A compact thin-film lithium niobate modulator chip

Abstract

This invention relates to a compact thin-film lithium niobate modulator chip, belonging to the field of optical communication devices. The thin-film lithium niobate modulator chip of this invention includes a waveguide optical path and modulation electrodes. The waveguide optical path includes an end-face coupling structure and an interference optical path. The waveguide arms in the interference optical path adopt a double-folded structure, with the two ends of the arc-shaped waveguide at the bend connected to S-shaped waveguides respectively, reducing the distance between the folded waveguide arms. The modulation electrodes include a traveling wave electrode, an electro-optic DC bias electrode, and a thermo-optic DC bias electrode. The electro-optic DC bias electrode is connected in parallel to increase the modulation length. This invention provides a compact modulator waveguide optical path, increasing the length of the waveguide arms while reducing the chip size, thereby increasing the length of the modulation electrodes, improving modulation efficiency, and reducing half-wave voltage.

Description

Technical Field

[0001] This invention belongs to the field of optical communication devices and relates to a compact thin-film lithium niobate electro-optic modulator chip. Background Technology

[0002] Lithium niobate, with its excellent electro-optic effect and wide transparency window, has become one of the most widely used materials in modulator products. With the maturity of micro-nano fabrication technology, thin-film lithium niobate materials capable of realizing submicron-sized waveguides have become a research hotspot. Due to their smaller size and higher modulation efficiency, they significantly improve modulator performance. Compared to modulators made of single-crystal lithium niobate, silicon photonics, and group III-V materials, they offer unparalleled performance advantages.

[0003] Due to its high refractive index difference, thin-film lithium niobate waveguides can reduce the size of optical modes by about 20 times compared to bulk lithium niobate waveguides. This enhances the interaction between the electric and optical fields, improving modulation efficiency. However, the fabrication of thin-film lithium niobate waveguides currently relies mainly on electron beam lithography, which is time-consuming and difficult to mass-produce. Typical modulators require the simultaneous placement of traveling wave electrodes, electro-optic and thermo-optic DC modulation electrodes. Limited by chip length, placing these electrodes horizontally necessitates shortening their length, reducing modulation efficiency and preventing the achievement of lower half-wave voltages. Furthermore, considering the minimum bending radius of waveguides, double folding of the waveguide arms undoubtedly increases the chip width. Therefore, there is a need to develop high-modulation-efficiency, miniaturized thin-film lithium niobate modulators. Summary of the Invention

[0004] The technical problem solved by this invention is to overcome the shortcomings of the prior art and propose a compact thin-film lithium niobate electro-optic modulator chip to improve the modulation efficiency of the modulator, reduce the half-wave voltage and reduce the chip size.

[0005] The solution of the present invention is:

[0006] A compact thin-film lithium niobate modulator chip includes a waveguide optical path and a modulation electrode;

[0007] The waveguide optical path includes an input end-face coupler, an input waveguide, a beam splitter, a waveguide arm, a beam combiner, an output waveguide, and an output end-face coupler connected in sequence; the waveguide arm is formed by a first waveguide arm and a second waveguide arm connected in parallel.

[0008] The first waveguide arm comprises, in sequence, a first straight waveguide, a first S-shaped curved waveguide, a first arc-shaped curved waveguide, a second S-shaped curved waveguide, a second straight waveguide, a third S-shaped curved waveguide, a second arc-shaped curved waveguide, a fourth S-shaped curved waveguide, a third straight waveguide, a fifth S-shaped curved waveguide, a fourth straight waveguide, and a sixth S-shaped curved waveguide; the second waveguide arm comprises, in sequence, a fifth straight waveguide, a seventh S-shaped curved waveguide, a third arc-shaped curved waveguide, an eighth S-shaped curved waveguide, a sixth straight waveguide, a ninth S-shaped curved waveguide, a fourth arc-shaped curved waveguide, a tenth S-shaped curved waveguide, a seventh straight waveguide, an eleventh S-shaped curved waveguide, an eighth straight waveguide, and a twelfth S-shaped curved waveguide.

[0009] The modulation electrode includes a traveling wave electrode, an electro-optic DC bias electrode, and a thermo-optic DC bias electrode. A terminating matching resistor is provided between the center electrode and the ground electrode of the traveling wave electrode. The center electrode of the traveling wave electrode is located between the first and fifth straight waveguides. The electro-optic DC bias electrode includes two parallel electrode segments. The center electrode of the first segment is located between the third and seventh straight waveguides, and the center electrode of the second segment is located between the third and seventh straight waveguides. The ground electrode of the first segment near the third S-shaped waveguide is connected to the ground electrode of the second segment near the fourth S-shaped waveguide, and the ground electrode on the other side of the first segment is connected to the ground electrode on the other side of the second segment. The thermo-optic DC bias electrode is located outside the fourth or eighth straight waveguide.

[0010] Preferably, the first S-shaped waveguide and the second S-shaped waveguide are located within the longitudinal range between the two endpoints of the first arc-shaped waveguide; the third S-shaped waveguide and the fourth S-shaped waveguide are located within the longitudinal range between the two endpoints of the second arc-shaped waveguide; the seventh S-shaped waveguide and the eighth S-shaped waveguide are located within the longitudinal range between the two endpoints of the third arc-shaped waveguide; and the ninth S-shaped waveguide and the tenth S-shaped waveguide are located within the longitudinal range between the two endpoints of the fourth arc-shaped waveguide.

[0011] Preferably, the fifth and sixth S-shaped waveguides are located below the horizontal position of the fourth straight waveguide; the eleventh and twelfth S-shaped waveguides are located above the horizontal positions of the two ends of the eighth straight waveguide.

[0012] Preferably, all S-shaped waveguides are formed by connecting two circular arcs with the same central angle.

[0013] Preferably, the beam splitter and beam combiner are one of the following: Y-branch, multimode interference coupler, and directional coupler.

[0014] Preferably, the traveling wave electrode and the electro-optic DC bias electrode are coplanar waveguide structures.

[0015] Preferably, the substrate materials used in the chip, from bottom to top, are a substrate layer, a silicon oxide layer, and a thin-film lithium niobate layer.

[0016] Preferably, the traveling wave electrode is grown directly on a thin-film lithium niobate layer, and then covered with a silicon oxide cladding layer.

[0017] Preferably, the fabrication process of the electro-optic DC bias electrode is as follows:

[0018] A silicon oxide overlay is applied to a thin-film lithium niobate layer, and then an electro-optic DC bias electrode is grown.

[0019] Preferably, the thermo-optical DC bias electrode is grown directly on a thin-film lithium niobate layer, and then covered with a silicon oxide cladding layer.

[0020] The advantages of this invention compared to the prior art are:

[0021] The waveguide arm in the optical path of this invention adopts a double-folded structure, which extends the waveguide length for modulation with a smaller chip size and improves modulation efficiency. At the bend, the two ends of the arc-shaped waveguide are respectively connected to S-shaped waveguides, which reduces the width of the chip and makes the chip more compact. Traveling wave electrodes, electro-optic DC bias electrodes and thermo-optic DC bias electrodes are set. The electro-optic DC bias electrodes are connected in parallel to increase the modulation length and effectively reduce the half-wave voltage. Attached Figure Description

[0022] Figure 1 This is a top view schematic diagram of a compact thin-film lithium niobate electro-optic modulator in an embodiment of the present invention;

[0023] Figure 2 This is a two-dimensional cross-sectional schematic diagram of the modulation region of the traveling wave electrode of the compact thin-film lithium niobate electro-optic modulator in an embodiment of the present invention;

[0024] Figure 3 This is a two-dimensional cross-sectional schematic diagram of the modulation region of the electro-optic DC bias electrode of the compact thin-film lithium niobate electro-optic modulator in an embodiment of the present invention;

[0025] Figure 4 This is a two-dimensional cross-sectional schematic diagram of the modulation region of the thermo-optic DC bias electrode of the compact thin-film lithium niobate electro-optic modulator in an embodiment of the present invention.

[0026] Wherein: 9-traveling wave electrode, 11-electro-optic DC bias electrode, 12-thermo-optic DC bias electrode, 13-underlying layer, 14-silicon oxide layer, 15-thin lithium niobate layer, 16-silicon oxide top cladding. Detailed Implementation

[0027] To make the objectives, technical solutions, and advantages of the present invention clearer, the technical solutions of the present invention will be described in detail below with reference to the embodiments and accompanying drawings.

[0028] The thin-film lithium niobate modulator of this invention includes a waveguide optical path and modulation electrodes. The waveguide optical path includes an end-face coupling structure and an interference optical path. The waveguide arms in the interference optical path adopt a double-folded structure, with the two ends of the arc-shaped waveguide at the bend connected to S-shaped waveguides respectively, reducing the distance between the folded waveguide arms. The modulation electrodes include a traveling wave electrode, an electro-optic DC bias electrode, and a thermo-optic DC bias electrode. The electro-optic DC bias electrodes are connected in parallel to increase the modulation length. This invention provides a compact modulator waveguide optical path that increases the length of the waveguide arms while reducing the chip size, thereby increasing the length of the modulation electrodes, improving modulation efficiency, and reducing half-wave voltage.

[0029] Specifically, this invention proposes a compact thin-film lithium niobate electro-optic modulator chip, including a waveguide optical path and modulation electrodes. The waveguide optical path includes an input end-face coupler 1, an input waveguide 2, a beam splitter 3, a waveguide arm, a beam combiner 6, an output waveguide 7, and an output end-face coupler 8 connected in sequence. The waveguide arm is formed by a first waveguide arm 4 and a second waveguide arm 5 connected in parallel. The first waveguide arm 4 includes a first straight waveguide 4-1, a first S-shaped curved waveguide 4-2, a first arc-shaped curved waveguide 4-3, a second S-shaped curved waveguide 4-4, a second straight waveguide 4-5, a third S-shaped curved waveguide 4-6, a second arc-shaped curved waveguide 4-7, a fourth S-shaped curved waveguide 4-8, a third straight waveguide 4-9, a fifth S-shaped curved waveguide 4-10, a fourth straight waveguide 4-11, and a sixth S-shaped curved waveguide 4-12 connected in sequence; the second... The second waveguide arm 5 includes the fifth straight waveguide 5-1, the seventh S-shaped curved waveguide 5-2, the third arc-shaped curved waveguide 5-3, the eighth S-shaped curved waveguide 5-4, the sixth straight waveguide 5-5, the ninth S-shaped curved waveguide 5-6, the fourth arc-shaped curved waveguide 5-7, the tenth S-shaped curved waveguide 5-8, the seventh straight waveguide 5-9, the eleventh S-shaped curved waveguide 5-10, the eighth straight waveguide 5-11, and the twelfth S-shaped curved waveguide 5-12, which are connected in sequence. The modulation electrode includes a traveling wave electrode 9, an electro-optic DC bias electrode 11, and a thermo-optic DC bias electrode 12. A terminating matching resistor 10 is provided between the center electrode and the ground electrode of the traveling wave electrode 9. The center electrode of the traveling wave electrode 9 is located between the first straight waveguide 4-1 and the fifth straight waveguide 5-1. The electro-optic DC bias electrode 11 includes two parallel electrode segments. The center electrode of the first segment is located between the third straight waveguide 4-5 and the seventh straight waveguide 5-5, and the center electrode of the second segment is located between the third straight waveguide 4-9 and the seventh straight waveguide 5-9. The ground electrode of the first segment near the third S-shaped curved waveguide 4-6 is connected to the ground electrode of the second segment near the fourth S-shaped curved waveguide 4-8, and the ground electrode on the other side of the first segment is connected to the ground electrode on the other side of the second segment. The thermo-optic DC bias electrode 12 is located outside the fourth straight waveguide 4-11 or the eighth straight waveguide 5-11.

[0030] All S-shaped waveguides are formed by connecting two circular arcs with the same central angle. The first and second S-shaped waveguides are connected to both ends of the first arc-shaped waveguide and are located inside the lateral range between the two ends of the first arc-shaped waveguide; the third and fourth S-shaped waveguides are connected to both ends of the second arc-shaped waveguide and are located inside the lateral range between the two ends of the second arc-shaped waveguide; the seventh and eighth S-shaped waveguides are connected to both ends of the third arc-shaped waveguide and are located inside the lateral range between the two ends of the third arc-shaped waveguide; the ninth and tenth S-shaped waveguides are connected to both ends of the fourth arc-shaped waveguide and are located inside the lateral range between the two ends of the fourth arc-shaped waveguide. The fifth and sixth S-shaped waveguides are connected to both ends of the fourth straight waveguide and are located below the horizontal position of the fourth straight waveguide; the eleventh and twelfth S-shaped waveguides are connected to both ends of the eighth straight waveguide and are located above the horizontal position of the two ends of the eighth straight waveguide.

[0031] Beam splitters and beam combiners can be one type of Y-branch, multimode interference coupler, directional coupler, etc. The traveling-wave electrode and electro-optic DC bias electrode of the compact thin-film lithium niobate electro-optic modulator chip are coplanar waveguide structures. The substrate materials used in the compact thin-film lithium niobate electro-optic modulator chip, from bottom to top, are a substrate layer, a silicon oxide layer, and a thin-film lithium niobate layer. A waveguide optical path is formed by etching the thin-film lithium niobate layer and then covering it with a silicon oxide top cladding. The traveling-wave electrode is grown directly on the thin-film lithium niobate layer, and then covered with a silicon oxide top cladding. The electro-optic DC bias electrode is grown after covering the thin-film lithium niobate layer with a silicon oxide top cladding. The thermo-optic DC bias electrode is grown directly on the thin-film lithium niobate layer, and then covered with a silicon oxide top cladding.

[0032] Example:

[0033] Reference Figures 1-4 This embodiment provides a compact thin-film lithium niobate electro-optic modulator chip, including a waveguide optical path and a modulation electrode.

[0034] The waveguide optical path includes: an input end-face coupler 1, an input waveguide 2, a beam splitter 3, a waveguide arm, a beam combiner 6, an output waveguide 7, and an output end-face coupler 8, connected in sequence. The waveguide arm includes a first waveguide arm 4 and a second waveguide arm 5 connected in parallel.

[0035] The first waveguide arm 4 includes a first straight waveguide 4-1, a first S-shaped curved waveguide 4-2, a first arc-shaped curved waveguide 4-3, a second S-shaped curved waveguide 4-4, a second straight waveguide 4-5, a third S-shaped curved waveguide 4-6, a second arc-shaped waveguide 4-7, a fourth S-shaped curved waveguide 4-8, a third straight waveguide 4-9, a fifth S-shaped curved waveguide 4-10, a fourth straight waveguide 4-11, and a sixth S-shaped curved waveguide 4-12, which are connected in sequence; The second waveguide arm 5 includes the fifth straight waveguide 5-1, the seventh S-shaped curved waveguide 5-2, the third arc-shaped curved waveguide 5-3, the eighth S-shaped curved waveguide 5-4, the sixth straight waveguide 5-5, the ninth S-shaped curved waveguide 5-6, the fourth arc-shaped waveguide 5-7, the tenth S-shaped curved waveguide 5-8, the seventh straight waveguide 5-9, the eleventh S-shaped curved waveguide 5-10, the eighth straight waveguide 5-11, and the twelfth S-shaped curved waveguide 5-12, which are connected in sequence.

[0036] The modulation electrode includes a traveling wave electrode 9, an electro-optic DC bias electrode 11, and a thermo-optic DC bias electrode 12. A terminating matching resistor 10 is provided between the signal electrode and the ground electrode of the traveling wave electrode 9.

[0037] Preferably, in this embodiment, all S-shaped waveguides are formed by connecting two arcs with the same central angle, which is 45°. To ensure low bending loss, the bending radius is set to 200 μm.

[0038] Furthermore, in this embodiment, the first S-shaped waveguide 4-2 and the second S-shaped waveguide 4-4 are respectively connected to both ends of the first arc-shaped waveguide 4-3, and are located inside the lateral range between the two ends of the first arc-shaped waveguide 4-3; the third S-shaped waveguide 4-6 and the fourth S-shaped waveguide 4-8 are respectively connected to both ends of the second arc-shaped waveguide 4-7, and are located inside the lateral range between the two ends of the second arc-shaped waveguide 4-7; the seventh S-shaped waveguide 5-2 and the eighth S-shaped waveguide 5-4 are respectively connected to both ends of the third arc-shaped waveguide 5-3, and are located inside the lateral range between the two ends of the third arc-shaped waveguide 5-3; the ninth S-shaped waveguide 5-6 and the tenth S-shaped waveguide 5-8 are respectively connected to both ends of the fourth arc-shaped waveguide 5-7, and are located inside the lateral range between the two ends of the fourth arc-shaped waveguide 5-7. This reduces the spacing of the folded waveguide arms by about half, thus reducing the width of the chip.

[0039] Furthermore, in this embodiment, the fifth S-shaped waveguide 4-10 and the sixth S-shaped waveguide 4-12 are respectively connected to both ends of the fourth straight waveguide 4-11 and are located below the horizontal position of the fourth straight waveguide 4-11; the eleventh S-shaped waveguide 5-10 and the twelfth S-shaped waveguide 5-12 are respectively connected to both ends of the eighth straight waveguide 5-11 and are located above the horizontal position of the two ends of the eighth straight waveguide 5-11. This increases the distance between the first waveguide arm 4 and the second waveguide arm 5, preventing thermal crosstalk generated by the thermo-optical DC bias electrode from affecting the modulation efficiency.

[0040] Furthermore, in this embodiment, the waveguides in the waveguide arm are all single-mode ridge waveguides with a width of 1 μm and a ridge height of 0.3 μm. The waveguide sidewall tilt angle is 75°.

[0041] Preferably, in this embodiment, the beam splitter 3 and the beam combiner 6 adopt a multimode interference coupler structure.

[0042] Preferably, in this embodiment, the traveling wave electrode 9 and the electro-optic DC bias electrode 11 are coplanar waveguide structures.

[0043] Furthermore, in this embodiment, the center electrode width of the traveling wave electrode 9 is 15 μm, and it is located between the first straight waveguide 4-1 and the fifth straight waveguide 5-1. The distance between the center signal electrode and the two side ground electrodes is 5.5 μm, and the electrode thickness is 0.9 μm. (Refer to...) Figure 2 The traveling wave electrode 9 is grown directly on the thin film lithium niobate layer 15, and then covered with a silicon oxide cladding layer 16.

[0044] Preferably, in this embodiment, the resistance of the terminal matching resistor 10 is 50Ω, which matches the output port impedance of the traveling wave electrode 9 to reduce signal reflection.

[0045] Furthermore, the center electrode width of the electro-optic DC bias electrode 11 is 15 μm. The first segment of the center electrode is located between the third straight waveguide 4-5 and the seventh straight waveguide 5-5, and is connected to the ground electrodes on both sides of the second segment. The second segment of the center electrode is located between the third straight waveguide 4-9 and the seventh straight waveguide 5-9, and is connected to the ground electrodes on both sides of the first segment. The distance between the center signal electrode and the two ground electrodes is 3 μm, reducing the electrode spacing to improve modulation efficiency. The electrode thickness is 0.9 μm. To reduce metal absorption loss, refer to... Figure 3 First, a silicon oxide cladding layer 16 is covered on the thin film lithium niobate layer 15, and then an electro-optic DC bias electrode 11 is grown.

[0046] Furthermore, the thermo-optical DC bias electrode 12 is located on one side of the fourth straight waveguide 4-11 or the eighth straight waveguide 5-11. (Refer to...) Figure 4The thermo-optical DC bias electrode 12 is grown directly on the thin film lithium niobate layer 15, and then covered with a silicon oxide cladding layer 16.

[0047] Preferably, in this embodiment, the substrate materials used for the chip, from bottom to top, are a 500μm silicon substrate layer 13, a 4.7μm thick silicon oxide layer 14, and a 0.6μm thin-film lithium niobate layer 15. A waveguide optical path is formed by etching the thin-film lithium niobate layer 15 and covering it with a 1μm silicon oxide overlayer 16.

[0048] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Any changes and improvements made by those skilled in the art within the scope of the present invention should be included within the protection scope of the present invention.

Claims

1. A compact thin film lithium niobate modulator chip, characterized by: The waveguide optical path comprises an input end face coupler (1), an input waveguide (2), a beam splitter (3), a waveguide arm, a beam combiner (6), an output waveguide (7), and an output end face coupler (8) connected in sequence; the waveguide arm is formed by the first waveguide arm (4) and the second waveguide arm (5) in parallel. The first waveguide arm (4) comprises a first straight waveguide (4-1), a first S-shaped curve waveguide (4-2), a first arc curve waveguide (4-3), a second S-shaped curve waveguide (4-4), a second straight waveguide (4-5), a third S-shaped curve waveguide (4-6), a second arc curve waveguide (4-7), a fourth S-shaped curve waveguide (4-8), a third straight waveguide (4-9), a fifth S-shaped curve waveguide (4-10), a fourth straight waveguide (4-11), and a sixth S-shaped curve waveguide (4-12) connected in sequence; the second waveguide arm (5) comprises a fifth straight waveguide (5-1), a seventh S-shaped curve waveguide (5-2), a third arc curve waveguide (5-3), an eighth S-shaped curve waveguide (5-4), a sixth straight waveguide (5-5), a ninth S-shaped curve waveguide (5-6), a fourth arc curve waveguide (5-7), a tenth S-shaped curve waveguide (5-8), a seventh straight waveguide (5-9), an eleventh S-shaped curve waveguide (5-10), an eighth straight waveguide (5-11), and a twelfth S-shaped curve waveguide (5-12) connected in sequence. The modulation electrode comprises a traveling wave electrode (9), an electro-optic DC bias electrode (11), and a thermo-optic DC bias electrode (12); a terminal matching resistor (10) is arranged between the center electrode and the ground electrode of the traveling wave electrode (9), and the center electrode of the traveling wave electrode (9) is located between the first straight waveguide (4-1) and the fifth straight waveguide (5-1); the electro-optic DC bias electrode (11) comprises two segments in parallel, wherein the center electrode of the first segment is located between the second straight waveguide (4-5) and the sixth straight waveguide (5-5), the center electrode of the second segment is located between the third straight waveguide (4-9) and the seventh straight waveguide (5-9), the center electrode of the first segment close to one side of the third S-shaped curve waveguide (4-6) is connected with the ground electrode of the second segment close to one side of the fourth S-shaped curve waveguide (4-8), and the ground electrode of the first segment on the other side is connected with the center electrode of the second segment on the other side; the thermo-optic DC bias electrode (12) is located outside the fourth straight waveguide (4-11) or the eighth straight waveguide (5-11). The first S-shaped curve waveguide (4-2) and the second S-shaped curve waveguide (4-4) are located inside the longitudinal range between the two end points of the first arc curve waveguide (4-3); the third S-shaped curve waveguide (4-6) and the fourth S-shaped curve waveguide (4-8) are located inside the longitudinal range between the two end points of the second arc curve waveguide (4-7); the seventh S-shaped curve waveguide (5-2) and the eighth S-shaped curve waveguide (5-4) are located inside the longitudinal range between the two end points of the third arc curve waveguide (5-3); and the ninth S-shaped curve waveguide (5-6) and the tenth S-shaped curve waveguide (5-8) are located inside the longitudinal range between the two end points of the fourth arc curve waveguide (5-7).

2. A compact thin film lithium niobate modulator chip according to claim 1, wherein: ​ 3. A compact thin film lithium niobate modulator chip according to claim 1, wherein: The fifth S-shaped curve waveguide (4-10) and the sixth S-shaped curve waveguide (4-12) are located below the horizontal position of the fourth straight waveguide (4-11); the eleventh S-shaped curve waveguide (5-10) and the twelfth S-shaped curve waveguide (5-12) are located above the horizontal position of the two end points of the eighth straight waveguide (5-11).

4. A compact thin film lithium niobate modulator chip according to claim 1, wherein: All S-shaped curve waveguides are connected by two circular arcs with the same central angle.

5. A compact thin film lithium niobate modulator chip according to claim 1, wherein: The beam splitter (3) and the beam combiner (6) are one of Y-branch, multimode interference coupler and directional coupler.

6. A compact thin film lithium niobate modulator chip according to claim 1, wherein: The traveling wave electrode (9) and the electro-optic DC bias electrode (11) are coplanar waveguide structures.

7. A compact thin film lithium niobate modulator chip according to claim 1, wherein: The substrate material used by the chip is sequentially the substrate layer (13), the silicon oxide layer (14) and the thin film lithium niobate layer (15) from bottom to top.

8. A compact thin film lithium niobate modulator chip according to claim 7, wherein: The traveling wave electrode (9) is directly grown on the thin film lithium niobate layer (15), and then covered with a silicon oxide overclad layer.

9. A compact thin film lithium niobate modulator chip according to claim 1, wherein: The processing technology of the electro-optic DC bias electrode (11) is: The silicon oxide overclad layer is covered on the thin film lithium niobate layer (15), and then the electro-optic DC bias electrode (11) is grown.

10. The compact thin film lithium niobate modulator chip of claim 1, wherein: The electro-optic DC bias electrode (11) is directly grown on the thin film lithium niobate layer (15), and then covered with a silicon oxide overclad layer.

Images