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This research explored the predictive effects of school safety on science achievement among Southeast Asian eighth graders in TIMSS 2015. In this research, principals’ responses of School Discipline Problems Scale, teachers’ responses of Safe and Orderly School Scale, as well as students’ responses on the Student Bullying Scale were reported. The data were obtained from 9,726 Malaysian students, 6,116 Singaporean students, and 6,482 Thai students who participated in TIMSS 2015. The secondary data analysis using International Database (IDB) Analyzer revealed that principals’ reports of school discipline problems were significantly linked to Grade 8 students’ science achievement in Malaysia, Singapore, and Thailand. Science teachers’ reports of safe and orderly school were significantly linked to Singaporean eighth graders’ science achievement. Student bullying was significantly linked to Grade 8 students’ science achievement in Malaysia and Singapore. Administrators, educators, and policymakers who wish to improve students’ science achievement in TIMSS would benefit from the findings of this research that revealed research evidences on significant impact of school safety involving cybersecurity. Awareness should be raised on the need to have more precautions taken on school safety especially on cybersecurity in the advent of digital era, learning from a country with success stories on school safety and cybersecurity such as Singapore.

Abstract Photonic topological systems may be exploited in topological quantum light generation, the development of topological lasers, the implementation of photonic routing systems and optical parametric amplification. Here, we leverage the strong light confinement of an ultra-silicon-rich nitride (USRN) topological waveguide adopting the 1D Su-Schrieffer-Heeger (SSH) system with a topological domain wall. We present the formation and propagation of temporal optical solitons in the topological waveguide, exhibiting two-fold temporal compression. We further observe a saturation in the output power at sufficiently high input powers. It is further observed that pulse propagation through a trivial, non-topological waveguide does not lead to similar temporal soliton dynamics. The demonstrated topological system allows for the temporal compression to be manipulated through power tuning via topological control of delocalization of the topological mode. This design degree of freedom allows temporal solitons to be generated in a topological waveguide while providing straightforward control of temporal pulses in practical applications.

Recent findings suggest that adding a visual depiction of a nose to virtual reality displays (virtual nose) can reduce motion sickness. If so, this would be a simple intervention that could improve the experience of a variety of VR applications. However, only one peer-reviewed study has reported a benefit from a virtual nose, and the effect was observed in a single low-powered experiment. To further test the effectiveness of a virtual nose for mitigating motion sickness in VR, we performed a preregistered experiment with higher power and better control. Subjects were presented with simulated movement in a virtual environment using a head-mounted display, and the resulting motion sickness was measured using the Fast Motion Sickness Scale (FMS) and the Simulator Sickness Questionnaire (SSQ). Conditions with and without a virtual nose were tested in separate sessions on different days, and the mean habituation effects were removed analytically. Awareness of the manipulation was assessed with a funnel debriefing procedure. The sample size (n = 32) was chosen to have over 90% power to detect the estimated effect size based on previous data (dz = 0.6). We found no significant difference between motion sickness in conditions with and without the virtual nose. The estimated effect size was close to zero, dz = - 0.02, with a 95% credible interval [- 0.37, 0.33]. Results from a Bayesian analysis imply that any benefit from a virtual nose is unlikely to be more than a 26% reduction in FMS scores, and any cost is unlikely to be more than a 23% increase. Our results do not support the hypothesis that a virtual nose is a general and effective way to relieve motion sickness in virtual reality.

Here the authors report the development of a topological nonlinear parametric amplification in a dimerized, Su-Schrieffer-Heeger waveguide. Kerr-induced chiral symmetry breaking is demonstrated, showcasing how nonlinearities may control transitions of topological modes to bulk states.

Abstract Chemical vapor deposition-based growth techniques allow flexible design of complementary metal-oxide semiconductor (CMOS) compatible materials. Here, we report the deuterated silicon-rich nitride films grown using plasma-enhanced chemical vapor deposition. The linear and nonlinear properties of the films are characterized, and we experimentally confirm that the silicon-rich nitride films grown with SiD4 eliminates Si–H and N–H related absorption. The performance of identical waveguides for films grown with SiH4 and SiD4 are compared demonstrating a 2 dB/cm improvement in line with that observed in literature. Waveguides fabricated on the SRN:D film are further shown to possess a nonlinear parameter of 95 W−1 m−1, with the film exhibiting a linear and nonlinear refractive index of 2.46 and 9.8 $$\times$$ × 10–18 m2W−1 respectively.

Abstract Supercontinuum generation is demonstrated in a 3-mm-long ultra-silicon-rich nitride (USRN) waveguide by launching 500 fs pulses centered at 1555 nm with a pulse energy of 17 pJ. The generated supercontinuum is experimentally characterized to possess a high spectral coherence, with an average |g 12| exceeding 0.90 across the wavelength range of the coherence measurement (1260 nm to 1700 nm). Numerical simulations further indicate a high coherence over the full spectrum. The experimentally measured supercontinuum agrees well with the theoretical simulations based on the generalized nonlinear Schrödinger equation. The generated broadband spectra using 500 fs pulses possessing high spectral coherence provide a promising route for CMOS-compatible light sources for self-referencing applications, metrology, and imaging.

Abstract Ultra-silicon-rich nitride with refractive indices ~ 3 possesses high nonlinear refractive index—100× higher than stoichiometric silicon nitride and presents absence of two-photon absorption, making it attractive to be used in nonlinear integrated optics at telecommunications wavelengths. Despite its excellent nonlinear properties, ultra-silicon-rich nitride photonics devices reported so far still have fairly low quality factors of $$\sim 6\times {10}^{4}$$ ∼ 6 × 10 4 , which could be mainly attributed by the material absorption bonds. Here, we report low temperature plasma-deposited dichlorosilane-based ultra-silicon-rich nitride (Si8N) with lower material absorption bonds, and ~ 2.5× higher quality factors compared to ultra-silicon-rich nitride conventionally prepared with silane-based chemistry. This material is found to be highly rich in silicon with refractive indices of ~ 3.12 at telecommunications wavelengths and atomic concentration ratio Si:N of ~ 8:1. The material morphology, surface roughness and binding energies are also investigated. Optically, the material absorption bonds are quantified and show an overall reduction. Ring resonators fabricated exhibit improved intrinsic quality factors $$\sim 1.5\times {10}^{5}$$ ∼ 1.5 × 10 5 , ~ 2.5× higher compared to conventional silane-based ultra-silicon-rich nitride films. This enhanced quality factor from plasma-deposited dichlorosilane-based ultra-silicon-rich nitride signifies better photonics device performance using these films. A pathway has been opened up for further improved device performance of ultra-silicon-rich nitride photonics devices at material level tailored by choice of different chemistries.

Abstract Optical pulses are fundamentally defined by their temporal and spectral properties. The ability to control pulse properties allows practitioners to efficiently leverage them for advanced metrology, high speed optical communications and attosecond science. Here, we report 11× temporal compression of 5.8 ps pulses to 0.55 ps using a low power of 13.3 W. The result is accompanied by a significant increase in the pulse peak power by 9.4×. These results represent the strongest temporal compression demonstrated to date on a complementary metal–oxide–semiconductor (CMOS) chip. In addition, we report the first demonstration of on-chip spectral compression, 3.0× spectral compression of 480 fs pulses, importantly while preserving the pulse energy. The strong compression achieved at low powers harnesses advanced on-chip device design, and the strong nonlinear properties of backend-CMOS compatible ultra-silicon-rich nitride, which possesses absence of two-photon absorption and 500× larger nonlinear parameter than in stoichiometric silicon nitride waveguides. The demonstrated work introduces an important new paradigm for spectro-temporal compression of optical pulses toward turn-key, on-chip integrated systems for all-optical pulse control.

Supercontinuum generation (SCG) through soliton fission provides high‐brightness, spectrally‐rich light needed for hyperspectral imaging, broadband spectroscopy, and fluorescence microscopy. The prospect of miniaturization has led to many demonstrations of this phenomenon in integrated platforms. However, due to the moderate dispersion and nonlinearity generally available in channel waveguides, femtosecond pulses have typically been required to date, as the use of picosecond pulses would require unpractically long devices to achieve soliton fission. Here, spectral bandwidth enhancement of the supercontinuum process through Bragg grating induced soliton‐effect compression and soliton fission is demonstrated. This approach uses picosecond pulses on a complementary metal oxide semiconductor (CMOS)‐compatible, millimeter‐scale platform, consisting of a monolithically integrated cladding‐modulated Bragg grating with a channel waveguide. The strong dispersion near the stopband of the grating enables compression and fission of picosecond higher‐order solitons, which enhances the spectral broadening in the channel waveguide. A 4.3 spectral bandwidth enhancement is reported, with respect to a reference waveguide of the same length. The output spectra are further studied both through simulations and experiments and determined to possess high spectral coherence. These results highlight a simple route to significantly augment the bandwidth of nonlinear processes such as SCG while maintaining low power and compact footprint.

Nonlinear integrated optics leveraging platforms with high nonlinear figure of merit offer energy efficient optical signal processing capabilities. Over the last five years, CMOS-compatible ultra-silico-rich nitride (USRN) has emerged as a promising platform on which to implement various nonlinear optics functions. Bandgap engineered to maximize the Kerr nonlinearity while maintaining two-photon absorption free behavior at telecommunications wavelengths, USRN possesses a nonlinear refractive index that is 100× larger than that in stoichiometric silicon nitride. In this article, we review the recent progress made in USRN-based nonlinear integrated optics devices. The impacts it has made spanning from high gain optical parametric amplification and observations of soliton effects in photonic waveguides and photonic crystal waveguide structures will be discussed. Finally, we assess the future outlook of CMOS-compatible USRN-based nonlinear optics.

Emerging compositionally engineered complementary metal-oxide-semiconductor (CMOS)-compatible platforms have been employed for high efficiencies in various on-chip applications, including optical parametric amplification and wavelength conversion. Combining the novel nonlinear optics platforms such as ultra-silicon-rich nitride (USRN: Si7N3) with periodic waveguide structures can lead to further enhancement of material nonlinearities via the slow light effect and enable ultra-compact devices. Four-wave mixing in a USRN-based, CMOS-compatible, photonic crystal waveguide (PhCWg) leading to on/off optical parametric signal gain reaching 3 dB, and a large instantaneous idler conversion efficiency of −1 dB is explored experimentally. Enhancement of Kerr nonlinearity in the presence of a sizable and near-constant group index allows the findings on an ultra-compact, 97 μm-long PhCWg, equivalent to a large on/off gain per unit length of 333 dB/cm.

Abstract Ring resonators on silicon rich nitride for potential use as rare-earth doped amplifiers pumped at 1310 nm with amplification at telecommunications-band are designed and characterized. The ring resonators are fabricated on 300 nm and 400 nm silicon rich nitride films and characterized at both 1310 nm and 1550 nm. We demonstrate ring resonators exhibiting similar quality factors exceeding 10,000 simultaneously at 1310 nm and 1550 nm. A Dysprosium-Erbium material system exhibiting photoluminescence at 1510 nm when pumped at 1310 nm is experimentally demonstrated. When used together with Dy-Er co-doped particles, these resonators with similar quality factors at 1310 nm and 1550 nm may be used for O-band pumped amplifiers for the telecommunications-band.

The formation of optical solitons arises from the simultaneous presence of dispersive and nonlinear properties within a propagation medium. Chip-scale devices that support optical solitons harness high field confinement and flexibility in dispersion engineering for significantly smaller footprints and lower operating powers compared to fiber-based equivalents. High-order solitons evolve periodically as they propagate and experience a temporal narrowing at the start of each soliton period. This phenomenon allows strong temporal compression of optical pulses to be achieved. In this paper, soliton-effect temporal compression of optical pulses is demonstrated on a CMOS-compatible ultra-silicon-rich nitride (USRN) waveguide. We achieve 8.7× compression of 2 ps optical pulses using a low pulse energy of ∼16 pJ, representing the largest demonstrated compression on an integrated photonic waveguide to date. The strong temporal compression is confirmed by numerical calculations of the nonlinear Schrödinger equation to be attributed to the USRN waveguide’s large nonlinearity and negligible two-photon absorption at 1550 nm.

Typical CMOS materials in the telecommunications band suffer from two-photon absorption or possess weak Kerr nonlinearities. Here, Ooiet al. demonstrate 42.5 dB optical parametric amplification in ultra-silicon-rich nitride waveguides, designed to have strong nonlinearities with negligible losses.