Charlton J. Chen

Learn More
We propose and demonstrate the digital resonance tuning of high-Q / V m silicon photonic crystal nanocavities using a self-limiting atomic layer deposition technique. Control of resonances in discrete steps of 122± 18 pm/hafnium oxide atomic layer is achieved through this postfabrication process, nearly linear over a full 17 nm tuning range. The cavity Q is(More)
Self-starting of passively mode-locked lasers with fast saturable absorption is studied. Our basic assumption is that the lasers will self-start when cw operation is unstable and mode-locked operation is stable. We start with a standard model, closely related to the Ginzburg – Landau equation, that is valid when the change in the time variation of the laser(More)
We demonstrate digital tuning of the slow-light regime in silicon photonic-crystal waveguides by performing atomic layer deposition of hafnium oxide. The high group-index regime was deterministically controlled ͑redshift of 140Ϯ 10 pm per atomic layer͒ without affecting the group-velocity dispersion and third-order dispersion. Additionally, differential(More)
We present the first time-resolved cryogenic observations of Forster energy transfer in large, monodisperse lead sulfide quantum dots with ground-state transitions near 1.5 microm (0.8 eV), in environments from 160 K to room temperature. The observed temperature-dependent dipole-dipole transfer rate occurs in the range of (30-50 ns) (-1), measured with our(More)
We examine the cavity resonance tuning of high-Q silicon photonic crystal heterostructures by localized laser-assisted thermal oxidation using a 532 nm continuous wave laser focused to a 2.5 μm radius spot-size. The total shift is consistent with the parabolic rate law. A tuning range of up to 8.7 nm is achieved with ∼ 30 mW laser powers. Over this tuning(More)
In this letter, we propose the use of the newly developed corrugated quantum well infrared photodetectors ͑C-QWIPs͒ for polarization detection. The corrugated structure, which serves as an optical coupler as well as the polarization-sensitive component, is in this case directly created into the active region of the QWIP, therefore dispensed with the need of(More)
We present the first time-resolved cryogenic observations of Fö rster energy transfer in large, monodisperse lead sulfide quantum dots with ground-state transitions near 1.5 µm (0.8 eV), in environments from 160 K to room temperature. The observed temperature-dependent dipole-dipole transfer rate occurs in the range of (30-50 ns)-1 , measured with our(More)
  • 1