[Show abstract][Hide abstract] ABSTRACT: We experimentally study the generation and amplification of stable picosecond-short optical pulses by a master oscillator power-amplifier configuration consisting of a monolithic quantum-dot-based gain-guided tapered laser and amplifier emitting at 1.26 µm without pulse compression, external cavity, gain- or Q-switched operation. We report a peak power of 42 W and a figure-of-merit for second-order nonlinear imaging of 38.5 W2 at a repetition rate of 16 GHz and an associated pulse width of 1.37 ps.
[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: In this paper, we study experimentally the generation of picosecond short optical pulses with an improved peak power of 42 W at a repetition rate of 16 GHz and an associated pulse width of 1.4 ps. Pulses from a tapered quantum dot laser emitting at 1250 nm are amplified using a tapered quantum dot optical amplifier without any pulse post-compression. We specifically investigate the amplification behavior of this master-oscillator power-amplifier configuration with a focus on the pulse peak power, pulse width, average power and amplified spontaneous emission towards improving the figure of merit for two photon excitation microscopy.
2014 16th International Conference on Transparent Optical Networks (ICTON); 07/2014
[Show abstract][Hide abstract] ABSTRACT: We report on photoinduced absorption bleaching of InAs/InGaAs chirped
quantum dot semiconductor optical amplifier (QD SOA) waveguide devices
investigated by the traditional femtosecond pump-probe technique
applied for a waveguide configuration. To gain broader spectra for the
device a chirped QD structure including three groups of quantum dots
each dedicated to a ground state transition at wavelength 1285, 1243 and
1211 nm was designed. Photoinduced transmission spectra consisting of
ground state transition for the groups of QD's involved showed
coincidence with the electroluminescence spectra and even more exceeded
to longer wavelength. From photoinduced transmission kinetics absorption
recovery in the range of picoseconds was considered. For comparison a
device with typical high photoinduced absorption demonstrating large
suppression of absorption bleaching was shown and interpreted.
[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: In this Letter, a design for a tapered InAs/InGaAs quantum dot semiconductor optical amplifier is proposed and experimentally evaluated. The amplifier's geometry was optimized in order to reduce gain saturation effects and improve gain efficiency and beam quality. The experimental measurements confirm that the proposed amplifier allows for an elevated optical gain in the saturation regime, whereas a five-fold increase in the coupling efficiency to a standard single mode optical fiber is observed, due to the improvement in the beam quality factor M<sup>2</sup> of the emitted beam.
[Show abstract][Hide abstract] ABSTRACT: Compact CW lasers in the visible spectral region are of great importance for vast number of applications including biophotonics, photomedicine, spectroscopy and confocal microscopy. Currently, commercially available lasers of this spectral region are bulky, expensive and inconvenient in use. Also, there is a lack of diode lasers emitting in the visible spectral range, particularly in the yellow region, where a range of important fluorescent probes are optimally excited. An attractive way to realize a compact yellow laser source is second harmonic generation (SHG) in a periodically poled nonlinear crystal containing a waveguide  which allows high-efficient frequency conversion even at moderate power level. In this respect, periodically poled lithium niobate (PPLN) waveguided crystal is one of the best candidates for efficient SHG. In recent years, the progress made with the fabrication of good quality waveguides in PPLN crystals in combination with availability of low-cost, good quality semiconductor diode lasers, offering the coverage of a broad spectral range between 1 μπι and 1.3 um , allows compact CW laser sources in the visible spectral region to be realized.
[Show abstract][Hide abstract] ABSTRACT: Ultrafast high peak power near infrared laser systems are important in nonlinear biomedical imaging applications including two-photon excitation fluorescence (TPEF) or second harmonic generation (SHG) microscopy that are currently dominated by pulsed solid state lasers. The detected intensity in TPEF and SHG depends quad-ratically on the pulse peak power and linearly on the pulse width and repetition rate. Quantum-dot (QD) based semiconductor pulse sources have shown to generate ultrashort pulses and high peak power . QD semiconductor optical amplifiers (SOA) are very suitable to increase the power of these ultrashort pulses due to their high gain saturation characteristics, broad gain bandwidth and fast gain recovery. Such combined systems are compact, efficient and robust thus being promising alternatives to solid state pulsed lasers. Recently, an external cavity laser and amplifier combination was reported exhibiting a pulse peak power of 30W and an average power of 208mW at a repetition rate of 648 MHz and a pulse width of 10.6 ps. This configuration has been successfully applied in TPEF .
The European Conference on Lasers and Electro-Optics; 05/2013
[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: Fundamental mode-locking is achieved in a 1.036 GHz cavity using a semiconductor quantum dot saturable absorber mirror with a fast relaxation time component of down to 550 fs. The dispersive cavity delivers 1.7 ps wide pulses with spectra supporting sub-picosecond pulse durations and an M² of 1.3. An average output power of up to 339 mW at wavelengths around 1,032 nm is achieved and the saturable absorber’s damage threshold is identified as a limitation for further power scaling.
Applied Physics B 03/2013; 110(3). DOI:10.1007/s00340-013-5375-8 · 1.86 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: A broadly tunable quantum-dot based ultra-short pulse master oscillator power amplifier with different diffraction grating orders as an external-cavity resonance feedback is studied. A broader tuning range, narrower optical spectra as well as higher peak power spectal density (maximun of 1.37 W/nm) from the second-order diffraction beam are achieved compared to those from the first-order diffraction beam in spite of slightly broader pulse duration from the secondorder diffraction.
[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. DOI:10.1109/JSTQE.2013.2239610 · 2.83 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: Observation of sub-picosecond pulses from a single section Fabry Perot InAs/GaAs edge emitting quantum dot (QD) based laser at 1.3 μm under continuous wave operation is reported. After group delay dispersion compensation, pulse durations as short as 770 fs in a 45 GHz repetition rate device have been measured, with 1.9 W of peak power and a narrow radio frequency spectrum of only a few kHz linewidth. The experiments show evidence of an unexplored mode locking regime in the InAs/GaAs quantum dot material system, which still needs theoretical modelling and further analysis.
[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.
[Show abstract][Hide abstract] ABSTRACT: A broadly tunable master-oscillator power-amplifier (MOPA) picosecond optical pulse source is demonstrated, consisting of an external cavity passively mode-locked laser diode with a tapered semiconductor amplifier. By employing chirped quantum-dot structures on both the oscillator's gain chip and amplifier, a wide tunability range between 1187 and 1283 nm is achieved. Under mode-locked operation, the highest output peak power of 4.39 W is achieved from the MOPA, corresponding to a peak power spectral density of 31.4 dBm/nm.
[Show abstract][Hide abstract] ABSTRACT: In this letter, we present the first 2-W flip chip quantum-dot (QD) semiconductor disk laser operating at 1200 nm. Compared to other techniques used for thermal management, e.g., intracavity heat spreader approach, the flip chip design preserves undisturbed optical spectrum and exhibits low intracavity losses. The latter is particularly essential for power scaling of lasers with QD gain media.
[Show abstract][Hide abstract] ABSTRACT: We demonstrate compact all-room-temperature laser sources broadly tunable in the visible spectral region in CW (between 567 nm and 629 nm) and picosecond regimes (between 600 nm and 627 nm) by frequency-doubling in a periodically-poled KTP waveguide using a tunable quantum-dot external-cavity diode lasers.
Laser Optics 2012, St. Petersburg, Russia; 06/2012
[Show abstract][Hide abstract] ABSTRACT: Wavelength tunability between 1192.9nm and 1287.4nm in modelocked regime is demonstrated in a multi-section QD laser in external cavity configuration. The maximum peak power of 532mW in pulsed operation was achieved at 1226nm wavelength.
Laser Optics 2012, St. Petersburg, Russia; 06/2012
[Show abstract][Hide abstract] ABSTRACT: In this paper, we present the generation of high peak-power picosecond optical pulses in the 1.26 μm spectral band from a repetition-rate-tunable quantum-dot external-cavity passively mode-locked laser (QD-ECMLL), amplified by a tapered quantum-dot semiconductor optical amplifier (QD-SOA). The laser emission wavelength was controlled through a chirped volume Bragg grating which was used as an external cavity output coupler. An average power of 208.2 mW, pulse energy of 321 pJ, and peak power of 30.3 W were achieved. Preliminary nonlinear imaging investigations indicate that this system is promising as a high peak-power pulsed light source for nonlinear bio-imaging applications across the 1.0 μm - 1.3 μm spectral range.