Generation of tunable visible picosecond pulses by frequency-doubling of a quantum-dot laser in a PPKTP waveguide

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%

Investigation of the Chromatic Dispersion in Two-Section InAs/GaAs Quantum-Dot Lasers

We present the measurements of the dispersion of InAs/GaAs quantum-dot lasers emitting at 1230 nm (ground state) and 1160 nm (excited state) from the analysis of their subthreshold emission spectra. Measurements from devices with various lengths allow us to deduce that the group velocity dispersion is as high as 2270 fs2mm−1 and is mainly due to the dispersion of bulk GaAs. The gain-induced dispersion varies with the injected current at a rate of ≃−2 fs2 mA−1mm−1, whereas the effect of a saturable absorber on the dispersion is found to be negligible. These results suggest that the implementation of integrated dispersion compensation could significantly reduce the pulse duration of these lasers in mode-locked regime and lead to an enhancement of the formation of optical frequency combs in these devices

Efficient generation of orange light by frequency-doubling of a quantum-dot laser radiation in a PPKTP waveguide

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 μm demonstrated better results in comparison with the narrower waveguides (3×5 μm and 2×6 μm) 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

Tunable single- and dual-wavelength SHG from diode-pumped PPKTP waveguides

A compact, all-room-temperature, widely tunable, continuous wave laser source in the green spectral region (502.1–544.2 nm) with a maximum output power of 14.7 mW is demonstrated. This was made possible by utilizing second-harmonic generation (SHG) in a periodically poled potassium titanyl phosphate (PPKTP) crystal waveguide pumped by a quantum-well external-cavity fiber-coupled diode laser and exploiting the multimode-matching approach in nonlinear crystal waveguides. The dual-wavelength SHG in the wavelength region between 505.4 and 537.7 nm (with a wavelength difference ranging from 1.8 to 32.3 nm) and sum-frequency generation in a PPKTP waveguide is also demonstrated

Broad Repetition-Rate Tunable Quantum-Dot External-Cavity Passively Mode-Locked Laser with Extremely Narrow Radio Frequency Linewidth

We report on a systematic investigation of a repetition-rate-tunable quantum-dot external-cavity passively mode-locked laser with a quasi-continuous frequency tuning range from 1 GHz to a record-low value of 191 MHz. A nearly constant pulse peak power at the different pulse repetition rates is revealed in the continuous frequency tuning range. The trend and optimization of the stable fundamental mode-locking are presented and interpreted. An RF linewidth of a record value of ~30 Hz is demonstrated, which indicates the low noise operation and high stability of the quantum-dot external-cavity passively mode-locked laser

Two-state semiconductor laser self-mixing velocimetry exploiting coupled quantum-dot emission-states: experiment, simulation and theory

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

73 nm wavelength tuning from a frequency- doubled quantum-dot laser in PPKTP waveguides

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 (4x4µm 2 , 3x5µm 2 and 2x6µm 2 ) were investigated. Keywords-Second Harmonic Generation; Nonlinear Crystals; Waveguides; Tunable Lasers; Quantum Dot Lasers I. INTRODUCTION Development of compact broadly tunable laser sources in the visible spectral region is currently very attractive area of research with applications ranging from photomedicine and biophotonics to confocal fluorescence microscopy and laser projection displays. In this respect, semiconductor lasers with their small size, high efficiency, reliability and low cost are very promising for realization of such sources by frequencydoubling of the infrared light in nonlinear crystal waveguides. Furthermore, the wide tunability offered by quantum-dot (QD) external-cavity diode lasers (ECDL), due to the temperature insensibility and broad gain bandwidth In this work we show a compact green-to-red tunable allroom-temperature CW laser source using a frequency-doubled InAs/GaAs QD-ECDL in periodically-poled potassium titanyl phosphate (PPKTP) crystal waveguides. This laser source generates frequency-doubled light over the 574nm-647nm wavelength range utilizing the significant difference in the effective refractive indices of high-order and low-order modes in multimode waveguide

Temperature dependence of pulse duration in a mode-locked quantum-dot laser: Experiment and theory

SCOPUS: cp.pinfo:eu-repo/semantics/publishe