[Show abstract][Hide abstract] ABSTRACT: We exploit the coupled emission-states of a single-chip semiconductor InAs/GaAs quantum-dot laser emitting simultaneously on ground-state (λGS = 1245 nm) and excited-state (λES = 1175 nm) to demonstrate coupled-two-state self-mixing velocimetry for a moving diffuse reflector. A 13 Hz-narrow Doppler beat frequency signal at 317 Hz is obtained for a reflector velocity of 3 mm/s, which exemplifies a 66-fold improvement in width as compared to single-wavelength self-mixing velocimetry. Simulation results reveal the physical origin of this signal, the coupling of excited-state and ground-state photons via the carriers, which is unique for quantum-dot lasers and reproduce the experimental results with excellent agreement.
[Show abstract][Hide abstract] ABSTRACT: A compact all-room-temperature CW 73-nm tunable laser source in the visible spectral region (574nm-647nm) has been demonstrated by frequency-doubling of a broadly-tunable InAs/GaAs quantum dot external-cavity diode laser in periodically-poled potassium titanyl phosphate waveguides with a maximum output power in excess of 12mW and a maximum conversion efficiency exceeding 10%. Three waveguides with different cross-sectional areas (4x4µm2, 3x5µm2 and 2x6µm2) were investigated.
Laser Optics 2014, St. Petersburg, Russia; 07/2014
[Show abstract][Hide abstract] ABSTRACT: Orange light with maximum conversion efficiency exceeding 10% and CW output power of 12.04 mW, 10.45 mW and 6.24 mW has been generated at 606, 608, and 611 nm, respectively, from a frequency-doubled InAs/GaAs quantum-dot external-cavity diode laser by use of a periodically-poled KTP waveguides with different cross-sectional areas. The wider waveguide with the cross-sectional area of 4×4 μm2 demonstrated better results in comparison with the narrower waveguides (3×5 μm2 and 2×6 μm2) which corresponded to lower coupling efficiency. Additional tuning of second harmonic light (between 606 and 614 nm) with similar conversion efficiency was possible by changing the crystal temperature.
SPIE Photonics West 2014, Nonlinear Frequency Generation and Conversion: Materials, Devices, and Applications XIII, San Francisco, CA; United States; 02/2014
[Show abstract][Hide abstract] ABSTRACT: The spectral analysis of amplified spontaneous emission is used to determine the linewidth enhancement factor (α-factor) in lasers based on InAs/InGaAs quantum dots (QDs) in a wide spectral range near the ground-state optical transition energy. The effect of the pump current and number of QDs on the spectral dependences of the α-factor is examined. The temperature dependence of the spectra of the α-factor is experimentally determined for the first time for lasers with InAs/InGaAs QDs. An explanation is suggested for the observed anomalous decrease in the α-factor with increasing temperature.
[Show abstract][Hide abstract] ABSTRACT: Microdisc resonators based on InAs/GaAs quantum dots separated from a
GaAs substrate by selective etching and fixed to a silicon substrate by
epoxy glue are studied using luminescence spectroscopy. A disc resonator
6 μm in diameter exhibits quasi-single-mode laser generation at a
temperature of 78 K with a threshold power of 320 μW and
λ/Δλ ˜ 27000.
[Show abstract][Hide abstract] ABSTRACT: Two-state lasing in devices based on undoped and p-type modulation-doped InAs/InGaAs quantum dots is studied for various cavity lengths and temperatures. Modulation doping of the active region strongly enhances the threshold current of two-state lasing, preserves ground-state lasing up to higher temperatures and increases ground-state output power. The impact of modulation doping is especially strong in short cavities.
Semiconductor Science and Technology 08/2013; 28(10):105016. · 1.92 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: A compact picosecond all-room-temperature orange-to-red tunable laser source in the spectral region between 600 and 627 nm is demonstrated. The tunable radiation is obtained by second-harmonic generation in a periodically poled potassium titanyl phosphate (PPKTP) multimode waveguide using a tunable quantum-dot external-cavity mode-locked laser. The maximum second-harmonic output peak power of 3.91 mW at 613 nm is achieved for 85.94 mW of launched pump peak power at 1226 nm, resulting in conversion efficiency of 4.55%.
[Show abstract][Hide abstract] ABSTRACT: Turn-on delay of laser diodes with quantum-sized active media is
investigated both theoretically and experimentally. In this research we
show the striking difference in turn-on delay of quantum dot and quantum
well laser diodes: With quantum-well lasers turn on delay tends to zero
in the limit of high pumping, while with quantum dot lasers turn-on
delay has the non-vanishing component which is independent of pumping.
Journal of Physics Conference Series 08/2013; 461(1):2030-.
[Show abstract][Hide abstract] ABSTRACT: The gain compression coefficient was evaluated by applying the frequency modulation/amplitude modulation technique in a distributed feedback InAs/InGaAs quantum dot laser. A strong dependence of the gain compression coefficient on the output power was found. Our analysis of the gain compression within the frame of the modified well-barrier hole burning model reveals that the gain compression coefficient decreases beyond the lasing threshold, which is in a good agreement with the experimental observations.
Journal of Applied Physics 06/2013; 113(23). · 2.21 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: A compact high-power yellow-green CW laser source at 561nm based on frequency-doubling of a quantum dot Fiber-Bragg-grating laser in a PPLN waveguide is demonstrated with output power in excess of 90mW and conversion efficiency of 52.34%.
[Show abstract][Hide abstract] ABSTRACT: We demonstrate all-room-temperature CW second harmonic generation with 174 nm tunability from blue to red (between 478 nm and 652 nm) in a single PPKTP waveguide pumped by broadly-tunable semiconductor laser diodes.
[Show abstract][Hide abstract] ABSTRACT: We demonstrate a compact all-room-temperature picosecond laser source broadly tunable in the visible spectral region between 600 nm and 627 nm. The tunable radiation is obtained by frequency-doubling of a tunable quantum-dot external-cavity mode-locked laser in a periodically-poled KTP multimode waveguide. In this case, utilization of a significant difference in the effective refractive indices of the high- and low-order modes enables to match the period of poling in a very broad wavelength range. The maximum achieved second harmonic output peak power is 3.25 mW at 613 nm for 71.43 mW of launched pump peak power at 1226 nm, resulting in conversion efficiency of 4.55%.
SPIE Photonics West 2013, Nonlinear Frequency Generation and Conversion: Materials, Devices, and Applications XII, San Francisco, CA; United States; 02/2013
[Show abstract][Hide abstract] ABSTRACT: Wavelength bistability and tunability are demonstrated in a two-sectional quantum-dot mode-locked laser with a nonidentical capping layer structure. The continuous wave output power of 30 mW (25 mW) and mode-locked average power of 27 mW (20 mW) are achieved for 1245 nm (1295 nm) wavelengths, respectively, under the injection current of 300 mA. The largest switching range of more than 50 nm and wavelength tuning range with picosecond pulses and stable lasing wavelengths between 1245 and 1295 nm are demonstrated for gain current of 300 and 330 mA.
IEEE Journal of Selected Topics in Quantum Electronics 01/2013; 19(4):1100907. · 4.08 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: DBR stabilized InAs/GaAs quantum dot comb laser diode is demonstrated. It generates 4+ low-noise comb lines within the temperature range 25-65°C. The DBR section improves comb spectrum stability in the changing operating conditions.
Optical Fiber Communication Conference and Exposition and the National Fiber Optic Engineers Conference (OFC/NFOEC), 2013; 01/2013
[Show abstract][Hide abstract] ABSTRACT: Quasi-phase-matching is an important and widely used technique in nonlinear optics enabling efficient frequency up-conversion. However, since its introduction almost half a century ago, this technique is well developed for near infrared (IR) but is intrinsically limited in spectral tunability in the visible range by the strict conditions set by the spatial modulation which compensates the momentum mismatch imposed by the dispersion. Here, we provide a fundamental generalization of quasi-phase-matching based on the utilization of a significant difference in the effective refractive indices of the high- and low-order modes in multimode waveguides. This concept enables to match the period of poling in a very broad wavelength range and opens up a new avenue for an order-of-magnitude increase in wavelength range for frequency conversion from a single crystal. Using this approach, we demonstrate an all-room-temperature continuous-wave (CW) second harmonic generation (SHG) with over 60 nm tunability from green to red in a periodically-poled potassium titanyl phosphate (PPKTP) waveguide pumped by a single broadly-tunable quantum-dot laser diode.
[Show abstract][Hide abstract] ABSTRACT: Broadband wavelength tunability over 136 nm (between 1182.5 nm and 1319 nm) of picosecond pulses in passive mode-locked regime is demonstrated in a multi-section quantum-dot laser in external cavity configuration at room temperature. The maximum peak power of 870 mW with 15 ps pulse duration was achieved at 1226 nm wavelength.