KR20020054204A - A semiconductor laser including doped polymer waveguide - Google Patents

Abstract

PURPOSE: A semiconductor laser element including doped polymer waveguide is provided to select a wavelength of a semiconductor laser element stably by applying an atomic ray transition to the semiconductor laser element. CONSTITUTION: A polymer waveguide(5) is doped with a material which has an atomic ray transition. A first semiconductor waveguide(3) which is linked with one end of the polymer waveguide(5) at a Brewster angle(6) offers a gain. A second semiconductor waveguide(4) which is linked with the other end of the polymer waveguide(5) at a Brewster angle(7) selects a wavelength. A resonator mirror(1,2) is linked with the first and the second semiconductor waveguide(3,4). An electrode injects a current into the first and the second semiconductor waveguide(3,4).

Description

A semiconductor laser including doped polymer waveguide

It relates to wavelength stabilization of semiconductor laser devices, and more particularly to stabilizing wavelengths of semiconductor laser devices using doping techniques of polymer waveguides and atomic beam transition materials.

Conventionally, laser diodes of the DFB type and the DBR type in which a lattice is etched under a gain medium for wavelength selection of a semiconductor laser device have been studied for a long time. In addition, techniques for monitoring the output wavelength and feedback of the injection current to the outside of the laser element have been developed, and techniques such as passive mode locking and active mode locking are known.

Further, there is being investigated a refractive index of each stacking another polymer layer constituting the optical waveguide and the optical splitter and the optical switch, a waveguide-to-many type, such as, recently, the polyimide (polyimide) circle charity transition is possible for the waveguide material (Nd ³⁺ Has been developed to obtain photoluminescence and gain.

However, the conventional semiconductor laser device has a disadvantage that the wavelength selection is not stable when the wavelength selection is used for a long time because the wavelength selection is changed according to the injection current or the external temperature.

Accordingly, an object of the present invention is to stabilize the wavelength selection of a semiconductor laser device by applying an atomic beam transition that is not affected by external temperature changes to the semiconductor laser device.

1 is a cross-sectional view showing an embodiment of a semiconductor laser device having enhanced longitudinal mode selectivity of the present invention;

2 is a cross-sectional view illustrating an electrode arrangement for injecting current into the laser device of FIG. 1;

3A to 3C are views for explaining the distribution of saturation absorption according to the position in the longitudinal direction in the polymer waveguide included in the semiconductor laser device having the enhanced longitudinal mode selectivity of the present invention.

FIG. 4 is a diagram for explaining an absorption spectrum, a gain spectrum of a gain medium, and a (gain-loss) spectrum of a grating-engraved gain region in a waveguide doped with an atomic beam transition material.

In order to achieve the above object, the present invention provides a semiconductor laser for stabilizing an output wavelength, comprising: a polymer waveguide doped with a material having an atomic beam transition; A first semiconductor waveguide having a gain connected at one end of the polymer waveguide at a Brewster angle; A second semiconductor waveguide engraved with a grating for wavelength selection connected to the other end of the polymer waveguide at Brewster angle; A resonator mirror coupled to the first and second semiconductor waveguides; And electrodes for injecting current into the first and second semiconductor waveguides.

The polymer waveguide comprises a core polymer doped with a material having the atomic beam transition and a clad polymer covering the core polymer.

The material having an atomic beam transition is characterized in that it uses any one selected from iodine, nidium, erbium and presidium.

And an antireflection coating on the resonator mirror connected to the second semiconductor waveguide.

As described above, the present invention utilizes a material capable of atom beam transition by doping the polymer, and applies stable transition wavelengths of these atoms to wavelength stabilization of a semiconductor laser. By using the material capable of atomic line transition, the output wavelength of the semiconductor laser can be stabilized by light emission of narrow line width of atoms inverted density in the region of high light intensity in the resonator by manual mode selection in the region of low light intensity in the resonator. have. Substances capable of doping atomic rays to a polymer include iodine, neodimium, erbium, and praseodymium, and the materials are 1.31 μm, 1.06 μm, 1.53 μm, It mainly transitions around 1.6 μm wavelength and shows gain. The polymer waveguide doped with one of these materials is connected to the inside of the resonator waveguide of the semiconductor laser device in each wavelength band to operate at a Brewster angle to obtain wavelength stabilization that is independent of the external environment at the level of the semiconductor laser device. To do that.

Hereinafter, the present invention will be described in detail with reference to FIGS. 1 to 4.

The semiconductor laser device having enhanced longitudinal mode selectivity of the present invention includes a polymer waveguide (5) doped with a material having an atomic beam transition and resonator mirrors (1), (2), InP, InGaAs, InGaAsP, InAlGaAs, and GaInNAs on both surfaces of the waveguide. A waveguide region 3 which gives a gain made of a semiconductor such as a semiconductor, and an area 4 engraved with a grating for wavelength selection made of a semiconductor such as InP, InGaAs, InGaAsP, InAlGaAs, GaInNAs, and the like. The polymer waveguide 5 such as polyimide is connected to the semiconductor waveguide 3 and the semiconductor waveguide 4 at the Brewster angles 6 and 7 so as to minimize the reflection loss of the connection portion. . Further, an electrode 8 for supplying current to the gain region and an electrode 9 for supplying current to the wavelength selection region are formed.

As shown in the structures of FIGS. 1 and 2, after etching deep into the Brewster angle through pattern etching on the waveguide of the fabricated semiconductor laser device, this part is filled with a core and a clad polymer. To form a waveguide. In order to obtain a polymer waveguide, the polymer corresponding to the core is coated with a material capable of atomic beam transition so as to have an appropriate ion density, and a polymer for cladding is coated thereon. The pattern is formed and connected to the waveguide of the semiconductor laser device.

The solubility of the solvent containing the substance capable of atomic beam transition to the solvent affects the ion density and the formation of the polymer waveguide, so appropriate solvent and solvent selection is required, and in some cases, the semiconductor waveguide (3) (4) and An adhesion promoter can be used to improve the adhesion between the polymer waveguides 5.

In the semiconductor laser device having the enhanced longitudinal mode selectivity configured as described above, when a current is injected through the electrodes 8 and 9 of the gain region and the wavelength selection region, a low current, that is, immediately after the threshold current, The wavelength selection is made due to the distribution of saturation absorption with position in the longitudinal direction (see FIG. 3). As can be seen in FIG. 3, the longitudinal mode possible in the resonator of the laser device forms a standing wave to have a constant light intensity distribution over time. There is also a standing wave distribution in the doped polymer waveguide 5 inside the resonator. As described above, the laser operation is started at the longitudinal mode wavelength at which (gain-loss) becomes the maximum among the longitudinal modes of the standing wave. Once selected, the longitudinal mode 10 has already undergone absorption because it has already been saturated and absorbed through the doped polymer waveguide 5, but the neighboring longitudinal modes 11 and 12 undergo absorption, so that the already selected longitudinal mode is subjected to laser operation. Is advantageous. The device must have a longitudinal mode close to the absorber line width of the polymer waveguide in which the (gain-loss) in the semiconductor laser structure, except for the initially doped polymer waveguide, is maximized. As shown in Fig. 4, the gain line width 13 in the laser structure is much wider than the absorption line width 15 of the polymer waveguide, but the gain wavelength and line width 14 of the gain region in which the grating is drawn are adjusted when the number of gratings is adjusted. It is possible to precisely bring the initial (gain-loss) maximum longitudinal mode wavelengths nearby.

In consideration of the change in the center wavelength of the wavelength selection region according to the amount of current injection in the wavelength selection region, appropriate current injection is performed. In addition, the absorption wavelength of the polymer waveguide doped with a material capable of atomic beam transition does not change depending on an external temperature or an injection current, thereby fixing the output wavelength for a long time. In addition, when the light intensity increases inside the resonator, that is, when the injection current is increased with a high reflecting mirror on the cross section, atomic ray transition light emission from the polymer waveguide may be injected into the laser resonator to enhance oscillation wavelength fixation. .

Since the semiconductor laser device of the present invention has an output wavelength stabilized by the wavelength of the atomic beam transition, the semiconductor laser device is not affected by external temperature change and has an effect of serving as a reference wavelength. Such a light source has a merit that it can be effectively applied in a large capacity optical communication system requiring DWDM, since wavelength stability is required for a long time when a semiconductor laser device is used.

Claims (5)

In the semiconductor laser for stabilization of the output wavelength, A polymer waveguide doped with a material having an atomic beam transition; A first semiconductor waveguide having a gain connected at one end of the polymer waveguide at a Brewster angle; A second semiconductor waveguide engraved with a grating for wavelength selection connected to the other end of the polymer waveguide at Brewster angle; A resonator mirror coupled to the first and second semiconductor waveguides; And Electrodes for injecting current into the first and second semiconductor waveguide Semiconductor laser device comprising a. The method of claim 1, The polymer waveguide, And the clad polymer covering the core polymer is doped with the material having the atomic beam transition. The method according to claim 1 or 2, The material having the atomic beam transition is any one selected from iodine, nidium, erbium and presidium. The method according to claim 1 or 2, The semiconductor laser device, characterized in that any one or a combination thereof selected from the group of InP, InGaAs, InGaAsP, InAlGaAs, GaInNAs . The method of claim 1, And an antireflection coating on the resonator mirror connected to the second semiconductor waveguide.