JPS58199583A - Multiple wavelength semiconductor laser - Google Patents

Abstract

PURPOSE:To simultaneously oscillate the light of multiplex wavelength by monolithically integrating a plurality of semiconductor lasers of different wavelength on the same substrate. CONSTITUTION:Thin film crystalline layers of N type InP layer 5, N type InGaAs layer 6, N type InP layer 7, N type InGaAsP layer 8 and N type InP layer 9 are sequentially grown on an InP substrate. The band gap energy of the layers 6, 8 is selected to obtain desired oscillating wavelength. Then, the substrate 4 is isolated to the underneath the layer 8, thereby forming a P type region 13. Further, after an anode oxidized film 10 is formed, ohmic electrodes 1, 2, 3 are formed. Points 11, 12 become active layers, and two light outputs intensities are independently controlled by the current which is flowed between the electrodes 2 and 1 and between the electrodes 3 and 2.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a multi-wavelength semiconductor laser that emits light of many different wavelengths from the same element, and more particularly to a two-wavelength semiconductor laser that emits two lights of different wavelengths.

In general, in order to effectively utilize the optical fiber band in optical communications using optical fibers, so-called wavelength multiplexing optical communications, in which communications are performed using a plurality of lights of different wavelengths at the same time, is useful.

Conventionally, in order to perform this wavelength-multiplexed optical communication, light oscillated by several lasers with different wavelengths was guided and transmitted through a single optical fiber using an optical mixer, and then the output light from the optical fiber was passed through an optical demultiplexer again. A wavelength multiplexing optical communication system has been used in which wavelengths are divided using a wavelength division multiplexing method, and the wavelengths are received by several photodetectors. However, this system has the disadvantage that the system is complicated and the light is considerably attenuated by the optical mixer and optical demultiplexer.

An object of the present invention is to provide a multi-wavelength semiconductor laser in which a plurality of lasers with different wavelengths are seven-nolithically integrated in close proximity on one substrate, and which emits light of a plurality of wavelengths from one laser element. It is.

That is, by directly guiding light oscillated by a multi-wavelength semiconductor laser that emits light of two or more wavelengths to an optical fiber, it is possible to realize wavelength division multiplexing optical communication more simply and with less loss.

The present invention will be described in detail below with reference to the drawings.

FIG. 1 is a diagram showing an embodiment of a multi-wavelength semiconductor laser according to the present invention. In FIG. 1, a two-wavelength semiconductor laser will be explained as an example as the simplest case. In FIG. 1, a two-wavelength semiconductor laser is constructed of an indium gallium arsenide phosphide ErLGaASP (hereinafter referred to as IybGaA, rP) quaternary crystal grown on an indium phosphide InP (hereinafter referred to as 7LP) substrate 4. . The manufacturing procedure will be explained below. First, an R-type InP layer 5, a R-type
, Le-type nP layer 7, n-type GaA, pP layer 8, Le-type I
Thin film crystal layers of the nP layer 9 are sequentially grown. Here, the bandgap energy of the two molded rLGcLA and pP thin film crystal layers 6 and 8 is selected so as to obtain a desired oscillation wavelength.

The typical thickness of each thin film layer is 100μ for the IrLP substrate 4.
m, n type I? LP layer 5 is 5 μm, n-type IrLGaA, p
PPO20, 3μm, n type IfLP layer 7, 5μm,
The yb-type l7LGaA, rP layer 8 has a thickness of 0.3p, m, and the n-type ■rLP layer 9 has a thickness of 2pm. After epitaxial growth,
A portion of the I7+, P substrate 4Ω is removed to below the molded yLGaAsP layer 8 by chemical etching, and then a P-type region 13 of zinc Zn or cadmium Cd is partially formed in that portion by a thermal diffusion method. Furthermore, after forming an anodic oxide film 10 as an insulating layer for current confinement, three ohmic electrodes 1, 2.3 are formed. In this example,
2 of the diffusion tip of zinc ZrL or cadmium Cd
Point 11.1 crossing two square InGaA#P layers 6 and 8
2 serves as an active layer, and two lights with different wavelengths are emitted from these points. The two light output intensities are between electrodes 2-1 (
(hereinafter referred to as LD21) and between the electrodes 3-2 (hereinafter referred to as L,
They are each independently controlled by the current flowing through them (referred to as D32).

Figure 2 is a diagram showing the relationship between the current flowing through the LD32 and the output optical power of the two-wavelength semiconductor laser of the present invention.
The band gap energies of LGaA9P layers 6 and 8 are 1.06 eV (electron volt) and 0.95+3, respectively.
It is V. The threshold current is about 240 mA, and the same value can be obtained for the LD21. The rather large threshold current is due to the leakage current component to the Pn junction in ItzP, and can be lowered by reducing the area of the Pn junction in InP.

FIG. 3 is a diagram showing the oscillation spectrum of the LD 32 of the two-wavelength semiconductor laser of the present invention. The oscillation wavelengths of the LD 32 and the LD 31 are extremely small, 1.17 μm and less than μm, respectively.

The device structure of the present invention makes it possible to bring the two light-emitting sporae (11, 12) close to 10 μm or less by controlling the diffusion depth and etching depth, and it is possible to place an optical fiber directly in front of these light-emitting spots. It is possible to couple the light emitted by directly into an optical fiber. Therefore, light of two or more wavelengths can be guided to a single optical fiber without using an optical mixer, so that loss is small and wavelength division multiplexing optical communication can be performed at low cost with a simple configuration.

In the above embodiment, a heavy wavelength semiconductor laser was constructed using InGa A, r P / InP based materials, but it goes without saying that various materials constituting ordinary semiconductor lasers can be used, such as arsenic, etc. Gallium aluminum GaAtAS and arsenide Ga! 0.8 μm if a multi-wavelength biological laser is constructed using GaAtAS/GcLAS material using J Lamb Cta Ag
A multi-wavelength semiconductor laser in the band can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an embodiment of the multi-wavelength semiconductor laser of the present invention, FIG. 2 is a diagram showing the relationship between the current and output optical power of the two-wavelength semiconductor laser of the present invention, and FIG. FIG. 3 is a diagram showing an oscillation spectrum of a semiconductor laser. 1.2,3: Electrode 4: IrLP substrate 5.7
, 9: n-type 17LP layer 6, B: n-type 1L
(, aA, pP layer 10: anodic oxide film 11, 12:
Active layer 13: PM diffusion region of Zi or CD Patent applicant: Kato Masayoshi/Maku/Figure 11 Mshi (mA)

Claims (1)

[Scope of Claims] (1) A multi-wavelength semiconductor laser characterized in that multiple types of semiconductor lasers with different wavelengths are monolithically integrated on the same substrate and can emit light of multiple wavelengths simultaneously. (2) In (1), the R-type IrLP layer is sequentially formed by epitaxial growth on the indium phosphide IrLP substrate,
type indium gallium arsenide phosphide IrLGOLA9P
A layer, a square IyLP layer, a square +zGaASP layer, and a square IrLP layer are formed, and a part of the surface is coated with a square InP layer, a square IrLGaA, a pP layer, and a square IrLP layer.
The layers are peeled off to the middle, and a P-type head region of zinc'ln or cadmium Cci is formed separately in the peeled part and the part that is not peeled off by thermal diffusion to the L-type IrLP layer, L-type IWGαAjP layer, and L-type IWP layer, respectively. , a two-wavelength semiconductor laser in which an anodic oxide film for current insulation is formed on the entire surface, electrodes are formed separately on the surface of the peeled part and the non-peeled part, and electrodes are also formed on the lower surface of the 17LP substrate. Features of multi-wavelength semiconductor laser. (3> A multi-wavelength semiconductor laser characterized in that in (2), gallium arsenide is used in place of indium phosphide ErLP, gallium arsenide gallium phosphide IrLGaA is used, and gallium aluminum arsenide GαktAs is used in place of 9P. (4) In (1), each thin film layer epitaxially grown on the IrLP substrate has a thickness of 100 μrn,'
A multi-wavelength semiconductor laser having a thickness of 5 μm, 0.3 ttrn, 5 tim, 0.3 pm and 2 pm.