Adiabatic mode conversion beam splitter suitable for TE0 mode evolution to TE1 mode

Abstract

The present invention belongs to the field of integrated optoelectronic technology and specifically relates to a TE 0 Mode EvolutionTE 1 The input end of the adiabatic mode conversion beam splitter of the present invention comprises a first silicon core; the lower substrate of the first silicon core is silicon dioxide; the upper part of the first silicon core is an upper cladding layer; the transmission mode of the first silicon core is a fundamental mode TE 0 mode; the output end of the adiabatic mode conversion beam splitter includes a second silicon core and a third silicon core; the lower substrate of the second silicon core and the third silicon core is silicon dioxide; the upper part of the second silicon core and the third silicon core is an upper cladding layer; the transmission mode of the second silicon core and the third silicon core is TE 1 mode, and TE 1 The power of the mode in the second silicon core and the third silicon core is equal. The function of the adiabatic mode conversion beam splitter proposed in the present invention is to convert the fundamental mode TE 0 The mode evolves into two TEs at the output end 1 mode, and the power is output evenly at the two output ends, while achieving conversion between different modes and uniform output of energy.

Description

Technical Field

[0001] The present invention belongs to the technical field of integrated optoelectronics, and in particular relates to an adiabatic mode conversion beam splitter suitable for TE0 mode evolution into TE1 mode. Background Art

[0002] Silicon photonics has become a very promising technology for large-scale photonic integrated chips due to its high integration and process compatibility with complementary metal oxide semiconductors. Currently, various large-scale photonic integrated chips are widely used, as reflected in the paper R Soref, "The past, present, and future of silicon photonics," IEEE J. Sel. Top. Quantum Electron., vol. 12, no. 6, pp. 1678-1687, Nov. 2006. Broadband optical power splitters with low insertion loss are necessary for realizing highly integrated photonic integrated chips and are widely used in optical power distribution and building more complex optical devices such as optical switches, optical modulators, optical multiplexers, optical phased arrays, etc. This is reflected in the paper Y. Wang, S. Gao, K. Wang, and E. Skafidas. "Ultra-broadband and low-loss 3dB optical power splitter based on adiabatic tapered silicon waveguides," Optics letters, vol. 41, no. 9, pp. 2053-2056, May 2016. Power splitter devices can realize high-fidelity, multi-channel circuits and achieve parallel processing, thereby improving operational efficiency. In optical sensing, the beam splitter divides the input optical signal into two paths: one path will be used for sensing and the other path will be used as a reference. Based on the silicon integrated platform, power splitters are mainly implemented through Y-type branches, directional couplers, and multi-mode interference couplers. However, these methods usually have many limitations. For example, when the branching angle is not small enough, the mode mismatch loss of the Y-type branch is relatively high; traditional directional couplers and multimode interference couplers are very sensitive to wavelength and polarization, resulting in very limited working bandwidth. Summary of the invention

[0003] The purpose of the present invention is to solve the problems of "high loss and narrow bandwidth" of the current mode conversion beam splitter, and to provide an adiabatic mode conversion beam splitter suitable for the evolution of TE0 mode into TE1 mode.

[0004] In order to achieve the above-mentioned purpose, the present invention adopts the following technical solutions:

[0005] An adiabatic mode conversion beam splitter suitable for evolving a TE0 mode into a TE1 mode, wherein the input end of the adiabatic mode conversion beam splitter comprises a first silicon core; the lower substrate of the first silicon core is silicon dioxide; the upper portion of the first silicon core is an upper cladding layer; the transmission mode of the first silicon core is a fundamental mode TE0 mode; the output end of the adiabatic mode conversion beam splitter comprises a second silicon core and a third silicon core; the lower substrates of the second silicon core and the third silicon core are silicon dioxide; the upper portions of the second silicon core and the third silicon core are an upper cladding layer; the transmission modes of the second silicon core and the third silicon core are both TE1 modes, and the power of the TE1 mode in the second silicon core and the third silicon core is equal.

[0006] Further as a preferred technical solution of the present invention, the upper cladding layer is air or silicon dioxide or silicon nitride.

[0007] As a further preferred technical solution of the present invention, the thickness of the first silicon core, the second silicon core and the third silicon core are all h2=0.4 μm, the thickness is all W>0.6 μm, and the refractive index of silicon n Si =3.455; the gap G between the second silicon core and the third silicon core = 0.4 μm.

[0008] As a further preferred technical solution of the present invention, the thickness of the silicon dioxide is h1≥h2, and the refractive index of the silicon dioxide is n SiO2 =1.445.

[0009] Further, as a preferred technical solution of the present invention, the input end and the output end of the first silicon core are connected in a linear manner; the tip of the first silicon core is G / 2 away from the second silicon core and the third silicon core; the input ends of the second silicon core and the third silicon core both increase linearly from zero width to the output end; the distance between the centers of the first silicon core and the second silicon core is (W+G) / 2; the distance between the centers of the first silicon core and the third silicon core is (W+G) / 2; the distance between the centers of the second silicon core and the third silicon core is (W+G).

[0010] The adiabatic mode conversion beam splitter suitable for TE0 mode evolution TE1 mode described in the present invention adopts the above technical solution and has the following technical effects compared with the prior art:

[0011] (1) The function of the adiabatic mode conversion beam splitter proposed in the present invention is to evolve the fundamental mode TE0 mode at the input end into two TE1 modes at the output end, and the power is output uniformly at the two output ends, while realizing the conversion between different modes and the uniform output of energy.

[0012] (2) The present invention has the advantages of low loss, large working bandwidth, and small size, and realizes an adiabatic mode conversion beam splitter suitable for TE0 mode evolution TE1 mode. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 A schematic diagram of an input end of an adiabatic mode conversion beam splitter according to an embodiment of the present invention;

[0014] Figure 2 Schematic diagram of the output end of the adiabatic mode conversion beam splitter according to an embodiment of the present invention;

[0015] Figure 3 A top view of a silicon core of an adiabatic mode conversion beam splitter according to an embodiment of the present invention;

[0016] Figure 4 A diagram showing the mode conversion efficiency of an adiabatic mode conversion beam splitter according to an embodiment of the present invention;

[0017] The reference numerals are: 1-silicon dioxide; 2-upper cladding; 3-first silicon core; 4-second silicon core; 5-third silicon core. DETAILED DESCRIPTION

[0018] The present invention is further explained below in detail with reference to the accompanying drawings so that those skilled in the art can more deeply understand the present invention and be able to implement it. However, the following reference examples are only used to explain the present invention and are not intended to limit the present invention.

[0019] like Figure 1-3 As shown, an adiabatic mode conversion beam splitter suitable for TE0 mode evolution TE1 mode, the input end of the adiabatic mode conversion beam splitter includes a first silicon core 3; the lower substrate of the first silicon core 3 is silicon dioxide 1; the upper part of the first silicon core 3 is an upper cladding 2; the transmission mode of the first silicon core 3 is a fundamental mode TE0 mode; the output end of the adiabatic mode conversion beam splitter includes a second silicon core 4 and a third silicon core 5; the lower substrates of the second silicon core 4 and the third silicon core 5 are silicon dioxide 1; the upper part of the second silicon core 4 and the third silicon core 5 is an upper cladding 2; the transmission modes of the second silicon core 4 and the third silicon core 5 are both TE1 modes, and the power of the TE1 mode in the second silicon core 4 and the third silicon core 5 is equal.

[0020] The upper cladding 2 is air or silicon dioxide or silicon nitride. The thickness of the first silicon core 3, the second silicon core 4 and the third silicon core 5 are all h2 = 0.4 μm, the thickness is all W> 0.6 μm, and the refractive index of silicon n Si =3.455; the gap G between the second silicon core 4 and the third silicon core 5 is 0.4 μm. The thickness of the silicon dioxide 1 is h1 ≥ h2, and the refractive index of the silicon dioxide 1 is n SiO2 =1.445.

[0021] The function of the adiabatic mode conversion beam splitter proposed in the present invention is to evolve the fundamental mode TE0 mode at the input end into two TE1 modes at the output end, and the power is output evenly at the two output ends, while realizing the conversion between different modes and the uniform output of energy. I and output width length L O There is no restriction, and the selection can be made according to actual needs. The input and output ends of the first silicon core 3 are connected in a linear manner; the tip of the first silicon core 3 is G / 2 away from the second silicon core 4 and the third silicon core 5; the input ends of the second silicon core 4 and the third silicon core 5 both increase linearly from zero width to the output end; the distance between the centers of the first silicon core 3 and the second silicon core 4 is (W+G) / 2; the distance between the centers of the first silicon core 3 and the third silicon core 5 is (W+G) / 2; the distance between the centers of the second silicon core 4 and the third silicon core 5 is (W+G).

[0022] For the design of thermal insulation devices, we first need to determine the "absolute length" and then use simulation methods to calculate the "absolute length" L. a Scan and obtain the "relative length" L r The corresponding transmission / conversion efficiency. Therefore, through simulation, the "absolute length" L of the adiabatic mode conversion beam splitter is a You can choose whatever you want, regardless of whether you choose L a Equal to 1μm, 2μm, 5μm or other lengths, the final "relative length" L r The corresponding mode conversion efficiency graphs are the same, such as Figure 4 shown. Figure 4 The power conversion efficiency of an adiabatic mode conversion beam splitter suitable for TE0 mode evolution TE1 mode designed in this embodiment is given. Figure 4 It can be seen that the "relative length" L required by the design of the present invention r =285μm, a power transmission efficiency of 90% can be achieved. It is proved that the adiabatic mode conversion beam splitter proposed in the present invention has the advantage of small size, and can realize the design of compact adiabatic mode conversion beam splitter, which helps the photonic chip to develop towards a higher degree of integration.

[0023] The specific implementation scheme described above further describes in detail the purpose, technical scheme and beneficial effects of the present invention. It should be understood that the above is only a specific implementation scheme of the present invention and is not intended to limit the scope of the present invention. Any equivalent changes and modifications made by any technician in the field without departing from the concept and principle of the present invention should fall within the scope of protection of the present invention.

Claims

1. An adiabatic mode conversion beam splitter suitable for TE0 mode evolution TE1 mode, characterized in that: The input end of the adiabatic mode conversion beam splitter comprises a first silicon core (3); the lower substrate of the first silicon core (3) is silicon dioxide (1); the upper portion of the first silicon core (3) is an upper cladding layer (2); the transmission mode of the first silicon core (3) is a fundamental mode TE0 mode; the output end of the adiabatic mode conversion beam splitter comprises a second silicon core (4) and a third silicon core (5); the lower substrates of the second silicon core (4) and the third silicon core (5) are silicon dioxide (1); the upper portions of the second silicon core (4) and the third silicon core (5) are an upper cladding layer (2); the transmission modes of the second silicon core (4) and the third silicon core (5) are both TE1 modes, and the power of the TE1 mode in the second silicon core (4) and the third silicon core (5) is equal; The upper cladding layer (2) is air or silicon dioxide or silicon nitride; The thickness of the first silicon core (3), the second silicon core (4) and the third silicon core (5) are h 2 = 0.4 μ m, thickness is W >0.6 μ m, the refractive index of silicon n Si = 3.455; the gap between the second silicon core (4) and the third silicon core (5) G = 0.4 μ m; The thickness of the silicon dioxide (1) h 1 ≥ h 2. Refractive index of silicon dioxide (1) n SiO2 = 1.445; The input end and the output end of the first silicon core (3) are connected in a linear manner; the tip of the first silicon core (3) is 1 / 40 mm away from the second silicon core (4) and the third silicon core (5). G / 2; the input ends of the second silicon core (4) and the third silicon core (5) both increase linearly from zero width to the output end; the distance between the centers of the first silicon core (3) and the second silicon core (4) is ( W + G ) / 2; the distance between the centers of the first silicon core (3) and the third silicon core (5) is ( W + G ) / 2; the distance between the center of the second silicon core (4) and the center of the third silicon core (5) is ( W + G ); Relative length L r = 285 μ m.

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