Patent Publication Number: US-2021191227-A1

Title: Device for deflecting laser beams

Description:
FIELD 
     The present invention relates to a device for deflecting laser beams. 
     BACKGROUND INFORMATION 
     Conventional beam deflection units based on optical phase shifters may function without moving components. Such beam deflection units are thus used as a substitute for mechanical mirrors. Deflection angles in the range of approximately 5° to 15° are typically achieved. 
     It is disadvantageous that the deflection angle is too small for LIDAR applications, which require much larger deflection angles. 
     United States Patent Application Publication No. US 2016/0049765 A1 describes a plurality of one-dimensional beam-forming chips that form a two-dimensionally scanning solid state array, so that a three-dimensional surroundings image may be detected. The solid state arrays are situated one above the other, and emit at one end of the particular chip. The control direction is situated in the chip plane. 
     It is disadvantageous that the deflection angles of the laser beams are determined by the orientation of the particular solid state array. In other words, the resolution in the vertical deflection dimension cannot be changed. 
     An object of the present invention is to change and increase the deflection angle. 
     SUMMARY 
     In accordance with an example embodiment of the present invention, a device for deflecting laser beams includes at least one light source that is configured for generating laser beams, and at least one integrated optical circuit. The integrated optical circuit is situated on a substrate. The substrate has a first main direction of extension, a second main direction of extension, and a third main direction of extension. The first main direction of extension and the second main direction of extension span a plane of the substrate surface, and the third main direction of extension is orthogonal to the plane of the substrate surface. The integrated optical circuit includes at least one waveguide and at least one emission means (emission element), the emission means functioning as an output of the integrated optical circuit and the laser beams emitting along a first direction. According to the present invention, a deflection means (i.e., deflector element) is provided which is spaced apart from the substrate along the first main direction of extension or along the second main direction of extension or along the third main direction of extension, the deflection means deflecting the laser beams along a second direction, the second direction being different from the first direction. 
     The advantage is that the deflection angle is changeable independently of the orientation of the substrate. 
     In one refinement of the present invention, the integrated optical circuit includes at least one optical phase shifter and at least two emission means. In other words, the integrated optical circuit is designed as a phase-controlled group antenna. A phase-controlled group antenna is also known as an optical phased array antenna. 
     An advantage is that the light that is emitted by the at least two emission means creates an interference which may be controlled by the phase shifter. This control allows the beam to be deflected along the first direction. This means that the direction of the laser beams at the output of the emission means may be different from the direction of the laser beams at the output of the deflection device. 
     In one refinement of the present invention, multiple integrated optical circuits are provided that are designed as one- or two-dimensional arrays and that are situated on a shared carrier substrate. In other words, the integrated optical circuits constitute or form an area array. 
     It is advantageous that multiple laser beams may be simultaneously deflected, and these laser beams may cover different scanning areas, i.e., allow parallelization of the laser beams. The laser beams that are emitted by the optical circuit are deflected in various directions, depending on the position and shape of the deflection means. In other words, the deflection means does not deflect every beam in the same direction. 
     In another embodiment of the present invention, the first direction corresponds to the third main direction of extension. 
     The advantage is that beams that are emitted perpendicularly with respect to the substrate surface may be deflected. 
     In one refinement of the present invention, the first direction corresponds to the first main direction of extension or to the second main direction of extension. 
     It is advantageous that beams that are emitted in the plane of the substrate surface at one end of the substrate of the integrated optical circuits may be deflected. 
     In another embodiment of the present invention, multiple integrated optical circuits are situated one above the other, spaced apart along the third main direction of extension. The carrier substrates on which the integrated optical circuits are situated are in particular situated in parallel. 
     An advantage is that the effort for alignment between the optical circuits may be minimized, and a simple configuration for deflecting the laser beams may thus be selected. 
     In one refinement of the present invention, the deflection means includes at least one lens. 
     It is advantageous that the lens additionally deflects the optical beam that is emitted by the integrated optical circuits. The lens has the advantage in particular that this additional deflection is continuous, so that areas into which no beams can be deflected may thus be prevented from arising in the overall deflection range. 
     In another embodiment of the present invention, the deflection means includes a microlens array. 
     The advantage is that the deflection angle range for the optical circuits may be set differently and individually. 
     In one refinement of the present invention, the deflection means includes a multistage prism. 
     It is advantageous that different deflection angles may be achieved. 
     Further advantages result from the description below of exemplary embodiments of the present invention and from the figures. 
    
    
     
       BRIEF DESCRIPTION OF EXAMPLE EMBODIMENTS 
       The present invention is explained below with reference to preferred specific embodiments and the figures. 
         FIG. 1  shows a schematic layout of an example device for deflecting laser beams in accordance with an example embodiment of the present invention. 
         FIG. 2  shows a device for deflecting laser beams, including an area array that emits in the plane of the substrate surface, in accordance with an example embodiment of the present invention. 
         FIG. 3  shows a device for deflecting laser beams, including multiple area arrays that emit in the plane of the substrate surface and are situated one above the other, in accordance with an example embodiment of the present invention. 
         FIG. 4  shows a device for deflecting laser beams, including multiple area arrays that emit perpendicularly with respect to the plane of the substrate surface, in accordance with an example embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS 
       FIG. 1  shows a schematic layout of device  100  for deflecting laser beams. Device  100  includes a coherent light source  101 , an integrated optical circuit  107 , and a deflection means  108 . Integrated optical circuit  107  includes at least one coupler  102 , which may be an evanescent coupler, a multimode waveguide, or a light splitter, for example. Integrated optical circuit  107  includes multiple waveguides  104  and multiple phase shifters  105  which set or control the phase of the light. Phase shifters  105  are, for example, thermally-, electrooptically-, magnetooptically-, or MEMS-based, or are based on nonlinear optical effects. Integrated optical circuit  107  also includes multiple emission means  105  that emit the laser beams into the surroundings. Emission means  105  are grating couplers or mirrors, for example, when the first direction or the propagation direction of the laser beams extends in parallel to the third main direction of extension. When the first direction or the propagation direction of the laser beams extends in parallel to the first main direction of extension or the second main direction of extension, i.e., in the plane of the substrate surface, emission means  105  is an edge coupler, for example. In the case of using an edge coupler, the efficiency of emission means  105  may be increased when inverse tapers are additionally provided downstream. The inverse tapers are necessary for designing the optical directional characteristic in such a way that the optical power is maximized in the predefined or desired deflection range. Deflection means  108  includes an optical element that is situated in the beam path of the laser beam in the propagation direction. This optical element deflects the laser beam of each integrated optical circuit  107  in a direction, i.e., the second direction, which is different from the first direction. In other words, the optical element changes the propagation direction of each laser beam. The optical element is designed in such a way that adjacent integrated optical circuits cover slightly overlapping or adjoining areas, so that no unscannable areas arise. This is ensured in that the scanning area of an individual optical circuit overlaps with the scanning area of the adjacent optical circuit. Deflection means  108  is a lens, a microlens array, or a multistage prism, for example. In other words, the light beam or laser beam that is emitted by the coherent light source is guided to integrated optical circuit  107  via coupler  102 , deflection means  108  being situated at the output of the integrated optical circuit, in the beam path of the first direction and spaced apart from the substrate of integrated optical circuit  107 . Integrated optical circuits  107  optionally include optical switches that are situated between coupler  102  and waveguides  104 . Alternatively, each integrated optical circuit  107  may include its own light source  101 . 
       FIG. 2  shows a device  200  for deflecting laser beams, including an area array that includes two integrated optical circuits  207  by way of example. The area array emits at one end of the particular substrate, in the plane of the substrate surface. Device  200  includes a coherent light source  201 , optical switches  203 , and a deflection means  208  in the form of a prism. In addition,  FIG. 2  shows beam path  209  of the laser light at the output of integrated optical circuits  207 , scanning areas  211  of the phased arrays in front of deflection unit  208  and deflected laser beams  210  after the deflection by deflection means  208 , as well as scanning areas  212  of the phased arrays behind deflection unit  208 . An overlap  213  of scanning areas  212  is also shown. 
       FIG. 3  shows a device  300  including multiple integrated optical circuits  307  that are situated in such a way that the radiation plane or the emission plane is spanned by second main direction of extension y and third main direction of extension z. Each integrated optical circuit  307  emits laser beams along the first direction, which in the present example is the same as first main direction of extension x. In addition, each optical circuit  307  is capable of dynamically, i.e., variably, deflecting the optical beam in a scanning area along second main direction of extension y. Deflection means  308  then transforms this deflection range to a new deflection range.  FIG. 3  shows by way of example beam path  309  of the laser light at the output of integrated optical circuits  307  and deflected laser beams  310  after the deflection by deflection means  308 . Deflection means  308  is an elliptical lens in the present example. 
       FIG. 4  shows multiple integrated optical circuits  407  that are situated in such a way that first main direction of extension x and second main direction of extension y span the radiation plane or the emission plane for the laser light. In other words, integrated optical circuits  407  are situated on a shared carrier substrate as a two-dimensional area array. The laser beams are emitted in the direction of third main direction of extension z. Deflection means  408  is situated at a distance above the shared carrier substrate. By way of example,  FIG. 4  shows beam path of the laser light at the output of integrated optical circuits  407  and deflected laser beams  410  after the deflection by deflection means  408 . Deflection means  408  is an elliptical lens in the present example. 
     Device  100 ,  200 ,  300 , and  400  for deflecting laser beams is used, for example, in LIDAR systems, preferably for vehicles, in pico projectors, or in head-up displays.