Dependence Of Optical Gain Research Articles

Polarization Angle Dependence of Optical Gain in a Hybrid Structure of Alexa-Flour 488/M13 Bacteriophage

We measured optical modal gain of a dye–virus hybrid structure using a variable stripe length method, where Alexa-fluor-488 dye was coated on a virus assembly of M13 bacteriophage. Inspired by the structural periodicity of the wrinkle-like virus assembly, the edge emission of amplified spontaneous emission was measured for increasing excited optical stripe length, which was aligned to be either parallel or perpendicular to the wrinkle alignment. We found that the edge emission showed a strong optical anisotropy, and a spectral etalon also appeared in the gain spectrum. These results can be attributed to the corrugated structure, which causes a similar effect to a DFB laser, and we also estimated effective cavity lengths.

Polarization axis fluctuations in a single mode VCSEL laser at 780nm

We present a transmission method to determine the polarization axis fluctuations for VCSEL (Vertical Cavity Surface Emitting Laser). The research is focused mainly on commercial lasers operatingat 780 nm, designed forlaser spectroscopy. The angle fluctuation of the laser linear axis polarization iselaborated to be less than 150 mrad. Measurement errors of this method are studied and calculated. The measurement uncertainty is ?1,4 mrad andthis is equivalent to ? 5? of arc.Changes of the linear polarization axis depending on the laser current and temperaturearepresented. Full Text: PDF References T. Ohtoshi et al., "Dependence of optical gain on crystal orientation in surface?emitting lasers with strained quantum wells", Appl. Phys. Lett.63, 1886 (1994). CrossRef K. Tateno et al., "Growth of vertical-cavity surface-emitting laser structures on GaAs (311)B substrates by metalorganic chemical vapor deposition", Appl. Phys. Lett.70, 3395 (1997). CrossRef O. Tadanaga et al., "An 850-nm InAlGaAs strained quantum-well vertical-cavity surface-emitting laser grown on GaAs (311)B substrate with high-polarization stability", IEEE Photon. Tech. Lett.12, 942 (2000) CrossRef K. Choquette, R. Leibenguth, "Control of vertical-cavity laser polarization with anisotropic transverse cavity geometries", IEEE Photon. Tech. Lett. 6, 40 (1994) CrossRef B. Weigl et al., "High-performance oxide-confined GaAs VCSELs", IEEE J. Sel. Top.Quantum Electron. 3, 409 (1997) CrossRef P. Dowd et al., "Complete polarisation control of GaAs gain-guided top-surface emitting vertical cavity lasers", Electron. Lett. 33, 1315 (1997) CrossRef M. Grabherr et al., "Volume production of polarization controlled single-mode VCSELs", Proc. SPIE,6908, 690803 (2008) CrossRef R. Roy et al., "First-Passage-Time Distributions under the Influence of Quantum Fluctuations in a Laser", Phys. Rev. Lett.45, 1486 (1980) CrossRef J. Martin-Regalado et al., "Polarization switching in vertical-cavity surface emitting lasers observed at constant active region temperature", Appl. Phys. Lett. 70, 3350 (1997) CrossRef M. B. Willemsen et al., "Polarization Switching of a Vertical-Cavity Semiconductor Laser as a Kramers Hopping Problem", Phys. Rev. Lett. 82, 4815 (1999) CrossRef M. B. Willemsen et al., "Anatomy of a Polarization Switch of a Vertical-Cavity Semiconductor Laser", Phys. Rev. Lett. 84, 4337 (2000) CrossRef T. Mukaihara et al., "Excess intensity noise originated from polarization fluctuation in vertical-cavity surface-emitting lasers", IEEE Photon. Technol. Lett. 7, 1113 (1995) CrossRef

Polarization axis fluctuations in a single mode VCSEL laser at 780nm

We present a transmission method to determine the polarization axis fluctuations for VCSEL (Vertical Cavity Surface Emitting Laser). The research is focused mainly on commercial lasers operatingat 780 nm, designed forlaser spectroscopy. The angle fluctuation of the laser linear axis polarization iselaborated to be less than 150 mrad. Measurement errors of this method are studied and calculated. The measurement uncertainty is ?1,4 mrad andthis is equivalent to ? 5? of arc.Changes of the linear polarization axis depending on the laser current and temperaturearepresented. Full Text: PDF References T. Ohtoshi et al., "Dependence of optical gain on crystal orientation in surface?emitting lasers with strained quantum wells", Appl. Phys. Lett.63, 1886 (1994). CrossRef K. Tateno et al., "Growth of vertical-cavity surface-emitting laser structures on GaAs (311)B substrates by metalorganic chemical vapor deposition", Appl. Phys. Lett.70, 3395 (1997). CrossRef O. Tadanaga et al., "An 850-nm InAlGaAs strained quantum-well vertical-cavity surface-emitting laser grown on GaAs (311)B substrate with high-polarization stability", IEEE Photon. Tech. Lett.12, 942 (2000) CrossRef K. Choquette, R. Leibenguth, "Control of vertical-cavity laser polarization with anisotropic transverse cavity geometries", IEEE Photon. Tech. Lett. 6, 40 (1994) CrossRef B. Weigl et al., "High-performance oxide-confined GaAs VCSELs", IEEE J. Sel. Top.Quantum Electron. 3, 409 (1997) CrossRef P. Dowd et al., "Complete polarisation control of GaAs gain-guided top-surface emitting vertical cavity lasers", Electron. Lett. 33, 1315 (1997) CrossRef M. Grabherr et al., "Volume production of polarization controlled single-mode VCSELs", Proc. SPIE,6908, 690803 (2008) CrossRef R. Roy et al., "First-Passage-Time Distributions under the Influence of Quantum Fluctuations in a Laser", Phys. Rev. Lett.45, 1486 (1980) CrossRef J. Martín-Regalado et al., "Polarization switching in vertical-cavity surface emitting lasers observed at constant active region temperature", Appl. Phys. Lett. 70, 3350 (1997) CrossRef M. B. Willemsen et al., "Polarization Switching of a Vertical-Cavity Semiconductor Laser as a Kramers Hopping Problem", Phys. Rev. Lett. 82, 4815 (1999) CrossRef M. B. Willemsen et al., "Anatomy of a Polarization Switch of a Vertical-Cavity Semiconductor Laser", Phys. Rev. Lett. 84, 4337 (2000) CrossRef T. Mukaihara et al., "Excess intensity noise originated from polarization fluctuation in vertical-cavity surface-emitting lasers", IEEE Photon. Technol. Lett. 7, 1113 (1995) CrossRef

Optical gain of multi‐stacked InAs quantum dots grown on InP(311)B substrate by strain‐compensation technique

AbstractWe used a strain‐compensation technique to fabricate multi‐stacked InAs quantum dot (QD) structures on InP(311)B substrates. We stacked 60 layers of InAs QDs without degrading the crystal quality and achieved a structure with a total QD density of 4.9 × 1012 cm‐2. Then dependence of optical gain on the number of QD layers stacked was investigated, using variable stripe‐length (VSL) method. The optical gain increased with increase in the number of QD layers. We obtained an optical gain of 49.7 cm‐1 when 60 QD layers were stacked. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Dependence of optical gain and interband transitions on the CdTe well width and temperature for CdTe/ZnTe single quantum wells

Optical gains and interband transition energies for CdTe/ZnTe single quantum wells (SQWs) with different CdTe well widths were investigated. Photoluminescence (PL) spectra for CdTe/ZnTe SQWs at various temperatures were experimentally obtained, and the corresponding optical gains were calculated by using an interacting pair Green’s function and by using an energy space integrated function. The peak energies in the gain spectra that take the Coulomb interaction between the electron and the hole into account were in qualitatively reasonable agreement with those determined from the PL spectra.

Dependence of optical gain on direction of optically pumped cavity on (0001)-plane for InGaN/GaN multiple quantum well structure

In this work, we demonstrate the theoretical prediction about the dependence of the optical gain on the orientation of the laser cavity in (0001) plane for the strained InGaN/GaN multiple quantum well structure. The net modal gain of the InGaN/GaN multiple quantum well has been measured by variable excitation stripe length method for optically pumped cavity along each crystal orientation on (0001) plane. The measured optical gain for the cavity along the [ 1 ̄ 2 1 ̄ 0 ] direction is larger than any other oriented cavities. ‘Crystal orientation’ is confirmed to be a parameter related to the optical gain for GaN-based strained structure. The results reveal that the best cavity orientation of GaN-based edge-emitting laser is in [ 1 ̄ 2 1 ̄ 0 ] direction.

OPTICAL GAIN IN AN INHOMOGENEOUS DISTRIBUTION OF CdS QUANTUM DOTS EMBEDDED IN GLASS MATRIX

The optical gain spectra of inhomogeneously distributed semiconductor Quantum dots (QDs) embedded in a dielectric matrix has been examined theoretically using density matrix treatment. The expression for the threshold field is required to obtain optical gain. We have examined the role of excitons and biexcitons in gain mechanism and found that the gain arising due to excitonic nonlinearity enhances in presence of biexcitons. A comparison of the optical gain spectra of single quantum dot (SQD) and inhomogeneous distribution of quantum dots (IDQ) shows that the exciton peak in SQD gets red shifted in IDQ while biexciton peak in SQD exhibits a blue shift. A detailed numerical analysis establishes a strong dependence of optical gain on size distribution function and it is found that an increased size distribution width yields larger gain and increased gain bandwidth. The nonlinear gain is also found to increase in a matrix possessing larger dielectric constant.

Room-temperature continuous-wave operation of GaInN multiquantum well laser diodes with low indium content

Based on the indium content dependence of optical gain in a GaInN multiquantum well (MQW) structure, room-temperature continuous-wave operation of GaInN MQW laser diodes is demonstrated. Amplified spontaneous emission spectra for Ga/sub 1-x/In/sub y/N (x=0.07 0.11) MQWs suggest that lower indium content leads to smaller bandgap inhomogeneity and an improvement in the laser performance. Ga/sub 0.93/In/sub 0.07/N MQW laser diodes were operated with a threshold current density of 11 kAcm/sup 2/.

Gain parameterization formulas in FEL optical-klystron configurations

We discuss simple formulas useful to analyze the free-electron laser dynamics when an optical-klystron configuration is employed. The small-signal gain dependence on the length of the dispersive section is discussed, as well as the effects of the inhomogeneous broadening contributions. We introduce the concept of saturation intensity for the optical-klystron and study the dependence on the various parameters of the device. We investigate the high gain effects and the saturated behavior. Regarding this last point, we present a formula accounting for the optical gain dependence on the intracavity power.

Dependence of optical gain on crystal orientation in surface-emitting lasers with strained quantum wells

We analyze theoretically optical gains in vertical-cavity surface-emitting lasers (VCSELs) for various crystal orientations. The calculation based on the multiband effective-mass theory takes into account the effects of anisotropy and nonparabolicity on the valence subband dispersion. It is found that in VCSELs employing InGaAs/InP strained quantum wells (QWs) with non-(001) orientations except (111), the polarization in the QW plane can be controlled and high gains are obtained. In particular, the gains in VCSELs with (NN1)-oriented (N≥2) strained QWs are markedly higher than those in the equivalent (001) lasers.

High-speed InP-InGaAs heterojunction phototransistors employing a nonalloyed electrode metal as a reflector

High-speed InP-InGaAs heterojunction phototransistors (HPT's) with a base terminal (three-terminal HPT's) have been fabricated. These HPT's have nonalloyed electrodes functioning as reflectors and a configuration in which light is incident through the substrate. These features lead to an increase in quantum efficiency in spite of the thin base and collector light-absorbing layers. Optical gain dependence on collector current is weak because of the low recombination current at the emitter-base interface. Maximum optical-gain cutoff frequencies of 22 and 14 GHz are obtained for a 3/spl times/3-/spl mu/m/sup 2/ emitter HPT illuminated by 1.3- and 1.55-/spl mu/m light, respectively. This HPT has the capability of operating as a high-speed heterojunction bipolar transistor (HBT) as well. A current-gain cutoff frequency (f/sub T/) of 128 GHz is obtained for a 3/spl times/9-/spl mu/m/sup 2/ emitter HBT fabricated on the same wafer. Equivalent circuit analysis, in which all the components are determined by measuring both the electrical and optical characteristics of a three-terminal HPT, shows good agreement with experimental results. >

Threshold-current analysis of InGaAs-InGaAsP multiquantum well separate-confinement lasers

An analysis of the threshold behavior of long-wavelength ( lambda =1.55 mu m) multiquantum well separate-confinement lasers with InGaAs wells and quaternary ( lambda /sub g/=1.3 mu m) barriers is presented. Using the effective mass approximation and Fermi statistics for carriers, an approximately logarithmic dependence of optical gain on carrier density for quantum well lasers with one confined electron state is predicted theoretically. This prediction is verified by measured threshold currents of broad-area lasers of various cavity lengths and different numbers of quantum wells. Moreover, the characteristic parameters, such as transparency current density, gain constant, and absorption outside the active region, are determined. >

Theory of signal light amplification by stimulated Raman scattering in twisted single-mode optical fibers

Characteristics of signal light amplification by stimulated Raman scattering are studied theoretically for the twisted single-mode fibers. Coupling equations for orthogonal modes in the fiber are derived and solved analytically. The optical gain dependence on fiber twist rate, fiber length, and so on are numerically investigated. The Raman gain for the twisted fiber with a rate of 1 turn/m is found to be reduced by 10 dB comparing with the nontwisted fiber for the fiber length less than 2 km, while it is almost independent of twist rate for the fiber longer than 10 km.

Optical-gain measurements in a cw transverse-discharge transverse-gas-flow CO2 : N2 : He planar-waveguide laser

Optical-gain measurements are reported for a dc-excited planar-hollow-waveguide CO2 : N2 : He laser for which the gas flow and discharge current are collinear, and both are transverse to the optical axis of the waveguide. A spatially uniform thin-sheet glow discharge was demonstrated for gas pressures between 80 and 400 Torr, using transverse dc excitation. The dependence of optical gain upon gas composition, gas pressure, discharge current, and wall temperature was characterized for a 1-mm-high planar hollow waveguide. Optimum gain was 4 dB/m at a pressure of 100 Torr and a wall temperature of 233 °K.