TY  - CONF
AU  - Vildoso, Paloma
AU  - Vicencio, Rodrigo A.
AU  - Petrović Jovana
PY  - 2023
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/12919
AB  - Conventional designs of multiport splitters rely on concatenation of directional couplers or multimode interference [1, 2]. However, the splitters show a considerable insertion loss and fast bandwidth drop with the number of ports. Inverse nanodesigns enable broadbandwidth semiconductor splitters, however, at high fabrication and design costs [3, 4]. In this work we present efficient and low-cost inverse design and experimental realization of multiport splitters with near-zero insertion loss, broad bandwidth and small footprint. Design is based on single-mode linearly coupled waveguide arrays which support periodic light propagation [5]. It allows for realisation of arbitrary splitting ratios by simple adjustment of waveguide separations. To demonstrate the technique, we designed equal 1×N power splitters and fabricated them in a borosilicate wafer by femtosecond laser writing method. The splitters show zero insertion loss within the experimental error, bandwidth of 20−60 nm and low imbalance < 0.5 dB. Their footprint scales exponentially with the waveguide separation, which can be reduced to the limit of mode confinement. Remarkably, the splitting ratio can be wavelength and array-length tuned. The proposed splitters offer new possibilities for path-entanglement generation, multipath interferometery on chip [6] and spatial mode multiplexing [7].
PB  - Belgrade : Institute of Physics
C3  - 16th Photonics Workshop (Conference) : book of abstracts; March 12-15, 2023; Kopaonik, 2023
T1  - Ultra-low-loss broadband multiport optical splitters
SP  - 19
EP  - 19
UR  - https://hdl.handle.net/21.15107/rcub_vinar_12919
ER  - 

@conference{
author = "Vildoso, Paloma and Vicencio, Rodrigo A. and Petrović Jovana",
year = "2023",
abstract = "Conventional designs of multiport splitters rely on concatenation of directional couplers or multimode interference [1, 2]. However, the splitters show a considerable insertion loss and fast bandwidth drop with the number of ports. Inverse nanodesigns enable broadbandwidth semiconductor splitters, however, at high fabrication and design costs [3, 4]. In this work we present efficient and low-cost inverse design and experimental realization of multiport splitters with near-zero insertion loss, broad bandwidth and small footprint. Design is based on single-mode linearly coupled waveguide arrays which support periodic light propagation [5]. It allows for realisation of arbitrary splitting ratios by simple adjustment of waveguide separations. To demonstrate the technique, we designed equal 1×N power splitters and fabricated them in a borosilicate wafer by femtosecond laser writing method. The splitters show zero insertion loss within the experimental error, bandwidth of 20−60 nm and low imbalance < 0.5 dB. Their footprint scales exponentially with the waveguide separation, which can be reduced to the limit of mode confinement. Remarkably, the splitting ratio can be wavelength and array-length tuned. The proposed splitters offer new possibilities for path-entanglement generation, multipath interferometery on chip [6] and spatial mode multiplexing [7].",
publisher = "Belgrade : Institute of Physics",
journal = "16th Photonics Workshop (Conference) : book of abstracts; March 12-15, 2023; Kopaonik, 2023",
title = "Ultra-low-loss broadband multiport optical splitters",
pages = "19-19",
url = "https://hdl.handle.net/21.15107/rcub_vinar_12919"
}

Vildoso, P., Vicencio, R. A.,& Petrović Jovana. (2023). Ultra-low-loss broadband multiport optical splitters. in 16th Photonics Workshop (Conference) : book of abstracts; March 12-15, 2023; Kopaonik, 2023
Belgrade : Institute of Physics., 19-19.
https://hdl.handle.net/21.15107/rcub_vinar_12919

Vildoso P, Vicencio RA, Petrović Jovana. Ultra-low-loss broadband multiport optical splitters. in 16th Photonics Workshop (Conference) : book of abstracts; March 12-15, 2023; Kopaonik, 2023. 2023;:19-19.
https://hdl.handle.net/21.15107/rcub_vinar_12919 .

Vildoso, Paloma, Vicencio, Rodrigo A., Petrović Jovana, "Ultra-low-loss broadband multiport optical splitters" in 16th Photonics Workshop (Conference) : book of abstracts; March 12-15, 2023; Kopaonik, 2023 (2023):19-19,
https://hdl.handle.net/21.15107/rcub_vinar_12919 .

TY  - CONF
AU  - Vildoso, Paloma
AU  - Vicencio, Rodrigo A.
AU  - Petrović, Jovana
PY  - 2023
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/11990
AB  - Efficiently achieving platform nonspecific designs with multiple functional requirements, such as arbitrary splitting ratio, low insertion losses, broad bandwidth, and small footprint, poses a significant challenge in the inverse design of optical Splitters. Traditional designs often fall short in meeting all the necessary criteria, while more successful nanophotonic inverse designs often demand substantial time and energy resources per device. Here, we present an efficient inverse design algorithm which provides universal designs of Splitters compliant with all the above constraints and offers significantly greater throughput compared to nanophotonic inverse design. To demonstrate the effectiveness of our method, we designed Splitters with various splitting ratios and fabricated 1×N power Splitters using direct laser writing in a borosilicate platform, which shows zero loss within marginal error, competitive imbalance of < 0.5 dB and a broad bandwidth range of 20 − 60 nm around 640 nm. Notably, our designs can be easily tuned to achieve different splitting ratios. Furthermore, we discussed the scalability of the Splitter footprint.
PB  - SPIE
C3  - SPIE - The International Society for Optical Engineering : Book proceedings
T1  - Low-loss broadband multiport optical splitters
VL  - 12673
DO  - 10.1117/12.2677821
ER  - 

@conference{
author = "Vildoso, Paloma and Vicencio, Rodrigo A. and Petrović, Jovana",
year = "2023",
abstract = "Efficiently achieving platform nonspecific designs with multiple functional requirements, such as arbitrary splitting ratio, low insertion losses, broad bandwidth, and small footprint, poses a significant challenge in the inverse design of optical Splitters. Traditional designs often fall short in meeting all the necessary criteria, while more successful nanophotonic inverse designs often demand substantial time and energy resources per device. Here, we present an efficient inverse design algorithm which provides universal designs of Splitters compliant with all the above constraints and offers significantly greater throughput compared to nanophotonic inverse design. To demonstrate the effectiveness of our method, we designed Splitters with various splitting ratios and fabricated 1×N power Splitters using direct laser writing in a borosilicate platform, which shows zero loss within marginal error, competitive imbalance of < 0.5 dB and a broad bandwidth range of 20 − 60 nm around 640 nm. Notably, our designs can be easily tuned to achieve different splitting ratios. Furthermore, we discussed the scalability of the Splitter footprint.",
publisher = "SPIE",
journal = "SPIE - The International Society for Optical Engineering : Book proceedings",
title = "Low-loss broadband multiport optical splitters",
volume = "12673",
doi = "10.1117/12.2677821"
}

Vildoso, P., Vicencio, R. A.,& Petrović, J.. (2023). Low-loss broadband multiport optical splitters. in SPIE - The International Society for Optical Engineering : Book proceedings
SPIE., 12673.
https://doi.org/10.1117/12.2677821

Vildoso P, Vicencio RA, Petrović J. Low-loss broadband multiport optical splitters. in SPIE - The International Society for Optical Engineering : Book proceedings. 2023;12673.
doi:10.1117/12.2677821 .

Vildoso, Paloma, Vicencio, Rodrigo A., Petrović, Jovana, "Low-loss broadband multiport optical splitters" in SPIE - The International Society for Optical Engineering : Book proceedings, 12673 (2023),
https://doi.org/10.1117/12.2677821 . .

TY  - JOUR
AU  - Vildoso, Paloma
AU  - Vicencio, Rodrigo A.
AU  - Petrović Jovana
PY  - 2023
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/10857
AB  - A major challenge in inverse design of optical splitters is to efficiently reach platform nonspecific designs constrained to multiple functional requirements: arbitrary splitting ratio, low insertion loss, broad bandwidth and small footprint. While the traditional designs fail to fulfill all these requirements, the more successful nanophotonic inverse designs require substantial time and energy resources per device. Here, we present an efficient inverse design algorithm that provides universal designs of splitters compliant with all above constraints. To demonstrate the capabilities of our method, we design splitters with various splitting ratios and fabricate 1 × N power splitters in a borosilicate platform by direct laser writing. The splitters show zero loss within the experimental error, competitive imbalance of <0.5 dB and broad bandwidth in the range 20 − 60 nm around 640 nm. Remarkably, the splitters can be tuned to achieve different splitting ratios. We further demonstrate scaling of the splitter footprint and apply the universal design to silicon nitride and silicon-on-insulator platforms to achieve 1 × 5 splitters with the footprints as small as 3.3 µm × 8 µm and 2.5 µm × 10.3 µm, respectively. Owing to the universality and speed of the design algorithm (several minutes on a standard PC) our approach renders 100 greater throughput than nanophotonic inverse design.
T2  - Optics Express
T1  - Ultra-low-loss broadband multiport optical splitters
VL  - 31
IS  - 8
SP  - 12703
EP  - 12716
DO  - 10.1364/OE.486855
ER  - 

@article{
author = "Vildoso, Paloma and Vicencio, Rodrigo A. and Petrović Jovana",
year = "2023",
abstract = "A major challenge in inverse design of optical splitters is to efficiently reach platform nonspecific designs constrained to multiple functional requirements: arbitrary splitting ratio, low insertion loss, broad bandwidth and small footprint. While the traditional designs fail to fulfill all these requirements, the more successful nanophotonic inverse designs require substantial time and energy resources per device. Here, we present an efficient inverse design algorithm that provides universal designs of splitters compliant with all above constraints. To demonstrate the capabilities of our method, we design splitters with various splitting ratios and fabricate 1 × N power splitters in a borosilicate platform by direct laser writing. The splitters show zero loss within the experimental error, competitive imbalance of <0.5 dB and broad bandwidth in the range 20 − 60 nm around 640 nm. Remarkably, the splitters can be tuned to achieve different splitting ratios. We further demonstrate scaling of the splitter footprint and apply the universal design to silicon nitride and silicon-on-insulator platforms to achieve 1 × 5 splitters with the footprints as small as 3.3 µm × 8 µm and 2.5 µm × 10.3 µm, respectively. Owing to the universality and speed of the design algorithm (several minutes on a standard PC) our approach renders 100 greater throughput than nanophotonic inverse design.",
journal = "Optics Express",
title = "Ultra-low-loss broadband multiport optical splitters",
volume = "31",
number = "8",
pages = "12703-12716",
doi = "10.1364/OE.486855"
}

Vildoso, P., Vicencio, R. A.,& Petrović Jovana. (2023). Ultra-low-loss broadband multiport optical splitters. in Optics Express, 31(8), 12703-12716.
https://doi.org/10.1364/OE.486855

Vildoso P, Vicencio RA, Petrović Jovana. Ultra-low-loss broadband multiport optical splitters. in Optics Express. 2023;31(8):12703-12716.
doi:10.1364/OE.486855 .

Vildoso, Paloma, Vicencio, Rodrigo A., Petrović Jovana, "Ultra-low-loss broadband multiport optical splitters" in Optics Express, 31, no. 8 (2023):12703-12716,
https://doi.org/10.1364/OE.486855 . .

TY  - JOUR
AU  - Stojanović, Mirjana G.
AU  - Stojanović Krasić, Marija
AU  - Maluckov, Aleksandra
AU  - Johansson, Magnus M.
AU  - Salinas, I. A.
AU  - Vicencio, Rodrigo A.
AU  - Stepić, Milutin
PY  - 2020
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/9664
AB  - We consider a two-dimensional octagonal-diamond network with a fine-tuned diagonal coupling inside the diamond-shaped unit cell. Its linear spectrum exhibits coexistence of two dispersive bands (DBs) and two flat bands (FBs), touching one of the DBs embedded between them. Analogous to the kagome lattice, one of the FBs will constitute the ground state of the system for a proper sign choice of the Hamiltonian. The system is characterized by two different flat-band fundamental octagonal compactons, originating from the destructive interference of fully geometric nature. In the presence of a nonlinear amplitude (on-site) perturbation, the single-octagon linear modes continue into one-parameter families of nonlinear compact modes with the same amplitude and phase structure. However, numerical stability analysis indicates that all strictly compact nonlinear modes are unstable, either purely exponentially or with oscillatory instabilities, for weak and intermediate nonlinearities and sufficiently large system sizes. Stabilization may appear in certain ranges for finite systems and, for the compacton originating from the band at the spectral edge, also in a regime of very large focusing nonlinearities. In contrast to the kagome lattice, the latter compacton family will become unstable already for arbitrarily weak defocusing nonlinearity for large enough systems. We show analytically the existence of a critical system size consisting of 12 octagon rings, such that the ground state for weak defocusing nonlinearity is a stable single compacton for smaller systems, and a continuation of a nontrivial, noncompact linear combination of single compacton modes for larger systems. Investigating generally the different nonlinear localized (noncompact) mode families in the semi-infinite gap bounded by this FB, we find that, for increasing (defocusing) nonlinearity the stable ground state will continuously develop into an exponentially localized mode with two main peaks in antiphase. At a critical nonlinearity strength a symmetry-breaking pitchfork bifurcation appears, so that the stable ground state is single peaked for larger defocusing nonlinearities. We also investigate numerically the mobility of localized modes in this regime and find that the considered modes are generally immobile both with respect to axial and diagonal phase-gradient perturbations.
T2  - Physical Review A
T1  - Localized modes in linear and nonlinear octagonal-diamond lattices with two flat bands
VL  - 102
IS  - 2
SP  - 023532
DO  - 10.1103/PhysRevA.102.023532
ER  - 

@article{
author = "Stojanović, Mirjana G. and Stojanović Krasić, Marija and Maluckov, Aleksandra and Johansson, Magnus M. and Salinas, I. A. and Vicencio, Rodrigo A. and Stepić, Milutin",
year = "2020",
abstract = "We consider a two-dimensional octagonal-diamond network with a fine-tuned diagonal coupling inside the diamond-shaped unit cell. Its linear spectrum exhibits coexistence of two dispersive bands (DBs) and two flat bands (FBs), touching one of the DBs embedded between them. Analogous to the kagome lattice, one of the FBs will constitute the ground state of the system for a proper sign choice of the Hamiltonian. The system is characterized by two different flat-band fundamental octagonal compactons, originating from the destructive interference of fully geometric nature. In the presence of a nonlinear amplitude (on-site) perturbation, the single-octagon linear modes continue into one-parameter families of nonlinear compact modes with the same amplitude and phase structure. However, numerical stability analysis indicates that all strictly compact nonlinear modes are unstable, either purely exponentially or with oscillatory instabilities, for weak and intermediate nonlinearities and sufficiently large system sizes. Stabilization may appear in certain ranges for finite systems and, for the compacton originating from the band at the spectral edge, also in a regime of very large focusing nonlinearities. In contrast to the kagome lattice, the latter compacton family will become unstable already for arbitrarily weak defocusing nonlinearity for large enough systems. We show analytically the existence of a critical system size consisting of 12 octagon rings, such that the ground state for weak defocusing nonlinearity is a stable single compacton for smaller systems, and a continuation of a nontrivial, noncompact linear combination of single compacton modes for larger systems. Investigating generally the different nonlinear localized (noncompact) mode families in the semi-infinite gap bounded by this FB, we find that, for increasing (defocusing) nonlinearity the stable ground state will continuously develop into an exponentially localized mode with two main peaks in antiphase. At a critical nonlinearity strength a symmetry-breaking pitchfork bifurcation appears, so that the stable ground state is single peaked for larger defocusing nonlinearities. We also investigate numerically the mobility of localized modes in this regime and find that the considered modes are generally immobile both with respect to axial and diagonal phase-gradient perturbations.",
journal = "Physical Review A",
title = "Localized modes in linear and nonlinear octagonal-diamond lattices with two flat bands",
volume = "102",
number = "2",
pages = "023532",
doi = "10.1103/PhysRevA.102.023532"
}

Stojanović, M. G., Stojanović Krasić, M., Maluckov, A., Johansson, M. M., Salinas, I. A., Vicencio, R. A.,& Stepić, M.. (2020). Localized modes in linear and nonlinear octagonal-diamond lattices with two flat bands. in Physical Review A, 102(2), 023532.
https://doi.org/10.1103/PhysRevA.102.023532

Stojanović MG, Stojanović Krasić M, Maluckov A, Johansson MM, Salinas IA, Vicencio RA, Stepić M. Localized modes in linear and nonlinear octagonal-diamond lattices with two flat bands. in Physical Review A. 2020;102(2):023532.
doi:10.1103/PhysRevA.102.023532 .

Stojanović, Mirjana G., Stojanović Krasić, Marija, Maluckov, Aleksandra, Johansson, Magnus M., Salinas, I. A., Vicencio, Rodrigo A., Stepić, Milutin, "Localized modes in linear and nonlinear octagonal-diamond lattices with two flat bands" in Physical Review A, 102, no. 2 (2020):023532,
https://doi.org/10.1103/PhysRevA.102.023532 . .