High-power mode-locked semiconductor lasers using flared waveguides

Abstract

We describe the use of flared waveguide diode lasers for obtaining increased output power under mode-locked operation. The flared waveguide expands the optical mode from a narrow region which gives a single lateral optical mode, to a wider multimode region for higher pulse saturation energy. Flared gain and flared absorber section geometry devices are compared to devices with conventional uniform waveguides. Using flared gain section devices, improvements in both pulse energy (6.8 pJ) and pulsewidth (3.3 ps) were measured compared to uniform waveguide devices. Peak powers of over 2 W are obtained, which, to our knowledge, is the highest peak power obtained directly from mode-locked single stripe diode lasers.

High-power passively mode-locked semiconductor lasers

“…To examine the limits of validity of the analytical model, we simulated a device with a commercially available finite element software. 1 For the heat sink, we take a cube 5 mm in size cooled from the bottom (when the semiconductor layer is on top). The simulation is run with a 4.5-m-thick Bragg mirror, a 1-m-thick active region and a 1.5-m-thick antireflective structure.…”

“…This requirement usually limits the usable mode area, and damage phenomena or gain saturation restrict the available pulse fluence. To increase the output power, several techniques have been used including flared waveguides [1], compound lasers with a tapered semiconductor amplifier section [2], and master-oscillator-power-amplifier systems with tapered [3] and inverse bow-tie amplifier geometries [4]. Such techniques increase the complexity of the system and are still currently limited to average powers well below 1 W.…”

High-power passively mode-locked tapered InAs/GaAs quantum-dot lasers

“…While the straight waveguide acts as a spatial filter in the cavity, the tapered section of increasing width delivers high power. As a result, tapered lasers show a great potential for providing single spatial mode, good quality beams with high power, as demonstrated by Mar et al [8]. In this paper, mode locking was achieved in an external cavity configuration, while using a quantum well In0.2Ga0.8As tapered laserresulting in the generation of 3.3-ps pulses with 2-W peak power in the waveband of 980 nm [8].…”

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

“…Mode locking is one of the most effective techniques for producing ultrashort pulses from semiconductors lasers. The combination of tapered waveguide laser design for higher power and passively mode locking technique for short pulse duration has been successfully shown by Mar et al [9]. In that paper, 2 W peak power with 3.3 ps pulse dura tion was demonstrated in a passively mode locked 1 The article is published in the original.…”

“…In that paper, 2 W peak power with 3.3 ps pulse dura tion was demonstrated in a passively mode locked 1 The article is published in the original. tapered laser (with In 0.2 Ga 0.8 As quantum well active region) using external cavity feedback [9]. Some other high power mode locked technologies can be used, for example: vertical external cavity surface emitting lasers (VECSELs) [10] or slab coupled optical waveguide lasers (SCOWLs) [11].…”