Disclosure of Invention
In order to solve the above problems, the present invention provides a surface emitting laser array, in which adjacent laser single tubes are arranged in a longitudinally staggered manner, so that a carrier is laterally injected into an active layer of a beam output region where no contact electrode is provided in each laser single tube, and beam shaping and coupling difficulties are reduced.
The technical scheme adopted by the invention is as follows:
the utility model provides a surface emitting laser array, its includes a plurality of laser instrument single tube that is located same chip, the laser instrument single tube vertically sets up, and a plurality of the laser instrument single tube is misplaced in proper order and arranges and is used for realizing the carrier side direction injection to the active layer in each laser instrument single tube light beam output region.
Preferably, the laser single tube includes a first DBR section, a first electrode region, a beam output region, a second electrode region, and a second DBR section, which are sequentially arranged from top to bottom, and the first DBR section, the first electrode region, the second electrode region, and the second DBR section are symmetrical with respect to the beam output region.
Preferably, shallow etching grooves are formed in the light beam output region and close to the first electrode region and the second electrode region of the single laser tubes on the two adjacent sides of the light beam output region, the lengths of the shallow etching grooves and the light beam output region are the same and are used for forming a ridge structure to limit an optical field in the waveguide, and the shallow etching grooves are of a polygonal structure.
Preferably, deep etching grooves are arranged in the first DBR region and the second DBR region and close to one side of the first electrode region and one side of the second electrode region of the single tube of the adjacent laser respectively, and the deep etching grooves are of a polygonal prism structure.
Preferably, the surfaces of the first and second DBR sections are each etched with a grating serving as a high reflectivity mirror, the grating being covered with a thin film to form the passive DBR section.
Preferably, the surface of the light beam output area is etched with a second-order grating for realizing surface output coupling and longitudinal feedback coupling of light.
Preferably, a contact electrode is disposed between the first DBR section and the beam output section, and the contact electrode is covered to a surface of the first DBR section;
a contact electrode is also disposed between the second DBR section and the beam output section, and covers a surface of the second DBR section.
Preferably, the first electrode region, the second electrode region, the first DBR region, and the second DBR region each include a p-side electrode layer, a p-side cap layer, a p-side cladding layer, an active layer, an n-side cladding layer, an n-side cap layer, a buffer layer, a substrate layer, and an n-side electrode, which are sequentially disposed from top to bottom. Wherein for the first DBR section and the second DBR section, an insulating film is additionally provided between the p-side electrode layer and the p-cap layer.
Preferably, the light beam output region comprises a p-type cover layer, a p-type cladding layer, an active layer, an n-type cladding layer, an n-type cover layer, a buffer layer, a substrate layer and an n-side electrode which are arranged in sequence from top to bottom.
Preferably, the substrate layers of the first DBR section and the second DBR section are provided with an insulating dielectric film, and the length of the insulating dielectric film is greater than the length of the first DBR section but less than the sum of the lengths of the first DBR section and the first electrode region.
Compared with the prior art, the cross section of the output light beam of the surface emitting laser array with the laser single tubes arranged along the longitudinal direction in a staggered mode is in a rectangular step shape, the light beam shape greatly reduces the light beam shaping difficulty, and the output light beam with high quality and high power density can be obtained easily through light spot shearing and splicing.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail with reference to the following embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
In the description of the present invention, it is to be understood that the terms "vertical", "lateral", "longitudinal", "front", "rear", "left", "right", "upper", "lower", "horizontal", and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, and are only for convenience of description of the present invention, and do not mean that the device or member to which the present invention is directed must have a specific orientation or position, and thus, cannot be construed as limiting the present invention.
In the description of the present invention, it should be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "connected," and "connected" are to be construed broadly, e.g., as meaning either a fixed connection, a removable connection, or an integral connection; can be mechanically or electrically connected; may be directly connected or indirectly connected through an intermediate. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.
The embodiment of the invention provides a surface-emitting laser array, which comprises a plurality of laser single tubes 100 positioned on the same chip, wherein the laser single tubes 100 are longitudinally arranged, and a plurality of adjacent laser single tubes 100 are sequentially arranged in a staggered manner to realize the lateral injection of carriers of active layers in light beam output regions of the laser single tubes 100;
specifically, the sequential staggered arrangement of the plurality of laser units 100 means that the top ends of the plurality of laser single tubes 100 are oblique lines instead of broken lines formed by vertical dislocation; in fig. 1, five laser single tubes 100 are arranged in a staggered manner to form a laser array;
thus, by adopting the structure, the cross section of the output beam of the surface emitting laser array in which the laser single tubes 100 are longitudinally arranged in a staggered manner is in a rectangular step shape, the beam shape greatly reduces the beam shaping difficulty, and the output beam with high quality and high power density can be easily obtained by cutting and splicing light spots.
As shown in fig. 2, the laser monotube 100 includes a first DBR section 1, a first electrode section 2, a beam output section 3, a second electrode section 4, and a second DBR section 5, which are sequentially arranged from top to bottom, and the first DBR section 1, the first electrode section 2, the second electrode section 4, and the second DBR section 5 are symmetrical with respect to the beam output section 3;
assuming that the adjacent laser single tubes 100 are sequentially shifted upward from left to right, the first DBR section 1 of the adjacent laser single tubes 100 forms an upward-inclined line segment. After dislocation, the left and right (lateral) adjacent two regions have different functions, and the first electrode regions 2 and the second electrode regions 4 of the adjacent laser monotube 100 are positioned at the left and right sides of the light beam output region 3, so that carriers injected from the electrode regions at the two sides can drift and diffuse to the active layer of the light beam output region positioned in the middle.
As shown in fig. 3, shallow etching grooves 6 are arranged in the light beam output region 3 at positions close to two sides of the first electrode region 2 and the second electrode region 4 of the single laser tube at two adjacent sides, the length of the shallow etching groove 6 is the same as that of the light beam output region 3, and the shallow etching groove 6 is in a polygonal prism structure and is used for forming a ridge-shaped structure to limit an optical field in the waveguide;
the shallow etching groove 6 is smaller in width and the same in length as the light beam output region 3, and is mainly used for forming a ridge structure to limit an optical field in the waveguide.
Deep etching grooves 7 are formed in the first DBR region 1 and the second DBR region 5 of each single laser tube and are respectively close to one side of the first electrode region 2 and the second electrode region 4 of the adjacent single laser tube, and the deep etching grooves 7 are of a polygonal prism structure;
thus, the trenches 7 are etched back to a depth up to the n-cap layer 26. The deep etching groove 7 is arranged for eliminating the influence of the first electrode region 2 and the second electrode region 4 on the first DBR region 1 and the second DBR region 5 respectively between the adjacent laser single tubes 100, and the shape of the deep etching groove can be adjusted and optimized according to the requirement.
As shown in fig. 4, the surfaces of the first DBR section 1 and the second DBR section 5 are each etched with a grating 11 serving as a high-reflectivity mirror, and the grating 11 is covered with a thin film 12 to form a passive DBR section;
a second-order grating 31 is etched on the surface of the light beam output area 3 to realize surface output coupling and longitudinal feedback coupling of light;
thus, after etching the grating 11 on the surfaces of the first DBR section 1 and the second DBR section 5 of the single laser tube 100, an insulating medium (e.g., SiO) is selected2Or Si3N4) The film 12 covers it to make a passive DBR section; and a second-order grating 31 is etched and manufactured on the surface of the chip corresponding to the light beam output area 3 in the laser single tube 100, so that the surface output coupling and the longitudinal feedback coupling of light are realized.
A contact electrode 8 is arranged between the first DBR section 1 and the beam output section 3 of the same laser single tube 100, and the contact electrode 8 covers the surface of the first DBR section 1;
a contact electrode 8 is also disposed between the second DBR section 5 and the beam output section 3 of the same laser single tube 100, and the contact electrode 8 covers the surface of the second DBR section 5.
As shown in fig. 5 to 6, each of the first electrode region 2, the second electrode region 4, the first DBR section 1 and the second DBR section 5 includes a p-side electrode layer 21, a p-cap layer 22, a p-cladding layer 23, an active layer 24, an n-cladding layer 25, an n-cap layer 26, a buffer layer 27, a substrate layer 28 and an n-side electrode 29, which are sequentially arranged from top to bottom.
The beam output region 3 comprises a p-type cover layer 22, a p-type cladding layer 23, an active layer 24, an n-type cladding layer 25, an n-type cover layer 26, a buffer layer 27, a substrate layer 28 and an n-type electrode 29 which are arranged from top to bottom in sequence.
An insulating dielectric film 281 is arranged between the substrate layer 28 of the first DBR section 1 and the second DBR section 5 and the n-plane electrode 29, and the length of the insulating dielectric film 281 is greater than the length of the first DBR section 1 but less than the sum of the lengths of the first DBR section 1 and the first electrode region 2;
thus, an insulating dielectric film 281 is formed on the substrate layers 28 of the first DBR section 1 and the second DBR section 5 at both ends of the laser single tube 100, and the longitudinal length of the insulating dielectric film 281 is greater than the length of the first DBR section 1 but less than the sum of the lengths of the first DBR section 1 and the first electrode section 2; then, the n-side of the whole laser monotube 100 is subjected to electrode fabrication, and the substrate layer 28 of the beam output region 3 and the region coated with the insulating medium film 281 are completely covered by the n-side electrode 29.
In this embodiment:
electrode regions (a first electrode region 2 and a second electrode region 4) of the laser monotube 100 at adjacent positions are positioned at the left side and the right side of a light beam output region 3 of the laser monotube 100, and shallow etching grooves 6 are formed in the light beam output region 3 at positions close to the two sides of the electrode regions of the adjacent lasers;
firstly, in the aspect of electricity, the parameters of the shallow etching area are set to be beneficial to adjusting the lateral transmission of carriers injected into the adjacent laser electrode area, so that the gain of an active layer in a light beam output area 3 is controllable, and the working threshold of a laser array is reduced;
secondly, in the aspect of optics, a ridge waveguide structure is formed in the light beam output region 3 by the arrangement of the shallow etching region, namely, the optical field in the cavity is limited along the lateral direction and the transverse direction, so that the stability of a laser mode is ensured; in addition, the mode coupling strength between adjacent lasers can be changed by adjusting the geometric dimension of the shallow etching groove, and the optimization of parameters such as mode field distribution, limiting factors and the like of the lasers is facilitated.
Compared with the traditional second-order grating surface-emitting distributed feedback laser, the second-order grating 31 and the electrode are separated, and carriers are supplied to the active layer of the light beam output region 3 in a lateral carrier injection mode; the arrangement is favorable for reducing the modulation difficulty of the carrier distribution in the device, and realizes the controllability of the light field distribution influenced by the carrier distribution;
in addition, the arrangement directly reduces or even eliminates the influence of carrier injection on the refractive index and loss of the grating layer, contributes to reducing the design difficulty of the device, and simultaneously improves the working stability of the device.
In the DBR regions (the first DBR region 1 and the second DBR region 3) of the laser single tube 100, a deep etching groove 7 is arranged at a position close to an adjacent laser electrode region (the first electrode region 2 or the second electrode region 4), so that the limitation on current carriers is favorably formed, the influence of the current carriers on the DBR regions is eliminated, and the leakage and the waste of the current carriers are reduced;
in addition, the arrangement of the shape and the depth of the deep-etching region directly influences the optical field distribution in the DBR region, and can be used for regulating and controlling the mode characteristics of the laser.
The cross section of the output beam of the surface emitting laser array with the laser single tubes 100 arranged along the longitudinal direction in a staggered mode is in a rectangular step shape, the beam shape greatly reduces the beam shaping difficulty, and the output beam with high quality and high power density can be obtained easily through spot shearing and splicing. The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present invention are included in the scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.