A multi-core waveguide optical amplifier and its preparation method and application

Abstract

The present invention relates to a multi-core waveguide optical amplifier and its preparation method and application. The multi-core waveguide optical amplifier includes a plurality of groups of optical amplification structures; each group of the optical amplification structures includes a first strip waveguide and a second strip waveguide; the first strip waveguide includes a pump light transmission waveguide and a first coupling waveguide connected to each other; the second strip waveguide includes a signal light transmission waveguide and a second coupling waveguide connected to each other; both the first coupling waveguide and the second coupling waveguide are in a wedge shape; the second coupling waveguide is disposed on the first coupling waveguide, and the position of the thick end of the second coupling waveguide corresponds to the position of the thin end of the first coupling waveguide; the height of the first coupling waveguide gradually increases in the direction opposite to the pump light transmission; the width of the second coupling waveguide gradually increases in the signal light transmission direction; the material of the second strip waveguide is erbium-doped alumina. The multi-core waveguide optical amplifier can achieve parallel amplification of multiple waveguides, has good coupling effect, low loss, and good gain effect.

Description

Technical Field

[0001] The present invention relates to the field of optoelectronic technologies, and more specifically, to a multi-core waveguide optical amplifier, a preparation method thereof, and an application thereof. Background Art

[0002] With the development of integrated optical circuits and waveguide optics, new types of photonic integrated circuits (PICs) have been proposed and studied. Optical waveguides have many advantages such as compatibility with CMOS processes, chip sizes ranging from centimeters to millimeters, low power consumption, and easy large-scale preparation, which are convenient for realizing the design of large-scale chip-level integration. Among them, in optical communication systems, miniaturizing optical path devices and reducing power consumption are of great significance for improving the capacity of transmission systems. Traditional fiber optic communication systems are mainly suitable for long-distance communication transmission. To compensate for transmission losses, optical amplifiers have been developed. Currently, optical amplifiers have mature applications in fiber optic communication. For example, the widely used erbium-doped fiber amplifier (EDFA) has excellent optical amplification effects in the communication band (C-band, 1535 nm - 1565 nm). With the rapid growth of information traffic, to meet the demand, more high-performance optical amplifiers need to be developed. Among them, multi-core single-mode fibers, multi-core multi-mode fibers, and adapted multi-core fiber amplifiers proposed with the development of space-division multiplexing technology have become the current research hotspots. For example, a Chinese patent named a multi-core fiber amplifier provides a multi-core fiber amplifier.

[0003] In on-chip integrated optical circuits, by referring to the device functions of fiber optic communication systems, a signal compensation and amplification process is also required in similar multi-channel waveguides. Due to the miniaturization brought about by integration, new challenges have been posed to device development. Therefore, the technology of parallel amplification of multi-channel waveguides of devices needs to be further studied. Summary of the Invention

[0004] The primary objective of the present invention is to overcome the problem that the research on parallel amplification of multi-channel waveguides of existing optical amplifiers is still lacking, and to provide a multi-core waveguide optical amplifier. This multi-core waveguide optical amplifier can achieve parallel amplification of multi-channel waveguides, has good coupling effects, low losses, good gain effects, and can adapt to complex on-chip optoelectronic integrated circuits.

[0005] A further objective of the present invention is to provide a preparation method for the above-mentioned multi-core waveguide optical amplifier.

[0006] A further objective of the present invention is to provide an application of the above-mentioned multi-core waveguide optical amplifier in the preparation of multi-channel integrated lasers or multi-channel high-power frequency comb emitters.

[0007] The above objectives of the present invention are achieved through the following technical solutions:

[0008] A multi-core waveguide optical amplifier includes several groups of optical amplification structures;

[0009] Each group of the optical amplification structures includes a first strip waveguide and a second strip waveguide; the first strip waveguide includes a pump light transmission waveguide and a first coupling waveguide connected to each other; the second strip waveguide includes a signal light transmission waveguide and a second coupling waveguide connected to each other; both the first coupling waveguide and the second coupling waveguide are wedge-shaped; the second coupling waveguide is arranged on the first coupling waveguide, and the position of the thick end of the second coupling waveguide corresponds to the position of the thin end of the first coupling waveguide;

[0010] The height of the first coupling waveguide gradually increases in the direction opposite to the transmission direction of the pump light; the width of the second coupling waveguide gradually increases in the signal light transmission direction;

[0011] The material of the second strip waveguide is erbium-doped alumina.

[0012] The working process of the multi-core waveguide optical amplifier is as follows: the pump lights of all paths are transmitted from the pump light transmission waveguide of the first strip waveguide to the first coupling waveguide of the first strip waveguide, and then the pump lights are coupled from the first coupling waveguide into the second coupling waveguide, so that the erbium ions in the second strip waveguide undergo energy level transitions, generating light in the same wavelength band as the signal light. Finally, the light is output along the signal light transmission waveguide, realizing the amplification of the signal light.

[0013] The multi-core waveguide optical amplifier of the present invention is provided with several groups of optical amplification structures. Among them, the second strip waveguide of each group of optical amplification structures is a gain waveguide. Each group of optical amplification structures realizes the efficient coupling of the pump light and the signal light longitudinally through the design of a specific gradient structure and the cooperation of a specific gain material (erbium-doped alumina), and has good light transmission and amplification effects, thereby realizing the multi-channel waveguide parallel amplification of the device. Specifically, the coupling efficiency of the multi-core waveguide optical amplifier in the longitudinal direction is 99-99.96%, the loss of the transmission waveguide is 1.2-1.6 dB / cm, and the gain can reach 13-24 dB.

[0014] That is, the multi-core waveguide optical amplifier of the present invention can realize multi-channel waveguide parallel amplification, has good coupling effect, low loss, good gain effect, and can adapt to complex on-chip optoelectronic integrated circuits.

[0015] Preferably, the number of groups of the optical amplification structures is 2-4 groups.

[0016] More preferably, the number of groups of the optical amplification structures is 2 groups.

[0017] Preferably, the pump light transmission waveguides of the first strip waveguides of each group of the optical amplification structures are respectively connected to the branch ports of the beam splitter.

[0018] Preferably, the material of the first strip waveguide is silicon nitride or chalcogenide material.

[0019] Preferably, the minimum distance between the thick end of the first coupling waveguide and the second coupling waveguide is 30-70 nm, and the minimum distance between the other end (the thin end) and the second coupling waveguide is 190-270 nm.

[0020] Preferably, the height of the first coupling waveguide gradually increases along the direction opposite to the pump light transmission until it is equal to the height of the pump light transmission waveguide; the width of the second coupling waveguide gradually increases along the signal light transmission direction until it is equal to the width of the signal light transmission waveguide.

[0021] More preferably, the height of one end of the first coupling waveguide connected to the pump light transmission waveguide is 180-240 nm, and the height of the other end is 20-40 nm.

[0022] More preferably, the width of one end of the second coupling waveguide connected to the signal light transmission waveguide is 0.8-1.5 μm, and the width of the other end is 0.6-0.8 μm.

[0023] Preferably, the length of the pump light transmission waveguide is 200-300 μm.

[0024] Preferably, the length of the signal light transmission waveguide is 1 to 2 cm.

[0025] Preferably, the width of the first coupling waveguide is equal to the width of the pump light transmission waveguide, and the width is 1.0-1.6 μm.

[0026] Preferably, the height of the second coupling waveguide is equal to that of the signal light transmission waveguide, and the height is 500-700 nm.

[0027] Preferably, the first coupling waveguide and the second coupling waveguide have the same length.

[0028] More preferably, the length is 600-1000 μm.

[0029] Preferably, the erbium ion concentration of the erbium-doped aluminum oxide is 2 to 4*10 21 / cm 3 .

[0030] Preferably, the first strip waveguide and the second strip waveguide are both wrapped by optical material.

[0031] More preferably, the optical material is silicon dioxide.

[0032] The method for preparing the multi-core waveguide optical amplifier comprises the following steps:

[0033] S1. Deposit the first strip waveguide material layer on the first optical material layer, and etch out the first strip waveguide (1) whose height gradually increases in the direction opposite to the propagation direction of the pump light;

[0034] S2. Cover the first strip waveguide to form the second optical material layer, then cover an electron glue layer on the second optical material layer, and etch a groove corresponding to the shape of the second strip waveguide on the electron glue layer;

[0035] S3. Deposit erbium-doped alumina in the groove by atomic layer deposition technology (ALD), and then perform polishing treatment to form the second strip waveguide;

[0036] S4. Cover and form the third optical material layer to obtain the multi-core waveguide optical amplifier.

[0037] Both the first strip waveguide and the second strip waveguide of the preparation method of the present invention are integrally formed, which can make the structure more integrated and further improve the coupling performance; the second strip waveguide is formed by atomic layer deposition technology, which can realize better integration of highly active and highly concentrated erbium ions in the second strip waveguide, and the optical signal amplification is more efficient.

[0038] Preferably, the deposition method in step S1 is chemical vapor deposition.

[0039] Preferably, the etching method in step S1 is electron beam lithography etching.

[0040] Preferably, the first optical material layer in step S1 is formed on a silicon layer.

[0041] The application of the above multi-core waveguide optical amplifier in the preparation of a multi-channel integrated laser or a multi-channel high-power frequency comb transmitter is also within the protection scope of the present invention.

[0042] Compared with the prior art, the beneficial effects of the present invention are:

[0043] (1) The multi-core waveguide optical amplifier of the present invention can achieve multi-channel waveguide parallel amplification, with good coupling effect, low loss, good gain effect, and can adapt to complex on-chip optoelectronic integrated circuits.

[0044] (2) Both the first strip waveguide and the second strip waveguide of the preparation method of the present invention are integrally formed, which can make the structure more integrated and further improve the coupling performance; the second strip waveguide is formed by atomic layer deposition technology, which can realize better integration of highly active and highly concentrated erbium ions in the second strip waveguide, and the optical signal amplification is more efficient. Brief Description of the Drawings

[0045] Figure 1 It is a schematic structural diagram of the multi-core waveguide optical amplifier of Example 1.

[0046] Figure 2 The Figure 1 right view of the multi-core waveguide optical amplifier.

[0047] Figure 3 The Figure 1 top view of the multi-core waveguide optical amplifier.

[0048] Figure 4 Schematic diagram of the preparation process of the multi-core waveguide optical amplifier of Example 1.

[0049] Figure 5 Optical field diagram of the pump light transmitted in the pump light transmission waveguide of the multi-core waveguide optical amplifier of the present invention.

[0050] Figure 6 Optical field evolution diagram of the pump light coupled from the first coupling waveguide to the second coupling waveguide of the multi-core waveguide optical amplifier of the present invention.

[0051] Figure 7 Side sectional view of the optical field transmission when the pump light is coupled from the first coupling waveguide to the second coupling waveguide of the multi-core waveguide optical amplifier of the present invention.

[0052] Figure 8 Optical field diagram of the signal light transmitted in the signal light transmission waveguide of the multi-core waveguide optical amplifier of the present invention.

[0053] Figure 9 Curve graph of the signal light gain of the multi-core waveguide optical amplifier of the present invention varying with different pump light powers. Specific embodiments

[0054] In order to describe the technical solution of the present invention more clearly and completely, the present invention is further described in detail below through specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention, and various changes can be made within the scope defined by the claims of the present invention.

[0055] Example 1

[0056] A multi-core waveguide optical amplifier in this embodiment, as Figure 1As shown, the multi-core waveguide optical amplifier includes two sets of optical amplification structures. Each set of optical amplification structures includes a first strip waveguide 1 and a second strip waveguide 2; the first strip waveguide 1 includes a pump light transmission waveguide 11 and a first coupling waveguide 12 connected to each other; the second strip waveguide 2 includes a signal light transmission waveguide 21 and a second coupling waveguide 22 connected to each other; both the first coupling waveguide 12 and the second coupling waveguide 22 are wedge-shaped, the second coupling waveguide 22 is disposed on the first coupling waveguide 12, and the position of the thick end of the second coupling waveguide 22 corresponds to the position of the thin end of the first coupling waveguide 12. The height of the first coupling waveguide 12 gradually increases in the direction opposite to the pump light transmission until it is equal to the height of the pump light transmission waveguide 11; the width of the second coupling waveguide 21 gradually increases in the signal light transmission direction until it is equal to the width of the signal light transmission waveguide 22. The pump light transmission waveguides 11 of the first strip waveguides 1 of the two sets of optical amplification structures are respectively connected to two branch ports of a beam splitter 3, and the beam splitter 3 is a 1 / 2 beam splitter.

[0057] Figure 2 and Figure 3 are respectively Figure 1 the right view and the top view of the multi-core waveguide optical amplifier. As Figure 2 and Figure 3 shown, the length L1 of the pump light transmission waveguide 11 is 250 μm, the width W1 is 1.4 μm, and the height H1 is 200 nm. The height H2 of one end of the first coupling waveguide 12 connected to the pump light transmission waveguide 11 is 200 nm, and the height H2' of the other end is 30 nm; the width W2 of the first coupling waveguide 12 is 1.4 μm; the length L2 of the first coupling waveguide 12 is 800 μm. The length L4 of the signal light transmission waveguide 21 is 2.0 cm, the width W4 is 1 μm, and the height H4 is 700 nm; the width W3 of one end of the second coupling waveguide 22 connected to the signal light transmission waveguide 21 is 1 μm, and the width W3' of the other end is 0.8 μm; the height H3 of the second coupling waveguide 22 is 700 nm; the length L3 of the second coupling waveguide 22 is 800 μm. The minimum distance between the thick end of the first coupling waveguide 12 (i.e., the end of the first coupling waveguide 12 connected to the pump light transmission waveguide 11) and the second coupling waveguide is 30 nm, and the minimum distance between the other end (the thin end, i.e., the end of the first coupling waveguide 12 not connected to the pump light transmission waveguide 11) and the second coupling waveguide is 200 nm.

[0058] The material of the first strip waveguide 1 is silicon nitride, and the material of the second strip waveguide 2 is erbium-doped alumina, wherein the erbium ion concentration in the erbium-doped alumina is 3.0*10 21 / cm 3 . The first strip waveguide 1 and the second strip waveguide 2 are wrapped by silica.

[0059] The preparation method of the multi-core waveguide optical amplifier includes the following steps:

[0060] 1. First, form a first silicon dioxide layer on the silicon layer, then deposit a silicon nitride layer on the silicon dioxide layer by chemical vapor deposition, and use electron beam exposure etching technology to etch out the first strip waveguide 1 with a height gradually increasing in the reverse direction of the pump light transmission.

[0061] 2. Cover the first strip waveguide with silicon dioxide to form a second silicon dioxide layer, then cover the surface of the second silicon dioxide layer with an electron glue layer by spin coating, and then etch a groove corresponding to the shape of the second strip waveguide 2 on the electron glue layer.

[0062] 3. Deposit erbium-doped alumina in the groove by atomic layer deposition technology, and then perform a polishing treatment to remove the excess erbium-doped alumina to form the second strip waveguide 2.

[0063] 4. Cover and form a third silicon dioxide layer to obtain a multi-core waveguide optical amplifier.

[0064] Both the first strip waveguide 1 and the second strip waveguide 2 are integrally formed, which can make the structure more integrated and further improve the coupling performance; the second strip waveguide 2 is formed by atomic layer deposition technology, which can realize better integration of highly active and highly concentrated erbium ions in the second strip waveguide 2, and the optical signal amplification is more efficient.

[0065] The processes of steps 1 to 4 are as Figure 4 shown.

[0066] Example 2

[0067] A multi-core waveguide optical amplifier in this example has a structure basically the same as that of Example 1, except that: the length L4 of the signal light transmission waveguide 21 is 1.5 cm.

[0068] The preparation method of this multi-core waveguide optical amplifier is the same as that of the multi-core waveguide optical amplifier in Example 1.

[0069] Example 3

[0070] A multi-core waveguide optical amplifier in this example has a structure basically the same as that of Example 1, except that: the length L4 of the signal light transmission waveguide 21 is 1.0 cm.

[0071] The preparation method of this multi-core waveguide optical amplifier is the same as that of the multi-core waveguide optical amplifier in Example 1.

[0072] Performance Test

[0073] Take the multi-core waveguide optical amplifier of Example 1 and assemble it into an optical amplification test system in the 1550 nm communication band (including a 1550 nm signal light laser, a 980 nm pump light laser, a spectrometer, and single-mode optical fibers for connection), and test the transmission loss, coupling, and gain of the multi-core waveguide optical amplifier.

[0074] The optical field diagram of the pump light transmitted in the pump light transmission waveguide 11 of one set of optical amplification structures is as Figure 5 shown. It can be seen from Figure 5 that the pump light is well confined within the waveguide size, realizing the effective transmission of light. After being detected by a power meter, the transmission loss is 1.2 - 1.6 dB / cm. The mode conversion process of the pump light between the first coupling waveguide 12 and the second coupling waveguide 22 in one set of optical amplification structures is as shown in (1) - (4) of Figure 6 , Figure 6 which is the optical field evolution diagram of the pump light coupled from the first coupling waveguide 12 to the second coupling waveguide 22. It can be seen from Figure 6 that within the designed coupling structure, the pump light can be effectively coupled to the second strip waveguide 2, and the coupling efficiency reaches 99.96%. Figure 7 This is the side sectional view of the optical field transmission of the pump light coupled from the first coupling waveguide 12 to the second coupling waveguide 22 in one set of optical amplification structures. It can be seen from Figure 7 that within the designed coupling structure size, the pump light can be effectively coupled to the second strip waveguide 2. The optical field diagram of the signal light transmitted in the signal light transmission waveguide 21 of one set of optical amplification structures is as Figure 8 shown. It can be seen from Figure 8 that the signal light is well confined within the waveguide size, realizing the effective transmission of light. After being detected by a power meter, the transmission loss is 1.2 - 1.6 dB / cm. Figures 3 to 6 The results of

[0075] show that the multi-core waveguide optical amplifier of the present invention has good coupling effect and low loss.

[0076] Pump lights with different initial powers are respectively injected into the multi-core waveguide optical amplifiers of Examples 1 - 3 (the lengths L4 of the corresponding signal light transmission waveguides are 2.0, 1.5, and 1.0 cm respectively), and Figure 9 , Figure 9 this is the curve graph of the signal light gain varying with different pump light powers. It can be seen from Figure 9It can be seen that as the power of the pump light increases, the signal light gain increases significantly and tends to balance after reaching a certain power; when the lengths of the signal light transmission waveguides are 1.0, 1.5, and 2.0 cm, the overall gain effects all gradually increase, indicating that for signal light transmission waveguides of different lengths, the pump light can fully excite the population inversion of erbium ions, and the gain is greater than the transmission loss, resulting in an optical amplification effect and increasing the overall gain; among them, the multi-core waveguide optical amplifier with a signal light transmission waveguide length of 2.0 cm (Example 1) accumulates the highest total gain, reaching 24 dB. The multi-core waveguide optical amplifier of the present invention can achieve parallel amplification of multiple waveguides, has good coupling effect, low loss, and good gain effect, and can be applied to multi-channel integrated lasers or multi-channel high-power frequency comb emitters.

[0077] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, rather than limitations on the implementation manners of the present invention. For those of ordinary skill in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation manners here. Any modifications, equivalent replacements, and improvements made within the spirit and principle of the present invention shall be included in the protection scope of the claims of the present invention.

Claims

1. A multi-core waveguide optical amplifier, characterized in that It includes several groups of optical amplification structures; Each group of the optical amplification structures includes a first strip waveguide (1) and a second strip waveguide (2); the first strip waveguide (1) includes a pump light transmission waveguide (11) and a first coupling waveguide (12) connected to each other; the second strip waveguide (2) includes a signal light transmission waveguide (21) and a second coupling waveguide (22) connected to each other; both the first coupling waveguide (12) and the second coupling waveguide (22) are wedge-shaped; the second coupling waveguide (22) is disposed on the first coupling waveguide (12), there is a gap between the second coupling waveguide and the first coupling waveguide, and the position of the thick end of the second coupling waveguide (22) corresponds to the position of the thin end of the first coupling waveguide (12); The height of the first coupling waveguide (12) gradually increases in the direction opposite to the pump light transmission; the width of the second coupling waveguide (22) gradually increases in the signal light transmission direction; The material of the second strip waveguide (2) is erbium-doped alumina.

2. The multi-core waveguide optical amplifier according to claim 1, characterized in that, The number of groups of the optical amplification structures is 2 to 4 groups.

3. The multi-core waveguide optical amplifier according to claim 1, wherein The material of the first strip waveguide (1) is silicon nitride or chalcogenide material.

4. The multi-core waveguide optical amplifier according to claim 1, wherein The minimum distance between the thick end of the first coupling waveguide (12) and the second coupling waveguide (22) is 30 to 70 nm, and the minimum distance between the other end and the second coupling waveguide (22) is 190 to 270 nm.

5. The multi-core waveguide optical amplifier according to claim 1, wherein The height of the first coupling waveguide (12) gradually increases in the direction opposite to the pump light transmission until it is equal to the height of the pump light transmission waveguide (11); the width of the second coupling waveguide (22) gradually increases in the signal light transmission direction until it is equal to the width of the signal light transmission waveguide (21).

6. The multi-core waveguide optical amplifier according to claim 1, wherein The first coupling waveguide (12) and the second coupling waveguide (22) have the same length.

7. The multi-core waveguide optical amplifier according to claim 1, wherein Both the first strip waveguide (1) and the second strip waveguide (2) are wrapped by optical materials.

8. The preparation method of the multi-core waveguide optical amplifier according to any one of claims 1 to 7, characterized in that, It includes the following steps: S1. Deposit a first strip waveguide material layer on a first optical material layer, and etch out the first strip waveguide (1) whose height gradually increases in the direction opposite to the pump light transmission; S2. Cover the first strip waveguide to form a second optical material layer, then cover an electron glue layer on the second optical material layer, and then etch a groove corresponding to the shape of the second strip waveguide (2) on the electron glue layer; S3. Use atomic layer deposition technology to deposit erbium-doped alumina in the groove, and then perform a polishing treatment to form the second strip waveguide (2); S4. Cover and form a third optical material layer to obtain the multi-core waveguide optical amplifier.

9. The preparation method according to claim 8, characterized in that, The deposition method described in step S1 is chemical vapor deposition.

10. Application of the multi-core waveguide optical amplifier according to any one of claims 1 to 7 in the preparation of a multi-channel integrated laser or a multi-channel high-power frequency comb transmitter.

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