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Diamond color centers have been widely studied in the field of quantum optics. The negatively charged silicon vacancy (SiV−) center exhibits a narrow emission linewidth at the wavelength of 738 nm, a high Debye–Waller factor, and unique spin properties, making it a promising emitter for quantum information technologies, biological imaging, and sensing. In particular, nanodiamond (ND)-based SiV− centers can be heterogeneously integrated with plasmonic and photonic nanostructures and serve as in vivo biomarkers and intracellular thermometers. Out of all methods to produce NDs with SiV− centers, ion implantation offers the unique potential to create controllable numbers of color centers in preselected individual NDs. However, the formation of single color centers in NDs with this technique has not been realized. We report the creation of single SiV− centers featuring stable high-purity single-photon emission through Si implantation into NDs with an average size of ∼20 nm. We observe room temperature emission, with zero-phonon line wavelengths in the range of 730–800 nm and linewidths below 10 nm. Our results offer new opportunities for the controlled production of group-IV diamond color centers with applications in quantum photonics, sensing, and biomedicine.

We study inverted core-shell nanocrystals (NCs), in which a core of a wide-gap semiconductor (ZnSe) is overcoated with a shell of a narrower gap material (CdSe). Depending on the core radius and the shell thickness, these NCs can exhibit either type-I or type-II behavior. We show that these heterostructures can be used to significantly increase the absorption cross sections and simultaneously decrease the efficiency of Auger recombination compared to monocomponent CdSe NCs emitting at the same wavelength. These properties enhance the lasing performance of inverted core-shell structures and allow, in particular, efficient amplified spontaneous emission in the range of blue colors. [ABSTRACT FROM AUTHOR]

We present low-temperature studies of the optical properties of single CdS nanorods in relation to their morphology. Keeping track of the same nanorods in the photoluminescence (PL) study and during scanning electron microscope imaging, we were able to distinguish intrinsic spectral features of the nanorods from those of nanocluster aggregates. We observed strong PL polarization in the direction perpendicular to the nanorod axis. The sharp peaks in the “blue” region of the PL spectra are redshifted relative to those of bulk CdS and of CdS microparticles in a glass matrix. Finally, we observe a very interesting “spectral diffusion” of the main emission peaks with the following characteristics: (a) Energy–energy correlation of the two main peaks, and (b) correlation and anticorrelation between energy and intensity for the two peaks. Possible mechanisms behind this phenomenon are discussed. © 2004 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Louis Tong,1– 4 Lei Zhou,3– 5 Siew Kwan Koh,5 Yan Gao,5 Hla Myint Htoon,1,3 AiHua Hou,1,3 Lu Deng,6 Qi-Ping Wei,7 Pat Lim8 1Ocular Surface Research Group, Singapore Eye Research Institute, Singapore; 2Corneal and External Eye Disease Service, Singapore National Eye Centre, Singapore; 3Eye-Academic Clinical Program, Duke-National University of Singapore (NUS) Medical School, Singapore; 4Department of Ophthalmology, Yong Loo Lin School of Medicine, NUS, Singapore; 5Ocular Proteomics Platform, Singapore Eye Research Institute, Singapore; 6Department of Statistics and Applied Probability, Faculty of Science, NUS, Singapore; 7Beijing University of Chinese Medicine, Beijing, People’s Republic of China; 8Singapore Chung Hwa Medical Institution, SingaporeCorrespondence: Louis TongSingapore National Eye Centre, 11, Third Hospital Avenue, 168751, SingaporeTel +65 9818 6221Fax +65 62252568Email Louis.tong.h.t@singhealth.com.sgLei ZhouSingapore Eye Research Institute, The Academia, 20 College Road, Level 6, 169856, SingaporeEmail zhou.lei@seri.com.sg

Xian Hui Lim,1 Monisha Esther Nongpiur,1– 3 Raymond P Najjar,2,3 Quan V Hoang,1– 4 Dan Milea,1– 3 Chee Wai Wong,1– 3 Rahat Husain,1,3 Hla Myint Htoon,2,3 Tin Aung,1– 3,5 Shamira Perera,1– 3 Tina Tzee Ling Wong1– 3,5 1Singapore National Eye Centre, Singapore; 2Singapore Eye Research Institute, Singapore; 3Duke-NUS Medical School, Singapore; 4Department of Ophthalmology, Edward S. Harkness Eye Institute, Columbia College of Physicians and Surgeons, New York, NY, USA; 5Department of Ophthalmology, Yong Loo Lin School of Medicine, National University of Singapore, SingaporeCorrespondence: Tina Tzee Ling WongSingapore National Eye Centre, 11 Third Hospital Avenue, 168751, SingaporeEmail tina.wong.t.l@singhealth.com.sgPurpose: To investigate features of the steady-state pattern electroretinogram (ssPERG) in subjects with glaucoma (G), high myopia (HM; spherical equivalent ≤-6D) and glaucoma with high myopia (GHM).Patients and Methods: Our study included 48 participants divided into 3 groups (G, HM, and GHM) who each underwent monocular ssPERG testing with Diopsys NOVA PERG protocols. The ConStim protocol detects distinct topographic patterns of dysfunction 16° and 24° around the central macula. MagD is the amplitude of the average signal and MagD/Mag ratio indicates the consistency of the response. ssPERG indices were compared between groups and correlated with functional (ie, visual field mean deviation (VFMD)) and structural (ie, average retinal nerve fibre layer (RNFL) thickness; Cirrus optical coherence tomography) features.Results: Participants had an average age of 59.4± 7.6 years. Mean Humphrey VFMD was − 14.22 ± 2.88dB, − 2.62 ± 1.18dB and − 12.80 ± 2.60dB for G, HM and GHM groups, respectively. Mean RNFL thickness was 63.0 ± 8.20μm, 69.5 ± 15.7μm and 60.6 ± 5.0μm for G, HM and GHM groups, respectively. For the 24° setting, no significant differences were noted for any of the parameters. For the 16° setting, MagD was lower in the GHM group compared to the HM group (0.29μV vs 0.52μV; p = 0.02). Significant differences were noted for the MagD/Mag ratio between HM and G groups (0.58 vs 0.40; p = 0.02) and between HM and GHM groups (0.58 vs 0.35; p = 0.002). There were positive correlations between both MagD 16° and MagD/Mag ratio 16° with VFMD (correlation coefficient [r]=0.37, p = 0.009; and r = 0.44, p = 0.002, respectively) and RNFL (r = 0.43, p = 0.002; and r = 0.48, p = 0.001, respectively).Conclusion: MagD/Mag ratio at 16° was significantly lower in glaucomatous eyes (with or without high myopia) compared to those with high myopia without glaucoma, suggesting that glaucoma has a distinct impact on MagD/Mag ratio at 16° irrespective of the presence of myopia.Keywords: pattern electroretinogram, visual field mean deviation, optical coherence tomography, retinal nerve fibre layer

Li Lim,1– 3,* Elizabeth Wen Ling Lim,4,* Mohamad Rosman,1– 3 Jane Chwee Wah Koh,1 Hla Myint Htoon1,3 1Singapore National Eye Centre, Singapore 168751, Singapore; 2Singapore Eye Research Institute, Singapore 169856, Singapore; 3Duke-NUS Medical School, Singapore 169857, Singapore; 4Yong Loo Lin School of Medicine, National University of Singapore, Singapore 119228, Singapore*These authors contributed equally to this workCorrespondence: Li LimSingapore National Eye Centre, 11 Third Hospital Ave, Singapore 168751, SingaporeTel +65 62277255Fax +65 62277290Email lim.li@singhealth.com.sgPurpose: To determine the long-term visual outcomes of simultaneous femtosecond laser-assisted laser in situ keratomileusis (femto-LASIK) and accelerated cross-linking (CXL) [LASIK Xtra] for the treatment of high myopia.Patients and Methods: All 163 consecutive eyes of 85 patients who underwent LASIK Xtra for the treatment of high myopia and/or myopic astigmatism (spherical equivalent ≥ − 6.00 D) in Singapore National Eye Centre from the years 2013 to 2017 were included in this retrospective case series. Post-operative follow-up was up to 3 years.Results: Of the 163 eyes, 67 were followed up for 1 year (mean 12.9 months), 69 for 2 years (mean 24.0 months) and 43 for 3 years (mean 36.4 months). Overall mean follow-up was 22.8 months (9– 46 months). The mean pre-operative spherical equivalent (SE) was − 8.60 ± 1.47 D [range: − 11.75 to − 4.75] (n = 163) and mean attempted correction SE was − 8.84 ± 1.41 D [range: − 11.88 to − 5.25]. Most eyes (> 95%) maintained an uncorrected distance visual acuity of 6/12 or better over 3 years. Visual outcomes were predictable with ≥ 95% of eyes achieving a SE correction within ± 1D of attempted correction over 3 years. There was a mild regression in SE refraction over 3 years with a mean of − 0.10 ± 0.45 D three years post-operatively (p = 0.03). The safety index was > 1.05 at 3 years follow-up. There were no significant post-operative complications though 24 eyes had mild haze and 2 eyes had grade 1 diffuse lamellar keratitis that resolved within 1 month.Conclusion: Our 3-year LASIK Xtra results show favorable safety, efficacy, predictability and stability outcomes in Asian patients with high myopia.Keywords: LASIK Xtra, refractive surgery, cross-linking