IEEE Journal of Quantum Electronics

Theoretical modeling of the photocurrent and detectivity optimization of a resonant-tunneling quantum-dot infrared photodetector (RT-QDIP) based on nonequilibrium Green's function (NEGF) is presented. The interaction with light used in the model is based on the first-order dipole approximation and the Fermi golden rule, which is used to obtain the transition rates due to photon emission or absorpt... View full abstract»

This paper proposes a novel structure to realize a high-extinction-ratio multipassband filter (HERMPF) with flat-top, low dispersion, and large passband and stopband bandwidths. Spectrum and chromatic dispersion of the HERMPF are given under ideal conditions, which show that such a filter has excellent performance. Analysis on fabrication tolerances is given as well, focusing on factors such as th... View full abstract»

A self-consistent numerical model has been developed for simulating lasing properties of a typical thin-disk laser in detail. The temperature-dependent form of the Boltzmann occupation factors, absorption and stimulated-emission cross sections, and thermal conductivity of the Yb:YAG crystal as a quasi-four-level atomic system have been utilized for obtaining various effective operating variables. ... View full abstract»

We study experimentally and numerically the polarization sensitivity of quantum well infrared photodetectors coupled to a diffraction grid. The polarization extinction ratio of such system is determined by two factors: polarization sensitivity of the diffraction grid and the intrinsic polarization sensitivity of the photodetector itself. The combined effect of these factors result in non-monotonic... View full abstract»

Recently, InGaN/GaN quantum wells with different nanostructures such as nanoholes and nanorods have been proposed to enhance the light emitting efficiency. This paper calculates the influence of nanostructures to the strain and band profile of the quantum well. The effects of strain relaxation and surface states are analyzed, which could possibly influence the diode emission properties. Our calcul... View full abstract»

In this paper, we describe high-speed 1.1-μm-range oxide-confined vertical-cavity surface-emitting lasers (VCSELs) for large-scale optical interconnection applications. For achieving high data rates up to 25 Gbit/s under high temperature, we applied InGaAs/GaAsP strain-compensated multiple quantum wells (SC-MQWs) as the active layer. The developed device showed 25 Gbit/s error-free operati... View full abstract»

A rigorous coupled-wave model is proposed to simulate the diffraction characteristics of a concentric circular metal grating (CCMG) for an incident transverse-magnetic (TM) wave at terahertz frequency. An infinite series of spatial harmonic Floquet waves with Hankel distribution is used to describe the high-order diffraction waves. The corresponding coupled-wave equations are then solved numerical... View full abstract»

p+np+ CMOS Si LED structures were modeled in order to investigate the effect of various depletion layer profiles and defect engineering on the photonic transitions in the 1.4-2.8 eV, 450-750 nm regime. Modeling shows that by utilizing a short linear increasing E-field in the p+n reverse-biased junction with a gradient of approximately 5 × 105 V cm View full abstract»

A full-vectorial finite-difference scheme utilizing the hexagonal Yee's cell is used in this paper to analyze the modes of photonic-bandgap fibers with C6 v symmetry. Because it respects the fiber's native symmetry, this method is free from any numerical birefringence. We also incorporate in it techniques for reducing the memory requirement (up to 3 to 4 times) and computational ... View full abstract»

Two- and three-photon absorption and excitation properties of CdTe/CdS/ZnS quantum tripods in chloroform have been investigated by using ~160-fs laser pulses in the spectral range of ~(1150-1650) nm. The two- and three-photon excited up-conversion emission is located around 740-nm position; the emission intensity follows the square law and cubic law on the excitation intensity for the former and t... View full abstract»

All-optical wavelength conversion in ultralong semiconductor optical amplifier (UL-SOA) is presented. Opposite to other SOA based single path wavelength converters the UL-SOA's property as an extinction ratio (ER) regenerator can be used additionally to the wavelength conversion. When converting to lower wavelengths, cross-gain modulation as well as four-wave mixing (FWM) can be used as wavelength... View full abstract»

A scheme to realize a tunable and switchable multi-wavelength laser with variable wavelength spacing is proposed based on broadband cascaded quadratic nonlinear interactions in an aperiodically poled MgO-doped lithium niobate (MgO:APPLN) waveguide. Four output wavelengths can be generated simultaneously from the laser and can be switched by tuning the operation temperature of MgO:APPLN. Additional... View full abstract»

We report lasing wavelength bistability with respect to applied bias on the saturable absorbers in two-section mode-locked quantum dot lasers. We show data from three different devices exhibiting wavelength bistability. All lasers display wavelength bistability. Only one lasing wavelength is present at a time, with all other wavelengths totally quenched. The switchable ranges (the wavelength diffe... View full abstract»

The development of type-II InAs/GaSb superlattice (SL) detectors with nBn and pin designs for the long-wave infrared (LWIR) spectral region is discussed. The dependence of dark current density and responsitivity of the pin photodetectors on doping type and level is investigated, and it is shown that dark current density decreases while responsivity and detectivity increase by p-doping the absorbin... View full abstract»

An amplitude modulated surface plasma wave, produced via mode conversion of a laser, is shown to resonantly excite a surface plasma wave at the modulation frequency over a rippled metal free space interface. The pump surface plasma wave (SPW) exerts a ponderomotive force on metal electrons, imparting them an oscillatory velocity at the modulation frequency. This velocity beats with the surface mod... View full abstract»

Transfer matrix method has been widely used to investigate the quantum phenomena in semiconductor materials and optoelectronic devices with an arbitrary potential profile. Free wave or complex exponential form transfer matrix method is easy to implement and also proved to be an efficient and accurate approach. However, there are numerical singularities in these kinds of matrices when the electron ... View full abstract»

We present a technique for suppressing relative intensity noise in a fiber laser, which uses two Pound-Drever-Hall feedback control loops to lock two optical fiber ring resonators in series. The resonators act as cascaded passive optical filters to remove high frequency intensity noise. We describe and discuss the control scheme for holding the cavities on resonance, and present the experimental r... View full abstract»

The mechanism of optical emission from a high-refractive-index waveguide excited by a traveling electron beam was quantitatively investigated. The wavelength of optical emission was 1.5 ¿¿m at an electron acceleration voltage of approximately 40 kV. This optical emission is understood to be a type of Cherenkov radiation. However, the dynamics of each electron were analyzed on the basis of quantum ... View full abstract»

Visible light photon counters (VLPCs) offer many attractive features as photon detectors, such as high quantum efficiency and photon number resolution. We report measurements of the single-photon timing jitter in a VLPC, a critical performance factor in a time-correlated single-photon counting measurement, in a fiber-coupled closed-cycle cryocooler. The measured timing jitter is 240 ps full-width-... View full abstract»

We have developed a procedure for the complete characterization of femtosecond-laser written Er/Yb-codoped glass waveguides. The procedure is based on precise measurements of both pump and 1.5 ¿¿m -band output powers when the waveguide is diode-laser pumped at 980 nm. The dependence of these optical powers on the input pump power is fitted to the results derived from a detailed numerical model of ... View full abstract»

In this paper, an approximate method for the analysis of 2-D square lattice photonic crystal laser operation above the threshold is presented. Our approach is based on coupled wave equations, including gain saturation effect, and energy theorem. An expression for the small signal gain coefficient as a function of the output power, losses, coupling strength depending on the shape of the primitive c... View full abstract»

We present a universal and rigorous approach to study difference frequency generation in the terahertz domain, especially when reaching for the quantum efficiency limit. Through the definition of a suitable figure of merit, we have been able to keep the number of degrees of freedom to a minimum, in order to draw up suitably normalized charts, that enable to predict the optical-to-terahertz convers... View full abstract»