CN1226815C - Phase control array laser device manufactured by using vertical cavity surface emitting semi-conductor laser - Google Patents

Abstract

The invention relates to a phased array laser device manufactured by a vertical cavity surface-emitting semiconductor laser, comprising: a computer, a total power supply, a seed laser, a phase shifter and a laser array composed of n surface-emitting semiconductor lasers; the phase shifter is arranged In front of the optical path of the seed laser, a vertical cavity surface emitting semiconductor laser in the laser array is placed in front of each phase shifter; the total power supply is electrically connected to each vertical cavity surface emitting semiconductor laser, and the total power supply is respectively connected to the computer and the seed laser. , The phase shifter is electrically connected. The direction of the laser beam emitted by the array is controlled by a phase shifter. By controlling the phase of each laser unit in the array, the beams are coherently superimposed to obtain the required beam pointing and scan according to a predetermined scheme in a certain space. The phase shifters are computer controlled. The laser array remains stationary during the scanning process, ie the laser itself does not require mechanical movement.

Description

Fabrication of Phased Array Laser Device Using Vertical Cavity Surface Emitting Semiconductor Laser

                      

The invention relates to a laser device, in particular to a phased array laser device manufactured by using a vertical cavity surface emitting semiconductor laser.

Background technique

Traditional semiconductor lasers often adopt the end-face emission mode, the output laser beam divergence is large, the beam is asymmetrical, and it is multi-mode operation, and the light waves emitted by the array elements composed of them lack coherence, as shown in reference [1] : GP. Agarwal and N. Dutta K., Semiconductor laser, 2nd ed. Van Nostrand Reinhold, New York 1993, P530. Therefore, this kind of end-emitting semiconductor laser is not suitable for making phased array laser devices. Recently, high-power phased-array laser devices have become possible due to the development of vertical-cavity surface-emitting semiconductor lasers. Vertical-cavity surface-emitting semiconductor lasers can operate in a single longitudinal mode, have good coherence, have good symmetry of the beam, can be tightly focused, and are easy to integrate on a single chip [Document 2: R.P.Stanley, R.Houdre, U.Oesterle, M.llegems, C . Weisbuch, Coupled semiconductor microcavities, Appl. Phys. Lett.65, 2093, 1994]. Moreover, the laser output wavelength can be designed according to needs, from visible light to mid-infrared band, by selecting laser materials and using energy band engineering to tailor them appropriately.

Contents of the invention

One of the objects of the present invention is to provide a phased array laser device made of a vertical cavity surface emitting semiconductor laser, the emission direction of the array laser beam is controlled by a phase shifter, and it can be scanned in space, after coherent superposition of multiple beams The laser beam has good directivity and high brightness. The second object of the present invention is to provide a phased array laser device with laser wavelengths that can be selected from visible light to mid-infrared bands as required, for use in military, scientific research, optical communication, astronomy, meteorology, environmental protection and other fields.

The object of the present invention is achieved like this: the present invention provides a kind of phased array laser device that utilizes vertical cavity surface emitting semiconductor laser to make, comprising: laser, control computer and total power supply; It is characterized in that: also comprises seed laser, A phase shifter and a laser array composed of n vertical cavity surface emitting semiconductor lasers; the phase shifter is placed in front of the optical path of the seed laser, and each phase shifter is placed in front of a vertical cavity surface emitting semiconductor laser in a laser array; wherein The total power supply is electrically connected to each vertical cavity surface-emitting semiconductor laser, and the other output ports of the total power supply are respectively connected to a computer, a seed laser, and a phase shifter.

The semiconductor laser is a vertical cavity surface-emitting semiconductor laser, and the active region of the semiconductor laser adopts a superlattice, quantum well or quantum dot structure. The laser can be a double coupled cavity, or an external cavity mirror structure. The external cavity mirror structure can insert an optical nonlinear crystal between the semiconductor laser chip and the external cavity environment, and can tune the laser output wavelength.

The wavelength of the semiconductor laser ranges from visible light to mid-infrared, and can be tailored and designed as required by selecting semiconductor laser materials and using energy band engineering.

The semiconductor laser array can be a 1xM one-dimensional line array, an MxN two-dimensional area array, or an annular circular area array; wherein M and N are positive integers greater than 1, respectively.

The seed laser has the same material, structure and performance as the semiconductor laser used in the laser array, and is a single vertical cavity surface emitting single longitudinal mode semiconductor laser.

The laser materials include: Indium Gallium (GaIn), Indium Arsenide (AsIn), Indium Phosphide (InP), Indium Tin (InSb), Indium Gallium Arsenide (InGaAs), Indium Aluminum Arsenide (InAlAs), Indium Calcium Phosphorus (InCaP), Indium Gallium Nitride (InGaN), Indium Gallium Arsenide Nitrogen (InGaAsN), Indium Gallium Arsenide Tin Nitrogen (InGaAsNSb), Aluminum Gallium Arsenide (AlGaAs), Aluminum Gallium Indium Phosphide (AlGaInP), Gallium Arsenide (GaAs ), aluminum tin oxide (AlSb) or gallium nitride (GaN), etc.

The phase shifter is an optical phase shifter made of the following electro-optic materials, such as: KDP, KD ^* P, LiNbO ₃ , KtaNbO ₃ , C ₆ H ₅ NO ₂ , GaAs, Gap or CdTe, etc.

Each vertical cavity surface-emitting semiconductor laser included in the laser array operates in the same single longitudinal mode, the laser has good coherence, and the laser beam after coherent superposition has good directionality and high brightness. The reference phase of each laser in the laser array is provided by the same single longitudinal mode seed laser. The direction of the laser beam emitted by the laser array is controlled by a phase shifter through a computer. The computer calculates the phase of each phase shifter according to external instructions, so that each laser unit in the laser array has the required phase shift, so as to form a laser beam in a specified direction. By adjusting the phase, the pointing of the laser beam can be changed, so that the beam can scan according to a predetermined rule in a certain space.

Advantages of the present invention:

The phased array laser device manufactured by using the vertical cavity surface emitting semiconductor laser, the laser can operate in a single longitudinal mode, the beam has good symmetry and coherence. For n-element laser arrays, the coherent superposition of their beams is enhanced, and the light intensity in a specific direction is proportional to n ² , rather than the simple addition of n light intensities. Therefore, the laser beam after multi-beam coherent superposition has good directivity and high brightness. The laser array is easy to be integrated in a large-scale monolithic chip and has a small volume. Moreover, by selecting semiconductor laser materials and using energy band engineering, the laser output wavelength can be tailored according to needs, from visible light to mid-infrared band. The laser array can be directly pumped by electricity, fully solidified, with high efficiency and long life, and can operate in continuous wave or pulse wave state. The direction of the laser beam emitted by the laser array is precisely controlled by the phase shifter through the computer, so that the beam can be scanned in a certain space according to a predetermined plan. During the scanning process, the laser array remains fixed, that is, the laser itself does not need to make mechanical movements, which makes the overall structure of the phased array laser device simple and compact, fast in response, and convenient and flexible to use. Therefore, the phased array laser device has the advantages of compact structure, full solidification, small size, high efficiency, long life, strong self-adaptability, etc. , astronomy, meteorology, environmental protection and other fields.

Description of drawings

Fig. 1 is a block diagram of a phased array laser device of the present invention.

Fig. 2 is a structural diagram of the direct epitaxy double-coupled cavity lasers (array element) forming the laser array in the phased array laser device of the present invention.

Fig. 3 is a structural diagram of the second type of laser (array element) in the device of the present invention.

Fig. 4 is the structure diagram of the embodiment of the third laser (array element) in the device of the present invention

Fig. 5 is the structural diagram of another embodiment of the laser (array element) in the device of the present invention

The illustrations are as follows:

1. Laser array; 2. Phase shifter; 3. Seed laser;

4. Computer; 5. Total power supply; 6. Aperture;

7. Upper reflector; 8. Quantum well A; 9. Middle reflector;

10. Quantum well B; 11. Lower reflector; 12. Substrate;

13. External output cavity mirror; 14. Quantum well; 15. Internal reflection cavity mirror;

16. Optical nonlinear crystals; 17. Microlenses.

18. Semiconductor laser

Detailed ways

Example 1

A near-infrared phased array laser device with a wavelength of 800-1000nm is produced according to FIG. 1, and the semiconductor laser 18 forming the laser array 1 is a coupled-cavity surface-emitting InGaAs/GaAs quantum well laser (FIG. 2). Among them, 12 is the substrate, 11 is the lower reflector, 10 is the quantum well B, 9 is the middle reflector, 8 is the quantum well A, 7 is the upper reflector, 6 is the aperture, and the transition between the conduction band and the valence band is used The mechanism enables each laser 18 to emit the same single longitudinal mode near-infrared laser. During the growth process of the quantum well material, if the barrier height and well width of the quantum well are properly adjusted, the output wavelength of the InGaAs/GaAs quantum well laser can be selected within the range of 800-1000nm. The array is a 100×100 two-dimensional array. The seed laser 3 is a single vertical cavity surface emitting InGaAs/GaAs quantum well laser, and its structure and performance are exactly the same as those of the lasers forming the array. The total power supply 5 works in a continuous pumping mode. Phase shifter 2 is a common optical phase shifter made of a KD ^* P photoelectric crystal. The phase shifter 2 is arranged in front of the optical path of the seed laser 3, and the front of each phase shifter 2 corresponds to a semiconductor laser 18 of a coupled cavity surface-emitting InGaAs/GaAs quantum well in the laser array 1; wherein the total power supply 5 is connected to each semiconductor laser respectively. The laser 18 is electrically connected, and the other output port of the total power supply 5 is electrically connected to the computer 4 , the seed laser 3 , and the phase shifter 2 respectively.

The external command is input to the control computer 4 to generate a beam dwell command, including parameters such as azimuth angle and launch time, and the control computer 4 calculates the phase of each phase shifter 2 according to the beam dwell command, so that each of the laser arrays 1 The laser unit has the required phase shift in order to form the laser beam in the specified direction. By changing the phase, the pointing of the laser beam can be changed, so that the beam scans according to a predetermined scheme in a certain space.

Example 2

According to Figure 1 and Figure 3, a 1.3 μm near-infrared phased array laser device is fabricated, and the laser array is a 100x100 two-dimensional array. The laser array in this device is made up of the semiconductor laser 18 of 100x100 vertical cavity surface emission, and this semiconductor laser 18 is the external cavity type surface emission InGaAsN/GaAs quantum well laser, as shown in Figure 3, among the figure 13 is the external output cavity mirror , 14 is a quantum well, and 15 is an internal reflection cavity mirror. Using the transition mechanism between the conduction band and the valence band, each laser 18 emits a 1.3 μm single longitudinal mode near-infrared laser. The seed laser 3 is a single vertical cavity surface emitting InGaAsN/GaAs quantum well laser, and its structure and performance are exactly the same as the laser 18 in the laser array. The total power supply 5 works in a continuous pumping mode. The phase shifter 2 is made of a piece of LiNbO ₃ . An optical nonlinear crystal 16 (Fig. 4) is inserted into the laser cavity of the laser array, and the phased array laser device can convert the working wavelength of the laser. Other structures are the same as in Embodiment 1.

Example 3

According to Fig. 1, a mid-infrared phased array laser device is made, and its structure is the same as that of Embodiment 1. The vertical cavity surface emitting semiconductor laser 18 forming an array in this device adopts an In _0.52 Al _0.48 As/In _0.53 Ga _0.47 As quantum well structure (as shown in FIG. 2 ). Using the sub-band transition and cascade tunneling mechanism, each laser 18 emits a single-mode mid-infrared laser with the same wavelength of 9.3 μm. The laser array is a 100x100 two-dimensional array. The seed laser 3 is a single vertical cavity surface emitting In _0.52 Al _0.48 As/In _0.53 Ga _0.47 As quantum cascade laser, and its structure and performance are exactly the same as those of the laser 18 constituting the laser array. The phase shifter 2 is made of another CdTe photoelectric crystal. The total power supply 5 works in a pulse pumping mode with a pulse width of 25 ns, and the peak power of each laser 18 is 1 kilowatt, so a 100x100 area array can obtain megawatt output power. Other structures are the same as in Embodiment 1.

Example 4

Make a blue light phased array laser device according to Fig. 1, its structure is the same as embodiment 1. The semiconductor laser 18 constituting the array in this device is a vertical cavity surface emitting InGaN/GaN quantum well laser with a microlens 17 ( FIG. 5 ). Using the transition mechanism between the conduction band and the valence band, each laser can emit the same single longitudinal mode blue laser. The array is a 100x100 two-dimensional array. The seed laser 3 is a single vertical cavity surface emitting InGaN/GaN quantum well laser, and its structure and performance are exactly the same as those of the lasers constituting the laser array. Phase shifter 2 is made of KDP photoelectric crystal. Laser 18 operates in a continuous manner.

Claims (8)

1. A phased array laser device utilizing a vertical cavity surface-emitting semiconductor laser to make, comprising: a laser, a control computer and a total power supply; it is characterized in that: a phase shifter is also included; the laser comprises a seed laser and consists of n A laser array composed of vertical cavity surface emitting single longitudinal mode semiconductor lasers; the phase shifter is arranged in front of the optical path of the seed laser, and each phase shifter is correspondingly arranged in front of a vertical cavity surface emitting single longitudinal mode semiconductor laser in the laser array; wherein One output port of the total power supply is electrically connected to each vertical cavity surface-emitting single longitudinal mode semiconductor laser, and the other output ports of the total power supply are respectively connected to the computer, the seed laser, and the phase shifter; the reference phase of each laser in the laser array is determined by The same single longitudinal mode seed laser is provided; the external command is input into the computer to generate the beam dwell command, and the control computer calculates the phase of each phase shifter according to the beam dwell command, so that each laser unit in the laser array has the required phase Shift, form the laser beam in the specified direction, adjust the phase, change the pointing of the laser beam, so that the beam scans according to the predetermined law in a certain space. 2. The phased array laser device manufactured by using vertical cavity surface emitting semiconductor laser according to claim 1, characterized in that: said vertical cavity surface emitting single longitudinal mode semiconductor laser is an external cavity mirror structure. 3. the phased array laser device utilizing vertical cavity surface emitting semiconductor lasers to make according to claim 1 is characterized in that: the active region of said vertical cavity surface emitting semiconductor lasers adopts superlattice, quantum well or quantum dots structure. 4. the phased array laser device utilizing the vertical cavity surface emitting semiconductor laser according to claim 2 is characterized in that: the structure of the external cavity mirror is to insert optical nonlinearity between the semiconductor laser chip and the external cavity mirror crystals. 5. The phased array laser device manufactured by using a vertical cavity surface emitting semiconductor laser according to claim 1, characterized in that: the laser wavelength of the semiconductor laser includes visible light to mid-infrared band. 6. The phased array laser device utilizing vertical cavity surface emitting semiconductor lasers to make according to claim 1, characterized in that: said semiconductor laser arrays comprise 1 × M one-dimensional line arrays, M × N two-dimensional arrays , or an annular circular surface array, where M and N are positive integers greater than 1, respectively. 7. The phased array laser device manufactured by vertical cavity surface emitting semiconductor laser according to claim 1, characterized in that: the material, structure and performance of the seed laser and the semiconductor laser used in the laser array are the same. 8. The phased array laser device made by utilizing a vertical cavity surface emitting semiconductor laser according to claim 1, wherein the laser material of the vertical cavity surface emitting semiconductor laser comprises: gallium indium, arsenic indium, InP, InSn, InGaAs, InAlAs, InCaP, InGaN, InGaAsN, InGaAsN, AlGaAs, AlGaInP, GaAs, Sn aluminum or gallium nitride.

Images