Ultrashort pulse generation by semiconductor mode-locked lasers at 760 nm

Abstract

We demonstrate the first semiconductor mode-locked lasers for ultrashort pulse generation at the 760 nm waveband. Multi-section laser diodes based on an AlGaAs multi-quantum-well structure were passively mode-locked, resulting in the generation of pulses at around 766 nm, with pulse durations down to ~4 ps, at pulse repetition rates of 19.4 GHz or 23.2 GHz (with different laser cavity lengths of 1.8 mm and 1.5 mm, respectively). The influence of the bias conditions on the mode-locking characteristics was investigated for these new lasers, revealing trends which can be ascribed to the interplay of dynamical processes in the saturable absorber and gain sections. It was also found that the front facet reflectivity played a key role in the stability of mode-locking and the occurrence of self-pulsations. These lasers hold significant promise as light sources for multi-photon biomedical imaging, as well as in other applications such as frequency conversion into the ultraviolet and radio-over-fibre communications.

Megahertz scan rates enabled by optical sampling by repetition-rate tuning

“…2-Section mode-locked laser diodes are compact semiconductor lasers which are utilized for their ability to provide a variety of output characteristics 12 – 14 which can be modulated by simple control of their electrical biasing conditions. Passive mode-locking, which leads to the generation of ultrashort pulses, may be achieved by forward biasing a gain section which is electrically isolated from a reverse-biased saturable absorber section, see Fig.…”

Monolithic InP Quantum Dot Mode-Locked Lasers Emitting at 730 nm

“…These include high-resolution biomedical fluorescence imaging, targeted cell transfection and biological nanosurgery, all of which would benefit from more compact and lower-cost optical sources [11]- [13]. To date, the shortest wavelengths in the red side of the visible spectrum accessed by monolithic electrically-pumped MLLs were 760 nm and 752 nm [14], [15], using AlGaAs multi-quantum-well structures.…”

Ultrashort pulse generation in a semiconductor laser with strong coherent optical feedback

“…In this paper, a novel technique is proposed to generate ultrashort pulses using a semiconductor laser (SL) with external optical feedback (EOF). Comparing to other techniques, an SL with EOF requires neither external modulation nor saturable absorbers and the pulses generated have a single centre wavelength which are important in several applications, such as dense wavelength-division multiplex (DWDM) communications [16] and multi-photon imaging for clinical diagnostics [17]. With the aid of rate equations, we identify a region where the ultrashort pulses are generated by exploring basic parameters of the SL with EOF, and specifically the laser injection current, the external cavity length and the feedback strength.…”

“…Semiconductor laser (SL) sources of ultrashort optical pulses are needed in optical communications systems as pulse sources for high-speed data transmission and all-optical signal processing [1]. To produce such sources, several techniques have been explored, such as gain switching [2][3][4][5][6][7] and different types of mode locking [8][9][10][11][12][13][14][15].…”