DFB laser with active cavity and passive cavity alternating structure
阅读说明：本技术 有源腔与无源腔交替结构的dfb激光器 (DFB laser with active cavity and passive cavity alternating structure ) 是由 徐长达 陈伟 班德超 祝宁华 于 2020-06-30 设计创作，主要内容包括：本公开提供一种有源腔与无源腔交替结构的DFB激光器,包括：衬底层；下限制层,位于衬底层上；下波导层,位于下限制层上；有源层,位于下波导层上；上波导层,位于有源层上；上限制层,位于上波导层上,其内设置有光栅结构；沿上限制层设置有一纵向脊波导；欧姆接触层,覆于脊波导上表面共同构成脊条结构；绝缘层,位于上限制层表面及脊条结构侧壁；以及P面电极,成梳齿状纵向间隔覆于脊条结构的上表面并覆满脊条结构侧壁后沿绝缘层延伸出一外部接入电极；其中,有源层中对应脊条结构有覆盖P面电极的部分形成多个有源腔,有源层中对应脊条结构未覆盖P面电极的部分形成多个无源腔,从而使得激光器沿纵向方向上形成有源腔与无源腔的交替结构。(The present disclosure provides a DFB laser with an active cavity and a passive cavity alternating structure, comprising: a substrate layer; a lower confinement layer on the substrate layer; a lower waveguide layer located on the lower confinement layer; an active layer on the lower waveguide layer; an upper waveguide layer on the active layer; the upper limiting layer is positioned on the upper waveguide layer, and a grating structure is arranged in the upper limiting layer; a longitudinal ridge waveguide is arranged along the upper limiting layer; the ohmic contact layer is covered on the upper surface of the ridge waveguide to jointly form a ridge structure; the insulating layer is positioned on the surface of the upper limiting layer and the side wall of the ridge structure; the P-surface electrode is covered on the upper surface of the ridge structure at intervals in a comb-tooth shape, covers the side wall of the ridge structure completely, and extends out of an external access electrode along the insulating layer; and a plurality of active cavities are formed in the active layer corresponding to the parts of the ridge structure, which cover the P-face electrode, and a plurality of passive cavities are formed in the active layer corresponding to the parts of the ridge structure, which do not cover the P-face electrode, so that the laser forms an alternating structure of the active cavities and the passive cavities along the longitudinal direction.)
1. A DFB laser with alternating active and passive cavity structures, comprising:
a substrate layer;
a lower confinement layer on the substrate layer;
a lower waveguide layer located on the lower confinement layer;
an active layer on the lower waveguide layer;
an upper waveguide layer on the active layer;
the upper limiting layer is positioned on the upper waveguide layer, and a grating structure is arranged in the upper limiting layer; a longitudinal ridge waveguide is arranged along the upper limiting layer;
the ohmic contact layer is covered on the upper surface of the ridge waveguide to jointly form a ridge structure;
the insulating layer is positioned on the surface of the upper limiting layer and the side wall of the ridge structure; and
the P-surface electrode is covered on the upper surface of the ridge structure at intervals in a comb-tooth shape, covers the side wall of the ridge structure completely, and extends out of an external access electrode along the insulating layer;
and a plurality of active cavities are formed in the active layer corresponding to the parts of the ridge structure, which cover the P-face electrode, and a plurality of passive cavities are formed in the active layer corresponding to the parts of the ridge structure, which do not cover the P-face electrode, so that the laser forms an alternating structure of the active cavities and the passive cavities along the longitudinal direction.
2. The DFB laser of claim 1, wherein the active cavity and the passive cavity have an alternating structure, and the active layer and the grating structure are the same throughout the laser.
3. The DFB laser with the alternating active cavity and passive cavity structure as claimed in claim 1, wherein the number of active cavities is greater than or equal to 2.
4. The DFB laser with the alternating active cavity and passive cavity structure as claimed in claim 1, wherein the number of the passive cavities is greater than or equal to 2.
5. The DFB laser of claim 1 having an alternating active cavity and passive cavity structure, the active cavity having a length greater than a length of the passive cavity.
6. The DFB laser of claim 1 having an alternating active cavity and passive cavity structure, a plurality of active cavities having the same length.
7. The DFB laser of claim 1 having an alternating active cavity and passive cavity structure, a plurality of active cavities having different lengths.
8. The DFB laser of claim 1 having an alternating active cavity and passive cavity structure, the passive cavities having the same length.
9. The DFB laser of claim 1 having an alternating active cavity and passive cavity structure, the passive cavities having different lengths.
Technical Field
The present disclosure relates to the field of semiconductor laser technology, and in particular, to a DFB laser with an active cavity and a passive cavity alternating structure.
Background
In recent years, under the push of the explosion development of the communication industry, the technology of semiconductor lasers is rapidly developed, wherein DFB lasers are the mainstream lasers for application due to excellent single-mode characteristics and perfect manufacturing process. To meet the increasing demand for communication data, how to increase the communication rate of DFB lasers becomes an urgent and long-term problem.
A typical method for increasing the communication rate of DFB lasers is to improve the active layer components and the differential optical gain coefficient (Tadokoro T, Yamanaka T, Kano F, et al. operation of a 25-Gbps direct modulation edge MQW-DFB laser up to 85 ℃ [ C]Optical Society of America, 2009: OThT 3.). Shortening the active cavity length and reducing the photon lifetime can also improve the communication rate of DFB lasers (K.Nakahara, T.Tsuchiya, T.Kitatani, et al.40-Gb/s direct modulation with high amplification efficiency operation of 1.3-mu m InGaAlAs multi quality well waveguide modified feedback laser J.]IEEE Photonics Technology Letters, 2007, 19 (19): 1436-1438.). However, it is difficult to continue to advance downward by shortening the active cavity length to reduce photon lifetime, because such fabrication methods and their dependence on cleavage accuracy, increased photon concentration and increased device temperature can also present challenges to proper device operation. Another method for increasing the communication rate of DFB lasers is the chirp management technique (Yu J, Jia Z, Huang M F, et al. applications of 40-Gb/schirp-managed laser in access and metro networks [ J]Journal of lightwave technology, 2009, 27 (3): 253-265). This method requires an additional optical filter with high accuracy. Yet another approach is to provide an optical feedback cavity to compensate the electrical-to-optical response of the DFB laser at high frequencies by optical resonance brought about by the optical feedback (tropipenz U)，Kreissl J，
BRIEF SUMMARY OF THE PRESENT DISCLOSURE
Technical problem to be solved
Based on the above problems, the present disclosure provides a DFB laser with an active cavity and a passive cavity alternating structure, so as to alleviate the technical problems that in the prior art, most DFB lasers based on the optical resonance effect need to perform secondary epitaxy on an active layer and a grating layer, and the requirement on the preparation process is high.
(II) technical scheme
The present disclosure provides a DFB laser with an active cavity and a passive cavity alternating structure, comprising: a substrate layer; a lower confinement layer on the substrate layer; a lower waveguide layer located on the lower confinement layer; an active layer on the lower waveguide layer; an upper waveguide layer on the active layer; the upper limiting layer is positioned on the upper waveguide layer, and a grating structure is arranged in the upper limiting layer; a longitudinal ridge waveguide is arranged along the upper limiting layer; the ohmic contact layer is covered on the upper surface of the ridge waveguide to jointly form a ridge structure; the insulating layer is positioned on the surface of the upper limiting layer and the side wall of the ridge structure; the P-surface electrode is covered on the upper surface of the ridge structure at intervals in a comb-tooth shape, covers the side wall of the ridge structure completely, and extends out of an external access electrode along the insulating layer; and a plurality of active cavities are formed in the active layer corresponding to the parts of the ridge structure, which cover the P-face electrode, and a plurality of passive cavities are formed in the active layer corresponding to the parts of the ridge structure, which do not cover the P-face electrode, so that the laser forms an alternating structure of the active cavities and the passive cavities along the longitudinal direction.
In the disclosed embodiments, the entire laser assumes the same active layer and grating structure.
In the disclosed embodiment, the number of active cavities is ≧ 2.
In the disclosed embodiment, the number of passive cavities is greater than or equal to 2.
In embodiments of the present disclosure, the length of the active cavity is greater than the length of the passive cavity.
In the disclosed embodiments, the plurality of active cavities are the same length.
In the disclosed embodiments, the lengths of the plurality of active cavities are not the same.
In the disclosed embodiment, the plurality of passive cavities are the same length.
In the disclosed embodiments, the plurality of passive cavities are not of the same length.
(III) advantageous effects
According to the technical scheme, the DFB laser with the alternating structure of the active cavity and the passive cavity has at least one or part of the following beneficial effects:
(1) the preparation process is mature, and the cost is reduced;
(2) the DFB laser communication rate is improved.
Drawings
Fig. 1 is a schematic perspective view of a DFB laser with an active cavity and a passive cavity alternating structure according to an embodiment of the disclosure.
Fig. 2 is a schematic diagram of a longitudinal cross-sectional structure of a DFB laser with an alternating active cavity and passive cavity structure according to an embodiment of the present disclosure.
[ description of main reference numerals in the drawings ] of the embodiments of the present disclosure
1-a substrate layer, 2-a lower confinement layer, 3-a lower waveguide layer, 4-an active layer, 5-an upper waveguide layer,
6-grating structure, 7-upper limiting layer, 8-insulating layer, 9-ohmic contact layer, 10-P surface electrode,
11-active cavity, 12-passive cavity.
Detailed Description
The invention provides a DFB laser with an active cavity and a passive cavity in an alternative structure, which is characterized in that the existing mature preparation process is utilized, the same active layer and grating layer are adopted, the length and the number of the active cavity and the passive cavity are adjusted by designing the size of a P-surface comb-shaped electrode, the alternative structure of the active cavity and the passive cavity is realized, and the aim of improving the communication rate of the DFB laser is fulfilled by the structure.
For the purpose of promoting a better understanding of the objects, aspects and advantages of the present disclosure, reference is made to the following detailed description taken in conjunction with the accompanying drawings.
In an embodiment of the present disclosure, there is provided a DFB laser with an alternating active cavity and passive cavity structure, as shown in fig. 1 and 2, including:
a substrate layer 1;
a lower limiting layer 2 positioned on the substrate layer;
a lower waveguide layer located on the lower confinement layer;
an active layer on the lower waveguide layer;
an upper waveguide layer on the active layer;
the upper limiting layer 7 is positioned on the upper waveguide layer, and a grating structure 6 is arranged in the upper limiting layer; a longitudinal ridge waveguide is arranged along the upper limiting layer;
the ohmic contact layer 9 is covered on the upper surface of the ridge waveguide to form a ridge structure;
the insulating layer 8 is positioned on the surface of the upper limiting layer and the side wall of the ridge structure;
the P-surface electrode 10 is covered on the upper surface of the ridge structure at intervals in a comb-tooth shape, covers the side wall of the ridge structure completely, and extends out of an external access electrode along the insulating layer;
and a plurality of active cavities 11 are formed in the active layer corresponding to the parts of the ridge structure, which cover the P-plane electrode, and a plurality of passive cavities 12 are formed in the active layer corresponding to the parts of the ridge structure, which do not cover the P-plane electrode, so that the laser forms an alternating structure of the active cavities and the passive cavities along the longitudinal direction.
The corresponding active layer can generate optical gain to form an active cavity in an area covered by the P-surface electrode on the ridge structure; and in the area without the coverage of the P-plane electrode, the corresponding active layer has no optical gain and becomes a passive cavity.
The whole laser adopts the same active layer and grating structure, thus greatly reducing the preparation difficulty of the laser.
In the embodiment of the disclosure, the number of active cavities is more than or equal to 2; the number of the passive cavities is more than or equal to 2. As shown in fig. 2, the number of active cavities and passive cavities is 8. However, the laser is not limited to the use of 8 active cavities and 8 passive cavities, and two or more active cavities and two or more passive cavities may be used to form a DFB laser with an alternating active and passive cavity structure.
The lengths of the active cavity and the passive cavity are not fixed, and the lengths of the active cavities can be the same or different under one laser; the lengths of the passive cavities may be the same or different. The 8 active cavities shown in fig. 2 are of the same length, but the laser is not limited to use active cavities of the same length, and active cavities of different lengths may be used.
In embodiments of the present disclosure, the length of the active cavity is greater than the length of the passive cavity.
In the disclosed embodiment, a disk electrode is used as the external access electrode. However, the laser is not limited to use a disk electrode as the external access, and may also use a square electrode or other electrodes of various shapes as the external access.
So far, the embodiments of the present disclosure have been described in detail with reference to the accompanying drawings. It is to be noted that, in the attached drawings or in the description, the implementation modes not shown or described are all the modes known by the ordinary skilled person in the field of technology, and are not described in detail. Further, the above definitions of the various elements and methods are not limited to the various specific structures, shapes or arrangements of parts mentioned in the examples, which may be easily modified or substituted by those of ordinary skill in the art.
From the above description, those skilled in the art should clearly understand the DFB laser of the present disclosure with an alternating active cavity and passive cavity structure.
In summary, the present disclosure provides a DFB laser with an alternating active cavity and passive cavity structure, where the whole laser has the same active layer and grating structure, and the DFB laser with an alternating active cavity and passive cavity structure is manufactured by a method of controlling optical gain by covering electrodes, that is, covering electrodes in a part of a ridge of the laser, and having current injection under the part to generate optical gain, thus forming an active cavity, and not covering electrodes in other parts of the ridge, thus forming a passive cavity without optical gain. With such a comb-shaped electrode, it is possible to easily produce an alternating structure of active and passive cavities in the longitudinal direction of the laser, and to control the lengths and the number of the active and passive cavities by changing the width of the comb-shaped electrode on the ridge and the electrode interval. The laser utilizes the passive cavity to reduce the photon life and improve the relaxation oscillation frequency of the directly modulated laser, and utilizes the light-light resonance effect to expand the directly modulated bandwidth of the laser.
It should also be noted that directional terms, such as "upper", "lower", "front", "rear", "left", "right", and the like, used in the embodiments are only directions referring to the drawings, and are not intended to limit the scope of the present disclosure. Throughout the drawings, like elements are represented by like or similar reference numerals. Conventional structures or constructions will be omitted when they may obscure the understanding of the present disclosure.
And the shapes and sizes of the respective components in the drawings do not reflect actual sizes and proportions, but merely illustrate the contents of the embodiments of the present disclosure. Furthermore, in the claims, any reference signs placed between parentheses shall not be construed as limiting the claim.
Unless otherwise indicated, the numerical parameters set forth in the specification and attached claims are approximations that can vary depending upon the desired properties sought to be obtained by the present disclosure. In particular, all numbers expressing quantities of ingredients, reaction conditions, and so forth used in the specification and claims are to be understood as being modified in all instances by the term "about". Generally, the expression is meant to encompass variations of ± 10% in some embodiments, 5% in some embodiments, 1% in some embodiments, 0.5% in some embodiments by the specified amount.
Furthermore, the word "comprising" does not exclude the presence of elements or steps not listed in a claim. The word "a" or "an" preceding an element does not exclude the presence of a plurality of such elements.
The use of ordinal numbers such as "first," "second," "third," etc., in the specification and claims to modify a corresponding element does not by itself connote any ordinal number of the element or any ordering of one element from another or the order of manufacture, and the use of the ordinal numbers is only used to distinguish one element having a certain name from another element having a same name.
In addition, unless steps are specifically described or must occur in sequence, the order of the steps is not limited to that listed above and may be changed or rearranged as desired by the desired design. The embodiments described above may be mixed and matched with each other or with other embodiments based on design and reliability considerations, i.e., technical features in different embodiments may be freely combined to form further embodiments.
Those skilled in the art will appreciate that the modules in the device in an embodiment may be adaptively changed and disposed in one or more devices different from the embodiment. The modules or units or components of the embodiments may be combined into one module or unit or component, and furthermore they may be divided into a plurality of sub-modules or sub-units or sub-components. All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and all of the processes or elements of any method or apparatus so disclosed, may be combined in any combination, except combinations where at least some of such features and/or processes or elements are mutually exclusive. Each feature disclosed in this specification (including any accompanying claims, abstract and drawings) may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise. Also in the unit claims enumerating several means, several of these means may be embodied by one and the same item of hardware.
Similarly, it should be appreciated that in the foregoing description of exemplary embodiments of the disclosure, various features of the disclosure are sometimes grouped together in a single embodiment, figure, or description thereof for the purpose of streamlining the disclosure and aiding in the understanding of one or more of the various disclosed aspects. However, the disclosed method should not be interpreted as reflecting an intention that: that is, the claimed disclosure requires more features than are expressly recited in each claim. Rather, as the following claims reflect, disclosed aspects lie in less than all features of a single foregoing disclosed embodiment. Thus, the claims following the detailed description are hereby expressly incorporated into this detailed description, with each claim standing on its own as a separate embodiment of this disclosure.
The above-mentioned embodiments are intended to illustrate the objects, aspects and advantages of the present disclosure in further detail, and it should be understood that the above-mentioned embodiments are only illustrative of the present disclosure and are not intended to limit the present disclosure, and any modifications, equivalents, improvements and the like made within the spirit and principle of the present disclosure should be included in the scope of the present disclosure.