CN119667978B - Broadband photon filter based on thin film lithium niobate optical waveguide - Google Patents
Broadband photon filter based on thin film lithium niobate optical waveguideInfo
- Publication number
- CN119667978B CN119667978B CN202411953457.4A CN202411953457A CN119667978B CN 119667978 B CN119667978 B CN 119667978B CN 202411953457 A CN202411953457 A CN 202411953457A CN 119667978 B CN119667978 B CN 119667978B
- Authority
- CN
- China
- Prior art keywords
- waveguide
- mode
- multimode
- coupling
- broadband
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Active
Links
Landscapes
- Optical Integrated Circuits (AREA)
Abstract
本发明公开了一种基于薄膜铌酸锂光波导的宽带光子滤波器，属于集成光电子技术领域。该宽带光子滤波器包括绝热滤波器、多模连接波导、宽带模式转换器，其中绝热滤波器和宽带模式转换器均为非对称定向耦合器结构。绝热滤波器将输入的TE基模波长选择性的转化为高阶TM模，其余TE基模从直通端输出。高阶TM模经多模连接波导进入宽带模式转换器，并全部转换为TE基模，并从交叉端输出。本发明创新性地将常见于模分复用的非对称定向耦合器结构用作光学滤波功能，结构简单。其基于模式绝热演化原理，适合应用于宽带光学滤波操作，且具有易于设计和加工、低损耗等的优点。
The present invention discloses a broadband photon filter based on a thin-film lithium niobate optical waveguide, which belongs to the field of integrated optoelectronic technology. The broadband photon filter includes an adiabatic filter, a multimode connection waveguide, and a broadband mode converter, wherein the adiabatic filter and the broadband mode converter are both asymmetric directional coupler structures. The adiabatic filter selectively converts the input TE fundamental mode wavelength into a high-order TM mode, and the remaining TE fundamental modes are output from the through-end. The high-order TM mode enters the broadband mode converter through the multimode connection waveguide, and is all converted into the TE fundamental mode and output from the cross-end. The present invention innovatively uses the asymmetric directional coupler structure commonly used in mode division multiplexing as an optical filtering function, and has a simple structure. It is based on the principle of mode adiabatic evolution, is suitable for application in broadband optical filtering operations, and has the advantages of easy design and processing, low loss, etc.
Description
Technical Field
The invention belongs to the technical field of integrated photoelectrons, and particularly relates to a broadband photon filter based on a thin-film lithium niobate optical waveguide.
Background
In recent years, thin film lithium niobate integrated photon platforms benefit from the high electro-optic coefficient of lithium niobate materials, low loss of waveguides, and high integration, and offer a useful solution for high performance modulators. Compared with bulk material lithium niobate, the high waveguide refractive index difference of the platform significantly enhances the optical field constraint, which plays an important role in improving the system integration level and reducing the energy consumption. The current rapid development of big data and artificial intelligence technology increases the demands of society for high-speed information transmission exponentially. The compact design of thin film lithium niobate integrated optics enables complex functionality to be achieved in limited space and reduces production costs, and is therefore particularly critical in meeting the ever-increasing demands of modern communication networks for data processing speed and efficiency. Based on this, designing and manufacturing various functional devices on a thin film lithium niobate platform has become one of the important directions in current integrated optics.
An optical filter is one of the important elements in an integrated optical system, which can transmit light of a specific wavelength to a designated port. Narrow-band multichannel optical filters are commonly used in wavelength division multiplexing systems, and use light with different wavelengths to simultaneously transmit optical information, so that the capacity of optical transmission is greatly improved. On-chip optical filters with a wide optical bandwidth and a large free spectral range are also critical in many applications. In a passive optical network, a broadband filter can separate uplink and downlink channels so as to realize single-fiber bidirectional transmission. In on-line monitoring of fiber optic links, a broadband filter may be used to reflect light of a particular wavelength (e.g., 1625-1675 nm) while light of that wavelength passes through without loss (e.g., 1260-1625 nm). And in on-chip wavelength converters and amplifiers, it can also be used for injection and separation of signal light and pump light.
A number of different integrated optical filter structures have been proposed on thin film lithium niobate platforms. These structures almost all employ the principle of beam interference, including, for example, arrayed waveguide gratings, tilted multimode interferometers, mach-Zehnder interferometers, and microring filters. These structures are limited by the wavelength sensitive nature of beam interference, typically with a narrow filter bandwidth or limited free spectral range. Apodized multimode bragg gratings are also common interferometric filter structures that, while capable of achieving a flat-top spectral response with a certain bandwidth, have an upper optical bandwidth limit limited by the coupling strength between forward and reverse transmission modes. On the other hand, due to its multimode waveguide structure, incident light is unnecessarily coupled with higher order modes of the waveguide at short wavelengths, limiting its free spectral range. It follows that filters based on the principle of beam interference are very difficult to implement on-chip optical filters with a wide optical bandwidth and an ultra-large free spectral range. In order to achieve this, it is necessary to propose a new filtering structure, starting from the underlying principle.
Disclosure of Invention
Aiming at the defects of the prior art, the invention provides a broadband photon filter based on a thin film lithium niobate optical waveguide by utilizing an asymmetric directional coupler structure based on a waveguide mode adiabatic evolution principle, the adiabatic filter converts the wavelength selectivity of an input TE fundamental mode into a high-order TM mode, and other TE fundamental modes are output from a through end. The high-order TM mode enters the broadband mode converter through the multimode connecting waveguide, is converted into TE basic mode completely, and is output from the crossing end. The broadband filter is applied to broadband optical filtering operation and has an ultra-large free spectral range.
According to a first aspect of the present invention, there is provided a broadband photon filter based on a thin film lithium niobate optical waveguide, comprising, from top to bottom, a lithium niobate thin film layer and a silica buffer layer, the lithium niobate thin film layer comprising an adiabatic filter, a multimode connection waveguide, and a broadband mode converter connected in sequence;
The adiabatic filter is of an asymmetric directional coupler structure and consists of a first front single-mode bent waveguide, a first single-mode coupling waveguide, a first rear single-mode bent waveguide, a first front multimode waveguide, a first multimode coupling waveguide and a first rear multimode waveguide;
the first multimode coupling waveguide is a tapered waveguide with gradually increasing width from left to right;
the first front single-mode bending waveguide, the first single-mode coupling waveguide and the first rear single-mode bending waveguide are sequentially connected, and the first front multimode waveguide, the first multimode coupling waveguide and the first rear multimode waveguide are sequentially connected;
On the left side of the first multimode coupling waveguide and the first single-mode coupling waveguide, the effective refractive index of the high-order TM mode transmitted in the first multimode coupling waveguide is equal to the effective refractive index of the TE fundamental mode transmitted in the first single-mode coupling waveguide at the wavelength λ1;
on the right side of the first multimode coupling waveguide and the first single-mode coupling waveguide, the effective refractive index of the high-order TM mode transmitted in the first multimode coupling waveguide is equal to that of the TE fundamental mode transmitted in the first single-mode coupling waveguide at a wavelength lambda 2, wherein lambda 2 is larger than lambda 1;
the broadband photon filter based on the thin film lithium niobate optical waveguide can enable TE basic mode entering the first single-mode coupling waveguide from the input end of the broadband filter through the first front single-mode bending waveguide, when the wavelength is in the range of (lambda 1, lambda 2), the TE basic mode gradually evolves into a high-order TM mode in the first multimode coupling waveguide, and further enters the first rear multimode waveguide;
The broadband photon filter based on the thin film lithium niobate optical waveguide can enable TE basic mode entering the first single-mode coupling waveguide from the input end of the broadband filter through the first front single-mode bending waveguide, and when the wavelength is not in the range of (lambda 1, lambda 2), the TE basic mode directly passes through the first single-mode coupling waveguide and enters the first rear single-mode bending waveguide and is output from the through end of the broadband filter.
Preferably, the projection lengths of the first front single-mode curved waveguide and the first rear single-mode curved waveguide in the horizontal direction are equal to the lengths of the first front multimode waveguide and the first rear multimode waveguide respectively, and the lengths of the first single-mode coupling waveguide and the first multimode coupling waveguide are equal.
The first multimode coupling waveguide and the first single-mode coupling waveguide are arranged close to each other to form a waveguide coupling region, wherein the close arrangement is that the first front single-mode bending waveguide bends from left to right to a direction close to the first front multimode waveguide, and the first rear single-mode bending waveguide bends from left to right to a direction far away from the first rear multimode waveguide.
Preferably, the broadband mode converter is an asymmetric directional coupler structure and is composed of a second front single-mode bent waveguide, a second single-mode coupled waveguide, a second rear single-mode bent waveguide, a second front multimode waveguide, a second multimode coupled waveguide and a second rear multimode waveguide;
the second single-mode coupling waveguide is a tapered waveguide with gradually increased width from left to right;
The second front single-mode bent waveguide, the second single-mode coupled waveguide and the second rear single-mode bent waveguide are sequentially connected, the second front multimode waveguide, the second multimode coupled waveguide and the second rear multimode waveguide are sequentially connected, and the second front single-mode bent waveguide, the second single-mode coupled waveguide and the second rear single-mode bent waveguide are respectively vertically opposite to the second front multimode waveguide, the second multimode coupled waveguide and the second rear multimode waveguide.
Preferably, the projection lengths of the second front single-mode curved waveguide and the second rear single-mode curved waveguide in the horizontal direction are respectively equal to the lengths of the second front multimode waveguide and the second rear multimode waveguide, and the lengths of the second single-mode coupling waveguide and the second multimode coupling waveguide are equal.
Preferably, the second multimode coupling waveguide and the second single-mode coupling waveguide are arranged close to each other so as to form a waveguide coupling region, wherein the close arrangement is that the second front single-mode bending waveguide bends from left to right towards a direction close to the second front multimode waveguide, and the second rear single-mode bending waveguide bends from left to right towards a direction far away from the second rear multimode waveguide.
Preferably, the left side of the multimode connection waveguide is connected with the right side of the first rear multimode waveguide, and the right side of the multimode connection waveguide is connected with the left side of the second front multimode waveguide.
Preferably, the broadband photon filter based on the thin film lithium niobate optical waveguide can enable the high-order TM mode output from the first rear multimode waveguide, enter the second multimode coupling waveguide through the multimode connecting waveguide and the second front multimode waveguide, gradually evolve into the TE fundamental mode in the second single-mode coupling waveguide, and output from the broadband filter cross end through the second rear single-mode bending waveguide.
Preferably, an upper cladding layer is also covered on the lithium niobate thin film layer;
preferably, the upper cladding is air or silicon dioxide.
According to another aspect of the invention, there is provided the use of a broadband photon filter based on a thin film lithium niobate optical waveguide in a cascaded multi-channel filter.
In general, compared with the prior art, the above technical solution conceived by the present invention mainly has the following technical advantages:
(1) In the broadband filter, the first multimode coupling waveguide is a tapered waveguide with gradually increased width, so that waveguide sections at two ends of the adiabatic filter respectively have different phase matching wavelengths (lambda 1 and lambda 2). For the incoming TE fundamental mode, when its wavelength is in the range of (λ1, λ2), it will meet the phase matching condition at some location in the waveguide coupling region and turn into a higher order TM mode. When the input TE fundamental mode is not in the wavelength range, the mode conversion does not occur because the input TE fundamental mode does not meet the phase matching condition in the whole waveguide coupling area. The broadband mode converter has a structure similar to that of an adiabatic filter, but the structure ensures that all input high-order TM modes can meet the phase matching condition at a certain position in the waveguide coupling region of the broadband mode converter, and then the broadband mode converter is converted into TE basic modes. The pass-through end has a band-stop spectral response and the cross-over end has a band-pass spectral response.
(2) The filter proposed in the present invention is based on the principle of adiabatic evolution of modes and is therefore suitable for application in broadband optical filtering operations and has an ultra-large free spectral range, significantly different from filters based on the principle of beam interference.
(3) The present invention innovatively uses the asymmetric directional coupler structure commonly found in mode division multiplexing as a filtering function. The structure is simple, and the bandwidth and the center wavelength of the filter can be adjusted only by changing the width of the waveguide. Compared with the traditional grating filter, the grating filter has the advantages of easy design and processing, low loss and the like.
Drawings
FIG. 1 is a schematic diagram of the overall structure of a broadband photonic filter based on a thin film lithium niobate optical waveguide according to the present invention.
Fig. 2 is a schematic cross-sectional view of a broadband photonic filter waveguide based on a thin film lithium niobate optical waveguide according to the present invention.
Fig. 3 is a schematic diagram of the working principle of the broadband photon filter based on the thin film lithium niobate optical waveguide of the present invention.
Fig. 4 is a graph of the spectral response of a broadband photonic filter based on a thin film lithium niobate optical waveguide according to the present invention.
Fig. 5 is a schematic diagram of the overall structure of the wavelength division demultiplexer of the broadband photonic filter based on the thin film lithium niobate optical waveguide of the present invention.
Fig. 6 is a graph of the spectral response of a wavelength division demultiplexer of a broadband photonic filter based on a thin film lithium niobate optical waveguide according to the present invention.
Detailed Description
The present invention will be described in further detail with reference to the drawings and examples, in order to make the objects, technical solutions and advantages of the present invention more apparent. It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the scope of the invention. In addition, the technical features of the embodiments of the present invention described below may be combined with each other as long as they do not collide with each other.
As shown in fig. 1, the invention provides a broadband photon filter based on a thin film lithium niobate optical waveguide, which comprises an adiabatic filter 1, a multimode connection waveguide 2 and a broadband mode converter 3. Wherein the thermal filter 1, the multimode connection waveguide 2, and the broadband mode converter 3 are sequentially connected to each other.
The adiabatic filter 1 is composed of a first front single-mode curved waveguide 101, a first single-mode coupling waveguide 102, a first rear single-mode curved waveguide 103, a first front multimode waveguide 104, a first multimode coupling waveguide 105, a first rear multimode waveguide 106. The first front single-mode curved waveguide 101, the first single-mode coupling waveguide 102, and the first rear single-mode curved waveguide 103 are connected in this order. The first front multimode waveguide 104, the first multimode coupling waveguide 105, and the first rear multimode waveguide 106 are sequentially connected. The first front single-mode curved waveguide 101, the first single-mode coupling waveguide 102, and the first rear single-mode curved waveguide 103 are respectively opposite to the first front multimode waveguide 104, the first multimode coupling waveguide 105, and the first rear multimode waveguide 106.
The projection lengths of the first front single-mode curved waveguide 101 and the first rear single-mode curved waveguide 103 in the horizontal direction are respectively equal to the lengths of the first front multimode waveguide 104 and the first rear multimode waveguide 106, and the lengths of the first single-mode coupling waveguide 102 and the first multimode coupling waveguide 105 are equal.
The first multimode coupling waveguide 105 and the first single-mode coupling waveguide 102 are arranged close to each other to form a waveguide coupling region, and the close arrangement is specifically that the first front single-mode bending waveguide 101 bends from left to right in a direction approaching the first front multimode waveguide 104, and the first rear single-mode bending waveguide 103 bends from left to right in a direction away from the first rear multimode waveguide 106.
The first multimode coupling waveguide 105 is a tapered waveguide of gradually increasing width.
The broadband mode converter is composed of a second front single-mode curved waveguide 301, a second single-mode coupling waveguide 302, a second rear single-mode curved waveguide 303, a second front multimode waveguide 304, a second multimode coupling waveguide 305, and a second rear multimode waveguide 306. The second front single-mode curved waveguide 301, the second single-mode coupling waveguide 302, and the second rear single-mode curved waveguide 303 are connected to each other in this order. The second front multimode waveguide 304, the second multimode coupling waveguide 305, and the second rear multimode waveguide 306 are sequentially connected to each other. The second front single-mode curved waveguide 301, the second single-mode coupled waveguide 302, and the second rear single-mode curved waveguide 303 are respectively opposite to the second front multimode waveguide 304, the second multimode coupled waveguide 305, and the second rear multimode waveguide 306.
The effective refractive index of the upper-order TM mode in the left side of the second multimode coupling waveguide 305 is greater than the effective refractive index of the TE fundamental mode in the left side of the second single-mode coupling waveguide 302, and the effective refractive index of the upper-order TM mode in the right side of the second multimode coupling waveguide 305 is less than the effective refractive index of the TE fundamental mode in the right side of the second single-mode coupling waveguide (302).
The projection lengths of the second front single-mode curved waveguide 301 and the second rear single-mode curved waveguide 303 in the horizontal direction are respectively equal to the lengths of the second front multimode waveguide 304 and the second rear multimode waveguide 306, and the lengths of the second single-mode coupling waveguide 302 and the second multimode coupling waveguide 305 are equal.
The second multimode coupling waveguide 305 and the second single-mode coupling waveguide 302 are arranged close to each other, so as to form a waveguide coupling region, and the close arrangement is specifically that the second front single-mode bending waveguide 301 bends from left to right in a direction approaching the second front multimode waveguide 304, and the second rear single-mode bending waveguide 303 bends from left to right in a direction away from the second rear multimode waveguide 306.
The second single-mode coupling waveguide 302 is a tapered waveguide of gradually increasing width.
The left side of the mode connection waveguide 2 is connected to the right side of the first rear multimode waveguide 106 and the right side of the multimode connection waveguide 2 is connected to the left side of the second front multimode waveguide 304.
On the left side of the first multimode coupling waveguide 105 and the first single-mode coupling waveguide 102, the high-order TM mode transmitted in the first multimode coupling waveguide 105 is phase-matched with the TE fundamental mode transmitted in the first single-mode coupling waveguide 102 at the wavelength λ1.
On the right side of the first multimode coupling waveguide 105 and the first single-mode coupling waveguide 102, the high-order TM mode transmitted in the first multimode coupling waveguide 105 is phase-matched with the TE fundamental mode transmitted in the first single-mode coupling waveguide 102 at wavelength λ2.
The TE fundamental mode entering the first single-mode coupling waveguide 102 from the broadband filter input via the first front single-mode bending waveguide 101 gradually evolves into a higher order TM mode in the first multimode coupling waveguide 105 when its wavelength is in the range of (λ1, λ2) and further into the first rear multimode waveguide 106;
The TE fundamental mode entering the first single-mode coupling waveguide 102 from the broadband filter input via the first front single-mode bending waveguide 101 passes directly through the first single-mode coupling waveguide 102 and into the first rear single-mode bending waveguide 103 and out of the broadband filter pass-through when its wavelength is not in the (λ1, λ2) range.
And the output from the first rear multimode waveguide 106 enters a high-order TM mode of the second multimode coupling waveguide 305 through the multimode connecting waveguide 2 and the second front multimode waveguide 304, gradually becomes a TE fundamental mode in the second single-mode coupling waveguide 302, and is output from the broadband filter crossover end through the second rear single-mode bending waveguide 303.
As shown in fig. 2, the adiabatic filter 1, the multimode connection waveguide 2, and the broadband mode converter 3 are fabricated on a lithium niobate thin film layer 402, wherein the lithium niobate thin film layer 402 is covered with an upper cladding 401, and the lithium niobate thin film layer 402 is bonded over a silicon dioxide buffer layer 403.
The upper cladding 401 is air or silicon dioxide.
The principle of the invention is shown in figure 3. In the adiabatic filter 1 of the present invention, since the first multimode coupling waveguide 105 is a tapered waveguide of which width is gradually increased, waveguide sections at both ends of the adiabatic filter 1 have different phase matching wavelengths (λ1 and λ2), respectively. Thus for the incoming TE fundamental mode, when its wavelength is in the range of (λ1, λ2), it will meet the phase matching condition at some location in the waveguide coupling region and turn into a higher order TM mode. When the input TE fundamental mode is not in the wavelength range, the mode conversion does not occur because the input TE fundamental mode does not meet the phase matching condition in the whole waveguide coupling area. The broadband mode converter 3 has a similar structure to the adiabatic filter 1, but its structure ensures that all incoming higher order TM modes meet the phase matching condition at a certain position in its waveguide coupling region and are then converted into TE fundamental modes. Thus for the wideband filter of the present invention, the pass-through end has a band-reject spectral response and the crossover end has a band-pass spectral response.
Specific embodiments of the invention are as follows:
example 1
The lithium niobate material platform based on the insulator is selected, the upper cladding is silicon dioxide, the thickness of the lithium niobate film layer is 500nm, and the thickness of the silicon dioxide buffer layer is 4700nm. The device is formed by electron beam exposure and dry etching on the lithium niobate thin film layer, the etching depth is 260nm, and the side wall of the waveguide structure has a 60-degree inclination angle.
The design center wavelength of the adiabatic filter is 1565nm, and the widths of the two sides of the first multimode coupling waveguide are respectively 2.21 mu m and 2.34 mu m, and the widths of the first front multimode waveguide and the first rear multimode waveguide are respectively 2.21 mu m and 2.34 mu m. The widths of the first front single-mode bending waveguide, the first single-mode coupling waveguide and the first rear single-mode bending waveguide are all 0.48 μm. The spacing between the first multimode coupling waveguide and the first single mode coupling waveguide is 0.6 μm. The maximum separation between the first front single-mode curved waveguide and the first front multimode waveguide is 2 μm. The maximum separation between the first rear single-mode curved waveguide and the first rear multimode waveguide is 2 μm. The lengths of the three sections of the adiabatic filter are 1300 μm, 700 μm and 1300 μm respectively.
The multimode connecting waveguide has a width of 2.34 μm.
The broadband mode converter selects the widths of two sides of the second single-mode coupling waveguide to be 0.4 μm and 0.6 μm respectively, and the widths of the second front single-mode waveguide and the second rear single-mode waveguide to be 0.4 μm and 0.6 μm respectively. The widths of the second front multimode bent waveguide, the second multimode coupling waveguide and the second rear multimode bent waveguide are all 2.34 mu m. The spacing between the second multimode coupling waveguide and the second single mode coupling waveguide is 0.45 μm. The maximum separation between the second front single-mode curved waveguide and the second front multimode waveguide is 2 μm. The maximum separation between the second rear single-mode curved waveguide and the second rear multimode waveguide is 2 μm. The three sections of the broadband mode converter have lengths of 300 μm, 1000 μm, 300 μm, respectively.
The device is verified in a simulation way through an eigenmode expansion solver (EME) method. Fig. 4 shows the spectral response curves of the device at the through and cross ends. From the graph results, it is seen that the device has a box-like flat top spectral response and has a 1-dB bandwidth of about 40nm at a central wavelength of 1565nm, an additional loss of less than 0.01dB, and a sideband suppression ratio of greater than 20dB, demonstrating good performance of the device.
Example 2
As shown in fig. 5, this embodiment includes a broadband filter 1 and a broadband filter 2 cascaded with each other to constitute a wavelength division demultiplexer. The input end of the broadband filter 2 is directly connected with the straight-through end of the broadband filter 1, the center wavelength of the broadband filter 1 is 1577nm, and the center wavelength of the broadband filter 2 is 1490nm. Light with different wavelengths is input from the input end of the wavelength division multiplexer, light with the center wavelength of 1577nm is output from the crossing end 1, light with the center wavelength of 1490nm is output from the crossing end 2, and the rest light is output from the straight-through end.
A lithium niobate material platform on insulator was selected and its parameters were the same as in example 1.
For the broadband filter 1, the widths of the two sides of the first multimode coupling waveguide are selected to be 2.25 μm and 2.35 μm, the widths of the first front multimode waveguide and the first rear multimode waveguide are selected to be 2.25 μm and 2.35 μm, respectively, and the rest parameters are the same as those of the embodiment 1. The multimode connecting waveguide has a width of 2.35 μm. The broadband mode converter selects the second front multimode bent waveguide, the second multimode coupling waveguide and the second rear multimode bent waveguide to have the widths of 2.35 μm, and the other parameters are the same as those of the embodiment 1.
For the broadband filter 2, the widths of the two sides of the first multimode coupling waveguide are selected to be 2.05 μm and 2.15 μm, the widths of the first front multimode waveguide and the first rear multimode waveguide are selected to be 2.05 μm and 2.15 μm, respectively, and the rest parameters are the same as those of the embodiment 1. The multimode connecting waveguide has a width of 2.15 μm. The broadband mode converter selects the second front multimode bent waveguide, the second multimode coupling waveguide and the second rear multimode bent waveguide to have the widths of 2.15 μm, and the other parameters are the same as those of the embodiment 1.
The device is verified in a simulation way through an eigenmode expansion solver (EME) method. Fig. 6 shows the spectral response curves of the device at the pass-through end and at the two crossover ends. From the graph results, it can be seen that the cascade device has a box-shaped flat-top spectral response, and the cross-over terminal 1 has a 1-dB bandwidth of about 30nm and an additional loss of less than 0.01dB, and the cross-over terminal 2 has a 1-dB bandwidth of about 30nm and an additional loss of less than 0.01 dB. The crosstalk between the two crossover ends was below 30dB, demonstrating good performance of the device.
Regarding the waveguide width of the broadband filter in the present invention, the waveguide structure in the structure of the present invention can be roughly classified into two types of single-mode waveguide and multi-mode waveguide. Wherein the single mode waveguide transmits the TE fundamental mode and the multimode waveguide transmits the high order TM mode. In order to achieve the phase matching condition, i.e. the effective propagation constants of the TE fundamental mode and the higher order TM mode are equal. Thus, the width of the multimode waveguide should be much larger than the width of the single mode waveguide. In addition, the waveguide width which is as small as possible is selected in the design, so that the constraint of the waveguide on a mode field is reduced, and the adiabatic evolution efficiency is improved.
Regarding the length of the sections in the present invention, the sections of the wideband filter should have a sufficient length. On the one hand, it ensures that the waveguide coupling region in the adiabatic filter and the broadband mode converter is able to fully complete the mode conversion. On the other hand, the single-mode curved waveguide length on both sides of the adiabatic filter directly affects the spectral response characteristics of the device at the phase-matched wavelength, determining whether it can exhibit a steep spectral response.
Regarding the waveguide pitch of the broadband filter in the present invention, the maximum waveguide pitch on both sides of the adiabatic filter should be large enough to suppress mode crosstalk and increase the spectral response roll-off and sideband suppression ratio. The distance between the waveguide coupling regions in the adiabatic filter should be properly selected. On the one hand, in order to ensure that the waveguide coupling region can efficiently complete the conversion between the TE mode and the high-order TM mode, the spacing should not be too large. On the other hand, further reduction of this spacing, while improving mode conversion efficiency, results in longer evolution lengths on both sides of the adiabatic filter to ensure spectral response roll-off. Similarly, the maximum waveguide spacing on both sides of the wideband mode transformer should also be sufficiently large. The spectral response roll-off is not concerned, so that the distance between waveguide coupling areas is reduced as much as possible, and the mode conversion efficiency is improved.
It will be readily appreciated by those skilled in the art that the foregoing description is merely a preferred embodiment of the invention and is not intended to limit the invention, but any modifications, equivalents, improvements or alternatives falling within the spirit and principles of the invention are intended to be included within the scope of the invention.
Claims (10)
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202411953457.4A CN119667978B (en) | 2024-12-27 | 2024-12-27 | Broadband photon filter based on thin film lithium niobate optical waveguide |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202411953457.4A CN119667978B (en) | 2024-12-27 | 2024-12-27 | Broadband photon filter based on thin film lithium niobate optical waveguide |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN119667978A CN119667978A (en) | 2025-03-21 |
| CN119667978B true CN119667978B (en) | 2025-09-16 |
Family
ID=94983596
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202411953457.4A Active CN119667978B (en) | 2024-12-27 | 2024-12-27 | Broadband photon filter based on thin film lithium niobate optical waveguide |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN119667978B (en) |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116449493A (en) * | 2023-05-24 | 2023-07-18 | 华中科技大学 | Large-tolerance polarization rotation beam splitter |
| CN118915233A (en) * | 2024-08-08 | 2024-11-08 | 广东工业大学 | Film lithium niobate rapid adiabatic mode converter and implementation method thereof |
Family Cites Families (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20090231686A1 (en) * | 2008-01-12 | 2009-09-17 | Robert Atkins | Multi-functional integrated optical waveguides |
| CN101846815B (en) * | 2010-04-30 | 2012-01-25 | 天津大学 | Bandwidth-adjustable optical wavelength filter capable of simultaneously extracting double wavelength |
| CN115016154A (en) * | 2022-04-15 | 2022-09-06 | 北京工业大学 | Polarization filtering type intensity modulator based on lithium niobate thin film |
| CN115327701B (en) * | 2022-07-27 | 2023-12-08 | 浙江大学 | Polarization insensitive optical filter based on x-cut film lithium niobate platform |
| CN118033817A (en) * | 2022-11-11 | 2024-05-14 | 上海交通大学 | Polarization beam splitting rotator based on integration on silicon carbide chip |
| CN118938521B (en) * | 2024-09-19 | 2025-12-05 | 浙江大学 | A bandpass/bandstop dual-output integrated microwave photonic filter |
-
2024
- 2024-12-27 CN CN202411953457.4A patent/CN119667978B/en active Active
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116449493A (en) * | 2023-05-24 | 2023-07-18 | 华中科技大学 | Large-tolerance polarization rotation beam splitter |
| CN118915233A (en) * | 2024-08-08 | 2024-11-08 | 广东工业大学 | Film lithium niobate rapid adiabatic mode converter and implementation method thereof |
Also Published As
| Publication number | Publication date |
|---|---|
| CN119667978A (en) | 2025-03-21 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| EP3317704B1 (en) | Integrated on-chip polarizer | |
| US9453962B2 (en) | Beam combiner | |
| JP2858655B2 (en) | Optical wavelength multiplexer / demultiplexer | |
| CN114641720B (en) | Polarization system and method | |
| JP2007114253A (en) | Waveguide-type optical branching element | |
| JP3152189B2 (en) | Planar waveguide grating element | |
| CN113311537B (en) | Polymer three-mode multiplexer based on cascade conical coupler | |
| CN113126206B (en) | Silicon-based polarization beam splitting chip based on sub-wavelength grating and manufacturing method thereof | |
| CN104918145A (en) | Monolithic integrated multi-wavelength polarization multiplexer/demultiplexer | |
| JP3615069B2 (en) | Arrayed waveguide grating optical multiplexer / demultiplexer | |
| WO2000011508A1 (en) | Array waveguide diffraction grating optical multiplexer/demultiplexer | |
| US6801692B2 (en) | Optical coupling structure | |
| EP3203282B1 (en) | Rib type optical waveguide and optical multiplexer/demultiplexer using same | |
| CN113589429B (en) | Array waveguide grating based on auxiliary waveguide | |
| CN117908185A (en) | An optical power coupler | |
| CN114839722A (en) | Heterogeneous multimode waveguide coupler | |
| US9804328B2 (en) | Optical multiplexing and de-multiplexing element and arrayed-waveguide grating-type optical wavelength filter | |
| CN112612080B (en) | Miniaturized broadband polarization beam splitter based on LNOI material preparation | |
| JP4776082B2 (en) | Planar optical waveguide type Mach-Zehnder circuit, planar optical waveguide circuit and optical multiplexer / demultiplexer using the planar optical waveguide type Mach-Zehnder circuit | |
| CN119667978B (en) | Broadband photon filter based on thin film lithium niobate optical waveguide | |
| CN114488406B (en) | A Compact Wavelength Multiplexer Based on the Principle of Multimode Interference | |
| JPH07230014A (en) | Optical integrated device for proximity junction between two waveguides | |
| CN110941048B (en) | Coarse wavelength division multiplexer/demultiplexer with high extinction ratio based on the principle of multimode interference | |
| CN118938391B (en) | A double-layer adiabatic converter for conversion between TE2 mode and TE4 mode | |
| CN116299851B (en) | High bandwidth power beam splitter based on mixed surface plasma waveguide |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant |