light-emitting waveguide region 1 results in a concave refractive index distribution added to the effective refractive index distribution of the waveguide, which suppresses the convex refractive index distribution caused by waste heat when the laser is working. Therefore, the beam divergence angle of the high-power operation of the laser is reduced, and the beam quality is improved.

Description of drawings

Attached Figure 1 is a schematic diagram of the structure of a wide-strip high-power semiconductor laser that introduces tensile stress, 1 is the light-emitting waveguide area, 2 is the chip substrate, 3 is the current confinement layer, 4 is the laser transition heat sink, and 5 is the welding pad , 6 is solder.

detailed description

As shown in Figure 1, the laser chip (mainly composed of a light-emitting waveguide region 1, a chip substrate 2, and a current confinement layer 3) is soldered to the laser transition heat sink 4 through solder 6, and the solder is introduced on both sides of the soldering surface. The pressure is applied to the middle part of the laser chip during the mounting block 5 and the welding process. Due to the solidification of the solder, the welded laser chip is bent, and a convex tension distribution is introduced in the light-emitting waveguide area 1 to suppress the loss of heat generated by waste heat when the laser is working. The convex refractive index distribution reduces the beam divergence angle of the high-power laser and improves the beam quality.

Illustrate the present invention below in conjunction with example, laser chip adopts the 808nm wavelength quantum well structure laser chip of 2 millimeter cavity length, the width of light-emitting waveguide region 1 is 100 microns, and chip substrate 2 is the thick N-GaAs material of 110 microns, and current confinement layer 3 is a SiO2 insulating layer with a thickness of 120 nanometers, the laser transition heat sink 4 is a Ti/Pt/Au covered AlN substrate with a thickness of 0.5 mm, the height of the welding pad 5 is 25 microns, and the solder 6 is AuSn alloy solder. During the assembly process, a pressure of 50 grams is applied to the middle of the laser chip by pressing the needle. The welding temperature is 320 degrees, and the welding atmosphere is 99.999% pure nitrogen. When the temperature drops below 50 degrees, the laser chip welding process is completed. Through the measurement of the far-field divergence angle when the laser is working, it shows that the far-field divergence angle of the laser is significantly reduced, from the usual 7.5 degrees to 5.0 degrees.

Claims (1)

1. A method for improving the beam quality of wide-strip high-power semiconductor lasers is characterized in that, by applying the tensile stress of convex intensity distribution to the light-emitting waveguide region (1) of wide-strip high-power semiconductor laser chips, weakening due to waveguide The convex refractive index distribution caused by the convex temperature distribution in the region suppresses the thermal lens effect of the laser waveguide, thereby improving the beam quality of the wide-strip high-power semiconductor laser.