JPS60100492A - Semiconductor laser device - Google Patents

Abstract

PURPOSE:To improve the electrical and optical characteristics, to improve the lifetime at the high output operation time and to enable to produce a monitoring light by setting a high reflectivity at one side of a light emitting output end face having a dielectric film and a low reflectivity at the other side and the output ratio to a specific range. CONSTITUTION:The reflectivities of the both end faces are regulated so that the ratio P2/P1 of the light output P1 from one side end face of a semiconductor laser device 11 having dielectric films 1-3 on the both end faces for producing the light output and the light output P2 from the other end face falls within a range of 0.05-0.200. A semiconductor laser element 11 is set in a sputtering unit, SiO2 is used as a target, and the first dielectric film SiO2 (having refractive index n1=1.45) 1 is coated in a thickness of lambda/6n1 on one side end face. Then, the second dielectric film SiO2 (having refractive index n2=1.45) 2 is coated in a thickness of lambda/4n2 on the other end face. Then, the target is switched to Si, the aqueous film containing amorphous Si (having refractive index n3=3.3) 3 of the third dielectric film is coated in a thickness of lambda/4n3, thereby obtaining P2/P1=0.1.

Description

[Detailed description of the invention] [Field of application of the invention] The present invention relates to a semiconductor laser device.

In particular, the structure of the light emitting output surface is used.

[Background of the invention]

Conventionally, the coating of the light emitting output end face of a semiconductor laser device has mainly been used for the sole purpose of preventing the end face from deteriorating. In addition, there have been recent examples of increasing the reflectance by using a multilayer film on one side, or lowering or lowering the reflectance on one side, but in this case the only effect is that the differential efficiency is improved or the limit of the light output that can be extracted is increased. Furthermore, the present invention has remarkable effects of increasing the kink level and improving the lifespan during high-output operation, and improves both the current-light output characteristics and the lifespan, realizing a high-output semiconductor laser. Monitor light is emitted from the end surface*
It has the feature of causing p to be emitted.

[Purpose of the invention]

The present invention provides an end face coating method aimed at improving the electrical and optical characteristics of a conductive laser device and improving its lifespan during high-output operation, and furthermore enables the extraction of monitor light. We provide all semiconductor laser devices.

[Summary of the invention]

By coating the light emitting end face of a semiconductor laser device with high reflection on one side and approximately low reflection on the other side, and setting the output ratio within a predetermined range, a significant improvement in laser performance can be obtained. Do you get it. Good results were also obtained in reliability tests. Furthermore, the reflectance of both end faces was adjusted to allow for the extraction of monitor light.

[Embodiments of the invention]

Hereinafter, the present invention will be specifically explained using examples. The semiconductor laser is Ga1-x AtxA8 (x = 0.0
5.

An example of a so-called C8P type laser element with an oscillation wavelength of 830 nm will be described. FIG. 1 is a cross section of a semiconductor laser device taken in a plane parallel to the direction in which laser light travels. 1 is a first dielectric film, 2 is a second dielectric film, 3 is a third dielectric film, and 11 is a GaA7As laser element portion. Note that 7.8 indicates the laser light emitted from the low reflectance side and the high reflectance side, respectively.

Regarding the sputtering method as a method for depositing dielectric film,
Also number 1. Regarding the example in which 5j02 is deposited as the second dielectric film and hydrogen-containing amorphous Si is deposited as the third dielectric film, the optical output ratio of both end faces P2/PI (where Pl: optical output from one end face, R2: Light output from the other end surface)
The case of 0.1 will be explained.

First, a first dielectric film 5jOz (refractive index n,: 1
．． 45) Total film thickness λ/6n1. A thickness of 93 nm is deposited. However, λ is the oscillation wavelength of the laser. Next, a second dielectric film 5jOz (refractive index nz: 1.45) is deposited on the other end face in a similar manner to a film thickness λ/4n, that is, 140 nm. Here, the target was changed to SiK, and a third dielectric film, hydrogen-containing amorphous Si (
refractive index n3 23,3) and film thickness λ/4nsh, i.e. 6
0 nm deposited.

In the above steps, the reflectance of the low reflection film (first dielectric film) is 1.
0%, high reflective film (the thickness of the second and third dielectric films is 75%)
become. The ratio P2/PI between the optical output Pi from the low reflection side and the optical output P2 from the high reflection side can be calculated from the following equation. Here, 几1: end face reflectance on the low reflective film side, R2: end face reflectance on the high reflective film side, R1 = 0.1 as described above.
, Substitute R2=0.75 into equation (1) and get P2/P
r=0.1 is obtained.

FIG. 2 shows an example of the current-light output characteristics of a laser device produced by this method. The solid line 21 is the characteristic before coating, the dotted line 22 is the characteristic when light is extracted from the low reflection film side, and the dotted line 20 is the characteristic when light is extracted from the high reflection film side. As you can see, by creating a structure in which one end face of the laser element has approximately low reflection and the other end face has high reflection, and the optical output is extracted from the low reflection side, even if the internal energy of the light is the same, the optical output is output from the low reflection side. Due to the effect of extracting more , the differential efficiency and kink level are increased by 1.5 to 2.5 times.
The threshold current becomes 0.85 to 1.1 times.

Although the structure of the present invention has the disadvantage that the threshold current slightly increases in the region where the reflectance of the first dielectric film is low, the threshold value slightly increases due to the significant improvement in the differential efficiency and kink level. This effect more than compensates for the Furthermore, when the laser element is used in all actual systems, such as optical desks, video desks, optical communications, etc., in order to stabilize the laser light output,
It is well known that it is essential to monitor the source material behind the laser element and to stabilize the laser light output using an automatic light output control circuit.

The laser element of the present invention adjusts the reflectance of both end faces so that the ratio between the front optical output P1 and the rear optical output P2 is within a certain range, that is, P2/PI = 0.05 to 0.20. As a result, sufficient optical output is always maintained as a monitoring source, and it is compatible with the aforementioned system and has all the effects of improving laser characteristics.

FIG. 3 shows an example of the life test characteristics of the product of the present invention at 70'Q and 30 mW operation. The solid line indicates the inventive product.The dotted line indicates the conventional structure.Since the conventional product operates above the kink level, the operating current increases significantly and the life characteristics are not good. - The product invented by Rikiki has excellent life characteristics because it is used in the linear region of current-light output characteristics and has the advantage that operating current is small due to high microefficiency.

Also, as a semiconductor laser device (J as -x ALx
A 5 (x=0.05) C8P type laser has been described, but there are no restrictions on the crystal material as long as it has a reflective surface as an optical resonator. Furthermore, it is clear that the present method can be applied to any structure of the laser element itself, such as a BH type laser other than the C8P type and various other semiconductor laser elements.

〔Effect of the invention〕

According to the present invention, by suppressing the optical output from the rear surface of a semiconductor laser, which has not been used effectively in the past, and increasing the optical output from the front surface by that amount, even if the internal energy of the light is the same, the optical output can be extracted to the outside. It is necessary to have the effect of increasing the laser characteristics, that is, the kink level, and the differential efficiency of 1.5 to 2.
Its strength is that it is 5 times more efficient (compared to conventional products). Also, the operation when cylinder output is 70030mW 'dtLN
, was able to be reduced from 200mA (conventional product) to 150mA, and the life characteristics were also significantly improved.

Furthermore, by adjusting the reflectance of both end faces of the laser element, the monitor output from the rear face can be optically dispersed.
This resulted in excellent compatibility with the system.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of a laser device showing an embodiment of the present invention, FIG. 2 is a diagram showing an example of the electrical and optical characteristics of the laser device, and FIG. 3 is a diagram showing an example of the life characteristics of the laser device 6. It is a diagram. 1... First dielectric film, 2... Second dielectric film, 3
・・・Fig.

Claims (1)

[Claims] 1. In a semiconductor laser device having at least all dielectric films on both end faces from which optical output is extracted, the optical output PI from one end face is
and the optical output P2 from the other end face (P2/PI
) is in the range of 0.05 to 0.20, the reflectance of both end faces is adjusted.