CN114675369A

CN114675369A - Waveguide grating device, optical waveguide phased array, optical scanning device, and optical communication device

Info

Publication number: CN114675369A
Application number: CN202011572753.1A
Authority: CN
Inventors: 张�林; 郭勇君
Original assignee: Tianjin University
Current assignee: Tianjin University
Priority date: 2020-12-24
Filing date: 2020-12-24
Publication date: 2022-06-28

Abstract

The application discloses waveguide grating device, it includes the basement and forms a plurality of dielectric layers on the basement, a plurality of dielectric layers include the waveguide core layer, are formed with the grating in the waveguide core layer, wherein the basement is etched away completely on being located the position under the grating to expose the dielectric layer, make waveguide grating device form the radiation channel in the upper and lower both sides of grating. The application also discloses an optical waveguide phased array and an optical scanning device with the waveguide grating device. According to the embodiment of the invention, the radiation of the grating substrate side is utilized, the waveguide grating which radiates in the up-down direction is formed, the energy utilization efficiency is improved, and the noise is restrained.

Description

Waveguide grating device, optical waveguide phased array, optical scanning device, and optical communication device

Technical Field

The present invention relates to an optical radiation control technology, and in particular, to a waveguide grating device, and an optical waveguide phased array, an optical scanning apparatus, and an optical communication apparatus having the same.

Background

Optical phased array (optical phase array) is a beam pointing control technology and is generally classified into liquid crystal phased array, Micro Electro Mechanical System (MEMS) phased array, and optical waveguide phased array. The optical waveguide phased array is small in size, light in weight, good in flexibility and low in power consumption; however, the far-field imaging of the optical phased array usually presents gaussian distribution, and the imaging precision is poor in large-angle scanning.

The optical waveguide phased array can be divided into an end-fire (end) optical phased array and a waveguide-grating antenna (waveguide-grating antenna) optical phased array according to different radiation units and principles. The radiation unit of the end radiation optical phased array is composed of a waveguide structure, and one-dimensional dynamic scanning is realized by changing the phase difference between adjacent waveguides. When the radiation unit of the optical waveguide phased array adopts a waveguide grating antenna structure, the incident wavelength can be changed in one dimension, and the phase difference can be changed in the other dimension, so that two-dimensional scanning imaging is realized.

When the waveguide grating antenna is used as a radiation unit, radiation on the substrate side is difficult to avoid, and the energy utilization rate is low. Therefore, it is proposed to add a metal reflective layer or a bragg mirror on the substrate side in the waveguide grating structure to reduce the radiation on the substrate side and improve the energy utilization. However, such techniques still have deficiencies. For example, the method of adding a metal reflective layer is not compatible with CMOS processes. Moreover, none of the above measures completely eliminates the radiation at the substrate side. In addition, the substrate side radiation undergoes multiple reflections in the structure, creating grating lobes, suppressing the signal-to-noise ratio, reducing the imaging accuracy.

For optical phased arrays, in addition to substrate side radiation, the scan range is an important parameter that limits the performance of the phased array.

In order to obtain higher scanning imaging resolution, shallow etching under precise control is usually required in the processing process of the waveguide grating antenna, and the processing process is complex and the processing cost is high.

Disclosure of Invention

It is an object of the present invention to provide a waveguide grating device, and an optical waveguide phased array, an optical scanning apparatus and a free space optical communication apparatus having the waveguide grating device, which at least partially overcome the disadvantages of the prior art.

According to an aspect of the present invention, there is provided a waveguide grating device comprising a substrate and a plurality of dielectric layers formed on the substrate, the plurality of dielectric layers including a waveguide core layer in which a grating is formed, wherein the substrate is completely etched away at a position directly below the grating to expose the dielectric layers, so that the waveguide grating device forms radiation channels on upper and lower sides of the grating.

Preferably, the plurality of dielectric layers are substantially symmetrical with respect to the waveguide core layer in number of layers, thickness, and refractive index.

In some advantageous embodiments, the plurality of dielectric layers further comprises a modulation layer overlying one side of the waveguide core layer and a cladding layer overlying the other side of the waveguide core layer. Preferably, the modulation layer and the cladding layer have substantially the same refractive index for an operating wavelength of the waveguide grating device and have thicknesses of the same order.

In some advantageous embodiments, the modulation layer may be made of LiNbO₃An electro-optic phase modulation layer is formed, and the capping layer may be Si₃N₄And (3) a layer.

In some advantageous embodiments, the dielectric layers further include an upper composite antireflection film and a lower composite antireflection film respectively disposed on upper and lower sides of the waveguide core layer, and each of the upper composite antireflection film and the lower composite antireflection film is composed of an 1/2 wavelength film disposed on an outer side with respect to the waveguide core layer and a 1/4 wavelength film disposed on an inner side.

In some advantageous embodiments, the plurality of dielectric layers comprises, in order: si formed as 1/2 wavelength film₃N₄Layer, SiO formed as 1/4 wavelength film₂Layer, LiNbO formed as electro-optical modulation layer₃Layer, Si layer formed as waveguide core layer, Si formed as cladding layer₃N₄Layer, SiO formed as 1/4 wavelength film₂Layer and Si formed as 1/2 wavelength film₃N₄And (3) a layer.

Preferably, the grating generates substantially symmetrical bi-directional radiation through the upper and lower side radiation channels.

In some advantageous embodiments, the waveguide core layer is further formed with waveguide splitting means symmetrically connected to both ends of the grating.

In some advantageous embodiments, the waveguide core layer is further formed with mirrors at both ends of the grating for optical transmission between the waveguide beam splitting device and the grating. Preferably, the mirror is a bragg mirror.

In some advantageous embodiments, the bragg mirror has two or more reflective surfaces of different orientations. Preferably, the bragg mirror has two reflecting surfaces opposite to each other.

In some advantageous embodiments, the waveguide core layer is configured such that the grating has a symmetrical structure in its direction of extension.

The grating may include a plurality of grooves, preferably, the depth of the plurality of grooves is the same as the thickness of the waveguide core layer.

In some advantageous embodiments, the waveguide core layer is formed with a plurality of the gratings, and the plurality of gratings are arranged in a one-dimensional or two-dimensional array.

According to another aspect of the present invention, there is also provided an optical waveguide phased array including a laser light source, a phase shift control device, and a waveguide grating device. The waveguide grating device comprises a substrate and a plurality of dielectric layers formed on the substrate, wherein the dielectric layers comprise a waveguide core layer, at least two gratings are formed in the waveguide core layer, the substrate is completely etched at a position right below the gratings to expose the dielectric layers, and therefore radiation channels are formed on the upper side and the lower side of the gratings by the waveguide grating device. Laser light emitted by the laser light source is transmitted into the grating of the waveguide grating device, so that bidirectional radiation is formed through the radiation channels on the upper side and the lower side. The phase shift control device is connected to the waveguide grating device to phase modulate the bidirectional radiation formed by the grating.

In some advantageous embodiments, the plurality of dielectric layers further comprises a modulation layer overlying one side of the waveguide core layer and a cladding layer overlying the other side of the waveguide core layer, the modulation layer and the cladding layer having substantially the same refractive index for an operating wavelength of the waveguide grating device and having thicknesses of the same order of magnitude; and the waveguide grating device comprises a positive electrode and a negative electrode, and is used for receiving signals from the phase shift control device and applying voltage to the modulation layer to realize electro-optic phase modulation.

In some advantageous embodiments, the modulation layer is made of LiNbO₃An electro-optic phase modulation layer formed of Si₃N₄And (3) a layer.

In some advantageous embodiments, the plurality of dielectric layers comprises, in order: si formed as 1/2 wavelength film ₃N₄Layer, SiO formed as 1/4 wavelength film₂Layer, LiNbO formed as electro-optical modulation layer₃Layer, Si layer formed as waveguide core layer, Si formed as cladding layer₃N₄Layer, SiO formed as 1/4 wavelength film₂Layer and Si formed as 1/2 wavelength film₃N₄And (3) a layer.

Preferably, the waveguide core layer is further formed with waveguide beam splitting devices, which are symmetrically connected to two ends of the grating, and are used for introducing light emitted by the laser light source from the two ends of the grating to form symmetrical input light opposite to each other in the extending direction of the grating.

In some advantageous embodiments, the waveguide core layer is further formed with bragg mirrors at both ends of the grating for optical transmission between the waveguide beam splitting device and the grating.

In some advantageous embodiments, the waveguide grating device further comprises first laser power distribution means formed thereon for transmitting light from the laser light sources to the waveguide splitting means, respectively.

In some advantageous embodiments, the first laser power distribution means comprises at least two laser power distribution means and is arranged on two sides or one side of the grating perpendicular to the extension direction of the grating.

In some advantageous embodiments, the optical waveguide phased array further comprises an n-level second laser power distribution device, wherein n is larger than or equal to 1, and the second laser power distribution device is connected between the laser light source and the waveguide grating device and used for transmitting light from the laser light source into the waveguide grating device after splitting.

Preferably, the waveguide core layer is configured such that the grating has a symmetrical structure in its extending direction.

According to still another aspect of the present invention, there is also provided an optical scanning device including a light emitting device and a light receiving device, wherein the light emitting device includes the optical waveguide phased array as described above.

Preferably, the light emitting device comprises at least two optical waveguide phased arrays, and the two optical waveguide phased arrays are arranged at an included angle of 90 degrees with each other, so that 360-degree full-field scanning imaging is formed.

The optical scanning device is a laser radar device or a scanning imaging device, such as a biosensor device.

According to yet another aspect of the present invention, there is also provided a free-space optical communication device including a light emitting/receiving device including the optical waveguide phased array as described above.

According to still another aspect of the present invention, there is also provided a waveguide grating device including a substrate and more than one dielectric layers formed on the substrate, the more than one dielectric layers including a waveguide core layer having a grating formed therein, the grating having a symmetrical structure in an extending direction thereof and having light receiving structures on both ends in the extending direction thereof.

Preferably, the waveguide core layer is further formed with waveguide beam splitting devices symmetrically connected to both ends of the grating for introducing symmetrical input light opposite to each other in an extending direction of the grating from both ends of the grating.

Preferably, the substrate is completely etched away at a position directly below the grating to expose the dielectric layer, so that the waveguide grating device forms a radiation channel on both upper and lower sides of the grating.

According to still another aspect of the present invention, there is also provided an optical waveguide phased array including a laser light source, a phase shift control device, and a waveguide grating device. The waveguide grating device includes a substrate and more than one dielectric layers formed on the substrate, the more than one dielectric layers including a waveguide core layer in which a grating is formed, the grating having a symmetrical structure in an extending direction thereof and having light receiving structures on both ends of the extending direction thereof. The laser light emitted by the laser light source is coupled into the grating from two ends of the grating of the waveguide-grating device, and more than one dielectric layer of the waveguide-grating device further comprises a modulation layer, and the phase-shifting control device is connected to the waveguide-grating device to perform phase modulation on the radiation formed by the grating.

Drawings

Other features, objects and advantages of the invention will become more apparent upon reading of the detailed description of non-limiting embodiments with reference to the following drawings:

Fig. 1 is a schematic perspective view of a layered structure of a waveguide grating device according to a first embodiment of the present invention;

FIG. 2 is a schematic longitudinal cross-sectional view of the waveguide grating device of FIG. 1 taken parallel to the direction of grating extension;

FIG. 3 is a schematic cross-sectional view of the waveguide grating device of FIG. 1 taken perpendicular to the direction of grating extension;

fig. 4 is a schematic perspective view of a layered structure of a waveguide grating device according to a modification of the first embodiment of the present invention;

FIG. 5 is a schematic longitudinal cross-sectional view of the waveguide grating device of FIG. 4 taken parallel to the direction of grating extension;

FIG. 6 is a far field radiation pattern of upward radiation of a grating of a waveguide grating device;

FIG. 7 is a far field radiation pattern of downward radiation of a grating of a waveguide grating device;

FIG. 8 is a light intensity distribution diagram of far-field radiation of a grating of a waveguide grating device in a pitch angle direction;

FIG. 9 is a light intensity distribution in the azimuthal direction of the far field radiation of the grating of the waveguide grating device;

FIG. 10 is a schematic perspective view of a waveguide grating device according to a second embodiment of the present invention;

fig. 11 is a schematic perspective view of a waveguide grating device according to a third embodiment of the present invention;

fig. 12 is a schematic perspective view of a waveguide grating device according to a modification of the third embodiment of the present invention;

Fig. 13 is a schematic perspective view of a waveguide grating device according to another modification of the third embodiment of the present invention;

fig. 14 is a schematic perspective view of a waveguide grating device according to a fourth embodiment of the present invention;

fig. 15 is a schematic perspective view of a waveguide grating device according to a modification of the fourth embodiment of the present invention;

fig. 16 is a schematic perspective view of a waveguide grating device according to another modification of the fourth embodiment of the present invention;

FIG. 17 is a schematic block diagram of an optical waveguide phased array in accordance with an embodiment of the invention;

FIG. 18 is a schematic diagram of a preferred implementation of an optical scanning device in accordance with an embodiment of the invention in which two phased arrays of optical waveguides are arranged at an angle of 90 to each other;

FIG. 19 schematically illustrates the scanning range of an optical scanning device having a single optical waveguide phased array;

fig. 20 schematically shows the scanning range of an optical scanning device having two optical waveguide phased arrays of the arrangement shown in fig. 18;

fig. 21 is a schematic perspective view of a waveguide grating device according to fifth embodiment of the present invention;

fig. 22 is a schematic perspective view of a waveguide grating device according to a sixth embodiment of the present invention.

Detailed Description

The present invention will be described in further detail with reference to the accompanying drawings and examples. It is to be understood that the specific embodiments described herein are merely illustrative of the relevant invention and not restrictive of the invention. For convenience of description, only portions related to the invention are shown in the drawings.

It should be noted that the embodiments and features of the embodiments in the present application may be combined with each other without conflict. The present invention will be described in detail below with reference to the embodiments with reference to the attached drawings.

Waveguide grating devices and optical waveguide phased arrays based thereon will be described below. Since the grating can be used as both the transmitting structure and the receiving structure, and the receiving and transmitting are inverse processes, the principle of the receiving structure is the same as that of the transmitting structure, so the grating will be described as the transmitting structure, and the receiving structure will not be described again.

First, a waveguide grating device 100 according to a first embodiment of the present invention will be described with reference to fig. 1 to 3.

Fig. 1 is a schematic perspective view of a layered structure of a waveguide grating device 100 according to a first embodiment of the present invention. As shown in fig. 1, the waveguide grating device 100 includes a substrate 110 and a plurality of dielectric layers 120 formed on the substrate, wherein the plurality of dielectric layers 120 includes a waveguide core layer 121. Waveguide core layer121 has at least one grating G formed therein. According to the embodiment of the present invention, in the waveguide-grating device 100, the substrate 110 is completely etched away at the position 110a directly below the grating G to expose the dielectric layer 120, so that the waveguide-grating device 100 forms the radiation channels P on both the upper and lower sides of the grating G ₁、P₂(see fig. 2 and 3).

The substrate generally provides strong reflection and/or absorption of the downward radiation from the grating in the waveguide core, so conventionally the grating is used only for unidirectional radiation on the side opposite the substrate, whereas radiation on the substrate side is undesirable. Even further techniques for suppressing and eliminating substrate-side radiation have been proposed in the prior art to improve energy utilization. In contrast, the inventors of the present invention propose to build up a more efficient radiation channel on the underside of the grating by completely etching away the substrate underneath the grating, actively using the substrate-side radiation of the grating, rather than suppressing it. In other words, according to the embodiment of the present invention, a waveguide grating structure/device for bidirectional radiation is provided, which extends the scanning range, makes full use of radiation energy, and suppresses noise. The use of a bidirectionally radiating waveguide grating in optical waveguide phased array technology can reduce the number of gratings/phased arrays of 1/2.

According to an advantageous embodiment of the present invention, the grating in the waveguide grating device 100 preferably has a substantially symmetrical structure up and down with respect to the waveguide core layer, thereby achieving symmetrical up-and-down dual-directional radiation, ensuring symmetry and uniformity of far-field radiation on both sides, and improving imaging performance. Furthermore, it should be appreciated that etching away the substrate directly under the grating according to embodiments of the present invention also helps to ensure symmetry of the bi-directional radiation.

Fig. 2 shows a longitudinal sectional schematic view (parallel to the x-y plane) taken along the extending direction (x direction shown in the figure) of the grating G in the waveguide grating device 100, fig. 3 shows a cross-sectional schematic view (parallel to the y-z plane) taken perpendicular to the extending direction, and shows a schematic layer structure. As shown, in some advantageous examples, the plurality of dielectric layers 120 of the waveguide grating device 100 may have a substantially symmetrical structure up and down with respect to the waveguide core layer 121. Here, the substantially symmetrical structure may refer to a symmetrical structure in terms of the number of layers, thickness, refractive index, and the like, but the present invention is not limited thereto.

For example, in the example shown in fig. 2 and 3, the plurality of dielectric layers 120 include, in addition to the waveguide core layer 121, a modulation layer 122 located on the lower side of the waveguide core layer 121 and a cladding layer 123 covering the upper side of the waveguide core layer 121. It should be understood that the positions of the modulation layer 122 and the cladding layer 123 relative to the waveguide core layer 121 may be reversed, and the invention is not limited in this respect. The descriptions of relative positions used in the context of the present application, including "upper," "lower," "front," "back," etc., are exemplary only and not limiting.

Preferably, the modulation layer 122 and the cladding layer 123 have substantially the same refractive index for the operating wavelength of the waveguide grating device 100 and have thicknesses of the same order. Taking the radiation with the operating wavelength of 1550nm as the center wavelength as an example, the modulation layer 122 may be a lithium niobate modulation layer, and the capping layer 123 may be a silicon nitride capping layer. Refractive indices of silicon nitride and lithium niobate at the above operating wavelengths (Si at 1550 nm)₃N₄Has a refractive index of 1.996 and is LiNbO₃Has a refractive index of 2.211) are approximately equal. The refractive indices of these two materials are much different than the refractive index 3.478 at 1550nm for the common material Si used for the waveguide core layer 121; thus, in contrast, the

dielectric layers

122, 123 on both sides of the waveguide core layer 121 can be considered approximately the same refractive index. Similarly in terms of thickness, although it is highly likely that the thicknesses of the modulation layer 122 and the cover layer 123 are different according to optimization calculations, it is preferable to have thicknesses of the same order.

The plurality of dielectric layers 120 may also include other layers. As shown in fig. 2 and 3, the dielectric layers 120 further include, for example, an upper composite antireflection film 124 and a lower composite antireflection film 125 respectively on the upper and lower sides of the waveguide core layer 121. The upper composite antireflection film 124 and the lower composite antireflection film 125 are each composed of an 1/2 wavelength film located on the outer side and an 1/4 wavelength film located on the inner side with respect to the waveguide core layer 121. For example only, the 1/2 wavelength film may be Si ₃N₄SiO of the wavelength film of

layers

124a, 125a, 1/4₂

Layers

124b, 125 b. Upper composite permeability increasingFilm 124 and lower composite antireflective film 125 are preferably not only the same in number of layers, materials (refractive indices) but also substantially the same in thickness.

In some preferred examples, the reinforcing films 124 and 125 formed by compounding the 1/4 wavelength film and the 1/2 wavelength film are obtained by optimizing parameters on the basis of a normal incidence antireflection film. The purpose of the optimization is to obtain uniform far field radiation over a large angular range and to improve the transmission. The composite antireflection film improves the transmittance of light with an incident angle smaller than a total reflection angle, and is favorable for inhibiting grating lobes in imaging.

Further, the grating G includes a plurality of notches formed in the waveguide core layer 121; since both the upper and lower radiation of the grating are to be utilized according to an embodiment of the present invention, it is preferable that the depths of these grooves have the same thickness as the waveguide core layer 121. Thus, the groove of the grating G can be realized by an etching process without precisely controlling the depth. Conventional waveguide gratings, however, typically need to be formed by precise shallow etching at the nanometer level in order to achieve a large numerical aperture. In contrast, waveguide grating devices according to advantageous embodiments of the present invention that do not require precise control of grating groove depth are simple and inexpensive to manufacture. For example, the grating structure according to the advantageous embodiment of the present invention can be processed synchronously with the waveguide core layer, and can be realized only by one electron beam lithography, which is easy to prepare; the preparation is carried out by adopting a mature CMOS process, so that the processing cost is low; the phase modulation structure can be integrally manufactured, and can be used for low-cost full-field-of-view full-solid optical phased array chips.

With combined reference to fig. 1 and 2, in the waveguide grating device 100 according to the first embodiment of the present invention, since the grating G is generally symmetrical in a direction (z direction) perpendicular to the extension direction of the grating along the plane of the waveguide core layer 121, the radiation formed by the grating G is symmetrical in the azimuth direction (direction of rotation about the x axis). On the other hand, in the waveguide grating device 100, the grating G is formed to receive the light source S from only one end of the grating₁This results in the grating G being asymmetric in its extension direction, the radiation being formed with a certain tilt angle in the elevation direction. Waveguide grating device according to a modification of the first embodiment of the present invention100A overcomes the above-mentioned problems by employing a grating having a symmetrical structure in the extension direction. Next, the waveguide grating device 100A will be described with reference to fig. 4 to 9.

Fig. 4 is a schematic perspective view of the layered structure of the waveguide grating device 100A, and fig. 5 is a schematic longitudinal sectional view of the waveguide grating device 100A taken parallel to the grating extending direction. As shown in the drawing, in the waveguide grating device 100A, the waveguide core layer 121 is configured such that the grating G has a symmetrical structure in the extending direction (x direction) thereof, and particularly the grating G has

light receiving structures

121a, 121b at both ends thereof. In the examples shown in fig. 4 and 5, the

light receiving structures

121a, 121b may be constituted by waveguides extending from both ends of the grating. Of course, it should be understood that the present invention is not limited to the specific configuration of the light receiving structure as long as the light radiation S can be radiated ₁、S₂The grating may be introduced from both ends of the grating or the light radiation may be received from both ends of the grating.

The waveguide grating device 100A has substantially the same structure as the waveguide grating device 100 except that the structural symmetry of the grating in the extending direction is different, and will not be described again here.

According to the waveguide grating device 100A of the present modification and the waveguide phased array having the same, radiation symmetrical with respect to the vertical position (the central zero-degree pitch position) in the pitch angle direction can be provided, which is advantageous for simplifying the phase shift control of the grating/phased array, facilitating the combined use of a plurality of gratings/phased arrays, and further, facilitating the improvement of the accuracy of scanning imaging.

For ease of understanding, an exemplary numerical example of the waveguide grating device 100A will be given below.

In this numerical example, the waveguide grating device 100A includes LiNbO for phase modulation₃Modulation layer 122, Si waveguide core layer 121 on LiNbO₃Above the modulation layer 122, the upper side of the waveguide core layer 121 is Si₃N₄And a cap layer 123. Si₃N₄Capping layer 123 and LiNbO₃The outer side of the modulation layer 122 is made of Si formed by 1/2-1/4 wavelength antireflection films₃N₄-SiO₂And the composite antireflection films 124 and 125 are of structures. In order to reduce reflection in the Si substrate, the Si substrate is coated with a layer of a metalThe Si substrate directly under the waveguide-grating antenna structure is completely etched away. Because the structures on the two sides of the waveguide core layer are not completely equal, the composite antireflection film structure with approximately equal thickness is adopted at the corresponding positions on the two sides of the waveguide core layer to improve the radiation uniformity of a far field, improve the imaging quality, improve the energy utilization rate, inhibit edge noise and reduce imaging blind spots. The corresponding dimensions of the above layers (excluding the substrate) are shown in table 1.

Table 1: layer structure parameters of waveguide grating device

In this numerical example, the grating G includes four grooves and has a symmetrical structure in the extending direction of the grating. Thus, referring to fig. 5, the notch has two different notch positions p with respect to the center of symmetry₁、p₂(i.e., distance from the center of symmetry) the notch width may also have two different widths w1, w 2. And etching 0.22 mu m (namely completely etching the waveguide core layer) at the corresponding position of the center of the waveguide core layer according to the notching parameters shown in the table 2 to obtain the waveguide-grating antenna structure.

Table 2: groove parameters of grating

Location of the notch	Numerical value (mum)	Width of the groove	Numerical value (μm)	Parameter(s)	Numerical value (μm)
						p₁	1.265	w₁	0.464	h_e	0.220
p₂	0.332	w₂	0.077	w	5.000

Incident light enters the grating from the waveguides at two ends of the grating respectively and radiates to the upper side and the lower side. The wavelength of the incident light is within a 100nm bandwidth centered around 1550 nm.

Fig. 6 and 7 are far field radiation patterns of upward radiation and downward radiation, respectively, of the grating of the waveguide grating device according to this data example. As can be seen from fig. 6 and 7, the upward and downward far field radiation of the grating has the characteristics of uniformity and symmetry.

Fig. 8 is a light intensity distribution diagram of far-field radiation in the pitch direction of the grating of the waveguide grating device according to this data example (z-0 section). As can be seen from fig. 8, in the pitch direction, the full width at half maximum (half-maximum) of the upward far-field radiation is 91.1 °, and the half-maximum of the downward far-field radiation is 97.0 °, so that the upward and downward far-field radiation can cover an angular range of about 180 ° in total. In addition, it can be seen from fig. 8 that the far-field radiation of the waveguide grating device is relatively uniform within a range of ± 45 °, and no grating lobes appear in the whole field of view.

Fig. 9 is a light intensity distribution diagram (y-0 section) of far-field radiation of a grating of a waveguide grating device in an azimuthal direction. As can be seen from fig. 9, in the azimuth direction, the half-width of the upward far-field radiation is 21.4 °, and the half-width of the downward far-field radiation is 22.0 °.

Next, a waveguide grating device 200 according to a second embodiment of the present invention will be described, and fig. 10 is a perspective view of an example of the waveguide grating device 200.

For clarity, the structure overlying the waveguide core layer is not shown in fig. 10, and is similarly processed in fig. 11-15. Moreover, in the figures corresponding to the various embodiments, corresponding structures are identified by like reference numerals, e.g., the substrate is identified by 110, 210, 310, 410, 510 in the figures for the various embodiments, respectively; the dielectric layers are respectively indicated by 120, 220, 320, 420 and 520 in the figures of the embodiments, and other structures are similar and will not be described one by one.

The waveguide grating device 200 according to the second embodiment of the present invention has substantially the same structure as the waveguide grating device 100A according to the modification of the first embodiment of the present invention, except that: in the waveguide grating device 200, the waveguide core layer 121 is formed with waveguide splitting means 230 symmetrically connected to both ends of the grating G. As shown in fig. 10, waveguide splitting device 230 may advantageously be a one-to-two waveguide splitter. Alternatively or additionally, the waveguide splitting device 230 may employ other suitable splitting devices such as a star coupler (star coupler), a main line waveguide coupler (bus-waveguide coupler), and the like.

As shown in fig. 10, in the waveguide grating device 200, the waveguide core layer 121 may further be formed with mirrors 240 at both ends of the grating G for light transmission between the waveguide beam splitting device 230 and the grating G. In a preferred embodiment according to the present invention, the mirror 240 may employ a bragg mirror.

The two ends of the grating are provided with the reflectors for transmitting light, so that the grating device adopting the bidirectional symmetrical light source can have a compact structure, and the requirements of miniaturization and high integration in application occasions such as an optical waveguide phased array and the like are met. Especially, the Bragg reflector is adopted, and the Bragg reflector has the advantages of small size, wide waveband and high efficiency, and is more beneficial to the miniaturization and efficiency improvement of the whole device.

Further, as can also be seen from fig. 10, the waveguide grating device according to the embodiment of the present invention is not limited to the formation of a single grating G, but may form two or more gratings. Furthermore, as shown in fig. 10, the waveguide grating device according to the embodiment of the present invention may further include a first laser power distribution device 250 formed thereon, for distributing laser light S entering the first laser power distribution device 250 in future ₀Power distribution is performed to be transmitted to two or more waveguide splitting devices 230, respectively. A first laser power splitting device 250 may be formed in the waveguide core layer 221 as shown in fig. 10; however, the present invention is not limited in this respect, and the first laser power distribution device 250 may be formed in a layer other than the waveguide core layer 221. The first laser power distribution device 250 and the waveguide beam splitting device 230 form a cascaded beam splitting structure to provide laser light as coherent light to two or more gratings G in a bilaterally symmetric manner.

In accordance with embodiments of the present invention, a plurality of gratings in a waveguide grating device may be arranged in a one-dimensional or two-dimensional array. The formation of the grating array is beneficial to the integration and miniaturization of the device, thereby being beneficial to the application of the device. In the waveguide grating device according to the embodiment of the present invention in which a plurality of gratings form a one-dimensional or two-dimensional array, the gratings are not limited to the gratings described above having a symmetrical structure in the extending direction thereof. In particular, a grating array based on such gratings, in a waveguide grating device according to an embodiment of the present invention in which the gratings generate bi-directional radiation through upper and lower radiation channels, already offers technical advantages. However, in order to demonstrate further technical features and advantages of the present invention, a waveguide grating device according to an embodiment of the present invention formed with a grating array will be described below by taking a grating having a symmetric structure in combination with a bi-directionally symmetric light source as an example.

First, a waveguide grating device formed with a one-dimensional grating array according to a third embodiment and its modifications of the present invention will be described with reference to fig. 11 to 13.

Fig. 11 is a schematic perspective view of a waveguide grating device 300 according to a third embodiment of the present invention, and fig. 12 and 13 respectively show two modifications of the waveguide grating device shown in fig. 11. As shown, in the waveguide

grating devices

300, 300A, 300B, a plurality of gratings G (4 gratings are exemplarily shown in the drawing) are arranged in a one-dimensional array along the extending direction of the gratings.

Although the waveguide splitting device 330, the reflecting mirror 340 and the laser power splitting device 350 are illustrated, it should be understood that the waveguide grating device according to the third embodiment and the modified examples of the present invention is not limited to having the above-described structure, and advantageous alternative embodiments are illustrated in fig. 11 to 13.

In the waveguide grating device 300 shown in fig. 11, more than one laser power splitting means 350 (first laser power splitting means) are provided, which are arranged on the same side of the grating G perpendicular to the grating extension direction and are cascaded with waveguide splitting means 330 for different gratings G, respectively.

In the waveguide grating device 300A shown in fig. 12, unlike the waveguide grating device 300, more than one laser power distribution device 350 is arranged on both sides of the grating G perpendicular to the grating extension direction.

In the waveguide grating device 300B shown in fig. 13, unlike the waveguide

grating devices

300, 300A, the laser power distribution device 350 is formed as a distribution structure itself having more than one level, thereby distributing the light of the same light source S0 to a plurality of different gratings. Further, in the example shown in fig. 13, the laser power distribution device 350 is connected to the waveguide beam splitting device 330 from both sides of the grating G perpendicular to the grating extending direction.

The waveguide-grating device 300B of the variation shown in fig. 13 may be directly connected to a laser light source that provides coherent light to multiple gratings G simultaneously, thereby eliminating the need for additional laser power distribution devices connected between the laser light source and the waveguide-grating device.

Further, in fig. 13, electrodes 360 are shown for applying a voltage to, for example, a lithium niobate modulation layer to achieve electro-optical phase modulation of the grating. Advantageously, the electrodes 360 are arranged at the light inlets of the waveguide splitting means 330, such that by the electrodes 360 being arranged at the light inlets of different waveguide splitting means 330, respectively, corresponding to different gratings G, a separate phase modulation of the respective gratings can be achieved. In other cases, the electrode 360 may be disposed on a common optical transmission channel of a plurality of gratings G for which the same phase modulation is desired, for example, a branch structure of the laser power distribution device 350, according to the specific application.

It should be understood that such electrodes for electro-optical phase modulation may be provided on waveguide grating devices according to embodiments of the present invention, although not shown in other figures.

Next, a waveguide grating device formed with a two-dimensional grating array according to a fourth embodiment and its modifications of the present invention will be described with reference to fig. 14 to 16.

Fig. 14 is a schematic perspective view of a waveguide grating device according to a fourth embodiment of the present invention, and fig. 15 and 16 show two modifications of the fourth embodiment, respectively. As shown, in the waveguide

grating devices

400, 400A, 400B, a plurality of gratings G (4 gratings are exemplarily shown in the drawing) are arranged in a two-dimensional array.

In the waveguide grating device 400 shown in fig. 14, a plurality of gratings G (8 are shown in the drawing) are arranged in such a manner as to be aligned with each other in the grating extending direction.

In the waveguide grating device 400A shown in fig. 15, the plurality of gratings G are arranged to be displaced from each other in the grating extending direction, and have a first pitch d1 in the grating extending direction and a second pitch d2 in a direction perpendicular to the grating extending direction, wherein the first pitch d1 and the second pitch d2 are both positive values.

In the waveguide grating device 400B shown in fig. 16, the plurality of gratings G are arranged to be displaced from each other in the grating extending direction, and the plurality of gratings G and their surrounding structures are also arranged in a complementary manner in a direction perpendicular to the grating extending direction, forming a compact structure. Specifically, the grating G of the symmetrical structure forms an approximately triangular structure with the mirrors 440 formed at both ends thereof and the waveguide splitting device 430 therefor; in the example shown in fig. 16, such an approximately triangular structure corresponding to each grating G is arranged in a complementary manner. The waveguide grating device shown in fig. 16 can have a compact structure, which is advantageous in reducing the dimension perpendicular to the grating extending direction.

Waveguide grating devices formed with one-dimensional or two-dimensional grating arrays have been described above with reference to the accompanying drawings. It should be understood that a one-dimensional or two-dimensional grating array of waveguide grating devices may have a periodic or non-periodic arrangement in accordance with embodiments of the present invention. According to an advantageous embodiment, when the arrangement is non-periodic, the phase difference inherent to the radiation electrodes can be compensated by means of the applied voltage for phase modulation (applied for example through the electrodes shown in fig. 13). The aperiodic arrangement can help to inhibit grating diffraction, improve energy utilization efficiency and reduce noise.

According to an embodiment of the present invention, there is also provided an optical waveguide phased array having the waveguide grating device according to an embodiment of the present invention.

Fig. 17 is a schematic structural block diagram of an optical waveguide phased array according to an embodiment of the present invention. As shown in fig. 17, the optical waveguide phased array 1 includes a laser light source 10, a waveguide grating device 20, and a phase shift control device 30, wherein the waveguide grating device 20 is a waveguide grating device according to an embodiment of the present invention, and wherein at least two gratings are formed in a waveguide core layer. The laser light emitted from the laser light source 10 is transmitted to the grating 21 (waveguide-grating antenna) of the waveguide-grating device 20, so that bidirectional radiation is formed through the radiation channels on the upper and lower sides of the grating. A phase shift control device 30 is connected to the waveguide grating device 20 to phase modulate the bi-directional radiation formed by the grating 22. Preferably, the grating 22 generates substantially symmetrical bi-directional radiation through the upper and lower side radiation channels.

In an advantageous embodiment, the waveguide-grating device 20 comprises positive and negative electrodes (not shown) for receiving signals from the phase-shift control device 30 to apply voltages to the modulation layer in the waveguide-grating device to achieve electro-optical phase modulation.

In an advantageous embodiment, the waveguide-grating device 20 further comprises a laser power splitting device 22 (first laser power splitting device) formed thereon for splitting the light from the laser light source 10 for the different gratings 21. Preferably, the waveguide core layer of the waveguide grating device 20 may have waveguide beam splitting means (see waveguide beam splitting means 230 in fig. 10) formed thereon, which are symmetrically connected to both ends of the grating 21, for introducing light emitted from the laser light source 10 from both ends of the grating to form symmetrical input light opposite to each other in the extending direction of the grating 21. In this case, the laser power distribution device 22 may split the light from the laser light source 10 and transmit the split light to the waveguide splitting devices corresponding to the different gratings 21, respectively.

Referring back to fig. 12, 14-16, in an advantageous embodiment the first laser power distribution means 22 may comprise at least two laser power distribution means and be arranged on both sides of the grating 21 perpendicular to the grating extension direction.

Although not shown in fig. 17, the optical waveguide phased array according to the embodiment of the present invention may further include a laser power distribution device (second laser power distribution device) separate from the waveguide grating device 20, connected between the laser light source 10 and the waveguide grating device 20, for transmitting light from the laser light source 10 to the waveguide grating device 20 after splitting the light. The second laser power distribution device may be, for example, a fiber-based laser beam splitting device. And an n (n is more than or equal to 1) level laser power distribution device can be added between the laser light source and the waveguide grating device according to the array arrangement requirement.

It should be appreciated that a phased array of optical waveguides according to embodiments of the present invention naturally has other features and technical advantages of a waveguide-grating device according to embodiments of the present invention, and will not be described in detail herein.

There is also provided, in accordance with an embodiment of the present invention, an optical scanning apparatus having an optical waveguide phased array in accordance with an embodiment of the present invention.

Next, a preferred implementation of the optical scanning device according to an embodiment of the invention will be described with reference to fig. 18-20. In this preferred implementation, the optical scanning device OS comprises two optical waveguide phased

arrays

1A, 1B according to an embodiment of the invention. In the illustration of fig. 18, only those in the optical waveguide phased array are shown for clarity and simplicity of illustration The waveguide grating structure represents the optical waveguide phased

array

1A, 1B. In the present preferred implementation, as shown in fig. 18, two optical waveguide phased

arrays

1A, 1B are arranged at an angle of 90 ° to each other. Thus, according to the embodiment of the present invention, the grating of the waveguide grating device in the optical waveguide phased array 1A passes through the radiation channels P on the upper and lower sides₁、P₂Forming bidirectional radiation; the grating of the waveguide grating device in the optical waveguide phased array 1B passes through the radiation channels P 'at the upper and lower sides'₁、P’₂Forming a bi-directional radiation.

Upward (downward) radiation of the grating in a waveguide grating device according to embodiments of the present invention can have good uniformity over large angles. For example, referring back to the numerical example above, the up/down radiation of the grating G can achieve approximately equal intensity scanning in a range of not less than 90 °. As known from fraunhofer diffraction principles, the scanning/imaging range of a grating array is determined by the imaging envelope of a single grating as a unit structure. Therefore, a single phased array according to an embodiment of the present invention can achieve scanning imaging of 180 ° or more in both the upward and downward directions, as shown in FIG. 19. While an optical scanning device OS with two phased

arrays

1A, 1B arranged at 90 deg. can realize 360 deg. full field of view scanning imaging, as shown in fig. 20.

According to the embodiment of the invention, two phased arrays capable of providing up-down bidirectional radiation are arranged in a 90-degree crossed manner, so that large-field imaging can be realized and the number of 1/2 phased arrays can be reduced compared with a common unidirectional radiation optical waveguide phased array.

The optical scanning device OS according to an embodiment of the present invention may be a laser radar device or a scanning imaging device, and may be a biosensing device, for example.

There is also provided, in accordance with an embodiment of the present invention, a free-space optical communication device including a light emitting/receiving device including the optical waveguide phased array as described above.

Fig. 21 is a schematic perspective view of a waveguide grating device 500 according to a fifth embodiment of the present invention. As shown in fig. 12, the waveguide grating device 500 includes a substrate 510 and more than one dielectric layer 520 formed on the substrate 510, wherein the more than one dielectric layer 520 includes a waveguide core layer 521. A grating G having a symmetrical structure in its extending direction (x-axis direction shown in the figure) and having

light receiving structures

521a, 521b on both ends of its extending direction is formed in the waveguide core layer 521. The waveguide-grating device 500 has a symmetrical grating structure similar to that of the waveguide-grating device 100A according to the variation of the first embodiment of the present invention shown in fig. 4, except that the substrate 510 directly below the grating G in the waveguide-grating device 500 may not be etched away. It is to be appreciated that the waveguide grating device 500 according to embodiment five of the present invention is not intended to provide up-down bi-directional radiation. Accordingly, the layer structure in the more than one dielectric layers 520 may or may not have a substantially symmetrical structure with respect to the waveguide core layer 521, including the number of layers, thickness, refractive index, and the like.

Preferably, in the waveguide grating device 500, the waveguide core layer 521 may be further formed with waveguide beam splitting means (not shown) symmetrically connected to both ends of the grating G for introducing symmetrical input light opposite to each other in the extending direction of the grating from both ends of the grating. The waveguide splitting means may be a one-to-two waveguide splitter. Alternatively or additionally, other suitable splitting devices such as star coupler (star coupler), main line waveguide coupler (bus-waveguide coupler) and the like may be used as the waveguide splitting device.

Fig. 22 is a schematic perspective view of a waveguide grating device 600 according to a sixth embodiment of the present invention. As shown in fig. 22, the waveguide grating device 600 has a grating array in which more than one grating G is arranged adjacent to each other in the grating extending direction. According to the sixth embodiment of the present invention, at least one composite bragg mirror 601 is formed between the gratings G adjacent to each other in the grating extending direction. The hybrid bragg reflector 601 may have two or more reflective surfaces with different directions (two reflective surfaces opposite to each other are shown in fig. 22), which may have a shape spliced by two "c" shapes back to back as shown in fig. 22, or may have, for example, a substantially S-shape; the invention is not limited in this respect. The adoption of the composite Bragg reflector is beneficial to realizing a more compact structure, thereby being beneficial to the miniaturization of devices. As shown in fig. 22, the waveguide grating device 600 may further comprise a common bragg mirror 602, for example arranged at the edge of the grating array.

It will be appreciated that the hybrid bragg mirror may be used in combination with waveguide grating devices and optical waveguide phased arrays as described above in accordance with other embodiments of the present invention.

The above description is only a preferred embodiment of the application and is illustrative of the principles of the technology employed. It will be appreciated by a person skilled in the art that the scope of the invention as referred to in the present application is not limited to the embodiments with a specific combination of the above-mentioned features, but also covers other embodiments with any combination of the above-mentioned features or their equivalents without departing from the inventive concept. For example, the above features may be replaced with (but not limited to) features having similar functions disclosed in the present application.

Claims

1. A waveguide grating device comprises a substrate and a plurality of dielectric layers formed on the substrate, wherein the dielectric layers comprise a waveguide core layer, a grating is formed in the waveguide core layer, the substrate is completely etched at a position right below the grating to expose the dielectric layers, and radiation channels are formed on the upper side and the lower side of the grating by the waveguide grating device.

2. A waveguide grating device as claimed in claim 1, wherein the plurality of dielectric layers are substantially symmetrical with respect to the waveguide core layer in number of layers, thickness and refractive index.

3. A waveguide grating device as claimed in claim 1, wherein the plurality of dielectric layers further comprises a modulation layer overlying one side of the waveguide core layer and a cladding layer overlying the other side of the waveguide core layer.

4. A waveguide grating device as claimed in claim 2, wherein the modulation layer and the cladding layer have substantially the same refractive index and have thicknesses of the same order of magnitude for an operating wavelength of the waveguide grating device.

5. A waveguide grating device as claimed in claim 3, wherein the modulation layer is formed from LiNbO₃An electro-optic phase modulation layer formed of Si₃N₄And (3) a layer.

6. The waveguide grating device as claimed in any one of claims 1 to 5, wherein the plurality of dielectric layers further comprises upper and lower composite anti-reflection films respectively disposed on upper and lower sides of the waveguide core layer, and each of the upper and lower composite anti-reflection films is composed of 1/2 wavelength films disposed on an outer side with respect to the waveguide core layer and 1/4 wavelength films disposed on an inner side.

7. The waveguide grating device of claim 1, wherein the plurality of dielectric layers sequentially comprises: si formed as 1/2 wavelength film₃N₄Layer, SiO formed as 1/4 wavelength film₂Layer, LiNbO formed as electro-optical modulation layer₃Layer, Si layer formed as waveguide core layer, Si formed as cladding layer₃N₄Layer, SiO formed as 1/4 wavelength film₂Layer and Si formed as 1/2 wavelength film₃N₄A layer.

8. A waveguide grating device as claimed in any one of claims 1 to 7, wherein the grating produces substantially symmetrical bi-directional radiation through the upper and lower radiation channels.

9. A waveguide grating device as claimed in claim 1, wherein the waveguide core layer is further formed with waveguide splitting means symmetrically connected to both ends of the grating.

10. A waveguide grating device as claimed in claim 9, wherein the waveguide core layer is further formed with mirrors at both ends of the grating for optical transmission between the waveguide beam splitting arrangement and the grating.

11. A waveguide grating device as claimed in claim 10, wherein the mirrors are bragg mirrors.

12. A waveguide grating device as claimed in claim 11, wherein the bragg mirrors have two or more reflecting surfaces of different orientations.

13. A waveguide grating device as claimed in claim 12, wherein the bragg mirror has two reflective surfaces opposite to each other.

14. A waveguide grating device as claimed in any one of claims 1 and 9 to 13, wherein the waveguide core layer is configured such that the grating has a symmetrical structure in its direction of extension.

15. A waveguide grating device as claimed in any one of claims 1 and 9 to 13, wherein the grating includes a plurality of grooves having a depth equal to the thickness of the waveguide core layer.

16. A waveguide grating device as claimed in any one of claims 1 and 9 to 13, wherein the waveguide core layer is formed with a plurality of said gratings, and the plurality of gratings are arranged in a one-dimensional or two-dimensional array.

17. An optical waveguide phased array comprises a laser light source, a phase shift control device and a waveguide grating device, wherein:

the waveguide grating device comprises a substrate and a plurality of dielectric layers formed on the substrate, wherein the dielectric layers comprise a waveguide core layer, at least two gratings are formed in the waveguide core layer, the substrate is completely etched at a position right below the gratings to expose the dielectric layers, and therefore radiation channels are formed on the upper side and the lower side of the gratings by the waveguide grating device;

Laser emitted by the laser light source is transmitted into the grating of the waveguide grating device, so that bidirectional radiation is formed through the radiation channels on the upper side and the lower side; and is

The phase shift control device is connected to the waveguide grating device to phase modulate the bi-directional radiation formed by the grating.

18. The optical waveguide phased array of claim 17, wherein the grating produces substantially symmetric bi-directional radiation through the upper and lower side radiation channels.

19. The optical waveguide phased array of claim 18, wherein the plurality of dielectric layers further comprises a modulation layer overlying one side of the waveguide core layer and a cladding layer overlying the other side of the waveguide core layer, the modulation layer and the cladding layer having substantially the same refractive index and having a thickness of the same order of magnitude for an operating wavelength of the waveguide grating device; and is

The waveguide grating device comprises a positive electrode and a negative electrode, and the positive electrode and the negative electrode are used for receiving signals from the phase shift control device and applying voltage to the modulation layer to realize electro-optic phase modulation.

20. The optical waveguide phased array of claim 19, wherein the modulation layer is formed from LiNbO₃An electro-optic phase modulation layer formed and the capping layer is Si ₃N₄And (3) a layer.

21. The optical waveguide phased array of any of claims 17 to 20, wherein the plurality of dielectric layers further comprises upper and lower composite antireflection films respectively located on upper and lower sides of the waveguide core layer, the upper and lower composite antireflection films each being composed of an 1/2 wavelength film located on an outer side and a 1/4 wavelength film located on an inner side with respect to the waveguide core layer.

22. An optical waveguide phase according to claim 17 or 18A control array, wherein the plurality of dielectric layers comprise in sequence: si formed as 1/2 wavelength film₃N₄Layer, SiO formed as 1/4 wavelength film₂Layer, LiNbO formed as electro-optical modulation layer₃Layer, Si layer formed as waveguide core layer, Si formed as cladding layer₃N₄Layer, SiO formed as 1/4 wavelength film₂Layer and Si formed as 1/2 wavelength film₃N₄And (3) a layer.

23. The optical waveguide phased array as claimed in claim 17, wherein said waveguide core layer is further formed with waveguide beam splitting means symmetrically connected to both ends of said grating for introducing light emitted from said laser light source from both ends of said grating to form symmetrical input lights facing each other in an extending direction of said grating.

24. The optical waveguide phased array as claimed in claim 23, wherein said waveguide core layer is further formed with bragg mirrors at both ends of said grating for optical transmission between said waveguide splitting means and said grating.

25. The optical waveguide phased array of claim 24, wherein the bragg mirrors have two or more reflective surfaces of different orientations.

26. The optical waveguide phased array of claim 25, wherein the bragg mirrors have two reflective surfaces that are opposite to each other.

27. The optical waveguide phased array of claim 23, wherein the waveguide grating device further comprises first laser power splitting means formed thereon for transmitting light from the laser light sources to the waveguide splitting means, respectively.

28. The optical waveguide phased array of claim 27, wherein the first laser power splitting means comprises at least two laser power splitting means and is disposed on two sides or one side of the grating perpendicular to the direction of extension of the grating.

29. The optical waveguide phased array as claimed in any one of claims 17, 23-28, wherein said optical waveguide phased array further comprises n-level second laser power splitting means, where n ≧ 1, said second laser power splitting means connected between said laser light source and said waveguide grating device for splitting light from said laser light source before transmission into said waveguide grating device.

30. The optical waveguide phased array of any of claims 17, 23-28, wherein the waveguide core is configured such that the grating has a symmetrical structure in its direction of extension.

31. The optical waveguide phased array of any of claims 17, 23-28, wherein the grating comprises a plurality of grooves having a depth that is the same as a thickness of the waveguide core layer.

32. The optical waveguide phased array of any one of claims 17, 23 to 28, wherein the waveguide core layer is formed with a plurality of the gratings, and the plurality of gratings are arranged in a one-dimensional or two-dimensional array.

33. An optical scanning device comprising a light emitting device and a light receiving device, wherein the light emitting device comprises an optical waveguide phased array as claimed in any of claims 17 to 32.

34. An optical scanning device according to claim 33, wherein said light emitting means comprises at least two said optical waveguide phased arrays, and said two optical waveguide phased arrays are arranged at an angle of 90 ° to each other.

35. An optical scanning device according to claim 33 or 34, wherein the optical scanning device is a lidar device.

36. An optical scanning device according to claim 33 or 34, wherein the optical scanning device is a scanning imaging device.

37. The optical scanning device of claim 36, wherein the optical scanning device is a biosensor device.

38. A free-space optical communications device comprising an optical transmitting/receiving device comprising an optical waveguide phased array as claimed in any of claims 17 to 32.

39. A waveguide grating device comprising a substrate and more than one dielectric layer formed on the substrate, the more than one dielectric layer comprising a waveguide core layer having a grating formed therein, the grating having a symmetrical structure in its extending direction and having light receiving structures on both ends of its extending direction.

40. A waveguide grating device as claimed in claim 39, wherein the waveguide core layer is further formed with waveguide beam splitting means symmetrically connected to both ends of the grating for introducing symmetrical input light from both ends of the grating that face each other in the direction of extension of the grating.

41. A waveguide grating device as claimed in claim 39, wherein the substrate is etched away completely at a location directly beneath the grating to expose the dielectric layer, such that the waveguide grating device forms a radiation channel on both the upper and lower sides of the grating.

42. An optical waveguide phased array comprising a laser light source, phase shift control means and a waveguide grating device as claimed in any one of claims 39 to 41, wherein laser light emitted by the laser light source is coupled into the grating from both ends of the grating of the waveguide grating device, and more than one dielectric layer of the waveguide grating device further comprises a modulation layer, the phase shift control means being connected to the waveguide grating device for phase modulating radiation formed by the grating.