We analyze the large (Formula Omitted10 nm) and abrupt jumps in emission wavelength, together with the multimode instabilities associated with them, which are observed in monolithically integrated ...master oscillator power amplifiers emitting at 1.5 Formula Omittedm. The physical origin of such phenomena is investigated in the framework of a travelling-wave model which phenomenologically incorporates thermal effects via self and cross-heating of the different sections of the device. The occurrence of the wavelength jumps and the instabilities as a function of the injected currents in the two sections is interpreted in terms of a thermally tuned competition between the modes of the master oscillator and the compound cavity modes.
We analyze the large (>10 nm) and abrupt jumps in emission wavelength, together with the multimode instabilities associated with them, which are observed in monolithically integrated master ...oscillator power amplifiers emitting at 1.5 μm. The physical origin of such phenomena is investigated in the framework of a travelling-wave model which phenomenologically incorporates thermal effects via self and cross-heating of the different sections of the device. The occurrence of the wavelength jumps and the instabilities as a function of the injected currents in the two sections is interpreted in terms of a thermally tuned competition between the modes of the master oscillator and the compound cavity modes.
We report flat and wide low-frequency Optical Frequency Combs generated by pulsed gain-switching of optically injected semiconductor lasers. Combs as wide as 133 GHz at 100 MHz repetition rate and ...good quality combs at a record low frequency of 10 MHz were obtained.
The suitability of a three-section master oscillator power amplifier for pseudorandom lidar is investigated by means of the experimental characterization and analysis of its emission characteristics ...under modulation. The proposed architecture consists of a distributed feedback laser, a modulation section, and a tapered semiconductor optical amplifier. The modulation section acts as an absorber or amplifier when driven at zero or positive bias. Under pseudorandom modulation at 25 Mb/s, a high optical modulation amplitude and extinction ratio were achieved. The characterization of the emission spectra under modulation revealed typical features of frequency modulation due to the carrier-induced refractive index changes.
A new method for measuring the linewidth enhancement factor (α-parameter) of semiconductor lasers is proposed and discussed. The method itself provides an estimation of the measurement error, thus ...self-validating the entire procedure. The α-parameter is obtained from the temporal profile and the instantaneous frequency (chirp) of the pulses generated by gain switching. The time resolved chirp is measured with a polarization based optical differentiator. The accuracy of the obtained values of the α-parameter is estimated from the comparison between the directly measured pulse spectrum and the spectrum reconstructed from the chirp and the temporal profile of the pulse. The method is applied to a VCSEL and to a DFB laser emitting around 1550 nm at different temperatures, obtaining a measurement error lower than ± 8%.
High-power 1060-nm InGaAs-(Al)GaAs quantum-dot (QD) laser material was developed with an integrated InGaAs quantum film acting as a tunnel injector for electrons. In comparison to a QD laser without ...tunnel-injection design, the new type of lasers exhibit a strongly improved temperature stability of the threshold current and internal quantum efficiency.
Data obtained from a mouse model indicated that the ectopic expression of the Grm1 gene is sufficient for transforming melanocytes and causing malignant melanoma in vivo. In addition, it has also ...been documented that the GRM1 gene is aberrantly expressed in human melanomas. Here we have performed a genetic association study to elucidate whether the GRM1 gene contributes to human melanoma susceptibility. To carry out this study, we initially genotyped 250 melanoma patients and 329 nonselected and nonrelated controls with three single nucleotide polymorphisms, rs854145, rs362962 and rs6923492, located in the intron 1, intron 4 and exon 10 of the GRM1 gene, respectively. To perform sample genotyping, we used pyrosequencing techniques. Regarding rs854145 and rs6923492, there were no differences in genotypic distribution or allelic frequency between patients and controls. However, we observed (i) a higher frequency of patients carrying the C allele of rs362962 than in controls (OR=1.40, CI=1.01-1.95, P=0.045), and (ii) that difference became greater in a subgroup of patients with a low level of sun exposure and tumours located on the trunk and extremities (OR=2.10, CI=1.26-3.51, P=0.0039). To confirm these observations, the sample size of both patient and control groups was increased. In total, 464 patients and 561 controls were genotyped for the rs362962 polymorphism. Only the second observation was confirmed (OR=1.69, CI=1.16-2.47, P=0.0064). Our results suggest that the GRM1 gene may contribute to melanoma susceptibility in that specific group of patients.
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