CN112448267B - Vertical cavity surface emitting laser array with uniform light emitting power and manufacturing method thereof - Google Patents

Vertical cavity surface emitting laser array with uniform light emitting power and manufacturing method thereof Download PDF

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Publication number
CN112448267B
CN112448267B CN202011329497.3A CN202011329497A CN112448267B CN 112448267 B CN112448267 B CN 112448267B CN 202011329497 A CN202011329497 A CN 202011329497A CN 112448267 B CN112448267 B CN 112448267B
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cavity surface
emitting laser
surface emitting
vertical cavity
laser unit
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CN112448267A (en
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金冬月
杨绍萌
张万荣
那伟聪
吴玲
杨滢齐
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Beijing University of Technology
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Beijing University of Technology
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
    • H01S5/00—Semiconductor lasers
    • H01S5/40—Arrangement of two or more semiconductor lasers, not provided for in groups H01S5/02 - H01S5/30
    • H01S5/42—Arrays of surface emitting lasers
    • H01S5/423—Arrays of surface emitting lasers having a vertical cavity
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
    • H01S5/00—Semiconductor lasers
    • H01S5/06—Arrangements for controlling the laser output parameters, e.g. by operating on the active medium
    • H01S5/068—Stabilisation of laser output parameters
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
    • H01S5/00—Semiconductor lasers
    • H01S5/10—Construction or shape of the optical resonator, e.g. extended or external cavity, coupled cavities, bent-guide, varying width, thickness or composition of the active region
    • H01S5/18—Surface-emitting [SE] lasers, e.g. having both horizontal and vertical cavities
    • H01S5/183—Surface-emitting [SE] lasers, e.g. having both horizontal and vertical cavities having only vertical cavities, e.g. vertical cavity surface-emitting lasers [VCSEL]
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
    • H01S5/00—Semiconductor lasers
    • H01S5/40—Arrangement of two or more semiconductor lasers, not provided for in groups H01S5/02 - H01S5/30
    • H01S5/4025—Array arrangements, e.g. constituted by discrete laser diodes or laser bar

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  • Physics & Mathematics (AREA)
  • Condensed Matter Physics & Semiconductors (AREA)
  • General Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Optics & Photonics (AREA)
  • Semiconductor Lasers (AREA)

Abstract

The embodiment of the invention provides a vertical cavity surface emitting laser array with uniform light emitting power and a manufacturing method thereof, wherein the array comprises: a plurality of vertical cavity surface emitting laser units; for any two vertical cavity surface emitting laser units, the resistance of the first vertical cavity surface emitting laser unit is greater than the resistance of the second vertical cavity surface emitting laser unit; in any two vertical cavity surface emitting laser units, the distance between the first vertical cavity surface emitting laser unit and the center of the vertical cavity surface emitting laser array is smaller than the distance between the second vertical cavity surface emitting laser unit and the center of the vertical cavity surface emitting laser array. The vertical cavity surface emitting laser array with uniform light output power and the manufacturing method thereof provided by the embodiment of the invention can effectively improve the uneven junction temperature distribution of the array and improve the uniformity and stability of the light output power on the basis of high integration of the vertical cavity surface emitting laser units, no increase of the area of the array and no change of the arrangement design of the table top.

Description

Vertical cavity surface emitting laser array with uniform light emitting power and manufacturing method thereof
Technical Field
The invention relates to the technical field of semiconductor lasers, in particular to a vertical cavity surface emitting laser array with uniform light emitting power and a manufacturing method thereof.
Background
A Vertical-Cavity Surface-Emitting Laser (VCSEL) is a Laser with a light-Emitting direction perpendicular to the Surface of a resonant Cavity, and has the advantages of low threshold current, small working current, small divergence angle, high coupling efficiency with an optical fiber, low batch production cost, easy integration into a two-dimensional array, and the like, and is currently widely applied to the fields of medical treatment, illumination, optical pumping, optical communication, optical storage, and the like. The two-dimensional vertical cavity surface emitting laser array formed by the parallel arrangement of the vertical cavity surface emitting laser units can effectively improve the light emitting power.
In the vertical cavity surface emitting laser array, due to the self-heating effect caused by the power dissipation of each vertical cavity surface emitting laser unit and the thermal coupling effect among the vertical cavity surface emitting laser units, the phenomenon of uneven junction temperature distribution can occur when the vertical cavity surface emitting laser array works. Further, the injection current of the vcsel array is not uniformly distributed, resulting in non-uniform optical power distribution of the vcsel array. At this time, the divergence angle of the light beam emitted by the vertical cavity surface emitting laser array is increased, so that the convergence of the light spot is deteriorated, thereby affecting the high light beam quality operation of the vertical cavity surface emitting laser array.
In the prior art, the phenomenon of uneven junction temperature distribution of a vertical cavity surface emitting laser array in the working process is improved by means of heat sink design (for example, water cooling equipment is added or a heat dissipation plate is optimized) or mesa arrangement design of the vertical cavity surface emitting laser unit (for example, the interval between the vertical cavity surface emitting laser units is increased or the interval between the vertical cavity surface emitting laser units is designed unevenly), and the like, so that the luminous power uniformity of the vertical cavity surface emitting laser array is improved. Although the heat sink design can weaken the influence of self-heating effect and thermal coupling effect from the aspect of substrate heat dissipation, the junction temperature of the unit of the vertical cavity surface emitting laser positioned near the center of the vertical cavity surface emitting laser array is still higher than the junction temperature of the unit of the vertical cavity surface emitting laser positioned at the outer side of the vertical cavity surface emitting laser array, and the light emitting power distribution cannot be changed from the essence; meanwhile, the water cooling device and the heat dissipation plate occupy a certain space, which is not favorable for high integration of the vertical cavity surface emitting laser unit in the vertical cavity surface emitting laser array. For the mesa layout design of the vertical cavity surface emitting laser units, the uneven distribution of junction temperature is improved by weakening the thermal coupling effect among the vertical cavity surface emitting laser units, and further the uniformity of the light output power of the vertical cavity surface emitting laser array is improved. However, the design can significantly increase the chip area of the vertical cavity surface emitting laser array, which is not beneficial to the high integration of the vertical cavity surface emitting laser array; meanwhile, the design method of the non-uniform mesa arrangement of the vertical cavity surface emitting laser array is too complex and has no universality.
Disclosure of Invention
The embodiment of the invention provides a vertical cavity surface emitting laser array with uniform light emitting power and a manufacturing method thereof, which are used for solving the defect that a vertical cavity surface emitting laser unit cannot be highly integrated in order to realize uniform light emitting power in the prior art and realizing high integration of the vertical cavity surface emitting laser unit and uniform distribution of the light emitting power.
The embodiment of the invention provides a vertical cavity surface emitting laser array with uniform light emitting power, which comprises: a plurality of vertical cavity surface emitting laser units;
for any two vertical cavity surface emitting laser units, the resistance of the first vertical cavity surface emitting laser unit is greater than the resistance of the second vertical cavity surface emitting laser unit;
in any two vertical cavity surface emitting laser units, the distance between the first vertical cavity surface emitting laser unit and the center of the vertical cavity surface emitting laser array is smaller than the distance between the second vertical cavity surface emitting laser unit and the center of the vertical cavity surface emitting laser array.
According to the vertical cavity surface emitting laser array with uniform light emitting power of one embodiment of the invention, the vertical cavity surface emitting laser unit comprises: a P electrode, a thin film resistor and a closed annular hole surrounding the center of the vertical cavity surface emitting laser unit;
the thin film resistor is positioned below the P electrode and is in contact with the P electrode;
the closed annular hole is formed by etching the P electrode, and the P electrode is divided into two parts which are not directly connected;
wherein, for any two vertical cavity surface emitting laser units, the width of the closed annular hole of the first vertical cavity surface emitting laser unit is greater than the width of the closed annular hole of the second vertical cavity surface emitting laser unit.
According to the vertical cavity surface emitting laser array with uniform light emitting power of one embodiment of the invention, the vertical cavity surface emitting laser unit comprises: an N substrate;
for any two vertical cavity surface emitting laser units, the doping concentration of the N substrate of the first vertical cavity surface emitting laser unit is less than the doping concentration of the N substrate of the second vertical cavity surface emitting laser unit.
According to the vertical cavity surface emitting laser array with uniform light emitting power of one embodiment of the invention, the vertical cavity surface emitting laser unit comprises: an N substrate;
for any two vertical cavity surface emitting laser units, the substrate thickness of the N substrate of the first vertical cavity surface emitting laser unit is greater than the substrate thickness of the N substrate of the second vertical cavity surface emitting laser unit.
The vertical cavity surface emitting laser array with uniform light emitting power according to one embodiment of the invention comprises: constant voltage power supply module.
The embodiment of the invention also provides a manufacturing method of the vertical cavity surface emitting laser array with uniform light emitting power, which comprises the following steps:
preparing a thin film resistor in contact with the P electrode below the P electrode and controlling the size of additional resistors provided by the thin film resistor of the vertical cavity surface emitting laser units at different positions in the vertical cavity surface emitting laser array, implanting impurity ions of different concentrations into N substrate ions below the vertical cavity surface emitting laser units at different positions in the vertical cavity surface emitting laser array, and depositing N substrates of different thicknesses below the vertical cavity surface emitting laser units at different positions in the vertical cavity surface emitting laser array by any of a plurality of manufacturing methods, so that the resistance of a first vertical cavity surface emitting laser unit is greater than that of a second vertical cavity surface emitting laser unit for any two vertical cavity surface emitting laser units;
in any two vertical cavity surface emitting laser units, the distance between the first vertical cavity surface emitting laser unit and the center of the vertical cavity surface emitting laser array is smaller than the distance between the second vertical cavity surface emitting laser unit and the center of the vertical cavity surface emitting laser array.
According to one embodiment of the present invention, a method for manufacturing a vcsel array with uniform optical power includes the steps of preparing a thin film resistor in contact with a P electrode below the P electrode and controlling the size of additional resistors provided by the thin film resistor of vcsel units at different positions in the vcsel array, including:
after a thin film resistor which is in contact with the P electrode is prepared below the P electrode, the P electrode is etched, so that a closed annular hole is formed around the center of the vertical cavity surface emitting laser unit, and the P electrode is divided into two parts which are not directly connected;
wherein, for any two vertical cavity surface emitting laser units, the width of the closed annular hole of the first vertical cavity surface emitting laser unit is greater than the width of the closed annular hole of the second vertical cavity surface emitting laser unit.
According to the method for manufacturing a vertical cavity surface emitting laser array with uniform light output power of an embodiment of the present invention, implanting impurity ions with different concentrations into N substrate ions below vertical cavity surface emitting laser units located at different positions in the vertical cavity surface emitting laser array specifically includes:
for any two vertical cavity surface emitting laser units, injecting first concentration impurity ions into N substrate ions of a first vertical cavity surface emitting laser unit, and injecting second concentration impurity ions into N substrate ions of a second vertical cavity surface emitting laser unit;
wherein the first concentration of impurity ions is less than the second concentration of impurity ions.
According to the method for manufacturing a vertical cavity surface emitting laser array with uniform light output power of an embodiment of the present invention, the depositing N substrates with different thicknesses below the vertical cavity surface emitting laser units located at different positions in the vertical cavity surface emitting laser array specifically includes:
for any two vertical cavity surface emitting laser units, depositing an N substrate with a first thickness below the first vertical cavity surface emitting laser unit, and depositing an N substrate with a second thickness below the second vertical cavity surface emitting laser unit;
wherein the first thickness is greater than the second thickness.
The vertical cavity surface emitting laser array with uniform light emitting power and the manufacturing method thereof provided by the embodiment of the invention have the advantages that any two vertical cavity surface emitting laser units of the vertical cavity surface emitting laser array have larger resistance closer to the center of the vertical cavity surface emitting laser array, the corresponding reduction of junction voltage drop is compensated through the increase of the resistance voltage drop of the vertical cavity surface emitting laser units at different positions, the real-time dynamic adjustment of the current flowing into each vertical cavity surface emitting laser unit can be realized, the uneven junction temperature distribution in the vertical cavity surface emitting laser array can be effectively improved on the basis of the high integration of the vertical cavity surface emitting laser units, the increase of the area of the vertical cavity surface emitting laser array and the change of the original table surface arrangement design of the vertical cavity surface emitting laser array, and the current in the vertical cavity surface emitting laser array can be in a relatively stable state, the uniformity and the stability of the light-emitting power of the vertical cavity surface emitting laser array can be improved, and the light-emitting power of the vertical cavity surface emitting laser array can be effectively improved.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and those skilled in the art can also obtain other drawings according to the drawings without creative efforts.
FIG. 1 is a top view of an array of VCSELs provided by an embodiment of the invention;
FIG. 2 is a top view of an array of VCSELs provided by an embodiment of the invention;
FIG. 3 is a cross-sectional view taken along the line A-A of the VCSEL array provided in FIG. 2;
FIG. 4 is a cross-sectional view taken in the direction B-B of an array of VCSELs as provided in FIG. 2;
FIG. 5 is a graph comparing the peak temperature of each cell of an VCSEL array provided by an embodiment of the present invention with that of a conventional VCSEL array;
FIG. 6 is a graph comparing the output power of a VCSEL array provided by an embodiment of the invention with that of a conventional VCSEL array;
FIG. 7 is a graph comparing the output power of a VCSEL array provided by an embodiment of the invention with that of a conventional VCSEL array;
FIG. 8 is a sectional view taken along the line A-A of a VCSEL unit in the VCSEL array provided in FIG. 1.
Detailed Description
In the description of the embodiments of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, and are only for convenience in describing the embodiments of the present invention and simplifying the description, but do not indicate or imply that the referred devices or elements must have specific orientations, be configured in specific orientations, and operate, and thus, should not be construed as limiting the embodiments of the present invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.
In the description of the embodiments of the present invention, it should be noted that, unless explicitly stated or limited otherwise, the terms "mounted," "connected," and "connected" are to be construed broadly, and may be, for example, fixedly connected, detachably connected, or integrally connected; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. Specific meanings of the above terms in the embodiments of the present invention can be understood in specific cases by those of ordinary skill in the art.
In order to overcome the above problems in the prior art, embodiments of the present invention provide a vertical cavity surface emitting laser array with uniform light output power and a manufacturing method thereof, and the inventive concept is that any two vertical cavity surface emitting laser units in the vertical cavity surface emitting laser array have a larger resistance of the vertical cavity surface emitting laser unit closer to the center of the vertical cavity surface emitting laser array, and the uniformity and stability of the light output power of the vertical cavity surface emitting laser array can be improved on the basis of not affecting the high integration of the vertical cavity surface emitting laser units.
Fig. 1 is a schematic top view of a vertical cavity surface emitting laser array according to an embodiment of the present invention. A vertical cavity surface emitting laser array according to an embodiment of the present invention is described below with reference to fig. 1. As shown in fig. 1, the vertical cavity surface emitting laser array includes: a plurality of vertical cavity surface emitting laser units.
Specifically, the arrangement of the vertical cavity surface emitting laser units in the vertical cavity surface emitting laser array is explained taking 3 × 3 as an example. As shown in fig. 1, the vcsel array includes 9 vcsel units, wherein the vcsel array in the first row includes: a vertical cavity surface emitting laser unit 111, a vertical cavity surface emitting laser unit 112, and a vertical cavity surface emitting laser unit 113, the second row of the vertical cavity surface emitting laser array including: a vertical cavity surface emitting laser unit 121, a vertical cavity surface emitting laser unit 122, and a vertical cavity surface emitting laser unit 123, the third row of the vertical cavity surface emitting laser array including: a vertical cavity surface emitting laser unit 131, a vertical cavity surface emitting laser unit 132, and a vertical cavity surface emitting laser unit 133.
The vertical cavity surface emitting laser unit 122 is located at the center of the vertical cavity surface emitting laser array, and the distances from the vertical cavity surface emitting laser unit 112, the vertical cavity surface emitting laser unit 121, the vertical cavity surface emitting laser unit 123, and the vertical cavity surface emitting laser unit 132 to the center of the vertical cavity surface emitting laser array are smaller than the distances from the vertical cavity surface emitting laser unit 111, the vertical cavity surface emitting laser unit 113, the vertical cavity surface emitting laser units 131 and 133 to the center of the vertical cavity surface emitting laser array.
It should be noted that the vertical cavity surface emitting laser units in the vertical cavity surface emitting laser array can be arranged in various ways. The arrangement of the vertical cavity surface emitting laser units in the vertical cavity surface emitting laser array and the number of the vertical cavity surface emitting laser units may be determined according to actual situations, and are not particularly limited in the embodiment of the present invention.
For any two vertical cavity surface emitting laser units, the resistance of the first vertical cavity surface emitting laser unit is greater than the resistance of the second vertical cavity surface emitting laser unit.
In any two vertical cavity surface emitting laser units, the distance between the first vertical cavity surface emitting laser unit and the center of the vertical cavity surface emitting laser array is smaller than the distance between the second vertical cavity surface emitting laser unit and the center of the vertical cavity surface emitting laser array.
In the vertical cavity surface emitting laser array according to the embodiment of the present invention, the resistance of the vertical cavity surface emitting laser unit located near the center of the vertical cavity surface emitting laser array is the largest, the resistance of the vertical cavity surface emitting laser unit is gradually decreased with the increase of the distance from the vertical cavity surface emitting laser unit to the center of the vertical cavity surface emitting laser array, and the resistance of the vertical cavity surface emitting laser unit distributed outside the vertical cavity surface emitting laser array is the smallest.
The resistance of the vertical cavity surface emitting laser unit 122 is the largest, and the resistances of the vertical cavity surface emitting laser unit 112, the vertical cavity surface emitting laser unit 121, the vertical cavity surface emitting laser unit 123, and the vertical cavity surface emitting laser unit 132 are equal and smaller than the resistance of the vertical cavity surface emitting laser unit 122. The resistances of the vertical cavity surface emitting laser unit 111, the vertical cavity surface emitting laser unit 113, the vertical cavity surface emitting laser unit 131, and the vertical cavity surface emitting laser unit 133 are equal to each other, and are smaller than the resistances of the vertical cavity surface emitting laser unit 112, the vertical cavity surface emitting laser unit 121, the vertical cavity surface emitting laser unit 123, and the vertical cavity surface emitting laser unit 132.
Different VCSEL units in the VCSEL array can have different resistances in various ways, for example: additional resistors with different sizes are added to the vertical cavity surface emitting laser units in the vertical cavity surface emitting laser array or the total resistance of the vertical cavity surface emitting laser units is adjusted.
It should be noted that the resistance of the vcsel unit is the sum of the total resistance and the additional resistance of the vcsel unit itself.
In the working process of the vertical cavity surface emitting laser array, a constant voltage power supply supplies power to the vertical cavity surface emitting laser array. Under the condition that the external voltage provided by the constant voltage power supply is not changed, the increase of the resistance voltage drop of the vertical cavity surface emitting laser unit in the vertical cavity surface emitting laser array due to the increase of the current can compensate the decrease of the junction voltage drop due to the increase of the current.
It is understood that the first VCSEL unit is closer to the center of the VCSEL array and the second VCSEL unit is farther from the center of the VCSEL array.
For any two vertical cavity surface emitting laser units, the resistance of the first vertical cavity surface emitting laser unit is larger, so that the reduction of the junction voltage drop of the first vertical cavity surface emitting laser unit is larger, and the increase of the resistance voltage drop is larger. The resistance of the second vertical cavity surface emitting laser unit is smaller, the reduction amount of the junction voltage drop of the second vertical cavity surface emitting laser unit is smaller, and the increase amount of the resistance voltage drop is smaller. The compensation of the voltage drop of the first and second vertical cavity surface emitting laser units to the junction voltage drop can make the current flowing into the first and second vertical cavity surface emitting laser units in a relatively stable state.
It should be noted that, in the embodiments of the present invention, the deviation of the light output powers of any two vertical cavity surface emitting laser units does not exceed the preset range by reasonably controlling the size of the resistor of each vertical cavity surface emitting laser unit in the vertical cavity surface emitting laser array.
It should be noted that the method for adding additional resistors with different sizes to the vertical cavity surface emitting laser units in the vertical cavity surface emitting laser array in the embodiment of the present invention does not affect the high integration of the vertical cavity surface emitting laser units in the vertical cavity surface emitting laser array and the original mesa configuration design of the vertical cavity surface emitting laser array.
The resistances of all the vertical cavity surface emitting laser units in the conventional vertical cavity surface emitting laser array are the same, and the heat generated by each vertical cavity surface emitting laser unit in the working process is thermally coupled with the vertical cavity surface emitting laser unit, so that the temperature distribution in the vertical cavity surface emitting laser array is not uniform under the combined action.
Junction temperature of the vertical cavity surface emitting laser units near the center of the vertical cavity surface emitting laser array is higher than that of the vertical cavity surface emitting laser units distributed outside the vertical cavity surface emitting laser array.
Specifically, conventional vertical cavity surface emitting laser arrays are powered with a constant current power supply.
The constant current power supply is adopted to provide external current for the vertical cavity surface emitting laser array, and considering that the current has a positive temperature coefficient, the current of the vertical cavity surface emitting laser flowing into the vertical cavity surface emitting laser unit near the center of the vertical cavity surface emitting laser array is continuously increased, the heat of the vertical cavity surface emitting laser array is gradually gathered near the center of the vertical cavity surface emitting laser array, and the steps are repeated, so that the light emitting power of the vertical cavity surface emitting laser unit near the center of the vertical cavity surface emitting laser array is rapidly reduced due to overlarge current, and the thermal roll-off phenomenon occurs.
Accordingly, since the current is gradually concentrated to the vertical cavity surface emitting laser unit located near the center of the vertical cavity surface emitting laser array, the current flowing into the vertical cavity surface emitting laser unit distributed outside the vertical cavity surface emitting laser array becomes gradually smaller, so that the light emitting power of the vertical cavity surface emitting laser unit distributed outside the vertical cavity surface emitting laser array is reduced due to insufficient current, thereby causing the light emitting power distribution of the vertical cavity surface emitting laser array to be more uneven, and further reducing the stability of the vertical cavity surface emitting laser array.
In view of the above-mentioned drawbacks of the conventional vcsel array, the embodiment of the present invention employs a constant voltage power supply to supply power to the vcsel array.
The constant voltage power supply provides constant external voltage for the vertical cavity surface emitting laser array, and the reduction of the junction voltage drop of each vertical cavity surface emitting laser unit along with the temperature rise and the increase of the resistance voltage drop of each vertical cavity surface emitting laser unit can be mutually compensated, so that the current flowing into each laser unit in the vertical cavity surface emitting laser array tends to be stable, the concentration of the current and the temperature is effectively restrained, the uniform distribution of the light emitting power, the temperature and the current is realized, and the light emitting power of the vertical cavity surface emitting laser array can be uniform and stable.
In the embodiment of the invention, the resistance of any two vertical cavity surface emitting laser units of the vertical cavity surface emitting laser array is larger, the voltage drop of the resistance of the vertical cavity surface emitting laser units at different positions is increased to compensate the corresponding reduction of the junction voltage drop, so that the real-time dynamic adjustment of the current flowing into each vertical cavity surface emitting laser unit can be realized, the uneven junction temperature distribution in the vertical cavity surface emitting laser array can be effectively improved on the basis of the high integration of the vertical cavity surface emitting laser units, the increase of the area of the vertical cavity surface emitting laser array and the change of the original mesa arrangement design of the vertical cavity surface emitting laser array, the current in the vertical cavity surface emitting laser array can be in a relatively stable state, and the uniformity and the stability of the light emitting power of the vertical cavity surface emitting laser array can be improved, and further the light emitting power of the vertical cavity surface emitting laser array can be effectively improved.
Fig. 2 is a top view of an array of vertical cavity surface emitting lasers according to an embodiment of the present invention. Fig. 3 is a sectional view taken along the direction a-a of the vcsel array provided in fig. 2. Fig. 4 is a cross-sectional view taken in the direction B-B of the vcsel array provided in fig. 2. A vertical cavity surface emitting laser array according to an embodiment of the present invention will be described with reference to fig. 2 to 4. As shown in fig. 2, the vertical cavity surface emitting laser unit includes: a P-electrode 301, a thin film resistor 302, and a closed loop hole 303 surrounding the center of the vcsel unit.
The vertical cavity surface emitting laser unit further includes: a silicon dioxide passivation layer 304, a P-DBR305, an oxide confinement layer 306, a quantum well active region 307, an N-DBR308, an N-substrate 309, and an N-electrode 310.
The P electrode 301 is located on the uppermost layer of the vertical cavity surface emitting laser unit and can conduct electricity.
The current supplied from the constant voltage power supply can flow into the elements such as the P-DBR305, the N-DBR308, and the N substrate 309 through the P electrode.
The P electrode 301 is generally a metal electrode, and can be obtained by a production method such as sputtering or evaporation.
The thin film resistor 302 is a resistor having a resistance film layer made of a resistance material with a certain resistivity, and the resistance value of the thin film resistor 302 is adjusted by adjusting the material composition of the resistance material and the thickness of the resistance film layer.
The thin film resistor 302 has the advantages of small volume, low noise and good stability, and can be obtained by vapor deposition and other preparation methods.
It should be noted that the resistance of the thin film resistor 302 is small, and the generated heat has negligible effect on the junction temperature distribution of the vcsel array. The thin film resistor 302 has a small size, and does not affect the original mesa layout design of the vcsel array and the integration of the vcsel units, such as a TiN thin film resistor.
The closed annular hole 303 around the center of the vertical cavity surface emitting laser unit may be a closed annular hole of a fixed width of an arbitrary shape in central symmetry.
The thin film resistor 302 is located below the P electrode 301 and is in contact with the P electrode 301.
As shown in fig. 3 or 4, the thin film resistor 302 is located between the P electrode 301 and the silicon dioxide passivation layer 304, the P-DBR305, the oxide confinement layer 306 or the quantum well active region 307, and is in contact with the P electrode 301 and the silicon dioxide passivation layer 304, the P-DBR305, the oxide confinement layer 306 or the quantum well active region 307, respectively. The current on the P electrode can flow into the thin film resistor 302.
The closed loop hole 303 is formed by etching the P electrode, and divides the P electrode into two parts which are not directly connected.
For any two vertical cavity surface emitting laser units, the width of the closed annular hole 303 of the first vertical cavity surface emitting laser unit is greater than the width of the closed annular hole 303 of the second vertical cavity surface emitting laser unit.
If the vcsel unit does not have the closed annular hole 303, the current supplied from the constant voltage power supply flows into the vcsel unit internal structure through the P-electrode.
If the P electrode is divided into two parts which are not directly connected by etching the P electrode on the outermost layer of the vcsel unit to form the closed annular hole 303 surrounding the center of the vcsel unit, the current supplied by the constant voltage power supply cannot directly flow into the internal structure of the vcsel unit through the P electrode. Under the action of an applied voltage, current reaches the other part of the P electrode through the thin film resistor 302 which is in contact with the P electrode 301 below the closed annular hole 303, so that the two parts of the P electrode 301 which are not directly connected are communicated, and the current can flow into the internal structure of the vertical cavity surface emitting laser unit.
The current flows through the thin film resistor 302 in contact with the P electrode 301 below the closed annular hole 303 surrounding the center of the vcsel unit, which corresponds to adding an additional resistor to the vcsel unit. The resistance value of the additional resistor is related to the width of the closed loop hole 303.
Specifically, the width of the closed loop hole 303 is the length of the thin film resistor 302 through which current needs to pass, and the longer the length of the thin film resistor 302 through which current needs to pass, the larger the additional resistance added by the vcsel unit.
The width of the closed annular hole 303 of the vertical cavity surface emitting laser unit near the center of the vertical cavity surface emitting laser array is the largest, the width of the closed annular hole 303 of the vertical cavity surface emitting laser unit decreases with the increase of the distance from the vertical cavity surface emitting laser unit to the center of the vertical cavity surface emitting laser array, and the vertical cavity surface emitting laser unit outside the vertical cavity surface emitting laser array may not have the closed annular hole 303. Therefore, the additional resistance of the vertical cavity surface emitting laser unit near the center of the vertical cavity surface emitting laser array is the largest, the additional resistance of the vertical cavity surface emitting laser unit decreases with increasing distance of the vertical cavity surface emitting laser unit from the center of the vertical cavity surface emitting laser array, and the vertical cavity surface emitting laser unit outside the vertical cavity surface emitting laser array may not have the additional resistance.
It should be noted that the vertical cavity surface emitting laser unit outside the vertical cavity surface emitting laser array may not have the closed annular hole 303, and the width of the closed annular hole 303 of the vertical cavity surface emitting laser unit outside the vertical cavity surface emitting laser array is 0.
Specifically, as shown in fig. 2 to 4, the width of the closed annular hole 303 of the vcsel unit 122 is L1The widths of the closed annular holes 303 of the VCSEL unit 112, the VCSEL unit 121, the VCSEL unit 123, and the VCSEL unit 132 are L2，L1Greater than L2. The vertical cavity surface emitting laser unit 111, the vertical cavity surface emitting laser unit 113, the vertical cavity surface emitting laser unit 131, and the vertical cavity surface emitting laser unit 133 do not have the closed annular hole 303.
Thus, vertical cavity surface emission laserAdditional resistance R of the optical unit 1221Additional resistors R of the VCSEL unit 112, the VCSEL unit 121, the VCSEL unit 123, and the VCSEL unit 1322，R1Greater than R2. The vertical cavity surface emitting laser unit 111, the vertical cavity surface emitting laser unit 113, the vertical cavity surface emitting laser unit 131, and the vertical cavity surface emitting laser unit 133 have no additional resistance.
In the examples of the present invention, R1Is 3 omega, R22 omega, each vcsel cell has its own total resistance of about 30 omega. The resistance of the vertical cavity surface emitting laser unit 122 is 33 ohms, the resistances of the vertical cavity surface emitting laser unit 112, the vertical cavity surface emitting laser unit 121, the vertical cavity surface emitting laser unit 123, and the vertical cavity surface emitting laser unit 132 are 32 Ω, and the resistances of the vertical cavity surface emitting laser unit 111, the vertical cavity surface emitting laser unit 113, the vertical cavity surface emitting laser unit 131, and the vertical cavity surface emitting laser unit are 30 Ω.
It should be noted that the current needs to pass through the length of the thin film resistor 302, and the resistance of the thin film resistor 302 at the length portion is smaller than the resistance of the thin film resistor 302 at the thickness portion. The current direction is always towards the direction of smaller resistance, depending on the nature of the current conduction. Therefore, after the current flows to one of the two segments of the P electrode 301 which are not directly connected, the current passes through the thin film resistor 302 which is below the closed annular hole 303 and is in contact with the P electrode 301 to reach the other part of the P electrode, and does not pass through the thin film resistor 302 and directly enter the internal structure of the vertical cavity surface emitting laser unit.
FIG. 5 is a graph comparing the peak temperature of each cell of an array of VCSELs provided by an embodiment of the invention with that of a conventional VCSEL array. As shown in fig. 5, the maximum peak-to-peak temperature difference between the cells of the conventional vertical plane emission laser array is as high as 34.6 ℃ when the applied bias voltage is 1.86V, whereas the maximum peak-to-peak temperature difference between the cells in the embodiment of the present invention is only 10.8 ℃, which is an improvement of 68.8%.
FIG. 6 is a graph comparing the output power of a VCSEL array provided by an embodiment of the invention with that of a conventional VCSEL array. As shown in fig. 6, the maximum high-low light-emitting power difference between the units of the vertical cavity surface emitting laser array in the embodiment of the present invention is only 0.97mW, which is improved by 47.3% compared with the maximum high-low light-emitting power difference of 1.84mW of the conventional vertical cavity surface emitting laser array, and further, the light-emitting power uniformity of each unit in the embodiment of the present invention is significantly improved. Compared with each vertical cavity surface emitting laser unit in the conventional vertical cavity surface emitting laser array, each vertical cavity surface emitting laser unit in the vertical cavity surface emitting laser array provided by the embodiment of the invention can keep the light emitting power unchanged or improve the light emitting power.
FIG. 7 is a graph comparing the output power of a VCSEL array provided by an embodiment of the invention with that of a conventional VCSEL array. As can be seen from FIG. 7, the maximum light-exiting power of the VCSEL array of the embodiment of the invention reaches 105.71mW when the applied bias voltage is 1.86V, while the maximum light-exiting power of the conventional VCSEL array is 104.34mW when the applied bias voltage is 1.82V, so that the maximum light-exiting power is increased by 1.31%.
The embodiment of the invention introduces the thin film resistor contacted with the P electrode below the P electrode, forms a closed annular hole by etching the P electrode surrounding the vertical cavity surface emitting laser unit, divides the P electrode into two parts which are not directly connected, so that the width of the closed annular hole of the vertical cavity surface emitting laser unit closer to the center of the vertical cavity surface emitting laser array of any two vertical cavity surface emitting laser units is larger, additional resistors with different sizes are added to the corresponding vertical cavity surface emitting laser units, the resistor of each vertical cavity surface emitting laser unit is controlled by introducing the thin film resistor and controlling the width of the closed annular hole, the introduced thin film resistor and the etched closed annular hole do not influence the high integration of the vertical cavity surface emitting laser unit, the area of the vertical cavity surface emitting laser array is not increased, and the original mesa arrangement design of the vertical cavity surface emitting laser array is not changed, the uniformity and the stability of the light emitting power of the vertical cavity surface emitting laser array can be improved.
FIG. 8 is a sectional view taken along the line A-A of a VCSEL unit in the VCSEL array provided in FIG. 1. A vertical cavity surface emitting laser array according to an embodiment of the present invention is described below with reference to fig. 8. As shown in fig. 8, the vertical cavity surface emitting laser unit includes: n substrate 309.
The vertical cavity surface emitting laser unit further includes: a silicon dioxide passivation layer 304, a P-DBR305, an oxide confinement layer 306, a quantum well active region 307, an N-DBR308, an N-substrate 309, and an N-electrode 310.
The N substrate 309 has a particular crystal plane structure and appropriate electrical, optical, and mechanical properties to support other upper layer structures in the vcsel unit.
The N substrate 811 is an N substrate of a region immediately below the vertical cavity surface emitting laser unit.
For any two VCSEL units, the doping concentration of the N substrate 811 of the first VCSEL unit is less than the doping concentration of the N substrate 310 of the second VCSEL unit.
By reducing the doping concentration of the N-substrate 811 directly below the vertical cavity surface emitting laser unit, the resistance value of the N-substrate 811 can be increased, which is equivalent to increasing the total resistance of the vertical cavity surface emitting laser unit itself, i.e., increasing the resistance of the vertical cavity surface emitting laser unit. The doping concentration of the N-substrate 811 is inversely related to the resistance of the vertical cavity surface emitting laser unit, and the lower the doping concentration of the N-substrate 811 directly below the vertical cavity surface emitting laser unit, the greater the resistance of the vertical cavity surface emitting laser unit.
The doping concentration of the N substrate 811 of the vertical cavity surface emitting laser unit near the center of the vertical cavity surface emitting laser array is the smallest, and the doping concentration of the N substrate 811 of the vertical cavity surface emitting laser unit increases as the distance of the vertical cavity surface emitting laser unit from the center of the vertical cavity surface emitting laser array increases. Therefore, the resistance of the vertical cavity surface emitting laser unit near the center of the vertical cavity surface emitting laser array is the largest, and the resistance of the vertical cavity surface emitting laser unit decreases as the distance of the vertical cavity surface emitting laser unit from the center of the vertical cavity surface emitting laser array increases.
Note that the N substrate of the conventional vertical cavity surface emitting laser unit is a GaAs substrate, the impurity ions are N-type impurities (As), and the doping concentration is 1018cm-3. In the embodiment of the present invention, the impurity ions are N-type impurities (As), and the doping concentration of the N-substrate 811 under the vertical cavity surface emitting laser unit near the center of the vertical cavity surface emitting laser array may be 5 × 1017cm-3The doping concentration of the N substrate 811 located under the VCSEL units outside the VCSEL array may be 1018cm-3。
In the embodiment of the invention, any two vertical cavity surface emitting laser units of the vertical cavity surface emitting laser array have lower doping concentration of the N substrate below the vertical cavity surface emitting laser unit closer to the center of the vertical cavity surface emitting laser array, the resistance of each vertical cavity surface emitting laser unit can be controlled by controlling the doping concentration of the N substrate below the vertical cavity surface emitting laser units at different positions, and the uniformity and the stability of the light emitting power of the vertical cavity surface emitting laser array can be improved on the basis of not changing the original structure of the vertical cavity surface emitting laser array.
Based on the content of the above embodiments, the vertical cavity surface emitting laser unit includes: n substrate 309.
The N substrate 309 has a particular crystal plane structure and appropriate electrical, optical, and mechanical properties to support other upper layer structures in the vcsel unit.
The N substrate 811 is an N substrate of a region immediately below the vertical cavity surface emitting laser unit.
For any two vertical cavity surface emitting laser units, the substrate thickness of the N substrate of the first vertical cavity surface emitting laser unit is greater than the substrate thickness of the N substrate of the second vertical cavity surface emitting laser unit.
By increasing the substrate thickness of the N substrate 811 immediately below the vertical cavity surface emitting laser unit, the resistance value of the N substrate 811 can be increased, which is equivalent to increasing the total resistance of the vertical cavity surface emitting laser unit itself, that is, increasing the resistance of the vertical cavity surface emitting laser unit. The substrate thickness of the N substrate 811 is positively correlated with the resistance of the vertical cavity surface emitting laser unit, and the thicker the substrate thickness of the N substrate 811 immediately below the vertical cavity surface emitting laser unit, the larger the resistance of the vertical cavity surface emitting laser unit.
The substrate thickness of the N-substrate 811 of the vertical cavity surface emitting laser unit near the center of the vertical cavity surface emitting laser array is the thickest, and the substrate thickness of the N-substrate 811 of the vertical cavity surface emitting laser unit decreases as the distance of the vertical cavity surface emitting laser unit from the center of the vertical cavity surface emitting laser array increases. Therefore, the resistance of the vertical cavity surface emitting laser unit near the center of the vertical cavity surface emitting laser array is the largest, and the resistance of the vertical cavity surface emitting laser unit decreases as the distance of the vertical cavity surface emitting laser unit from the center of the vertical cavity surface emitting laser array increases.
In the embodiment of the invention, the substrate thickness of the N substrate below the vertical cavity surface emitting laser unit closer to the center of the vertical cavity surface emitting laser array is thicker, the resistance of each vertical cavity surface emitting laser unit can be controlled by controlling the substrate thickness of the N substrate below the vertical cavity surface emitting laser unit at different positions, and the uniformity and the stability of the light emitting power of the vertical cavity surface emitting laser array can be improved on the basis of not changing the original structure of the vertical cavity surface emitting laser array.
Based on the content of the above embodiments, the vertical cavity surface emitting laser array includes: constant voltage power supply module.
The conventional vertical cavity surface emitting laser adopts a constant current power supply for power supply.
The constant current power supply is adopted to provide external current for the vertical cavity surface emitting laser array, so that the vertical cavity surface emitting laser array has a thermal roll-off phenomenon, the light emitting power distribution of the vertical cavity surface emitting laser array is further uneven, and the stability of the vertical cavity surface emitting laser array is reduced.
In view of the above-mentioned drawbacks of the conventional vcsel array, the constant voltage power supply module in the embodiment of the invention can provide a constant voltage to the vcsel array.
Specifically, the constant voltage power supply module can be used as a power supply, is not connected with an external power supply, and directly provides constant external voltage for each vertical cavity surface emitting laser.
The constant voltage power supply module can also be used for converting electric energy input by an external power supply into constant voltage by the external power supply to supply power to each straight cavity surface emitting laser.
The constant voltage power supply module of the vertical cavity surface emitting laser array in the embodiment of the invention can provide constant voltage for the vertical cavity surface emitting laser array, can make the reduction of the junction voltage drop of each vertical cavity surface emitting laser unit along with the temperature rise compensate with the increase of the resistance voltage drop of each vertical cavity surface emitting laser unit, can effectively restrain the concentration of current and temperature, can make the current in the vertical cavity surface emitting laser array in a relatively stable state, and can improve the uniformity and the stability of the light output power of the vertical cavity surface emitting laser array.
An embodiment of the present invention further provides a method for manufacturing a vertical cavity surface emitting laser array, including: the resistance of the first vertical cavity surface emitting laser unit is larger than that of the second vertical cavity surface emitting laser unit for any two vertical cavity surface emitting laser units by preparing a thin film resistor contacted with the P electrode below the P electrode, controlling the size of additional resistance provided by the thin film resistor of the vertical cavity surface emitting laser unit at different positions in the vertical cavity surface emitting laser array, implanting impurity ions with different concentrations into N substrate ions below the vertical cavity surface emitting laser unit at different positions in the vertical cavity surface emitting laser array, and depositing N substrates with different thicknesses below the vertical cavity surface emitting laser unit at different positions in the vertical cavity surface emitting laser array.
In any two vertical cavity surface emitting laser units, the distance between the first vertical cavity surface emitting laser unit and the center of the vertical cavity surface emitting laser array is smaller than the distance between the second vertical cavity surface emitting laser unit and the center of the vertical cavity surface emitting laser array.
The vertical cavity surface emitting laser array may be prepared by one of the following vertical cavity surface emitting laser array manufacturing methods, or may be prepared by combining a plurality of the above vertical cavity surface emitting laser array manufacturing methods.
Specifically, a layer of thin film resistor can be prepared on the existing internal structure of the vertical cavity surface emitting laser unit by a preparation method such as vapor deposition, and then a P electrode can be prepared on the thin film resistor by a preparation method such as sputtering or vapor deposition, so that the existing internal structure of the vertical cavity surface emitting laser unit, the thin film resistor and the P electrode are in contact with each other. And the size of the additional resistance provided by the thin film resistor can be controlled, so that for any two vertical cavity surface emitting laser units, the additional resistance provided by the thin film resistor of the first vertical cavity surface emitting laser unit closer to the center of the vertical cavity surface emitting laser array is larger than the additional resistance provided by the thin film resistor of the second vertical cavity surface emitting laser unit farther from the center of the vertical cavity surface emitting laser array. Therefore, the resistance of the first vertical cavity surface emitting laser unit closer to the center of the vertical cavity surface emitting laser array is larger than the resistance of the second vertical cavity surface emitting laser unit farther from the center of the vertical cavity surface emitting laser array.
Impurity ions of different concentrations can be ion-implanted into the N substrate below the vertical cavity surface emitting laser units located at different positions in the vertical cavity surface emitting laser array through a preparation method such as ion implantation, so that for any two vertical cavity surface emitting laser units, the first vertical cavity surface emitting laser unit closer to the center of the vertical cavity surface emitting laser array increases the self total resistance by reducing the doping concentration of the N substrate, and the second vertical cavity surface emitting laser unit farther from the center of the vertical cavity surface emitting laser array increases the self total resistance by reducing the doping concentration of the N substrate. Therefore, the resistance of the first vertical cavity surface emitting laser unit closer to the center of the vertical cavity surface emitting laser array is larger than the resistance of the second vertical cavity surface emitting laser unit farther from the center of the vertical cavity surface emitting laser array.
N substrates with different thicknesses can be deposited below the vertical cavity surface emitting laser units located at different positions in the vertical cavity surface emitting laser array by a preparation method of prolonging deposition time and the like, so that for any two vertical cavity surface emitting laser units, the first vertical cavity surface emitting laser unit closer to the center of the vertical cavity surface emitting laser array increases the own total resistance through the increased substrate thickness of the N substrates, and the second vertical cavity surface emitting laser unit farther from the center of the vertical cavity surface emitting laser array increases the own total resistance through the increased substrate thickness of the N substrates. Therefore, the resistance of the first vertical cavity surface emitting laser unit closer to the center of the vertical cavity surface emitting laser array is larger than the resistance of the second vertical cavity surface emitting laser unit farther from the center of the vertical cavity surface emitting laser array.
It should be noted that the resistance of the vcsel unit is the sum of the total resistance and the additional resistance of the vcsel unit itself.
The embodiment of the invention can obtain the vertical cavity surface emitting laser array by preparing the thin film resistor contacted with the P electrode below the electrode and controlling the size of the additional resistor provided by the thin film resistor, implanting impurity ions with different concentrations into N substrate ions below the vertical cavity surface emitting laser units positioned at different positions in the vertical cavity surface emitting laser array by a preparation method such as ion implantation and depositing N substrates with different thicknesses below the vertical cavity surface emitting laser units positioned at different positions in the vertical cavity surface emitting laser array by a preparation method such as deposition time extension or the combination of the preparation methods, has simple manufacturing method, mature technology, strong controllability and lower input cost, does not influence the high integration of the vertical cavity surface emitting laser units in the manufacturing process, does not increase the area of the vertical cavity surface emitting laser array and does not change the original mesa arrangement design of the vertical cavity surface emitting laser array, the manufactured vertical cavity surface emitting laser array has uniform and stable light emitting power.
Based on the content of the foregoing embodiments, preparing a thin film resistor in contact with the P electrode below the P electrode and controlling the magnitude of the additional resistance provided by the thin film resistor of the vcsel unit at different positions in the vcsel array specifically includes:
after a thin film resistor in contact with the P electrode is prepared below the P electrode, the P electrode is etched, so that a closed annular hole is formed around the center of the vertical cavity surface emitting laser unit, and the P electrode is divided into two parts which are not directly connected.
Wherein, for any two vertical cavity surface emitting laser units, the width of the closed ring-shaped hole of the first vertical cavity surface emitting laser unit is larger than that of the closed ring-shaped hole of the second vertical cavity surface emitting laser unit.
After a thin film resistor in contact with the P electrode is prepared below the P electrode, the P electrode can be etched by a method such as photoetching.
The P electrode is divided into two parts which are not directly connected by a closed annular hole which is formed by etching the P electrode on the outermost layer of the vertical cavity surface emitting laser unit and surrounds the center of the vertical cavity surface emitting laser unit, and current provided by the constant voltage power supply cannot directly flow into the internal structure of the vertical cavity surface emitting laser unit through the P electrode. Under the action of an external voltage, current reaches the other part of the P electrode through a thin film resistor which is arranged below the closed annular hole and is in contact with the P electrode, so that the two parts of the P electrode which are not directly connected are communicated, and the current can flow into the internal structure of the vertical cavity surface emitting laser unit.
The current flows through the thin film resistor which is arranged below the closed annular hole surrounding the center of the vertical cavity surface emitting laser unit and is in contact with the P electrode, and the additional resistor is added to the vertical cavity surface emitting laser unit. The magnitude of the additional resistance is related to the width of the closed annular aperture.
Specifically, the width of the closed ring-shaped hole is the length of the thin film resistor through which current needs to pass, and the longer the length of the thin film resistor through which current needs to pass, the larger the resistance value of the additional resistor of the vertical cavity surface emitting laser unit.
The width of the closed annular hole of the vertical cavity surface emitting laser unit near the center of the vertical cavity surface emitting laser array is the largest, the width of the closed annular hole of the vertical cavity surface emitting laser unit is reduced along with the increase of the distance from the vertical cavity surface emitting laser unit to the center of the vertical cavity surface emitting laser array, and the vertical cavity surface emitting laser unit outside the vertical cavity surface emitting laser array can be free of the closed annular hole. Therefore, the additional resistance of the vertical cavity surface emitting laser unit near the center of the vertical cavity surface emitting laser array is the largest, the additional resistance of the vertical cavity surface emitting laser unit decreases with increasing distance of the vertical cavity surface emitting laser unit from the center of the vertical cavity surface emitting laser array, and the vertical cavity surface emitting laser unit outside the vertical cavity surface emitting laser array may not have the additional resistance.
In the embodiment of the invention, the thin film resistor which is in contact with the P electrode is prepared below the P electrode, the P electrode is etched around the center of the vertical cavity surface emitting laser unit by utilizing the photoetching method and other methods, so that a closed annular hole is formed around the center of the vertical cavity surface emitting laser unit, the P electrode is divided into two parts which are not directly connected, so that the width of the closed annular hole of any two vertical cavity surface emitting laser units, the vertical cavity surface emitting laser unit which is closer to the center of the vertical cavity surface emitting laser array is larger, and the corresponding vertical cavity surface emitting laser units are added with the additional resistors with different sizes, so that the vertical cavity surface emitting laser array can be obtained The area of the vertical cavity surface emitting laser array is not increased, the original table surface arrangement design of the vertical cavity surface emitting laser array is not changed, and the light emitting power of the manufactured vertical cavity surface emitting laser array is uniform and stable.
Based on the content of the above embodiments, implanting impurity ions of different concentrations into N substrate ions below vertical cavity surface emitting laser units located at different positions in a vertical cavity surface emitting laser array specifically includes:
for any two vertical cavity surface emitting laser units, first concentration impurity ions are implanted into the N substrate ions of the first vertical cavity surface emitting laser unit, and second concentration impurity ions are implanted into the N substrate ions of the second vertical cavity surface emitting laser unit.
Wherein the first concentration of impurity ions is less than the second concentration of impurity ions.
Specifically, the concentration of impurity ions implanted into the N substrate below the vertical cavity surface emitting laser unit near the center of the vertical cavity surface emitting laser array may be increased as the distance from the vertical cavity surface emitting laser unit to the center of the vertical cavity surface emitting laser array increases.
By reducing the doping concentration of the N substrate directly below the vertical cavity surface emitting laser unit, the resistance value of the N substrate can be increased, which is equivalent to increasing the total resistance of the vertical cavity surface emitting laser unit itself, that is, increasing the resistance of the vertical cavity surface emitting laser unit. The doping concentration of the N substrate is inversely related to the resistance of the vertical cavity surface emitting laser unit, and the lower the doping concentration of the N substrate directly below the vertical cavity surface emitting laser unit, the larger the resistance of the vertical cavity surface emitting laser unit.
Therefore, the resistance of the vertical cavity surface emitting laser unit near the center of the vertical cavity surface emitting laser array is the largest, and the resistance of the vertical cavity surface emitting laser unit decreases as the distance of the vertical cavity surface emitting laser unit from the center of the vertical cavity surface emitting laser array increases.
In the embodiment of the invention, the N substrate below the vertical cavity surface emitting laser unit near the center of the vertical cavity surface emitting laser array is ion implanted with the impurity ions with the minimum concentration by the ion implantation method and the like, the concentration of the ion implanted impurity ions in the N substrate below the vertical cavity surface emitting laser unit is increased along with the increase of the distance between the vertical cavity surface emitting laser unit and the center of the vertical cavity surface emitting laser array, the vertical cavity surface emitting laser array can be obtained, the manufacturing method is simple, the technology is mature, the original structure of the vertical cavity surface emitting laser array is not changed in the manufacturing process, and the light emitting power of the manufactured vertical cavity surface emitting laser array is uniform and stable.
Based on the content of the above embodiments, depositing N substrates with different thicknesses below the vcsel units located at different positions in the vcsel array specifically includes:
for any two VCSEL units, an N substrate of a first thickness is deposited below the first VCSEL unit, and an N substrate of a second thickness is deposited below the second VCSEL unit.
Wherein the first thickness is greater than the second thickness.
Specifically, the N substrate of the maximum thickness may be deposited under the vertical cavity surface emitting laser unit near the center of the vertical cavity surface emitting laser array by a method of extending the deposition time or the like, and the thickness of the N substrate deposited under the vertical cavity surface emitting laser unit decreases as the distance of the vertical cavity surface emitting laser unit from the center of the vertical cavity surface emitting laser array increases.
By increasing the substrate thickness of the N substrate directly below the vertical cavity surface emitting laser unit, the resistance value of the N substrate can be increased, which is equivalent to increasing the total resistance of the vertical cavity surface emitting laser unit itself, that is, increasing the resistance of the vertical cavity surface emitting laser unit. The substrate thickness of the N substrate is positively correlated with the resistance of the vertical cavity surface emitting laser unit, and the thicker the substrate thickness of the N substrate directly below the vertical cavity surface emitting laser unit, the larger the resistance of the vertical cavity surface emitting laser unit.
Therefore, the resistance of the vertical cavity surface emitting laser unit near the center of the vertical cavity surface emitting laser array is the largest, and the resistance of the vertical cavity surface emitting laser unit decreases as the distance of the vertical cavity surface emitting laser unit from the center of the vertical cavity surface emitting laser array increases.
According to the embodiment of the invention, the N substrate with the maximum thickness is deposited below the vertical cavity surface emitting laser unit near the center of the vertical cavity surface emitting laser array by methods of prolonging the deposition time and the like, the thickness of the N substrate deposited below the vertical cavity surface emitting laser unit is reduced along with the increase of the distance from the vertical cavity surface emitting laser unit to the center of the vertical cavity surface emitting laser array, the vertical cavity surface emitting laser array can be obtained, the manufacturing method is simple, the technology is mature, the original structure of the vertical cavity surface emitting laser array is not changed in the manufacturing process, and the light emitting power of the manufactured vertical cavity surface emitting laser array is uniform and stable.
Finally, it should be noted that: the above examples are only intended to illustrate the technical solution of the present invention, but not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.

Claims (7)

1. A vertical cavity surface emitting laser array with uniform optical power, comprising: a plurality of vertical cavity surface emitting laser units;
for any two vertical cavity surface emitting laser units, the resistance of the first vertical cavity surface emitting laser unit is greater than the resistance of the second vertical cavity surface emitting laser unit;
in any two vertical cavity surface emitting laser units, the distance between the first vertical cavity surface emitting laser unit and the center of the vertical cavity surface emitting laser array is smaller than the distance between the second vertical cavity surface emitting laser unit and the center of the vertical cavity surface emitting laser array;
the vertical cavity surface emitting laser unit includes: a P electrode, a thin film resistor and a closed annular hole surrounding the center of the vertical cavity surface emitting laser unit;
the thin film resistor is positioned below the P electrode and is in contact with the P electrode;
the closed annular hole is formed by etching the P electrode, and the P electrode is divided into two parts which are not directly connected;
wherein, for any two vertical cavity surface emitting laser units, the width of the closed annular hole of the first vertical cavity surface emitting laser unit is greater than the width of the closed annular hole of the second vertical cavity surface emitting laser unit.
2. The VCSEL array of claim 1, wherein the VCSEL unit includes: an N substrate;
for any two vertical cavity surface emitting laser units, the doping concentration of the N substrate of the first vertical cavity surface emitting laser unit is less than the doping concentration of the N substrate of the second vertical cavity surface emitting laser unit.
3. The VCSEL array of claim 1, wherein the VCSEL unit includes: an N substrate;
for any two vertical cavity surface emitting laser units, the substrate thickness of the N substrate of the first vertical cavity surface emitting laser unit is greater than the substrate thickness of the N substrate of the second vertical cavity surface emitting laser unit.
4. The VCSEL array having uniform output power as claimed in any one of claims 1 to 3, comprising: constant voltage power supply module.
5. A method for manufacturing a vertical cavity surface emitting laser array with uniform light emitting power is characterized by comprising the following steps:
preparing a thin film resistor in contact with the P electrode below the P electrode and controlling the size of additional resistors provided by the thin film resistor of the vertical cavity surface emitting laser units at different positions in the vertical cavity surface emitting laser array, so that the resistance of the first vertical cavity surface emitting laser unit is greater than that of the second vertical cavity surface emitting laser unit for any two vertical cavity surface emitting laser units;
in any two vertical cavity surface emitting laser units, the distance between the first vertical cavity surface emitting laser unit and the center of the vertical cavity surface emitting laser array is smaller than the distance between the second vertical cavity surface emitting laser unit and the center of the vertical cavity surface emitting laser array;
the preparing of the thin film resistor in contact with the P electrode below the P electrode and the controlling of the size of the additional resistor provided by the thin film resistor of the vcsel unit at different positions in the vcsel array specifically include:
after a thin film resistor which is in contact with the P electrode is prepared below the P electrode, the P electrode is etched, so that a closed annular hole is formed around the center of the vertical cavity surface emitting laser unit, and the P electrode is divided into two parts which are not directly connected;
wherein, for any two vertical cavity surface emitting laser units, the width of the closed annular hole of the first vertical cavity surface emitting laser unit is greater than the width of the closed annular hole of the second vertical cavity surface emitting laser unit.
6. The method of claim 5, further comprising:
implanting impurity ions of different concentrations into N substrate ions located below the vertical cavity surface emitting laser units at different positions in the vertical cavity surface emitting laser array;
the implanting of impurity ions of different concentrations into N substrate ions located below vertical cavity surface emitting laser units at different positions in the vertical cavity surface emitting laser array specifically includes:
for any two vertical cavity surface emitting laser units, injecting first concentration impurity ions into N substrate ions of a first vertical cavity surface emitting laser unit, and injecting second concentration impurity ions into N substrate ions of a second vertical cavity surface emitting laser unit;
wherein the first concentration of impurity ions is less than the second concentration of impurity ions.
7. The method of claim 5, further comprising:
depositing N substrates with different thicknesses below the vertical cavity surface emitting laser units at different positions in the vertical cavity surface emitting laser array;
depositing N substrates with different thicknesses below the vertical cavity surface emitting laser units at different positions in the vertical cavity surface emitting laser array specifically comprises:
for any two vertical cavity surface emitting laser units, depositing an N substrate with a first thickness below the first vertical cavity surface emitting laser unit, and depositing an N substrate with a second thickness below the second vertical cavity surface emitting laser unit;
wherein the first thickness is greater than the second thickness.
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CN109560463A (en) * 2017-09-26 2019-04-02 朗美通经营有限责任公司 The transmitter array with change interval between neighbouring transmitter

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