Maria Ana Cataluna

High-power picosecond and femtosecond pulse generation from a two-section mode-locked quantum-dot laser

We demonstrate mode locking in a two-section quantum-dot laser that produces output powers up to 45 mW at 1260 nm. The pulse duration could be varied from 2 ps to as short as 400 fs at the 21 GHz pulse repetition rate.

Broadly tunable high-power InAs/GaAs quantum-dot external cavity diode lasers

A record broadly tunable high-power external cavity InAs/GaAs quantum-dot diode laser with a tuning range of 202 nm (1122 nm-1324 nm) is demonstrated. A maximum output power of 480 mW and a side-mode suppression ratio greater than 45 dB are achieved in the central part of the tuning range. We exploit a number of strategies for enhancing the tuning range of external cavity quantum-dot lasers. Different waveguide designs, laser configurations and operation conditions (pump current and temperature) are investigated for optimization of output power and tunability.

Stable mode locking via ground- or excited-state transitions in a two-section quantum-dot laser

The authors demonstrate stable mode locking that involves transitions within either the ground state (1260nm) or the excited state (1190nm) in a two-section quantum-dot laser, at repetition frequencies of 21 and 20.5GHz, respectively. The average power of the mode-locked output was in excess of 35mW for operation in the ground state and 25mW in the excited state. The selection of pulse generation between these states in the mode-locking regime is controlled by the electrical biasing conditions.

Dual-wavelength mode-locked quantum-dot laser, via ground and excited state transitions: Experimental and theoretical investigation

We report a dual-wavelength passive mode locking regime where picosecond pulses are generated from both ground (lambda = 1263 nm) and excited state transitions (lambda = 1180 nm), in a GaAs-based monolithic two-section quantum-dot laser. Moreover, these results are reproduced by numerical simulations which provide a better insight on the dual-wavelength mode-locked operation.

Stable mode-locked operation up to 80 /spl deg/C from an InGaAs quantum-dot laser

We demonstrate the mode-locked operation of a two-section quantum-dot laser in a broad temperature range. Stable mode-locking was observed at temperatures ranging from 20 /spl deg/C to 70 /spl deg/C, with signal-to-noise ratios well over 20 dB and a -3-dB linewidth smaller than 80 kHz. In the temperature range between 70 /spl deg/C and 80 /spl deg/C, the mode-locking was less stable. It was found that in order to provide stable mode-locked operation with increasing temperature, the reverse bias on the absorber section must be reduced accordingly.

High peak-power picosecond pulse generation at 1.26 µm using a quantum-dot-based external-cavity mode-locked laser and tapered optical amplifier

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.

Reduced surface sidewall recombination and diffusion in quantum-dot lasers

We examine the surface recombination rate in quantum-dot semiconductor lasers and determine the diffusion length (1.0 mum) and, for the first time, provide a value for surface recombination velocity (5times104 cm/s) in quantum-dot material. As a result of strong carrier confinement in the dots, these values are much lower than in comparable quantum-well lasers (5times105 cm/s and 5 mum, respectively) allowing the creation of narrow (2-3 mum wide) lasers with comparable threshold currents to those of broad area devices

Investigation of transition dynamics in a quantum-dot laser optically pumped by femtosecond pulses

The behavior of a quantum-dot edge-emitting laser, optically pumped by femtosecond pulses, has been investigated. It has been observed that pulses generated by the laser from ground-state transitions have longer durations than those generated from the excited states. Interestingly, the shortest pulses were generated when the transitions from the first excited-state were dominant.

High peak power and sub-picosecond Fourier-limited pulse generation from passively mode-locked monolithic two-section gain-guided tapered InGaAs quantum-dot lasers

We report on the development of a new generation of high-power ultrashort pulse quantum-dot lasers with tapered gain section. Two device designs are proposed and fabricated, with different total lengths and absorber-to-gain-section length-ratios. These designs have been informed by numerical simulations of the dynamic mode-locking regimes and their dependence on the structural parameters. One device design demonstrated a record-high peak power of 17.7 W with 1.26 ps pulse width and a second design enabled the generation of a Fourier-limited 672 fs pulse width with a peak power of 3.8 W. A maximum output average power of 288 mW with 28.7 pJ pulse energy was also attained. In addition, the integrated timing jitter of 2.6 ps and far-field patterns are demonstrated.

Temperature dependence of pulse duration in a mode-locked quantum-dot laser

In this paper, we demonstrate, experimentally and theoretically, that in a mode-locked two-section quantum-dot laser, the pulsewidth decreases with temperature. The primary cause is the increase of carrier capture rate with temperature, leading to a faster absorption recovery