Passive and Hybrid Mode-Locking of an External-Cavity GaInN Laser Diode Incorporating a Strong Saturable Absorber

Abstract

We produced clean 3-ps-duration optical pulses from a bi-sectional GaInN laser diode with an external-cavity configuration. The peak power of the optical pulses was 3 W under passive and hybrid mode-locking at a 1 GHz repetition rate.

100 W peak-power 1 GHz repetition picoseconds optical pulse generation using blue-violet GaInN diode laser mode-locked oscillator and optical amplifier

“…19 Recently, using an external-cavity mode-locking configuration of GaInN LDs, stable optical pulse generation at the rate of 1 GHz with a pulse duration of 3 ps was achieved. 20,21 Considering the nanoseconds range of carrier lifetimes of semiconductor lasers, in order to generate high peak power short optical pulses, increasing the average power with picoseconds pulses at gigahertz-order repetition is the most effective method to induce multiphoton processes, as demonstrated for two-photon imaging. 13 We have therefore developed a master oscillator power amplifier ͑MOPA͒ optical pulse source by fabricating a GaInN semiconductor optical amplifier ͑SOA͒ to increase the optical power of a modelocked LD ͑MLLD͒.…”

“…Details of the device structure have been described in our previous report. 21 The mode-locked laser oscillator consists of the BS-LD, a wavelength-selecting optical filter ͑ selector͒, and an external mirror with a reflectivity of 5%. It should be noted that we reduced the external mirror reflectivity from 20% from that in the previous report, 21 to further increase the optical output power while confirming that the temporal durations of optical pulses were maintained at 3 ps.…”

“…21 The mode-locked laser oscillator consists of the BS-LD, a wavelength-selecting optical filter ͑ selector͒, and an external mirror with a reflectivity of 5%. It should be noted that we reduced the external mirror reflectivity from 20% from that in the previous report, 21 to further increase the optical output power while confirming that the temporal durations of optical pulses were maintained at 3 ps. The oscillator was passively mode-locked to produce clean optical pulses without noticeable subpulse components at 1 GHz repetition under the following operating conditions: gain current of 115 mA, SA reverse voltage of Ϫ18 V, and temperature of 15°C.…”

“…The time-bandwidth product for the output pulses was 1.7, indicating that the pulses were not Fourier transform limited. 21 It should be mentioned that increasing the MLLD optical power is important, since this eliminates the need for pre-amplification by another SOA. Optical pulses from the MLLD were passed through an optical isolator, and a half-wave ͑ / 2͒ plate was a͒ used to obtain the maximum SOA gain ͑maximum gain is obtained with TE polarized input light͒.…”

Intensity Correlation Analysis on Blue-Violet FemtosecondPulses from a Dispersion-Compensated GaInN Mode-LockedSemiconductor Laser Diode

“…A double-quantum-well GaInN BS-LD was operated in a dispersion-compensated external cavity under passive mode locking. The epitaxial structure of the device has previously been reported [14]. The p-electrode of the BS-LD had a gain section and an SA section.…”