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Yong-hee Lee - One of the best experts on this subject based on the ideXlab platform.
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Spontaneous emission factor of oxidized vertical-Cavity surface-emitting lasers from the measured below-threshold Cavity Loss
Applied Physics Letters, 1997Co-Authors: Jongwoo Shin, He Shin, Yong-hee LeeAbstract:A method to estimate the spontaneous emission factor β is proposed and applied to the 780 nm oxidized vertical-Cavity surface-emitting lasers. The proportionality of the measured Cavity Loss multiplied by optical power to injected current is used. Our results agree better with theoretical calculations than those of conventional light-current curve fitting. The spontaneous emission factor of 0.0021 is obtained for a 2-μm-square device at room temperature. Since only the below-threshold information of Cavity Loss and output power are used in our method, the obtained β values are independent of any complex and unexpected above-threshold effects such as thermally induced mode-size contraction, as they should be.
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Measurement of Cavity Loss and threshold gain in a vertical-Cavity surface-emitting laser using an external mirror
17th Congress of the International Commission for Optics: Optics for Science and New Technology, 1996Co-Authors: Yong-hee LeeAbstract:The threshold gain and the Cavity Loss are important parameters for the optimum design of vertical-Cavity surface-emitting lasers(VCSELs). The internal Loss is commonly determined from the dependence of the external slope efficiency on Cavity length[1]. This method inevitably assumes that internal Loss is same for each devices. Here we try to determine the Cavity Loss by varying the amount of light fed back to the VCSEL using an external mirror. The schematic diagram of the experimental setup is shown in Fig. 1. The tested VCSEL consists of super lattice structure surrounded by AlAs/Al0.3Ga0.7As distributed Bragg reflectors. Current is constricted by proton implantation outside a 15- μm diameter circle. A 15- μp m opening in the p-metalization acts as an output aperture. In the continuous wave operation, the threshold current of VCSEL undergoes a periodic change depending on the external Cavity length. We found the position of the minimum threshold current by using a piezo-electric translator to the external mirror. Then, we measured the threshold current for different values of feedback.
Connie J. Chang-hasnain - One of the best experts on this subject based on the ideXlab platform.
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Comparative study of the analog performance of a vertical-Cavity surface-emitting laser under gain and Cavity Loss modulation
Applied Physics Letters, 2000Co-Authors: Janice Hudgings, R.j. Stone, S.f. Lim, Kam Y. Lau, Connie J. Chang-hasnainAbstract:The analog performance of a vertical-Cavity surface-emitting laser is compared for gain and Cavity Loss modulation. Direct gain modulation consistently results in a larger spur free dynamic range (SFDR) than does Cavity Loss modulation; the maximum SFDR achieved is 96.5 dB Hz2/3. Analysis of the physical origins of variations in the measured SFDR with applied electrical bias indicates potential strategies for improving the analog response of these lasers.
S.-f. Yu - One of the best experts on this subject based on the ideXlab platform.
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Second-harmonic distortion in vertical-Cavity surface-emitting lasers with lateral Loss effects
IEEE Journal of Selected Topics in Quantum Electronics, 1999Co-Authors: P.c. Chui, S.-f. YuAbstract:The influence of lateral Loss effects on the second-harmonic distortion (SHD) of vertical-Cavity surface-emitting lasers is investigated theoretically. Two parameters, differential confinement factor and differential Cavity Loss, are defined for the consideration of self-focusing and diffraction Loss. It is found that SHD increases at low modulation frequencies due to the presence of differential Cavity Loss, especially for lasers with small core radius.
A V Kiryanov - One of the best experts on this subject based on the ideXlab platform.
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an experimental analysis of self q switching via stimulated brillouin scattering in an ytterbium doped fiber laser
Laser Physics Letters, 2013Co-Authors: Yuri O. Barmenkov, A V Kiryanov, M V AndresAbstract:An experimental study of self-Q-switching (SQS) in an ytterbium doped fiber laser (YDFL) arranged using a twin-core GTWave assembly is reported. The main mechanisms that initiate, amplify, and limit SQS pulses in amplitude are revealed to be stimulated Brillouin and Raman scattering (SBS/SRS) and Yb3+ amplified spontaneous emission. The parameters featuring SQS oscillation in terms of efficiency and stability of pulsing are found to be intra-Cavity Loss and feedback strength. An analysis of the YDFL SQS regime?s features?pulsing time series, optical and RF spectra, amplitude and timing jitter?is provided for the two experimental situations: (i) when SQS pulsing stochastically intermits with regular active Q-switching pulses, given by the action of an intra-Cavity acousto-optical modulator, and (ii) when a pure SQS mode is intentionally implemented in the YDFL without a modulator. The close relationship of the processes involved and SQS parameters in these two circumstances is demonstrated. Giant pulses with durations of 70?80?ns are shown to be generated at threshold intra-Cavity powers of around 250?W (SBS threshold) and limited at approximately 2?kW of peak power (SRS threshold). At SBS-SQS, we show that at high values of intra-Cavity Loss, and thus reduced feedback, the amplitude and timing jitter values can be reduced to 5% and 7%, respectively.
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the use of erbium fiber laser relaxation frequency for sensing refractive index and solute concentration of aqueous solutions
Laser Physics Letters, 2008Co-Authors: H Arellanosotelo, Yuri O. Barmenkov, A V KiryanovAbstract:We report a novel-principle fiber-laser intra-Cavity sensor for measuring refractive index and solute concentration of aqueous solutions. The sensor operation is based on a variation of the laser oscillation relaxation frequency (the measured parameter), sensitive to the intra-Cavity Loss change. The sensor capacity is demonstrated on the example of measurements of sugar concentration in water. A modeling of the sensor operation is presented, allowing its performance optimization.
Janice Hudgings - One of the best experts on this subject based on the ideXlab platform.
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Comparative study of the analog performance of a vertical-Cavity surface-emitting laser under gain and Cavity Loss modulation
Applied Physics Letters, 2000Co-Authors: Janice Hudgings, R.j. Stone, S.f. Lim, Kam Y. Lau, Connie J. Chang-hasnainAbstract:The analog performance of a vertical-Cavity surface-emitting laser is compared for gain and Cavity Loss modulation. Direct gain modulation consistently results in a larger spur free dynamic range (SFDR) than does Cavity Loss modulation; the maximum SFDR achieved is 96.5 dB Hz2/3. Analysis of the physical origins of variations in the measured SFDR with applied electrical bias indicates potential strategies for improving the analog response of these lasers.