Determination of the nonlinear thermo-optic coefficient of silicon nitride and oxide using an effective index method

Johnson, Karl M.; Alshamrani, Naif; Almutairi, dhaifallah; Grieco, Andrew; Horvath, Cameron; Westwood‐Bachman, Jocelyn N.; McKinlay, Alexandria; Fainman, Yeshaiahu

doi:10.1364/oe.477102

Cited by 8 publications

(2 citation statements)

References 25 publications

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“…Our measured TO-coefficient for LPCVD-SiN is within 5% of the values reported in Refs. 9 and 24; the excellent agreement with LPCVD-SiN literature values (Table 1) indicates that our setup enables accurate control of the sample temperature. We find a larger discrepancy for the SiO2 TO-coefficient (e.g., dnSiO2/dT=0.95×10−5/°C 9 and dnSiO2/dT=0.57×10−5/°C 24 ), which we attribute to the different oxides used in our sample in which the bottom SiO2 is thermal and the top SiO2 is PECVD-deposited.…”

Section: Low-loss Sin Platformsupporting

confidence: 77%

“…Although Refs. 9 and 24 also report thermal and PECVD-SiO2, the PECVD deposition parameters likely result in substantially different material properties including TO-coefficients. Nonetheless, our measurements give an accurate baseline TO tuning coefficient for the LPCVD-SiN/SiO2-cladded waveguides, which we improve upon via polymer post-processing.…”

Section: Low-loss Sin Platformmentioning

confidence: 99%

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Enhanced thermo-optic effects in silicon nitride photonic integrated circuits via polymer claddings

Pruessner,

Tyndall,

Walsh

et al. 2023

J. Nanophoton.

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Silicon nitride (SiN) has been receiving increased attention for photonic integrated circuits (PICs) due to its ultra-low optical losses, phase stability, and broadband transparency. However, SiN waveguides have a low thermo-optic coefficient and exhibit weak electro-optic effects. For this reason, most foundry-processed SiN PICs remain passive or exhibit inefficient tuning. In this work, we investigate polymer claddings to enhance the thermo-optic phase shifting in foundry-processed low-loss, thin core SiN PICs. We first develop a thermal testing setup and measure the response of standard foundry SiN∕SiO 2 waveguides. By taking advantage of the differing TE and TM modal overlap with the SiN core and SiO 2 cladding, we extract the LPCVD-SiN thermo-optic coefficient as dn SiN ∕dT ¼ 2.57 × 10 −5 ∕°C at λ ¼ 1550 nm and dn SiN ∕dT ¼ 2.82 × 10 −5 ∕°C at λ ¼ 780 nm. We next consider SiN waveguides in which the top SiO 2 cladding is replaced with a spin-coated thermo-optic polymer. The thin waveguide core (t SiN ¼ 150 to 220 nm) enables a weakly confined mode with a large overlap with the top polymer cladding. Measurements at λ ¼ 780 nm wavelength show up to a 12-fold improvement in the thermo-optic phase shift of these polymer-cladded SiN waveguides compared with SiO 2 cladded devices while inducing negligible excess loss. Finally, we show broadband Mach-Zehnder interferometer measurements demonstrating thermo-optic tuning at visible wavelengths. The simple spin-coat post-processing of foundry SiN PICs in this work offers a potential path toward efficient optical phase shifting in low-loss SiN waveguides over a broad wavelength range

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Section: Low-loss Sin Platformsupporting

confidence: 77%

Section: Low-loss Sin Platformmentioning

confidence: 99%

Enhanced thermo-optic effects in silicon nitride photonic integrated circuits via polymer claddings

Pruessner,

Tyndall,

Walsh

et al. 2023

J. Nanophoton.

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Mode Conversion Trimming in Asymmetric Directional Couplers Enabled by Silicon Ion Implantation

Xu,

Taheriniya,

Varri

et al. 2024

Nano Lett.

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An on-chip asymmetric directional coupler (DC) can convert fundamental modes to higher-order modes and is one of the core components of mode-division multiplexing (MDM) technology. In this study, we propose that waveguides of the asymmetric DC can be trimmed by silicon ion implantation to tune the effective refractive index and facilitate mode conversion into higher-order modes. Through this method of tuning, transmission changes of up to 18 dB have been realized with one ion implantation step. In addition, adjusting the position of the ion implantation on the waveguide can provide a further degree of control over the transmission into the resulting mode. The results of this work present a promising new route for the development of highefficiency, low-loss mode converters for integrated photonic platforms, and aim to facilitate the application of MDM technology in emerging photonic neuromorphic computing.

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Amplified spontaneous emission from europium-based molecular complexes coupled to photonic crystal cavities

Emmanuele,

Wang,

Smith

et al. 2023

Applied Physics Letters

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Rare-earth ion-based materials bear many remarkable optical properties that render them highly appealing for lighting and quantum-related applications. However, their small oscillator strength and weak emission often pose limitations. Here, we synthesize and couple Eu(III)-based molecular complexes to nanobeam photonic crystals supporting air modes. A reasonable spatial overlap between the molecular complexes and cavity modes leads to an average spontaneous emission coupling efficiency of 0.19. Our pump power-dependent photoluminescence measurements evidence amplified spontaneous emission from the molecular complexes with an amplification threshold as low as 4.4 W/cm2, likely benefiting from the efficient coupling. These findings suggest that integrating rare-earth ion-based molecular complexes with photonic structures could be a viable approach for regulating their emission characteristics for particular applications.

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Determination of the nonlinear thermo-optic coefficient of silicon nitride and oxide using an effective index method

Cited by 8 publications

References 25 publications

Enhanced thermo-optic effects in silicon nitride photonic integrated circuits via polymer claddings

Enhanced thermo-optic effects in silicon nitride photonic integrated circuits via polymer claddings

Mode Conversion Trimming in Asymmetric Directional Couplers Enabled by Silicon Ion Implantation

Amplified spontaneous emission from europium-based molecular complexes coupled to photonic crystal cavities

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