Laser & Optoelectronics Progress, Volume. 62, Issue 15, 1500002(2025)
Three-Dimensional Photonic Integrated Chips: Quantum Computation and Non-Classical Physics (Invited)
Fig. 1. Types of waveguides fabricated by femtosecond laser direct writing and shaping techniques for cross-sections. (a) Types of waveguides fabricated by femtosecond laser direct writing (from left to right: type I, type II, and depressed cladding waveguides)[25]; (b) waveguides with circular cross sections written by the combination of a cylindrical lens and a slit[21]; (c) waveguides with circular cross sections written by multi-foci-shaped femtosecond pulses[23]; (d) waveguides with circular cross sections fabricated by overlap-controlled multi-scan method, the rightmost insets show the design diagram of scanline overlapping schemes (up) and the refractive index distribution of the prepared fundamental-mode waveguides (down)[24]
Fig. 2. Photonic quantum logical gates fabricated by femtosecond laser direct writing. (a) CNOT gate for polarization-encoded qubits[31]; (b) heralded CNOT gate for polarization-encoded qubits[32]; (c) quantum chips composed of one H gate and one CNOT gate for generating path-encoded Bell states[34]; (d) 3D layout of the path-encoded three-qubit Toffoli gate[35]
Fig. 3. Photonic quantum walk simulators and specialized algorithm chips fabricated by femtosecond laser direct writing. (a) 2D continuous-time quantum walk with single photon[36]; (b) 2D continuous-time quantum walk with correlated photon pair[37]; (c) 2D continuous-time quantum walk with three identical photons[38]; (d) using polarization as an additional synthetic dimension to achieve quantum walk of correlated photon pairs[39]; (e) quantum fast hitting algorithm[40]; (f) generating Haar random unitary matrix using stochastic quantum walk[43]
Fig. 4. Topologically protected photonic quantum computation chips fabricated by femtosecond laser direct writing. (a) HOM interference achieved in 1D off-diagonal AAH array[46]; (b) excitation of boundary states (left) and bulk states (right) in a 1D off-diagonal AAH array[47]; (c) quantum-entangled states evolving through topological edge and bulk channels[48]; (d) single-photon corner states in higher-order topological insulators[52]; (e) higher-order topological biphoton corner states[53]; (f) Sierpinski carpet fractal anomalous Floquet topological insulator with its inner and outer edge modes[57]
Fig. 5. 3D photonic chips fabricated by femtosecond laser direct writing for nonreciprocal photonics research. (a) Photonic Floquet topological insulator and its one-way edge states without backscattering[13]; (b) photonic topological Anderson insulator, the left-side 1D waveguide array enables selective excitation of specific modes[67]; (c) chain-driven honeycomb lattice[68]; (d) Sierpinski triangle fractal photonic Floquet topological insulator[70]
Fig. 6. 3D photonic chips fabricated by femtosecond laser direct writing for non-Hermitian physics research. (a) Passive PT-symmetric system based on a lossy directional coupler[76]; (b) Floquet PT-symmetric system[78]; (c) topologically trivial non-Hermitian SSH array with two-state PT-symmetric dynamically encircling EP system as sublattice[86]; (d) anti-PT-symmetric dynamically encircling EP system[87]; (e) eigenstate generation and all-optical logic operation based on dynamically encircling EP[84]
Fig. 7. 3D photonic chips fabricated by femtosecond laser direct writing for non-Hermitian topological system research. (a) 2D diagonal non-Hermitian SSH array structure and the distribution of its corner states[88]; (b) non-Hermitian helical waveguide array structure and Weyl exceptional ring[89]; (c) PT-symmetric non-Hermitian SSH array[90]; (d) PT-symmetric topological insulators and their counter-propagating edge states[91]; (e) multilayer SSH lattice with a dissipative middle layer[92]; (f) 1D non-Hermitian skin effect and 2D skin-topological effect[14]
Fig. 8. 3D photonic chips fabricated by femtosecond laser direct writing for non-Abelian physics research. (a) Two-mode braiding (left) and non-Abelian braiding of three modes (right)[98]; (b) Lieb lattice with modulated coupling coefficients[102]; (c) 2D non-Abelian Thouless pump photonic waveguide system[103]; (d) degenerate non-Hermitian system with non-Abelian holonomy[104]
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Ruiqi Wang, Yuliang Tang, Yan Li. Three-Dimensional Photonic Integrated Chips: Quantum Computation and Non-Classical Physics (Invited)[J]. Laser & Optoelectronics Progress, 2025, 62(15): 1500002
Category: Reviews
Received: Apr. 14, 2025
Accepted: May. 28, 2025
Published Online: Aug. 6, 2025
The Author Email: Yan Li (li@pku.edu.cn)
CSTR:32186.14.LOP250995