End-face emitting laser system

Abstract

An end-emitting laser (EEL) system and a method for manufacturing the same are disclosed. The EEL system comprises an EEL structure configured to generate laser radiation along a first longitudinal axis defined by the active layer of the EEL system. Furthermore, the EEL system comprises a photonic crystal structure. The photonic crystal structure is defined by a two-dimensional periodic array distributed within the array plane and is arranged to couple the generated laser radiation laterally across the EEL system. The presence of the photonic crystal structure within the EEL system causes light to be scattered within the photonic crystal in a direction perpendicular to the output field generated by the EEL system. The described EEL system makes it possible to increase the area of ​​the EEL system while maintaining single spatial and longitudinal mode operation, thereby obtaining a high-power coherent beam.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor laser devices. In particular, the present invention relates to an edge-emitting laser (EEL) system and a method for manufacturing the same.

Background Art

[0002] A semiconductor laser device is a solid-state laser based on a semiconductor gain medium, and optical amplification is usually realized by the induced recombination of charge carriers. Most semiconductor laser devices are laser diodes based on a semiconductor gain medium, and are excited by current in a region where an n-type doped semiconductor material and a p-type doped semiconductor material are in contact. Since the photon energy of a laser diode is close to the bandgap energy, different emission wavelengths can be realized by using compositions with different bandgap energies.

[0003] There are a variety of semiconductor laser devices, covering a wide parameter range and various application fields. An edge-emitting laser (EEL) device is a type of semiconductor laser device. The edge-emitting laser is a prototype of semiconductor laser device technology and has been used for decades. In an EEL, both laser feedback and emission occur in the plane, so light exits from the end of the laser, and gain reflection is provided by facet mirrors arranged at both ends of the laser. The edge-emitting laser can be operated in either continuous wave mode or pulse mode.

[0004] As those skilled in the art will understand, EEL devices include, but are not limited to, Fabry-Perot lasers (FP), distributed feedback lasers (DFB lasers), and distributed Bragg reflection lasers (DBR lasers). In these devices, both laser feedback and emission occur in-plane. Fabry-Perot (FP) lasers provide optical feedback through facet mirrors at both ends of the laser. DBR and DFB lasers, on the other hand, both incorporate a grating structure within the laser device, which provides optical feedback and is configured to produce a single-mode output beam. In DFB lasers, the grating structure is positioned along the active region, while in DBR lasers, the grating structure is positioned outside the active region.

[0005] EEL devices, which achieve high power output and single-mode operation simultaneously in a relatively small footprint, are suitable for many commercial laser applications.

[0006] EEL devices generally emit greater power as their size increases, meaning that simply increasing the area of ​​the laser structure can yield higher operating power. However, widening the EEL results in a loss of spatial coherence as a trade-off for higher power, due to the negative effects of spatial mode hopping exhibited by the device. Similarly, increasing the length of the EEL device causes the laser to oscillate in additional longitudinal modes. As a result, large-area EELs are limited to applications where the end user can tolerate multimode operation.

[0007] In Fabry-Perot type EELs, single-mode operation can be achieved by providing an external resonator outside the EEL device. However, this method results in optical loss and significantly increases the overall device area. Therefore, DFB and DBR type end-emitting lasers have been developed as methods for generating a single-mode output beam from an EEL device. However, the grating elements within these structures are known to cause significant optical loss, which reduces the maximum achievable output of end-emitting lasers.

[0008] A common method for obtaining high power output with EEL devices is to create a one-dimensional array of end-emitting lasers, known as a laser bar. The output from each element (end-emitting laser) in the laser bar is combined into a single output beam, thereby achieving a higher combined power output. Furthermore, a two-dimensional array of end-emitting lasers can also be formed by stacking these laser bars vertically.

[0009] However, since each EEL is an independent element within a laser bar or laser stack, they operate independently of each other. Therefore, the resulting combined output beam, while high-power, is not coherent and may exhibit a broadened output frequency. Nevertheless, the coherent light source characteristics, such as uniformity and high energy density, are desirable in a wide range of applications, including welding, cutting, high-speed data transmission, signal processing, and interferometry. [Overview of the project]

[0010] Therefore, an object of one embodiment of the present invention is to provide an end-face emitting laser system that is different from those known in the art.

[0011] A further object of one embodiment of the present invention is to provide an end-emitting laser system with improved operating parameters compared to those known in the art. The improved operating parameters include a coherent power field that exhibits increased output.

[0012] According to a first aspect of the present invention, an end-emitting laser (EEL) system is provided, which is: A first end-emitting laser (EEL) configured to generate laser radiation along a first longitudinal axis defined by the active layer of the first end-emitting laser, It comprises one or more photonic crystal structures defined by a two-dimensional periodic array distributed within the array plane, One or more photonic crystal structures are arranged to laterally couple the generated laser radiation across the first end-emitting laser.

[0013] The presence of a photonic crystal structure within the end-emitting laser (EEL) system causes light to scatter in a direction perpendicular to the direction of the output field generated along the longitudinal axis defined by the active layer of the first EEL. The presence of the photonic crystal structure maintains coherence across the entire width of the EEL system, thereby enabling the laser to generate an output field that maintains single spatial and longitudinal mode operation. As a result, the area of ​​the active layer of the first EEL can be increased to obtain higher power from the end-emitting laser system, and the presence of the photonic crystal structure within the EEL system prevents the output beam from exhibiting spatial or longitudinal mode hopping. In this way, the EEL system can generate a coherent beam while simultaneously achieving higher power than similar devices known in the art.

[0014] Preferably, the end-emitting laser system may include first and second confinement layers located on both sides of the active layer of the first end-emitting laser.

[0015] Preferably, the end-face emitting laser system may further include a first cladding layer located on a first confinement layer and a second cladding layer located on a second confinement layer.

[0016] The photonic crystal structure may be located within the layers of the first end-emitting laser, i.e., within one or more layers of the active layer, first confinement layer, second confinement layer, first cladding layer and / or second cladding layer.

[0017] Alternatively, the photonic crystal structure may be located outside the layer of the first end-face emitting laser. Specifically, the photonic crystal structure can be bonded to one or both end faces, where the end faces are the longitudinal ends of the first end-face emitting laser.

[0018] Preferably, the end-face emitting laser system may further include first and second electrical contact layers located on both sides of the outer surface of the first end-face emitting laser.

[0019] Preferably, the width of the first end-emitting laser is greater than 10 μm. Alternatively, the width of the first end-emitting laser is greater than 20 μm or greater than 50 μm.

[0020] Preferably, the end-face emitting laser system further comprises a second end-face emitting laser (EEL) configured to generate laser radiation along a second longitudinal axis defined by the active layer of the second end-face emitting laser, the second longitudinal axis being parallel to a first longitudinal axis, and one or more photonic crystal structures being arranged to couple the generated laser radiation between the first and second end-face emitting lasers (EEL).

[0021] By adding a second end-face emitting laser to the EEL system, the combined output of the EEL system can be increased by combining the outputs from the first and second end-face emitting lasers. Furthermore, by providing one or more photonic crystal structures and coupling the generated laser radiation between the first and second end-face emitting lasers, the output fields from the first and second end-face emitting lasers become coherent.

[0022] One or more photonic crystal structures may be arranged to couple the generated laser radiation between a first end-face emitting laser and a second end-face emitting laser by generating a coupling field that is coplanar with the array plane defined by the one or more photonic crystal structures.

[0023] One or more photonic crystal structures may be arranged to couple the generated laser radiation between a first end-face emitting laser and a second end-face emitting laser by generating a coupling field orthogonal to the array plane defined by the one or more photonic crystal structures.

[0024] Preferably, the edge-emitting laser system further comprises three or more edge-emitting lasers arranged to form a one-dimensional or two-dimensional array of edge-emitting lasers, and one or more photonic crystal structures are arranged to couple the generated laser emission between the three or more edge-emitting lasers.

[0025] By providing a plurality of edge-emitting lasers within the edge-emitting laser system, the output fields from each EEL can be combined to significantly enhance the combined output of the EEL system. The presence of a photonic crystal structure that acts to couple the generated laser emission between the plurality of EELs results in the generation of a coherent output field from each EEL. In this way, an edge-emitting laser system that generates a coherent output at a higher output can be realized. Such characteristics are desirable for many commercial laser applications.

[0026] Preferably, the edge-emitting laser system comprises a regular two-dimensional array, and an edge-emitting laser is arranged at each site of the array.

[0027] Alternatively, the edge-emitting laser system is an irregular two-dimensional array. The irregular array can include a regular two-dimensional array in which one or more of the sites of the array do not have an edge-emitting laser.

[0028] Optionally, one or more wavelength-selective reflectors can be arranged outside one or more of the photonic crystal structures. The presence of the one or more reflectors can reduce the effect of unwanted light leakage from the one or more photonic crystal structures.

[0029] According to a second aspect of the present invention, a method of manufacturing an edge-emitting laser system is provided, the method comprising: - a step of preparing a first edge-emitting laser; - a step of configuring the first edge-emitting laser to generate laser emission along a first longitudinal axis defined by an active layer of the first edge-emitting laser; - The steps of preparing one or more photonic crystal structures defined by a two-dimensional periodic array distributed within the array plane, - The process comprises the step of arranging one or more photonic crystal structures so as to couple the generated laser radiation laterally across a first end-face emitting laser.

[0030] Preferably, the method for manufacturing the end-face emitting laser system further includes the step of providing first and second confinement layers on both sides of the active layer of the first end-face emitting laser.

[0031] Preferably, the method for manufacturing the end-face emitting laser system further includes the steps of providing a first cladding layer on a first confinement layer and providing a second cladding layer on a second confinement layer.

[0032] Preferably, the method for manufacturing the end-emitting laser system further includes the step of arranging the photonic crystal structure within the layers of the first end-emitting laser, i.e., one or more layers among the active layer, the first confinement layer, the second confinement layer, the first cladding layer and / or the second cladding layer.

[0033] Alternatively, a method for manufacturing an end-face emitting laser system includes the step of arranging a photonic crystal structure outside the layer of a first end-face emitting laser. Specifically, this method may include the step of bonding the photonic crystal structure to one or both end faces, where the end faces are both ends in the longitudinal direction of the first end-face emitting laser.

[0034] Preferably, the method for manufacturing the end-face emitting laser system further includes the step of providing first and second electrical contact layers on both sides of the outer surface of the first end-face emitting laser.

[0035] Preferably, the method for manufacturing the end-face emitting laser system further includes the step of forming the width of the first end-face emitting laser to be greater than 10 μm. Alternatively, the method for manufacturing the end-face emitting laser system further includes the step of forming the width of the first end-face emitting laser to be greater than 20 μm or greater than 50 μm.

[0036] Preferably, the method for manufacturing the end-face emitting laser system is: - The step of preparing a second end-face emitting laser, - The step of configuring a second end-face emitting laser to generate laser radiation along a second longitudinal axis defined by the active layer of the second end-face emitting laser, - The step of aligning the second longitudinal axis parallel to the first longitudinal axis, -The further step includes arranging one or more photonic crystal structures so as to couple the generated laser radiation between a first end-emitting laser and a second end-emitting laser.

[0037] A method for manufacturing an end-face emitting laser system further includes the step of arranging one or more photonic crystal structures to couple the generated laser radiation between a first end-face emitting laser and a second end-face emitting laser by generating a coupling field that is coplanar with an array plane defined by one or more photonic crystal structures.

[0038] A method for manufacturing an end-face emitting laser system further includes the step of arranging one or more photonic crystal structures to couple the generated laser radiation between a first end-face emitting laser and a second end-face emitting laser by generating a coupling field orthogonal to an array plane defined by one or more photonic crystal structures.

[0039] Preferably, the method for manufacturing the end-face emitting laser system is: The steps include: preparing an end-face emitting laser with a value of -3 or higher, - The steps of arranging three or more end-emitting lasers to form a one-dimensional or two-dimensional array of end-emitting lasers, - Further comprising the step of arranging one or more photonic crystal structures so as to couple the generated laser radiation between three or more end-emitting lasers.

[0040] A method for manufacturing an end-emitting laser system further includes the step of preparing a regular two-dimensional array of end-emitting lasers and arranging multiple end-emitting lasers such that each end-emitting laser is located at a site in the array.

[0041] Alternatively, a method for manufacturing an end-emitting laser system includes the step of preparing a disordered two-dimensional array of end-emitting lasers. The disordered array may be provided by arranging a plurality of end-emitting lasers such that no end-emitting lasers are present at one or more array sites of a regular array.

[0042] Optionally, a method for manufacturing an end-emitting laser system includes the step of providing one or more wavelength-selective reflectors on the outside of one or more photonic crystal structures.

[0043] Embodiments of a second aspect of the present invention may include features for carrying out preferred or optional features of a first aspect of the present invention, and vice versa. [Brief explanation of the drawing]

[0044] Hereinafter, various embodiments of the present invention will be described as examples with reference to the drawings. [Figure 1] Figure 1 shows a cross-sectional view of an edge-emitting laser known from prior art. [Figure 2] Figure 2 shows a cross-sectional view of an end-face emitting laser system according to one embodiment of the present invention. [Figure 3] Figure 3 shows experimental results illustrating the output spectra from the end-emitting laser in Figure 1 and the end-emitting laser system in Figure 2. [Figure 4] Figure 4 shows a cross-sectional view of an end-face emitting laser system according to another embodiment of the present invention. [Figure 5] Figure 5 shows a cross-sectional view of an end-face emitting laser system according to another embodiment of the present invention. [Figure 6] Figure 6 shows a cross-sectional view of an end-face emitting laser system according to another embodiment of the present invention. [Figure 7] Figure 7 shows a cross-sectional view of an end-face emitting laser system according to another embodiment of the present invention. [Figure 8] Figure 8 shows a cross-sectional view of an end-face emitting laser system according to another embodiment of the present invention. [Figure 9] Figure 9 shows a cross-sectional view of an end-face emitting laser system according to another embodiment of the present invention. [Figure 10] Figure 10 shows an end-face emitting laser system according to another embodiment of the present invention. [Figure 11] Figure 11 shows an end-face emitting laser system according to another embodiment of the present invention. [Figure 12] Figure 12 shows an end-face emitting laser system according to another embodiment of the present invention. [Figure 13] Figure 13 shows an end-face emitting laser system according to another embodiment of the present invention.

[0045] In the following description, the same reference numerals are used for similar parts throughout the specification and drawings. The drawings are not necessarily to scale, and the proportions of certain parts are exaggerated to better illustrate the details and features of the embodiments of the invention. [Modes for carrying out the invention]

[0046] Figure 1 is a cross-sectional view of a typical end-emitting laser (EEL) known in the art, denoted collectively by reference numeral 1. The x and y axes are shown for reference, with the height of the EEL1 along the y-axis and the length of the EEL1 along the x-axis.

[0047] Figure 1 shows that EEL1 contains multiple layers.

[0048] First, within the EEL1, there is a waveguide region including a first confinement layer 2 and a second confinement layer 3. Between these confinement layers, there is an active layer 4 that generates laser radiation in a direction substantially parallel to the longitudinal axis 5 of the EEL1 when a drive current is passed through the EEL1.

[0049] The active layer 4 can be composed of various structures, as is known to those skilled in the art. Specifically, the active layer 4 of EEL1 can be one or more quantum well structures. Generally, the active layer 4 includes multiple quantum wells arranged at equal intervals between half-wavelength structures, and these structures electrically excite the active layer 4 by the input drive current.

[0050] The waveguide region is located between the first cladding layer 6 and the second cladding layer 7. One of the cladding layers 6 or 7 is composed of an n-type semiconductor material, and the other cladding layer 6 or 7 is composed of a p-type semiconductor material. The end-emitting laser 1 further includes a substrate layer 8, and the other layers 2, 3, 4, 6, and 7 are formed or grown on the substrate layer 8.

[0051] Electrical connection with the end-face emitting laser 1 is made using a first electrical contact layer 9 and a second electrical contact layer 10. The electrical contact layers 9 and 10 are located on the outer surfaces on both sides of the EEL 1.

[0052] As a result of the above structure, when current is supplied between the first electrical contact layer 9 and the second electrical contact layer 10, the EEL1 starts laser oscillation, and the output field 11 is radiated from the output surface 12 of the EEL1 in a direction approximately parallel to the x-axis.

[0053] If necessary, one or more intermediate layers can be placed between the substrate layer 8 of EEL1 and the first cladding layer 6. Furthermore, one or more intermediate layers can also be placed between the second cladding layer 7 and the second electrical contact layer 10.

[0054] The first cladding layer 6 and the second cladding layer 7 have lower refractive indices than the first confinement layer 2 and the second confinement layer 3, thereby guiding the propagating laser radiation within the waveguide region.

[0055] The output field 11 generated by the EEL1 described above typically has multiple modes or wavelengths. As mentioned earlier, most known methods for achieving single-mode operation result in a low output of EEL1.

[0056] Hereinafter, with reference to Figure 2, an end-face emitting laser system 13 according to one embodiment of the present invention and its manufacturing method will be described. In particular, Figure 2 shows a cross-sectional view of the end-face emitting laser system 13 according to one embodiment of the present invention.

[0057] The end-emitting laser system 13 in Figure 2 has a similar structure to the EEL1 shown in Figure 1. However, unlike the EEL1 in Figure 1, the EEL system 13 incorporates a photonic crystal structure 14 within the second cladding layer 7 of the EEL system 13.

[0058] The photonic crystal structure 14 is a material such as a semiconductor material and contains a two-dimensional periodic array of vacancies or all-semiconductor atoms distributed within the array plane. The array of vacancies or atoms usually forms a periodic lattice structure, and the refractive index of the vacancies or atoms is different from that of the photonic crystal material. The lattice structure of the photonic crystal structure 14 causes Bragg diffraction within the photonic crystal, resulting in light resonating at a specific wavelength determined by the periodicity or lattice constant of the photonic crystal structure 14.

[0059] The vacancies or atoms formed within the photonic crystal structure 14 typically have periodic properties and can be formed in a variety of shapes or geometric shapes. In the embodiments described herein, the atoms include round atoms arranged in a square lattice with a lattice constant of 305 nm. Those skilled in the art will understand that in other embodiments, the vacancies or atoms in the photonic crystal structure may have different shapes or structures and different lattice constants. For example, the atoms may include different regular or irregular geometric shapes (e.g., triangular, elliptical, rhombic, square, or chevron shapes), and the lattice may include different regular or irregular lattice structures with different lattice constants (e.g., triangular, hexagonal, or kagome shapes).

[0060] The output field 11 from the EEL system 13 is emitted from the output surface 12 located at the end face of the EEL system 13, and the generated radiation travels along a direction approximately parallel to the longitudinal axis 5 of the EEL system 13. However, within the photonic crystal structure 14, the generated laser radiation is scattered in a direction perpendicular to the longitudinal axis 5. This orthogonal scattering is coplanar and orthogonal to the array plane of the photonic crystal structure 14. Therefore, the presence of the photonic crystal structure 14 within the first cladding layer 6 of the EEL system 13 maintains coherence across the width direction of the EEL system 13. As a result, the EEL system 13 generates an output field 11 in which single spatial mode and longitudinal mode operation is maintained, and a coherent, high-power output field 11 can be obtained.

[0061] Figure 3 shows evidence that the spatial and longitudinal modes of operation of the EEL system 13 are singular. Figure 3 shows the output spectra 15, 16, and 17 generated from the output fields 11 of EEL1 in Figure 1 and EEL system 13 in Figure 2. Specifically, output spectrum 15 was obtained from EEL1 in Figure 1 when operated with a drive current twice the threshold current of the device. Similarly, output spectra 16 and 17 were obtained from EEL system 13 in Figure 2 when operated with drive currents 1.5 times and 2 times the threshold current of the device, respectively. For comparison, an additional output spectrum 18 was generated from EEL1 in Figure 1 with the DBR positioned outside the active layer 4 of the device and optically coupled.

[0062] As is clear from the figure, the output spectra 16 and 17 obtained from the EEL system 13 in Figure 2 show linewidths of 1.7 nm and 1.9 nm, respectively. These are both significantly narrower than the linewidth (approximately 2.8 nm) of the output spectrum 15 obtained from EEL1 in Figure 1. This indicates that the EEL system 13 generates an output field 11 containing a single spatial and longitudinal mode. Evidence that the EEL system 13 operates in a single spatial and longitudinal mode is due to the presence of the photonic crystal structure 14 is shown by referring to the output spectrum 18. Unlike when the photonic crystal structure 14 is incorporated within the EEL system 13, the linewidth of the generated output field 11 is actually increased to 3.12 nm due to the optical feedback generated by the presence of the DBR located outside the active layer 4 of EEL1 and optically coupled to it.

[0063] One of the special advantages of the EEL system 13 described above is that it can maintain single-mode operation in both spatial and longitudinal modes even when its width is increased to the order of tens of micrometers. In a similar EEL 1 known in the art, increasing the width of the EEL 1 to a dimension exceeding 10 micrometers results in multi-mode spatial operation. However, the presence of the photonic crystal structure 14 within the EEL system 13 allows the EEL system 13 to maintain single-mode operation even when its width is increased. By increasing the width of the EEL system 13, the output of the output field 11 of the EEL system 13 can also be significantly increased.

[0064] The EEL system 13 in Figure 2 may further comprise one or more wavelength-selective reflectors 19 positioned outside the semiconductor structure of the EEL system 13. The wavelength-selective reflectors 19a, 19b are designed to reflect light of a selected wavelength, i.e., the wavelength of the output field 11. The positions of the one or more wavelength-selective reflectors 19a, 19b are selected to reflect orthogonal scattered light generated by the photonic crystal structure 14 into the active layer 4 of the EEL system 13, thereby reducing the effects of light leakage from the EEL system 13 and increasing the output of the output field 11 of the EEL system 13.

[0065] Figure 4 shows an EEL system 20 according to another embodiment of the present invention. The EEL system 20 in Figure 4 is similar to that shown in Figure 2, but in Figure 4 the photonic crystal structure 14 is provided in a different layer of the EEL system 20, namely within the first cladding layer 6.

[0066] Those skilled in the art will understand that the photonic crystal structure 14 can be located within any layer of the EEL system, and that it is not necessary to have the photonic crystal structure 14 within the second cladding layer 7 or the first cladding layer 6, as shown in Figures 2 and 4. The photonic crystal structure 14 can be located at any position within the EEL system that can generate an orthogonal scattering field that acts to maintain coherence throughout the entire EEL system. Furthermore, if one or more additional intermediate layers are placed between the first cladding layer 6 and the substrate layer 8, or between the second cladding layer 7 and the second electrical contact layer 10 of the EEL system, the photonic crystal structure 14 can also be located within those intermediate layers.

[0067] As an example, yet another embodiment of the EEL system 21 is shown in Figure 5. In Figure 5, the EEL system 21 has a structure similar to that of the EEL systems 13 and 20 shown in Figures 2 and 4, respectively, but in this embodiment, both a first photonic crystal structure 14a and a second photonic crystal structure 14b are provided. The first photonic crystal structure 14a is provided in the first cladding layer 6 of the EEL system 21, and the second photonic crystal structure 14b is provided in the second cladding layer 7 of the EEL system 21.

[0068] Those skilled in the art will understand that the number of photonic crystal structures 14 in an EEL system is not limited to two, and that additional photonic crystal structures 14 can be placed in the EEL system as needed. Furthermore, as shown in Figure 5, each photonic crystal structure 14 may be located in a different layer, or the photonic crystal structures 14 may be located in the same layer of the EEL system.

[0069] Another embodiment of the EEL system 22 is shown in Figure 6, in which the photonic crystal structure 14 is present in all of layers 2, 3, 4, 6, and 7 of the EEL system 22. In particular, the photonic crystal structure 14 extends from the first cladding layer 6 through the first confinement layer 2, the active layer 4, and the second confinement layer 3, respectively, to the second cladding layer 7.

[0070] Those skilled in the art will understand that the photonic crystal structure 14 may reside in fewer layers than shown in Figure 6, or in any intermediate layers that may be added to the EEL system 22. For example, the photonic crystal structure 14 may extend from the first cladding layer 6 to the active layer 4 (i.e., in this case, not within the second confinement layer 3 or the second cladding layer 7).

[0071] Another embodiment of the EEL system 23 is shown in Figure 7, in which the photonic crystal structure 14 within the EEL system 23 is provided as a photonic crystal layer. In the EEL system 23 of Figure 7, the photonic crystal structure 14 is located within the first cladding layer 6 of the EEL system 23. However, those skilled in the art will understand that such a photonic crystal layer can be located within any layer of the EEL system 23.

[0072] Another embodiment of the EEL system 24 is shown in Figure 8, where, similar to Figure 7, the photonic crystal structure 14 is provided as a photonic crystal layer. However, the photonic crystal layer in the EEL system 24 of Figure 8 is an additional intermediate layer 25 provided within the EEL system 24, and the photonic crystal structure 14 is not present in the other layers 2, 3, 4, 7, and 8.

[0073] It should be noted that multiple photonic crystal layers can be placed within the EEL system. Additional photonic crystal layers can be placed as separate intermediate layers or as photonic crystal layers within any of the existing layers 2, 3, 4, 6, or 7 of the EEL system.

[0074] Figure 9 shows yet another embodiment of the EEL system 26. In the EEL system 26 of Figure 9, the photonic crystal structure 14 is located outside the other layers of the EEL system 26. Specifically, the photonic crystal structure 14 is bonded to the end faces, i.e., the longitudinal ends, of the EEL system 26. Those skilled in the art will understand that multiple photonic crystal structures 14 can be located outside the EEL system. For example, two photonic crystal structures 14 can be bonded to each of the longitudinal ends of the EEL system 26. Furthermore, the height of the photonic crystal structure 14 may be increased or decreased (along the y-axis) compared to that shown in Figure 9.

[0075] Those skilled in the art will understand that the EEL system 26 can be combined with any of the embodiments shown in Figures 2 and 4 to 8. In this way, an EEL system can be provided that includes the photonic crystal structure 14 outside and / or within the other layers of the EEL system.

[0076] Figure 10 shows yet another embodiment of the EEL27. Here, for ease of reference, the x, y, and z axes are shown, with the height of the EEL system 27 along the y axis, the length along the x axis, and the width along the z axis.

[0077] Specifically, Figure 10 shows an EEL system 27 that substantially comprises two EEL systems 13a and 13b of the type shown in Figure 2. The EEL systems 13a and 13b are arranged side by side along the z-axis, thereby providing the EEL system 27 with two output fields 11a and 11b. The first output field 11a and the second output field 11b can be combined, thereby allowing the EEL system 27 to provide a higher combined output, approximately twice that of a single EEL system 13.

[0078] The photonic crystal structure 14 provided within the EEL system 27 scatters light, forming a first coupling field 28 between the first EEL system 13a and the second EEL system 13b, and this first coupling field 28 propagates along the z-axis. Specifically, the first coupling field 28 is coplanar with the array plane defined by the photonic crystal structure 14. As a result, the first coupling field 28 acts to maintain coherence within the EEL system 27, and the two output fields 11a and 11b become coherent with each other.

[0079] Therefore, this EEL system 27 provides a coherent output combined with a higher output than that of the embodiments described above.

[0080] In addition, instead of providing two separate photonic crystal structures 14 in each of the first EEL system 13a and the second EEL system 13b, it is also possible to connect the first EEL system 13a and the second EEL system 13b along their width (z-axis) with a single photonic crystal structure 14. As with the embodiments described above, those skilled in the art will understand that the EEL system 27 may also include further photonic crystal structures 14 provided within or outside the layers of either the first EEL system 13a or the second EEL system 13b.

[0081] Furthermore, it is possible to add an additional EEL system 13 of the type shown in Figure 2 to the EEL system 27 to form a one-dimensional array of elements arranged side by side, in which case the photonic crystal structure 14 forms a coupling field 28 between all the individual EEL systems 13 of the EEL system 27. Such an array of EEL elements is generally known as a laser bar, and when this array is integrated into a single chip, extremely high output can be obtained by combining the optical outputs from each EEL element in the laser bar. However, unlike prior art laser bars, the output fields 11 of each EEL 13 in the EEL system 27 are coherent with each other.

[0082] Figure 11 shows yet another embodiment of the EEL system 29. The EEL system 29 is similar to the system in Figure 10 and comprises a first EEL system 13a and a second EEL system 13b. However, in the EEL system 29 of Figure 11, the second EEL system 13b is positioned on top of the first EEL 13a, forming a stack along the y-axis.

[0083] As a result, the photonic crystal structure 14 generates a second bonding field 30, and this second bonding field 30 between the EEL systems 13a and 13b propagates along the y-axis perpendicular to the photonic crystal structure 14.

[0084] Those skilled in the art will also understand that the EEL system 13 of the type shown in Figure 2 can be further added to the EEL system 29 in Figure 11 to form a single stack. In this case, a second bonding field 30 generated by the photonic crystal structure 14 bonds all the individual EEL systems 13 within the EEL system 29.

[0085] Figure 12 shows yet another embodiment of the EEL system 31, which combines the EEL systems 27 and 29 shown in Figures 10 and 11, respectively. By combining arrays of both side-by-side and stacked EEL systems, a regular 3x3 two-dimensional array is generated.

[0086] The photonic crystal structure 14 is placed within the EEL system 31 and forms both a first coupling field 28 and a second coupling field 30 between all EEL systems 13a to 13i within the EEL system 31. This generates multiple coherent output fields 11a to 11i, which can be combined to produce a single high-power output beam.

[0087] Those skilled in the art will understand that the EEL system 31 may have fewer or more EEL elements 13 than shown in Figure 12, thereby increasing or decreasing the size of the two-dimensional array and, consequently, the number of output fields 11.

[0088] Figure 13 shows yet another embodiment of the EEL 32, which is also a combination of the EEL systems 27 and 29 shown in Figures 10 and 11. However, here an irregular two-dimensional array is constructed by a combination of side-by-side and stacked elements. Specifically, in Figure 13, there are no EEL elements at the central array site of the EEL system 32 (i.e., 13e in Figure 12).

[0089] Those skilled in the art will understand that the arrays of EEL systems 13a to 13i within the EEL system 32 can be assembled into any desired geometric shape. For example, EEL elements 13 can be removed from array sites different from those shown in Figure 13. Furthermore, EEL elements 13 can be removed from multiple array sites. Similar to the embodiments described above, the EEL system 32 may have fewer EEL elements 13 than shown in Figure 13, or more elements can be added to the EEL system 32 to form a larger, irregular two-dimensional array and obtain a higher output.

[0090] Each embodiment in Figures 10 to 13 describes the use of the type of EEL system 13 shown in Figure 2. However, those skilled in the art will understand that the EEL elements can be any of the EEL systems 13, 20, 21, 22, 23, 24, and 26 described with reference to Figures 2, 4 to 9, or any combination thereof.

[0091] In summary, the present invention provides an EEL device with improved operating parameters, replacing known EEL devices. In particular, the present invention provides an EEL system manufactured to produce a high-power, coherent output beam, while maintaining single spatial and longitudinal mode operation. The disclosed EEL system increases output without causing significant optical loss or loss of coherence due to the detrimental effects of spatial mode hopping or longitudinal mode hopping exhibited by the device. Furthermore, the operating parameters of the EEL system can be improved without increasing the overall area occupied by the device.

[0092] An end-emitting laser (EEL) system and a method for manufacturing the same are disclosed. The EEL system comprises an EEL structure configured to generate laser radiation along a first longitudinal axis defined by the active layer of the EEL system. Furthermore, the EEL system comprises a photonic crystal structure. The photonic crystal structure is defined by a two-dimensional periodic array distributed within the array plane and is arranged to couple the generated laser radiation laterally across the EEL system. The presence of the photonic crystal structure within the EEL system causes light to be scattered within the photonic crystal in a direction perpendicular to the output field generated by the EEL system. The described EEL system makes it possible to increase the area of ​​the EEL system while maintaining single spatial and longitudinal mode operation, thereby obtaining a high-power coherent beam.

[0093] Throughout this specification, unless otherwise specified in the context, the terms “comprise” or “include,” or variations such as “comprises” or “comprising,” “includes” or “including,” should be understood to mean that they include the elements or groups of elements described, but not that they exclude other elements or groups of elements.

[0094] Furthermore, references to prior art in this specification should not be interpreted as indicating that the prior art constitutes part of common technical knowledge.

[0095] The above description of the present invention is presented for illustrative and explanatory purposes and is not intended to be exhaustive or to limit the invention to the exact form of the disclosure. The embodiments described have been selected and described to best illustrate the principles of the invention and their practical applications, thereby enabling those skilled in the art to best utilize the invention in various embodiments and variations suited to specific intended applications. Accordingly, further changes or improvements can be incorporated without departing from the scope of the invention as defined by the appended claims.

Claims

1. An end-face emitting laser system, A first end-face emitting laser, configured to generate laser radiation along a first longitudinal axis defined by its active layer, It comprises one or more photonic crystal structures defined by a two-dimensional periodic array distributed within the array plane, An end-face emitting laser system characterized in that the one or more photonic crystal structures are arranged to couple the generated laser radiation laterally across the first end-face emitting laser.

2. In the end-face emitting laser system according to claim 1, An end-face emitting laser system characterized in that the first end-face emitting laser further comprises first and second confinement layers located on both sides of the active layer.

3. In the end-face emitting laser system according to claim 2, An end-face emitting laser system characterized in that the first end-face emitting laser further comprises a first cladding layer located on the first confinement layer and a second cladding layer located on the second confinement layer.

4. In the end-face emitting laser system according to any one of claims 1 to 3, An end-face emitting laser system characterized in that the one or more photonic crystal structures can be arranged in the layers of the first end-face emitting laser, i.e., in one or more layers among the active layer, the first confinement layer, the second confinement layer, the first cladding layer and / or the second cladding layer.

5. In the end-face emitting laser system according to any one of claims 1 to 4, An end-face emitting laser system characterized in that the one or more photonic crystal structures can be arranged outside the layer of the first end-face emitting laser.

6. In the end-face emitting laser system according to claim 5, An end-face emitting laser system characterized in that the one or more photonic crystal structures are coupled to one or both end faces of the first end-face emitting laser, and the end faces are both ends of the first end-face emitting laser in the longitudinal direction.

7. In the end-face emitting laser system according to any one of claims 1 to 6, An end-face emitting laser system characterized in that the width of the first end-face emitting laser exceeds 10 μm, or exceeds 20 μm, or exceeds 50 μm.

8. In the end-face emitting laser system according to any one of claims 1 to 7, The system further comprises a second end-face emitting laser, the second end-face emitting laser being configured to generate laser radiation along a second longitudinal axis defined by its active layer, The second longitudinal axis is parallel to the first longitudinal axis, An end-face emitting laser system characterized in that the one or more photonic crystal structures are arranged to couple the generated laser radiation between the first end-face emitting laser and the second end-face emitting laser.

9. In the end-face emitting laser system according to claim 8, An end-face emitting laser system characterized in that the one or more photonic crystal structures are arranged to couple the generated laser radiation between the first end-face emitting laser and the second end-face emitting laser by generating a coupling field that is coplanar with the array plane defined by the one or more photonic crystal structures.

10. In the end-face emitting laser system according to claim 8 or 9, An end-face emitting laser system characterized in that the one or more photonic crystal structures are arranged to couple the generated laser radiation between the first end-face emitting laser and the second end-face emitting laser by generating a coupling field orthogonal to the array plane defined by the one or more photonic crystal structures.

11. In the end-face emitting laser system according to any one of claims 1 to 10, An end-face emitting laser system further comprising three or more end-face emitting lasers arranged to form a one-dimensional or two-dimensional array of end-face emitting lasers, wherein the one or more photonic crystal structures are arranged to couple the generated laser radiation between the three or more end-face emitting lasers.

12. In the end-face emitting laser system according to claim 11, An end-face emitting laser system characterized by comprising a regular two-dimensional array, with an end-face emitting laser positioned at each site of the array.

13. In the end-face emitting laser system according to claim 12, An end-face emitting laser system comprising an irregular two-dimensional array, wherein the irregular array includes a regular two-dimensional array in which no end-face emitting lasers are present at one or more sites of the array.

14. In the end-face emitting laser system according to any one of claims 1 to 13, An end-face emitting laser system characterized in that one or more wavelength-selective reflectors may be positioned outside the one or more photonic crystal structures.

15. A method for manufacturing an end-face emitting laser system, - The step of preparing a first end-face emitting laser, - The step of configuring the first end-face emitting laser to generate laser radiation along a first longitudinal axis defined by the active layer of the first end-face emitting laser, - A step of preparing one or more photonic crystal structures defined by a two-dimensional periodic array distributed within the array plane, A method for manufacturing an end-face emitting laser system, comprising the steps of: - arranging the one or more photonic crystal structures so as to couple the generated laser radiation laterally across the first end-face emitting laser.

16. In the method for manufacturing the end-face emitting laser system according to claim 15, A method for manufacturing an end-face emitting laser system, further comprising the step of providing first and second confinement layers on both sides of the active layer of the first end-face emitting laser.

17. In the method for manufacturing the end-face emitting laser system according to claim 16, A method for manufacturing an end-face emitting laser system, further comprising the steps of providing a first cladding layer on the first confinement layer and providing a second cladding layer on the second confinement layer.

18. In a method for manufacturing an end-face emitting laser system according to any one of claims 15 to 17, A method for manufacturing an end-face emitting laser system, further comprising the step of arranging the one or more photonic crystal structures within the layers of the first end-face emitting laser, i.e., within one or more layers selected from the active layer, the first confinement layer, the second confinement layer, the first cladding layer, and / or the second cladding layer.

19. A method for manufacturing an end-face emitting laser system according to any one of claims 15 to 18, A method for manufacturing an end-face emitting laser system, further comprising the step of arranging the one or more photonic crystal structures outside the layer of the first end-face emitting laser.

20. A method for manufacturing an end-face emitting laser system according to any one of claims 15 to 19, - The step of configuring a second end-face emitting laser to generate laser radiation along a second longitudinal axis defined by the active layer of the second end-face emitting laser, - The step of arranging the second longitudinal axis parallel to the first longitudinal axis, A method for manufacturing an end-face emitting laser system, further comprising the step of arranging the one or more photonic crystal structures so as to couple the generated laser radiation between the first and second end-face emitting lasers.

21. A method for manufacturing an end-face emitting laser system according to any one of claims 15 to 20, A method for manufacturing an end-face emitting laser system, further comprising the step of arranging the one or more photonic crystal structures so as to couple the generated laser radiation between the first and second end-face emitting lasers by generating a coupling field that is coplanar with the array plane defined by the one or more photonic crystal structures.

22. A method for manufacturing an end-face emitting laser system according to any one of claims 15 to 21, A method for manufacturing an end-face emitting laser system, further comprising the step of arranging the one or more photonic crystal structures such that the generated laser radiation is coupled between the first and second end-face emitting lasers by generating a coupling field orthogonal to an array plane defined by the one or more photonic crystal structures.

23. In a method for manufacturing an end-face emitting laser system according to any one of claims 15 to 22, - The step of preparing three or more end-face emitting lasers, - The step of arranging the three or more end-face emitting lasers to form a one-dimensional or two-dimensional array of end-face emitting lasers, A method for manufacturing an end-face emitting laser system, comprising the step of arranging the one or more photonic crystal structures so as to couple the generated laser radiation between the three or more end-face emitting lasers.

24. In the method for manufacturing the end-face emitting laser system according to claim 23, A method for manufacturing an end-emitting laser system, characterized by including the step of preparing a regular two-dimensional array of end-emitting lasers and arranging a plurality of end-emitting lasers such that an end-emitting laser is positioned at each site of the array.

25. In the method for manufacturing the end-face emitting laser system according to claim 23, A method for manufacturing an end-face emitting laser system, comprising the step of preparing an irregular two-dimensional array of end-face emitting lasers, wherein the irregular array includes a regular two-dimensional array in which no end-face emitting lasers are present at one or more sites of the array.

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