Luis C. Archundia

Dispersion managed semiconductor mode-locked ring laser

A novel breathing-mode external sigma-ring-cavity semiconductor mode-locked laser is developed. Intracavity pulse compression and stretching produce linearly chirped pulses with an asymmetric exponential temporal profile. External dispersion compensation reduces the pulse duration to 274 fs (within 10% of the bandwidth limit).

FROG measured high-power 185-fs pulses generated by down-chirping of the dispersion-managed breathing-mode semiconductor mode-locked laser

A dispersion-managed breathing-mode mode-locked semiconductor ring laser generates linear down-chirped pulses which are dispersion compensated to duration as short as 185 fs and characterized by second-harmonic generation frequency-resolved optical gating. Down-chirping when compared to up-chirping allows broader mode-locked spectra and shorter pulse generation owing to the temporal and spectral semiconductor gain dynamics. The measured average output power is 14 mW at 323-MHz pulse repetition rate, implying a peak power of /spl sim/230 W, and a focused intensity of /spl sim/4.6 GW/cm/sup 2/. To our knowledge, this is the highest peak power and the shortest pulse generation from an electrically pumped all-semiconductor system, obtained only by linear chirp compensation.

External cavity multiwavelength semiconductor hybrid mode-locked laser intracavity gain dynamics

The intracavity gain dynamics of an external cavity semiconductor hybrid mode-locked laser is measured under multiwavelength operation. The results show a temporal skew between pulses corresponding to different wavelength channels. A measurement of the temporal evolution of the gain reveals a slow gain depletion, avoiding carrier heating and carrier cooling, and decreasing self-phase modulation effects and gain competition between wavelength channels, making multiwavelength operation possible.

Time- and spectrally resolved ultrafast gain dynamics of a semiconductor optical amplifier under phase-correlated multiwavelength pulse amplification

The ultrafast gain dynamics of an AlGaAs semiconductor optical amplifier (SOA) are measured under phase-correlated multiwavelength pulse amplification using time-resolved pump–probe techniques. Both the temporal and spectral gain dynamics are measured. Carrier heating due to two photon absorption, carrier cooling, four-wave mixing, and cross-phase modulation effects are observed. These effects are evident when amplifying dispersion compensated pulses, and it is shown how these effects decrease when amplifying nondispersion compensated (chirped) pulses. This helps to avoid nonlinear effects in the gain media (SOA), which, in turn, helps to support the operation of external cavity multiwavelength semiconductor mode-locked lasers where the intracavity pulses are inherently chirped.

Precision laser ranging using extremely chirped pulses from chirped fiber Bragg gratings

Spectrally resolved interferometry combining up-chirped and down-chirped pulses allows for millimeter range resolution in laser ranging applications. Key in our approach is the use of temporally stretched optical pulses of 5 nanoseconds in duration. These stretched pulses were obtained from a femtosecond semiconductor mode-locked laser and were up-chirped and down-chirped using a chirped fiber Bragg grating and recombined to realize spectral interferometry. This approach provides a means to achieve the high pulse energies required for a laser radar application which are easy to achieve using nanosecond pulses but maintains the high spatial resolution associated with femtosecond optical pulses.

Experimental characterization and numerical simulations of dispersion-managed breathing-mode semiconductor mode-locked ring laser

Strong self-phase modulation (SPM) in semiconductor gain media induces nonlinear chirp impressed on propagating pulses, which can be difficult to compensate. Our approach is to employ an intracavity dispersion management scheme to decrease the detrimental effect of SPM by utilizing the concept of chirped pulse amplification inside a laser cavity. Stretching the pulse before the cavity gain element minimizes SPM and extracts energy more efficiently. The subsequently compressed pulse bleaches the semiconductor saturable absorber (SA) more easily. The breathing-mode semiconductor mode-locked ring laser regime describes how the pulse alternately experiences stretching and compression while propagating within the ring cavity.

High resolution laser range detection using extremely chirped pulses from a mode-locked semiconductor laser

Spectral interfere merry is used in conjunction with pairs of time reversed, extremely chirped femtosecond pulses to demonstrate high energies with simultaneous high resolution range measurements using a femtosecond mode-locked semiconductor laser.

Intracavity gain dynamics of an external cavity multi-wavelength hybrid semiconductor mode-locked laser

The intracavity gain dynamics of an external cavity semiconductor mode-locked laser are measured, showing how pulses corresponding to different wavelengths are temporally skewed, leading to a slow gain depletion avoiding nonlinearities, which enables multiwavelength operation.

Semiconductor mode-locked laser intracavity gain dynamics measurements under three wavelength operation

The intracavity gain dynamics of an external cavity semiconductor hybrid mode-locked laser are measured under three wavelength operation. The results show a partial coherence and a temporal skew among pulses corresponding to different wavelength channels. The temporal skew broadens the temporal pulse profile and the partial coherence decreases the temporal beating between wavelength channels. A measurement of the temporal evolution of the gain reveals a slow gain depletion, avoiding nonlinearities, and gain competition between wavelength channels, making multiwavelength operation feasible.

Numerical simulations and FROG measurements of 185 fs pulses generated from down-chirped dispersion-managed breathing-mode semiconductor mode-locked laser

Balancing of spectral and temporal semiconductor gain dynamics allows broadening of mode-locked spectra. Our numerical model accurately describes SHG-FROG measurements of 185 fs pulses generated by down chirping of a dispersion-managed breathing-mode semiconductor mode-locked laser.