Vertical resonant cavity surface emitting laser with multiple reflectors

Abstract

The invention provides a vertical cavity surface emitting laser with a plurality of reflectors, the vertical cavity surface emitting laser is provided with a first resonant cavity and a second resonant cavity by arranging the plurality of reflectors, the second resonant cavity is far away from a current limiting layer, and a light beam is mainly emitted after resonance in the second resonant cavity. According to the structure, the problem that light beams are influenced by scattering of the current limiting layer is solved, and the light-emitting effect of the vertical-cavity surface-emitting laser is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to a laser, in particular to a vertical cavity surface emitting laser. BACKGROUND

[0002] A conventional vertical cavity surface emitting laser includes a current confinement layer, which is generally composed of an oxide. When a light beam resonates in a resonant cavity, it often encounters scattering due to the influence of the current confinement layer, which affects the light emitting effect of the laser.

[0003] In the prior art, to improve the above-mentioned problems, the confinement aperture of the current confinement layer is narrowed, which, however, increases the impedance of the laser, which is not conducive to the light emission of the laser, or more power is required to emit light.

[0004] Therefore, how to improve the light emitting effect of the vertical cavity surface emitting laser through structural design improvement to overcome the above-mentioned defects has become one of the important issues to be solved in this industry. SUMMARY

[0005] The technical problem to be solved by the present application is to provide a vertical cavity surface emitting laser with multiple mirrors, which includes an active light emitting layer, a first mirror, a current confinement layer, a second mirror and a third mirror.

[0006] The two opposite sides of the active light emitting layer define a first side and a second side, respectively. The first mirror is located on the first side of the active light emitting layer, and the first mirror has a first reflecting surface. The current confinement layer is located on the second side of the active light emitting layer, and the current confinement layer has a confinement aperture. The second mirror is located on the second side, and the current confinement layer is located between the second mirror and the active light emitting layer. The second mirror has two opposite surfaces defining a penetration surface and a second reflecting surface, respectively. The penetration surface faces the current confinement layer, and the second reflecting surface is away from the current confinement layer. The second mirror and the first mirror form a first resonant cavity. The third mirror is located on the second side, and the second mirror is located between the current confinement layer and the third mirror. The third mirror has opposite third reflecting surface and light emitting surface, and the third reflecting surface faces the second mirror. The second mirror and the third mirror form a second resonant cavity.

[0007] The current is injected from the current confinement hole to the active light emitting layer, so that the active light emitting layer generates a first light beam and a second light beam at the first side and the second side respectively. The first light beam is reflected by the first reflector to generate a first reflected light beam. The first reflected light beam passes through the active light emitting layer, and the active light emitting layer absorbs a part of the first reflected light beam and excites the first light beam and the second light beam. Another part of the first reflected light beam penetrates the active light emitting layer and defines a first penetrating light beam. A light beam reflected by the second reflector from the second light beam and the first penetrating light beam defines a second reflected light beam. The second reflected light beam passes through the active light emitting layer again, and excites the active light emitting layer to generate the first light beam and the second light beam. A light beam penetrating the second reflector and entering the second resonant cavity from the second light beam and the first penetrating light beam defines a second penetrating light beam. The second penetrating light beam resonates between the second reflector and the third reflector to generate a laser beam. The laser beam is emitted from the light emitting surface of the third reflector.

[0008] According to an embodiment, the current confinement layer is an oxide layer.

[0009] According to an embodiment, the first reflector, the second reflector and the third reflector are Bragg reflectors.

[0010] According to an embodiment, the reflectivity of the first reflector is greater than 99.9%.

[0011] According to an embodiment, the distance between the second reflector and the third reflector is greater than the distance between the first reflector and the second reflector.

[0012] One of the advantages of the present application is that the vertical cavity surface emitting laser with multiple reflectors can form a first resonant cavity and a second resonant cavity through the first reflector, the second reflector and the third reflector. The light beam mainly resonates in the second resonant cavity. Since the second resonant cavity is far away from the current confinement layer, the light beam is less affected by the current confinement layer. After resonating in the second resonant cavity, the laser beam is emitted, which improves the light emitting effect of the vertical cavity surface emitting laser.

[0013] One of the advantages of the present application is that the thickness of the second reflector can be designed to make the second penetrating light beam in the second resonant cavity reflect nearly 100% when it contacts the second reflecting surface of the second reflector, so as to lock it in the second resonant cavity for resonance. Finally, the laser beam is emitted from the light emitting surface of the third reflector with lower reflectivity.

[0014] The details of other effects and embodiments of the present application are described below with reference to the drawings. BRIEF DESCRIPTION OF DRAWINGS

[0015] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the accompanying drawings needed to be used in the embodiments or prior art description will be briefly introduced. Obviously, the accompanying drawings in the following description only represent some embodiments described in the present application, and for those skilled in the art, other drawings can be obtained from these drawings without any creative effort.

[0016] Figure 1 The use state diagram of an embodiment of the present application. DETAILED DESCRIPTION

[0017] The following is to illustrate the embodiments of the present application related to "vertical cavity surface emitting laser with multiple mirrors" through specific embodiments. Those skilled in the art can understand the advantages and effects of the present application from the disclosed content. The present application can be implemented or applied through other different embodiments, and each detail in the present specification can be modified and changed based on different viewpoints and applications without departing from the concept of the present application. In addition, the drawings of the present application are only simple schematic illustrations, not the actual size description, and the prior declaration is made. The following embodiments will further illustrate the related technical content of the present application in detail, but the disclosed content is not used to limit the protection scope of the present application.

[0018] It should be understood that although the terms "first", "second", "third" and the like can be used herein to describe various components or signals, these components or signals should not be limited by these terms. These terms are mainly used to distinguish one component from another component, or one signal from another signal. In addition, the term "or" used herein can include any one or more combinations of the associated listed items.

[0019] Please refer to Figure 1Fig. 1 is a schematic diagram of a vertical cavity surface emitting laser (VCSEL) according to a first embodiment of the present application. It is noted that the circuit board and the metal electrode are omitted in this embodiment. The VCSEL Z1 includes a light emitting layer 10, a first mirror 11, a current confinement layer 13, a second mirror 14, and a third mirror 12. The light emitting layer 10 has a first side S1 and a second side S2. The first mirror 11 is located on the first side S1 of the light emitting layer 10. The first mirror 11 has a first reflecting surface 111. The current confinement layer 13 is located on the second side S2 of the light emitting layer 10. The current confinement layer 13 has a confinement hole 131. The second mirror 14 is located on the second side S2. The current confinement layer 13 is located between the second mirror 14 and the light emitting layer 10. The second mirror 14 has a penetration surface 141 and a second reflecting surface 142. The penetration surface 141 faces the current confinement layer 13. The second reflecting surface 142 is away from the current confinement layer 13. The first mirror 11 and the second mirror 14 form a first resonant cavity C1. The third mirror 12 is located on the second side S2. The second mirror 14 is located between the current confinement layer 13 and the third mirror 12. The third mirror 12 has a third reflecting surface 121 and an output surface 122. The third reflecting surface 121 faces the second mirror 14. The second mirror 14 and the third mirror 12 form a second resonant cavity C2.

[0020] When a current is injected into the light emitting layer 10 through the confinement hole 131, the light emitting layer 10 generates a first light beam L1 and a second light beam L2 on the first side S1 and the second side S2, respectively. The first light beam L1 is reflected by the first mirror 11 to generate a first reflected light beam L11. The first reflected light beam L11 passes through the light emitting layer 10. The light emitting layer 10 absorbs a portion of the first reflected light beam L11 and re-emits the first light beam L1 and the second light beam L2. Another portion of the first reflected light beam L11 passes through the light emitting layer 10 to generate a first penetration light beam L12. The second light beam L2 and the first penetration light beam L12 are reflected by the second mirror 14 to generate a second reflected light beam L21. The second reflected light beam L21 passes through the light emitting layer 10 to re-excite the light emitting layer 10 to generate the first light beam L1 and the second light beam L2. The second light beam L2 and the first penetration light beam L12 pass through the second mirror 14 and enter the second resonant cavity C2 to generate a second penetration light beam L22. The second penetration light beam L22 resonates between the second mirror 14 and the third mirror 12 to generate a laser beam L3. The laser beam L3 is emitted by the output surface 122 of the third mirror 12.

[0021] The second reflected light beam 21 is a small portion of the second light beam L2 and the light beam reflected by the second mirror 14 from the first transmitted light beam L12. The active light emitting layer 10 is excited by the second reflected light beam 21 to generate the first light beam L1 and the second light beam L2 again. In this way, the resonant cavity C1 has a continuously generated light beam.

[0022] On the other hand, the second transmitted light beam L22 is a large portion of the second light beam L2 and the light beam transmitted by the first transmitted light beam L12 from the second mirror 14. The second transmitted light beam L22 enters the second resonant cavity C2 to generate the laser beam L3 by resonating back and forth in the second resonant cavity C2 and is emitted from the light emitting surface 122.

[0023] According to some embodiments, the second mirror 14 can be designed to have different thicknesses so that the second transmitted light beam L22 in the second resonant cavity C2 can be reflected by the second reflecting surface 142 of the second mirror 14 in a nearly 100% manner. The second transmitted light beam L22 resonates back and forth in the second resonant cavity C2 to generate the laser beam L3.

[0024] The active light emitting layer 10 includes a plurality of film layers for forming multiple quantum wells, such as a plurality of undoped well layers and barrier layers alternately stacked with each other. The materials of the well layers and the barrier layers are determined according to the wavelength of the light beam L to be generated. For example, when the light beam L to be generated is red light, the well layers and the barrier layers can be gallium arsenide layers and aluminum gallium arsenide (AlxGa(1-x)As) layers, respectively. When the light beam L to be generated is blue light, the barrier layers and the well layers can be gallium nitride (GaN) layers and indium gallium nitride (InGaN) layers, respectively.

[0025] In some embodiments, the current confinement layer 13 is an oxide layer.

[0026] In some embodiments, the first mirror 11, the second mirror 14, and the third mirror 12 are Bragg mirrors. In other words, the first mirror 11, the third mirror 12, and the second mirror 14 can be distributed Bragg reflectors (DBRs) formed by alternately stacking two thin films having different refractive indices to reflect and resonate light beams having predetermined wavelengths. In some embodiments, the reflectivity of the first mirror 11 is greater than 99.9%.

[0027] According to some embodiments, the second mirror 14 includes a plurality of film layers made of materials having different refractive indices. The number of layers and the thickness of the film layers can be adjusted according to the phase angle and the interference requirement to obtain the reflection effect.

[0028] To make the vertical cavity surface emitting laser with multiple mirrors Z1 output (emit) a purer laser beam (stable mode), in some embodiments, the distance H1 between the second mirror 14 and the third mirror 12 is greater than the distance H2 between the first mirror 11 and the second mirror 14.

[0029] It should be particularly noted that the first light beam L1 and the second light beam L2 emitted by the active light-emitting layer 10 under current excitation, wherein the proportion of the second light beam L2 is greater than that of the first light beam L1. In some cases, the portion of the second light beam L2 passing through the second mirror 15 is much larger than the portion reflected by the second mirror 15.

[0030] “Advantages of embodiments”

[0031] One of the advantages of the present application is that the vertical cavity surface emitting laser with multiple mirrors provided by the present application can form a first resonant cavity and a second resonant cavity through the first mirror, the second mirror and the third mirror, and the light beam mainly resonates in the second resonant cavity. Since the second resonant cavity is far away from the current confinement layer, the light beam will be less affected by the current confinement layer, and the laser beam will be emitted after resonating in the second resonant cavity, thereby improving the light-emitting effect of the vertical cavity surface emitting laser.

[0032] One of the advantages of the present application is that the thickness of the second mirror can be designed to make the second penetrating light beam in the second resonant cavity reflect nearly 100% when it contacts the second reflecting surface of the second mirror, thereby being locked in the second resonant cavity for resonance, and finally emitting a laser beam from the light-emitting surface of the third mirror with lower reflectivity.

[0033] The above-described embodiments and / or implementations are only used to illustrate the preferred embodiments and / or implementations of the present application, and do not limit the embodiments of the present application in any form. Any person skilled in the art can make some changes or modifications to other equivalent embodiments without departing from the scope of the technical means disclosed in the present application, but should be considered as the same technology or embodiment as the present application.

Claims

1. A vertical resonant cavity surface-emitting laser with multiple mirrors, characterized in that, The vertical resonant cavity surface-emitting laser with multiple mirrors includes: An active light-emitting layer, wherein a first side and a second side are defined on opposite sides of the active light-emitting layer; A first reflector is located on the first side of the active light-emitting layer, and the first reflector has a first reflective surface; A current-limiting layer is located on the second side of the active light-emitting layer, and the current-limiting layer has a limiting hole; A second reflector is located on the second side. The current confinement layer is located between the second reflector and the active light-emitting layer. The two opposing surfaces of the second reflector define a penetrating surface and a second reflecting surface, respectively. The penetrating surface faces the current confinement layer, and the second reflecting surface is away from the current confinement layer. A first resonant cavity is formed between the second reflector and the first reflector. A third reflector is located on the second side, and the second reflector is located between the current confinement layer and the third reflector; the third reflector has a third reflecting surface and a light-emitting surface facing each other, the third reflecting surface facing the second reflector, wherein a second resonant cavity is formed between the second reflector and the third reflector; and In this process, a current is injected into the active light-emitting layer through the current-limiting hole, causing the active light-emitting layer to generate a first light beam and a second light beam on the first side and the second side, respectively. The first light beam is reflected by the first reflector to generate a first reflected light beam. The first reflected light beam passes through the active light-emitting layer, and the active light-emitting layer absorbs a portion of the first reflected light beam and excites the first light beam and the second light beam. The other portion of the first reflected light beam penetrates the active light-emitting layer to define a first penetrating light beam. Wherein, the second beam and the beam reflected by the second mirror from the first penetrating beam define a second reflected beam, and the second reflected beam passes through the active light-emitting layer, thereby exciting the active light-emitting layer to generate the first beam and the second beam again; and The second beam, which penetrates the second reflector and enters the second resonant cavity from the first penetrating beam, is defined as a second penetrating beam. The second penetrating beam resonates back and forth between the second reflector and the third reflector to generate a laser beam, which is emitted from the light-emitting surface of the third reflector.

2. The vertical resonant cavity surface-emitting laser with multiple mirrors according to claim 1, characterized in that, The current-limiting layer is an oxide layer.

3. The vertical resonant cavity surface-emitting laser with multiple mirrors according to claim 1, characterized in that, The first reflector, the second reflector, and the third reflector are Bragg reflectors.

4. The vertical resonant cavity surface-emitting laser with multiple mirrors according to claim 1, characterized in that, The reflectivity of the first reflector is above 99.9%.

5. The vertical resonant cavity surface-emitting laser with multiple mirrors according to claim 1, characterized in that, The distance between the second reflector and the third reflector is greater than the distance between the first reflector and the second reflector.

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