CA1318722C - Surface emitting lasers with combined output - Google Patents
Surface emitting lasers with combined outputInfo
- Publication number
- CA1318722C CA1318722C CA000606257A CA606257A CA1318722C CA 1318722 C CA1318722 C CA 1318722C CA 000606257 A CA000606257 A CA 000606257A CA 606257 A CA606257 A CA 606257A CA 1318722 C CA1318722 C CA 1318722C
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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
- H01S5/10—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
- H01S5/185—Surface-emitting [SE] lasers, e.g. having both horizontal and vertical cavities having only horizontal cavities, e.g. horizontal cavity surface-emitting lasers [HCSEL]
- H01S5/187—Surface-emitting [SE] lasers, e.g. having both horizontal and vertical cavities having only horizontal cavities, e.g. horizontal cavity surface-emitting lasers [HCSEL] using Bragg reflection
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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
RD-19,523P
SURFACE EMITTING LASERS WITH COMBINED OUTPUT
ABSTRACT OF THE DISCLOSURE
Surface emitting lasers are laterally aligned and coupled together and also have their light output signals combined. This results in greater phase and frequency coherency and narrower and reduced amplitude sidelobes. Preferably, not more than two lasers are longitudinally aligned along the same axis for still greater coherency compared with adding the light output signals of more than two longitudinally aligned lasers.
The lasers can be of the DH-LOC type or of the QW type.
SURFACE EMITTING LASERS WITH COMBINED OUTPUT
ABSTRACT OF THE DISCLOSURE
Surface emitting lasers are laterally aligned and coupled together and also have their light output signals combined. This results in greater phase and frequency coherency and narrower and reduced amplitude sidelobes. Preferably, not more than two lasers are longitudinally aligned along the same axis for still greater coherency compared with adding the light output signals of more than two longitudinally aligned lasers.
The lasers can be of the DH-LOC type or of the QW type.
Description
-- 1 -- RD--19, 523P
8lTRFACE EMIq!TING T~A8ER8 Wl:T~ ~OM13:CNED OU~I!P~JT
BACRGRO~D OF THE I~V~NTION
The present invention relates to surface emitting lasers, the more particularly, to means for phase locking and combining the outputs of a pair of such lasers.
Surface emitting lasers have an advantage over edge emitting lasers in that since their light Qmitting surface (the area of a grating) is larger, the power density is lower, and therefore, more power can be generated without destructive heating effects.
Further, the active section of a surface emitting laser can be made longer than that of a Fabry-Perot (FPI
cavity laser for more gain without spurious frequency generation due to the use o~ the grating. For still higher power outputs surface emitting lasers can have their outputs combined using an optical waveguide and a grating or distributed Bragg reflector (DBR) such as shown in FIGURE 1 of the article "Dynamically Stable 0 Phase Mode Operation Of A Grating-surface-emitting Diode-laser Array", by N. W. Carlson et al., optics Letters, Volume 13, No. 4, April 1988, pp. 312-314.
However, in such devices, due to losses in the waveguide, the phase locking of tha numerous lasers may not be sufficient to prevent spurious frequency generation as well as an incoherent light beam with a broad main beamwidth and high amplitude and broad RD-19,523P
beamwidth sidelobes. Ik is known from P. Zory et al., "Grating-Coupled Double-Heterostructure AlGaAs Diode Lasers," IEEE Journal of Quantum Electronics, Volume QE-11, No. 7, July 1985, pp. 451-457, to longitudinally align two lasers. However, the power is limited to that of a single pair of lasers.
It is, there~ore, desirable to have a high power output from surface emitting lasers with good phase locking and a coherent output light beam.
S~MNARY OF ~HE INVE~ON
A surface emitting semiconductor laser device in accordance with the invention for emitting an output light signal perpendicular to a major surface thereof, comprises a substrate having first and second opposing major surfaces; first contact means over said first major surface of said substrate; first and second longitudinally spaced apart and laterally aligned laser regions defining a central region therebetween and said laser regions being disposed on said second major surface of sald substrate; an optical medium extending over the central region and the first and second laser regions through which light generated by the first and second laser regions propagates; a capping layer and second contact means overlying the optical medium; and a single optical grating surface etched into the second contact means and the capping layer to extend over said central region in optical communication with the optical medium to define said major surface of said laser device, wherein the first and second laser regions are disposed on opposing sides longitudinally of the grating surface, said grating surface having grating periods for phase locking and combining the light propagating in the optical medium and generated by said first and second laser regions and for allowing said output light signal to be emitted therethrough 131872~
RD-19,523P
perpendicular to said major surface o~ said laser device.
BRIEF DE8CRIPTION OF T~E DR~WINGE~
FIGURE 1 is a side cross-sectional view of a double heterostructure-large optical cavity (DH-LOC) laser used in a first embodiment of the invention;
FIGURE 2 is a top view of FIGURE 1;
FIGURE 3 is a side cross-sectional view of a quantum well (QW) laser used in a second embodiment of the invention; and FIGURE 4 is a top view of an embodiment of the invention showing a plurality of laterally adjacent lasers.
DETAILED D~CRIPTION OF TH~ PREF~RRED EMBODIMENTS
FIGURE 1 shows a device, generally designated by numeral 10, comprising an N-contact 11, such as sintered Ni/Ge/Au, underneath a substrate 12, such as GaAs, of N-conductivity type with a doping level of about 10l8 cm~3 and a thickness of about lOO~m (micrometers). The central top of the substrate 12 has a l~m deep channel 13 (described in detail below) so that the lasers (described below) are of the channeled substrate planar (CSP) type. Overlying the substrate 12 is an N-cladding layer 14 of N-conductivity type.
The layer 14 also provides a barrier to holes.
Overlying the layer 14 is an active layer 16 with a thickness between about 500 to 2000 A (Angstroms~, preferably about 800A. The active layer 16 is not intentionally doped, and typically comprises Alz Ga1_zAs wherein O _ z < 0.13. ~ barrier layer 18, which provides a barrier for electrons, overlies the active layer 16 and has a thickness of about 200-lOOOA
and is not intentionally doped. It is to be understood that the layers 16 and 18 normally acquire some doping from their respective adjacent layers during 1 31 87~2 RD-19,523P
fabrication. A large optical cavity (LOC) or optical medium waveguide layer 20 overlies the layer 18 and typically comprises AlyGal_yAs, wherein 0.15 < y < 0.4, with a thickness between about 0.25 to l~m and N-conductivity doping of about 5 x 1ol7 cm~3. In the middle of the upper surface of the waveguide layer 20 is a granting surface 22 comprising surface corrugations with a peak-to-valley amplitude of about 1000 A and with a spacing of about A/ne, where ~ is the wavelength of the generated light and ne is the effective index of refraction of the guided mode. The profile of the corrugations is chosen such that the ~/ne periodic structure comprises significant components at A/ne, for example, by using V grooves where the width of the top of the grooves is about half of the intergroove spacing, A P-cladding layer 24 has segments 24a and 24b that overlie the ends of the layer 20, respectively, and is P-conductivity type doped. The layers 14, 18 and 24 typically are of ~1xGal_xAs, wherein 0.3 < x < 0.~. The cladding layers 14 and 24 typically have a thickness of about l~m and a doping level of about 5 x 10 17cm~3. A capping layer 26 has segments 26a and 26b that overlie the layer segments 24a and 24b, respectively, and typically is of GaAs P-conductivity doped with a doping level between about 1013 to lO19cm~3 and thickness of about 0.5~m. A
P-contact layer 28 has segments 28a and 28b that overlie the layer segments 26a and 26b, respectively, and typically comprises successive layers of Ti/Pt/Au, with the Ti layer next to the layer 26. At the sides of the structure are reflective facet layers 30a and 3Ob such as appropriately cleaved ends with a dielectric stack of alternate layers of SiO2 and A1203.
Typically about three such pairs (six layers~ are used, each layer having a thickness of about one quarter 1 3 1 872~
RD-19,523P
wavelength, such as shown in U.S. Patent No. 4,092,659.
It will be appreciated that longitudinally aligned DH-LOC lasers 32a and 32b are formed by the structure described above, ~ach having a length L1 preferably of about 200~m. The grating length L2 is preferably about 300~m. Thus, the lasers or laser regions 32a and 32b are spaced apart on opposing sides o~ the grating surface 22 with the grating 22 extending over a central region of the laser device between the laser regions 32a and 32b. As shown in FIG~RE 2 the device 11 has a width W o~ about 300~m. The top of the channel 13 at the top of the substrate 12, indicated by the dotted lines 34a and 34b, is preferably about 4 to 8~m wide, while the bottom of the channel 13, indicated by the dotted lines 36A and 36B, is narrower. The sidewalls therebetween, designated 38a and 38b, make an angle of about 57 degrees with the top of the substrate 12.
This embodiment can be made by the liquid phase epitaxial process with appropriate reagents an dopants all as known in the art. The channel 13 can be formed by etching the substrate 12 along its lllA plane using Caros solution at 20C, which in this case is a mixture of H2S04/H202/H20 in a 5/1/1 ratio by volume.
Similarly the respective segments of the layers 24, 26 and 28 can be formed by etching the central portions of the layers 24, 26, and 28, while masking their end portions, whi~h are part of the lasers 32a and 32~. A
preferential etchant, such as 1/1/8 Caros solution can be used.
In operation, a positive voltage is applied to the P-contact 28 and a negative voltage to the N-contact 11. Holes are injected from the P-contact 28 into the active layer 16 with the cladding layer 14 providing a barrier against further downward movement RD-19,523P
by holes. Similarly, electrons are injected from the N-contact 11 into the active layer 16 with the barrier layer 18 providing a barrier against further upward movement by electrons. At a threshold current, population in~ersion occurs and, therefore, stimulated emission of photons. Photons generated by both laser regions 32a and 32b axe present in the waveguide 20 and a first portion of the photons incident on the grating surface, through the interaction with the ~/ne component of the grating, is emitted perpendicular to the waveguide 20 as indicated by the arrows 34. A
second portion of the pho~ons incident on the grating surface 22 is reflected back into the laser regions 32a and 32b through the action of the ~/ne component of the grating surface 22, thereby increasing the optical feed back and enhancing the lasing action. Because the amount of reflection is dependent on the wavelength of the light generated by each laser device, a significant amount of feedback is present only at one specific period. The light generated by the laser regions 32a and 32b is thereby frequency locked. The remaining portion of the photons incident on the grating surface 22 generated by each o~ the laser regions 32a and 32b is transmitted through the optical medium 20 to the other laser region, thereby phase locking the two laser regions together. Since both laser regions 32a and 32b share the same device, the light generated by both laser regions is locked in both frequency and phase, and is emitted through the grating surface perpendicular to the grating surface.
It will be appreciated that since only two longitudinally aligned laser regions 32a and 32b are used, the waveguide 20 can be relatively short, and hence, have a low loss, there~ore, and phase the frequency locking of the two lasers 32a and 32b is RD-19,523P
greater than if more such lasers are used. In turn, this results in stabilizinq the longitudinal mode of the lasers 32 resulting in a single emission frequency compared to the plurality of modes in an Fabry-Perot cavity laser. Further, more light power output is available compared to using just a single laser.
FIGURE 3 shows a second embodiment of the laser regions 32a and 32b which are of the QW type.
Only the laser 32a is shown as it will be understood that the laser 32b is identical. Elements of FIGURE 3 that correspond to elements in FI~UR~ 1 are given corresponding reference numerals. The cladding layers 14 and 24 are between about 0.5 to 2.5~m thick and comprise AlxGal_xAs, wherein 0.4 < x < 1, with a doping level between 1ol7 to 5 x 1ol8 cm~3 of the appropriate conductivity type dopant. The central portion of the cladding 24 comprises the DBR 22 and is about 1000A
thick at the valleys of the DBR 220 Undoped confining layers 36 and 40 are between about S00 to 4000A thick and comprise AlxGal_xAs, wherein 0.15 < x < 0.60, and can be either graded or ungraded. The undoped quantum well layer 38 is between about 10 to 400A thick and comprises AlxGal_xAs, wherein 0 < x < l.
In general, the QW embodiment of FIGURE 3 has a lower threshold current, reduced variation of the threshold current with temperature, and increased di~ferential quantum efficiency compared to DH-LOC
lasers.
FIGURE 4 shows a device in accordance with an embodiment of the invention to obtain more light output power compared to using just a single pair of lasers, while maintaining phase and frequency coherency. In this embodiment, the substrate 12 is laterally extended compared to FIGURE 2, as are the reflective facet layers 30a and 30b and the grating surface 22. The 1 3 ~ 8722 RD-19,523P
grating surface 22 thereby comprises only a single integral means for phase locking and combining the outputs of all of the lasers to achieve a high coherency. For the sake of clarity, only the channels 13 are shown of the CSP-LOC laser regions 32a and 32b.
Each of the five channels 13 extends under only a pair of corresponding longitudinally aligned lasers as in FIGURE 1. Thus, there are a total of ten lasers.
Also, the channels 13a, 13b, 13c, 13d, and 13e are mutually laterally aligned with a typical center-to-center spacing "d" between about 4 to 10~m.
Thus, the lasers have their lateral optical modes (parallel to the junction plane) coupled together resulting in phase and frequency coupling and coherency for the entire array. The entire array will, therefore, provide single wavelength light output from the grating surface 22 normal 'co the substrate 12.
Depending upon L1 and the efficiency of grating surface 22 it is possible to increase the light output by about 10 to 50 times that of a single laser. QW lasers as shown in FIGURE 3 could also be used in FIGURE 4 instead of DH-LOC lasers.
8lTRFACE EMIq!TING T~A8ER8 Wl:T~ ~OM13:CNED OU~I!P~JT
BACRGRO~D OF THE I~V~NTION
The present invention relates to surface emitting lasers, the more particularly, to means for phase locking and combining the outputs of a pair of such lasers.
Surface emitting lasers have an advantage over edge emitting lasers in that since their light Qmitting surface (the area of a grating) is larger, the power density is lower, and therefore, more power can be generated without destructive heating effects.
Further, the active section of a surface emitting laser can be made longer than that of a Fabry-Perot (FPI
cavity laser for more gain without spurious frequency generation due to the use o~ the grating. For still higher power outputs surface emitting lasers can have their outputs combined using an optical waveguide and a grating or distributed Bragg reflector (DBR) such as shown in FIGURE 1 of the article "Dynamically Stable 0 Phase Mode Operation Of A Grating-surface-emitting Diode-laser Array", by N. W. Carlson et al., optics Letters, Volume 13, No. 4, April 1988, pp. 312-314.
However, in such devices, due to losses in the waveguide, the phase locking of tha numerous lasers may not be sufficient to prevent spurious frequency generation as well as an incoherent light beam with a broad main beamwidth and high amplitude and broad RD-19,523P
beamwidth sidelobes. Ik is known from P. Zory et al., "Grating-Coupled Double-Heterostructure AlGaAs Diode Lasers," IEEE Journal of Quantum Electronics, Volume QE-11, No. 7, July 1985, pp. 451-457, to longitudinally align two lasers. However, the power is limited to that of a single pair of lasers.
It is, there~ore, desirable to have a high power output from surface emitting lasers with good phase locking and a coherent output light beam.
S~MNARY OF ~HE INVE~ON
A surface emitting semiconductor laser device in accordance with the invention for emitting an output light signal perpendicular to a major surface thereof, comprises a substrate having first and second opposing major surfaces; first contact means over said first major surface of said substrate; first and second longitudinally spaced apart and laterally aligned laser regions defining a central region therebetween and said laser regions being disposed on said second major surface of sald substrate; an optical medium extending over the central region and the first and second laser regions through which light generated by the first and second laser regions propagates; a capping layer and second contact means overlying the optical medium; and a single optical grating surface etched into the second contact means and the capping layer to extend over said central region in optical communication with the optical medium to define said major surface of said laser device, wherein the first and second laser regions are disposed on opposing sides longitudinally of the grating surface, said grating surface having grating periods for phase locking and combining the light propagating in the optical medium and generated by said first and second laser regions and for allowing said output light signal to be emitted therethrough 131872~
RD-19,523P
perpendicular to said major surface o~ said laser device.
BRIEF DE8CRIPTION OF T~E DR~WINGE~
FIGURE 1 is a side cross-sectional view of a double heterostructure-large optical cavity (DH-LOC) laser used in a first embodiment of the invention;
FIGURE 2 is a top view of FIGURE 1;
FIGURE 3 is a side cross-sectional view of a quantum well (QW) laser used in a second embodiment of the invention; and FIGURE 4 is a top view of an embodiment of the invention showing a plurality of laterally adjacent lasers.
DETAILED D~CRIPTION OF TH~ PREF~RRED EMBODIMENTS
FIGURE 1 shows a device, generally designated by numeral 10, comprising an N-contact 11, such as sintered Ni/Ge/Au, underneath a substrate 12, such as GaAs, of N-conductivity type with a doping level of about 10l8 cm~3 and a thickness of about lOO~m (micrometers). The central top of the substrate 12 has a l~m deep channel 13 (described in detail below) so that the lasers (described below) are of the channeled substrate planar (CSP) type. Overlying the substrate 12 is an N-cladding layer 14 of N-conductivity type.
The layer 14 also provides a barrier to holes.
Overlying the layer 14 is an active layer 16 with a thickness between about 500 to 2000 A (Angstroms~, preferably about 800A. The active layer 16 is not intentionally doped, and typically comprises Alz Ga1_zAs wherein O _ z < 0.13. ~ barrier layer 18, which provides a barrier for electrons, overlies the active layer 16 and has a thickness of about 200-lOOOA
and is not intentionally doped. It is to be understood that the layers 16 and 18 normally acquire some doping from their respective adjacent layers during 1 31 87~2 RD-19,523P
fabrication. A large optical cavity (LOC) or optical medium waveguide layer 20 overlies the layer 18 and typically comprises AlyGal_yAs, wherein 0.15 < y < 0.4, with a thickness between about 0.25 to l~m and N-conductivity doping of about 5 x 1ol7 cm~3. In the middle of the upper surface of the waveguide layer 20 is a granting surface 22 comprising surface corrugations with a peak-to-valley amplitude of about 1000 A and with a spacing of about A/ne, where ~ is the wavelength of the generated light and ne is the effective index of refraction of the guided mode. The profile of the corrugations is chosen such that the ~/ne periodic structure comprises significant components at A/ne, for example, by using V grooves where the width of the top of the grooves is about half of the intergroove spacing, A P-cladding layer 24 has segments 24a and 24b that overlie the ends of the layer 20, respectively, and is P-conductivity type doped. The layers 14, 18 and 24 typically are of ~1xGal_xAs, wherein 0.3 < x < 0.~. The cladding layers 14 and 24 typically have a thickness of about l~m and a doping level of about 5 x 10 17cm~3. A capping layer 26 has segments 26a and 26b that overlie the layer segments 24a and 24b, respectively, and typically is of GaAs P-conductivity doped with a doping level between about 1013 to lO19cm~3 and thickness of about 0.5~m. A
P-contact layer 28 has segments 28a and 28b that overlie the layer segments 26a and 26b, respectively, and typically comprises successive layers of Ti/Pt/Au, with the Ti layer next to the layer 26. At the sides of the structure are reflective facet layers 30a and 3Ob such as appropriately cleaved ends with a dielectric stack of alternate layers of SiO2 and A1203.
Typically about three such pairs (six layers~ are used, each layer having a thickness of about one quarter 1 3 1 872~
RD-19,523P
wavelength, such as shown in U.S. Patent No. 4,092,659.
It will be appreciated that longitudinally aligned DH-LOC lasers 32a and 32b are formed by the structure described above, ~ach having a length L1 preferably of about 200~m. The grating length L2 is preferably about 300~m. Thus, the lasers or laser regions 32a and 32b are spaced apart on opposing sides o~ the grating surface 22 with the grating 22 extending over a central region of the laser device between the laser regions 32a and 32b. As shown in FIG~RE 2 the device 11 has a width W o~ about 300~m. The top of the channel 13 at the top of the substrate 12, indicated by the dotted lines 34a and 34b, is preferably about 4 to 8~m wide, while the bottom of the channel 13, indicated by the dotted lines 36A and 36B, is narrower. The sidewalls therebetween, designated 38a and 38b, make an angle of about 57 degrees with the top of the substrate 12.
This embodiment can be made by the liquid phase epitaxial process with appropriate reagents an dopants all as known in the art. The channel 13 can be formed by etching the substrate 12 along its lllA plane using Caros solution at 20C, which in this case is a mixture of H2S04/H202/H20 in a 5/1/1 ratio by volume.
Similarly the respective segments of the layers 24, 26 and 28 can be formed by etching the central portions of the layers 24, 26, and 28, while masking their end portions, whi~h are part of the lasers 32a and 32~. A
preferential etchant, such as 1/1/8 Caros solution can be used.
In operation, a positive voltage is applied to the P-contact 28 and a negative voltage to the N-contact 11. Holes are injected from the P-contact 28 into the active layer 16 with the cladding layer 14 providing a barrier against further downward movement RD-19,523P
by holes. Similarly, electrons are injected from the N-contact 11 into the active layer 16 with the barrier layer 18 providing a barrier against further upward movement by electrons. At a threshold current, population in~ersion occurs and, therefore, stimulated emission of photons. Photons generated by both laser regions 32a and 32b axe present in the waveguide 20 and a first portion of the photons incident on the grating surface, through the interaction with the ~/ne component of the grating, is emitted perpendicular to the waveguide 20 as indicated by the arrows 34. A
second portion of the pho~ons incident on the grating surface 22 is reflected back into the laser regions 32a and 32b through the action of the ~/ne component of the grating surface 22, thereby increasing the optical feed back and enhancing the lasing action. Because the amount of reflection is dependent on the wavelength of the light generated by each laser device, a significant amount of feedback is present only at one specific period. The light generated by the laser regions 32a and 32b is thereby frequency locked. The remaining portion of the photons incident on the grating surface 22 generated by each o~ the laser regions 32a and 32b is transmitted through the optical medium 20 to the other laser region, thereby phase locking the two laser regions together. Since both laser regions 32a and 32b share the same device, the light generated by both laser regions is locked in both frequency and phase, and is emitted through the grating surface perpendicular to the grating surface.
It will be appreciated that since only two longitudinally aligned laser regions 32a and 32b are used, the waveguide 20 can be relatively short, and hence, have a low loss, there~ore, and phase the frequency locking of the two lasers 32a and 32b is RD-19,523P
greater than if more such lasers are used. In turn, this results in stabilizinq the longitudinal mode of the lasers 32 resulting in a single emission frequency compared to the plurality of modes in an Fabry-Perot cavity laser. Further, more light power output is available compared to using just a single laser.
FIGURE 3 shows a second embodiment of the laser regions 32a and 32b which are of the QW type.
Only the laser 32a is shown as it will be understood that the laser 32b is identical. Elements of FIGURE 3 that correspond to elements in FI~UR~ 1 are given corresponding reference numerals. The cladding layers 14 and 24 are between about 0.5 to 2.5~m thick and comprise AlxGal_xAs, wherein 0.4 < x < 1, with a doping level between 1ol7 to 5 x 1ol8 cm~3 of the appropriate conductivity type dopant. The central portion of the cladding 24 comprises the DBR 22 and is about 1000A
thick at the valleys of the DBR 220 Undoped confining layers 36 and 40 are between about S00 to 4000A thick and comprise AlxGal_xAs, wherein 0.15 < x < 0.60, and can be either graded or ungraded. The undoped quantum well layer 38 is between about 10 to 400A thick and comprises AlxGal_xAs, wherein 0 < x < l.
In general, the QW embodiment of FIGURE 3 has a lower threshold current, reduced variation of the threshold current with temperature, and increased di~ferential quantum efficiency compared to DH-LOC
lasers.
FIGURE 4 shows a device in accordance with an embodiment of the invention to obtain more light output power compared to using just a single pair of lasers, while maintaining phase and frequency coherency. In this embodiment, the substrate 12 is laterally extended compared to FIGURE 2, as are the reflective facet layers 30a and 30b and the grating surface 22. The 1 3 ~ 8722 RD-19,523P
grating surface 22 thereby comprises only a single integral means for phase locking and combining the outputs of all of the lasers to achieve a high coherency. For the sake of clarity, only the channels 13 are shown of the CSP-LOC laser regions 32a and 32b.
Each of the five channels 13 extends under only a pair of corresponding longitudinally aligned lasers as in FIGURE 1. Thus, there are a total of ten lasers.
Also, the channels 13a, 13b, 13c, 13d, and 13e are mutually laterally aligned with a typical center-to-center spacing "d" between about 4 to 10~m.
Thus, the lasers have their lateral optical modes (parallel to the junction plane) coupled together resulting in phase and frequency coupling and coherency for the entire array. The entire array will, therefore, provide single wavelength light output from the grating surface 22 normal 'co the substrate 12.
Depending upon L1 and the efficiency of grating surface 22 it is possible to increase the light output by about 10 to 50 times that of a single laser. QW lasers as shown in FIGURE 3 could also be used in FIGURE 4 instead of DH-LOC lasers.
Claims (4)
1. A surface emitting semiconductor laser device for emitting an output light signal perpendicular to a major surface thereof, comprising:
a substrate having first and second opposing major surfaces;
first contact means over said first major surface of said substrate;
first and second longitudinally spaced apart and laterally aligned laser regions defining a central region therebetween and said laser regions being disposed on said second major surface of said substrate;
an optical medium extending over the central region and the first and second laser regions through which light generated by the first and second laser regions propagates;
a capping layer and second contact means overlying the optical medium;
a single optical grating surface etched into the second contact means and the capping layer to extend over said central region in optical communication with the optical medium to define said major surface of said laser device, wherein the first and second laser regions are disposed on opposing sides longitudinally of the grating surface, said grating surface having grating periods for phase locking and combining the light propagating in the optical medium and generated by said first and second laser regions and for allowing said output light signal to be emitted therethrough perpendicular to said major surface of said laser device.
a substrate having first and second opposing major surfaces;
first contact means over said first major surface of said substrate;
first and second longitudinally spaced apart and laterally aligned laser regions defining a central region therebetween and said laser regions being disposed on said second major surface of said substrate;
an optical medium extending over the central region and the first and second laser regions through which light generated by the first and second laser regions propagates;
a capping layer and second contact means overlying the optical medium;
a single optical grating surface etched into the second contact means and the capping layer to extend over said central region in optical communication with the optical medium to define said major surface of said laser device, wherein the first and second laser regions are disposed on opposing sides longitudinally of the grating surface, said grating surface having grating periods for phase locking and combining the light propagating in the optical medium and generated by said first and second laser regions and for allowing said output light signal to be emitted therethrough perpendicular to said major surface of said laser device.
2. The device of claim 1 wherein the first -10- RD-19,523P
and second laser regions each comprises a plurality of laterally aligned phase-locked lasers disposed on said second major surface of said substrate with corresponding spaced-apart lasers of each of the first and second longitudinal laser regions being longitudinally aligned.
and second laser regions each comprises a plurality of laterally aligned phase-locked lasers disposed on said second major surface of said substrate with corresponding spaced-apart lasers of each of the first and second longitudinal laser regions being longitudinally aligned.
3. The device of claim 2 wherein each of the lasers comprises a double heterojunction large optical cavity laser.
4. The device of claim 2 wherein each of said lasers comprises a quantum well laser.
Applications Claiming Priority (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US07/230,105 US4894833A (en) | 1988-08-09 | 1988-08-09 | Surface emitting lasers with combined output |
| US35405989A | 1989-05-19 | 1989-05-19 | |
| US230,105 | 1989-05-19 | ||
| US354,059 | 1989-05-19 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1318722C true CA1318722C (en) | 1993-06-01 |
Family
ID=26923926
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000606257A Expired - Fee Related CA1318722C (en) | 1988-08-09 | 1989-07-20 | Surface emitting lasers with combined output |
Country Status (6)
| Country | Link |
|---|---|
| JP (1) | JP2825540B2 (en) |
| CA (1) | CA1318722C (en) |
| DE (1) | DE3926053C2 (en) |
| FR (1) | FR2635418B1 (en) |
| GB (1) | GB2221791B (en) |
| IT (1) | IT1231098B (en) |
Families Citing this family (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5779924A (en) * | 1996-03-22 | 1998-07-14 | Hewlett-Packard Company | Ordered interface texturing for a light emitting device |
| US7419912B2 (en) * | 2004-04-01 | 2008-09-02 | Cree, Inc. | Laser patterning of light emitting devices |
| JP5799623B2 (en) * | 2011-07-13 | 2015-10-28 | 三菱電機株式会社 | Laser element |
| JP6282485B2 (en) * | 2014-02-24 | 2018-02-21 | スタンレー電気株式会社 | Semiconductor light emitting device |
| JP6527695B2 (en) * | 2014-12-22 | 2019-06-05 | スタンレー電気株式会社 | Semiconductor light emitting device |
Family Cites Families (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4006432A (en) * | 1974-10-15 | 1977-02-01 | Xerox Corporation | Integrated grating output coupler in diode lasers |
| US3969686A (en) * | 1975-03-26 | 1976-07-13 | Xerox Corporation | Beam collimation using multiple coupled elements |
| US4092659A (en) * | 1977-04-28 | 1978-05-30 | Rca Corporation | Multi-layer reflector for electroluminescent device |
| JPS63114288A (en) * | 1986-10-31 | 1988-05-19 | Fujitsu Ltd | Semiconductor light emitting element |
-
1989
- 1989-07-20 CA CA000606257A patent/CA1318722C/en not_active Expired - Fee Related
- 1989-08-03 FR FR8910470A patent/FR2635418B1/en not_active Expired - Lifetime
- 1989-08-07 GB GB8918020A patent/GB2221791B/en not_active Expired - Lifetime
- 1989-08-07 DE DE3926053A patent/DE3926053C2/en not_active Expired - Lifetime
- 1989-08-07 IT IT8921463A patent/IT1231098B/en active
- 1989-08-09 JP JP1204925A patent/JP2825540B2/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| DE3926053C2 (en) | 2000-09-28 |
| FR2635418A1 (en) | 1990-02-16 |
| DE3926053A1 (en) | 1990-03-22 |
| GB2221791B (en) | 1992-11-18 |
| GB8918020D0 (en) | 1989-09-20 |
| IT1231098B (en) | 1991-11-18 |
| FR2635418B1 (en) | 1994-12-02 |
| JPH02119196A (en) | 1990-05-07 |
| IT8921463A0 (en) | 1989-08-07 |
| JP2825540B2 (en) | 1998-11-18 |
| GB2221791A (en) | 1990-02-14 |
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