Search

The modal gain of the undoped and doped B 0.1 In 0.9 P / GaP and B 0.1 In 0.9 P / BP quantum dot (QD) structures are studied due to their importance, especially in Si-based devices. The first structure has three peaks, while the second structure has two peaks, where the first excited state (ES) peak is contained in the ground state (GS) one. The second ES peak is the highest for both structures. The B 0.1 In 0.9 P / GaP structure has a dip absorption results from the fourth state transition, peaked at 765 nm wavelength and covers the wavelength spectrum 600 - 2480 nm . The modal gain of B 0.1 In 0.9 P / BP QD structure doubles the other structure, peaked at 775 nm , and its spectrum covers 600 - 1360 nm . The difference in the bandwidth of their spectra comes from the bandgap difference of their barriers. In both structures, doping changes the spectrum from absorption to gain, indicating its high importance in increasing gain. For these two structures as QD semiconductor optical amplifiers (QDSOAs), the signal gain is increased by two orders compared to Sb-based QDSOAs and by one order compared to InGaAs / GaAs QDSOAs. [ABSTRACT FROM AUTHOR]

This work studies the modal gain from InxGa1−xAsySb1−y/GaAsSb$I{n_x}G{a_{1 - x}}A{s_y}S{b_{1 - y}}/GaAsSb$ quaternary quantum dots (QD) structures at different mole fractions of the structure. The quaternary structures are more flexible in attaining lattice‐matching systems. First, the In‐ and As‐mole fractions are varied. Four In‐mole fractions are studied (x=0.01,0.03,0.05,$(x\; = \;0.01,\;0.03,\;0.05,\;$ and 0.07), and their emitted wavelengths cover the range 571.4−5000nm$571.4 - 5000\ {\rm nm}$. Both In‐ and the As‐mole fraction increment results in a red‐shifted wavelength. Doping is also investigated where the structures are exhibited five times increment of modal gain, and the wavelength is blue‐shifted under doping. A multi‐peak behaviour is exhibited by these structures, which is essential in applications for choosing the required wavelength. These results promise that these structures can work in UV, visible, and infrared (IR) wavelength ranges. [ABSTRACT FROM AUTHOR]

Abstract We investigate the modal properties (effective index and modal gain) of an active, Erbium-doped single-mode slab waveguide made of silica tin-dioxide glass-ceramics on Silica. Completed with a photo-inscribed Bragg grating, such a structure is a good candidate for realizing an optically pumped laser emitter. For total Erbium concentration of 9.84 × 10−4 mol/cm3 and a cross-section (for stimulated transitions) of σ ≈ 2 × 10−25 m2 in a discussed structure, the maximum achievable material gain in DFB with Quarter-Wave phase Shift (QWS-DFB) is σ N tot ≈ 23 m−1. Taking into account the confinement factor, the maximum achievable modal gain, in complex amplitude, over the length of 10 mm is at about (α max L) ≈ 0.09. Highlights • Modal properties of Er3+-doped SiO 2 -SnO 2 glass-ceramics waveguide were investigated. • The threshold properties of a DFB of discussed system were evaluated. • The potential of Er3+-doped SiO 2 -SnO 2 waveguide as a laser source was investigated. [ABSTRACT FROM AUTHOR]

The self-heating effect in 1.3-μm InAs/GaAs quantum dot (QD) lasers with different doping levels has been investigated by comparing the characteristics of the threshold current density (Jth) and modal gain measured in continuous wave and pulsed modes with the heat sink temperature ranging from 20°C to 120°C. The results show that the p-doping can significantly reduce the self-heating effect in QD lasers.

We report the theoretical investigation of an electrically injected plasmonic nanolaser in visible regime. The green nanolaser is based on a hybrid waveguide which employs semiconductor nanowire gain medium to compensate the loss in metallic cavity. Two-dimensional sub-wavelength confinements (mode area about λ/100) and net modal gain are simultaneously achieved for quasi-one-dimensional surface plasmon mode supported in such waveguide. The device structure is further optimized for room temperature operation with achievable injected current density about several kilo ampere/square centimetres (kA/cm). The approach is also beneficial to developing other nanophotonic devices on sub-wavelength scale. [ABSTRACT FROM AUTHOR]

In order to enhance the optical confinement and to reduce the vertical electron leakage current of InGaN-based multiple quantum well (MQW) laser diodes, a 2 nm GaN/5 nm In0.05Ga0.95N composite layer is designed as the last barrier layer between the MQW and AlGaN blocking layer in the p-region. The device simulation shows that the laser diode then has a lower threshold current and a higher output light power under same injection current than the conventional laser diodes without such a composite barrier layer. It is found that the thickness of InGaN has little influence on the P- I characteristic, while the In composition significantly changes the threshold current and output light power properties of laser diodes, which is attributed to the enhanced optical confinement and reduced vertical electron leakage current escaping from active region to p-doped region. The influences of the two parameters to modal gain are analyzed, too. [ABSTRACT FROM AUTHOR]

The effect of channel-width chirping on near- and far-field intensity patterns of the six supermodes was investigated. The supermode discrimination was evaluated in various channel-chirped index guided laser arrays. The results show that the linearly channel-chirped laser array has very good supermode discrimination which is better than that of a uniform laser array, the V channel-chirped laser array has the smallest radiation angle of the fundamental supermode among the calculated arrays, and the asymmetrically V channel-chirped array has a very small radiation angle of the fundamental supermode, which is smaller than that of the uniform array and also allows for very good fundamental supermode discrimination against the higher-order supermodes, which is better than that of the V channel-chirped laser array. [ABSTRACT FROM AUTHOR]

High performance 1.3-μm GaAs-based InAs/InGaAs quantum dot (QD) lasers have been fabricated. The QD lasers have demonstrated low threshold current, high output power as well as high temperature operation. Temperature-dependent (20–100 °C) and excitation power-dependent (12–700 mW) photoluminescence (PL) measurements have been carried out on the QD laser structures. Both ground state (GS) and excited state (ES) luminescence has been observed in the PL spectra as well as in the lasing spectra. Rate equations were used to interpret the PL behavior of the QD structures. High radiative recombination efficiency in the QD structure has been verified even at 100 °C. The excitonic modal gain has been calculated and compared with the experimentally obtained modal gain value by the Hakki–Paoli method from the QD laser with good agreement. [ABSTRACT FROM PUBLISHER]

Numerical modeling of cylindrical semiconductor nano-lasers has been undertaken accommodating local gain variations in the active region of the device. Analysis is performed using both the cylindrical transfer matrix method and the finite element method. Calculations have thereby been performed of the modal gain and the lasing condition for the device. The model has been applied to annular active core structures and a comparison has been made of the requirements for achieving lasing via the excitation of TE01 and TM01 modes. For representative structures, it is shown that TE and TM mode lasing can be supported in devices having cavity lengths in the order of 1 and 60 \mum, respectively. [ABSTRACT FROM AUTHOR]