P. Loza-Alvarez

Amplitude and phase measurement of mid-infrared femtosecond pulses by using cross-correlation frequency-resolved optical gating

We describe a cross-correlation-based frequency-resolved optical gating (XFROG) technique for simultaneously measuring the amplitude and phase of two ultrashort pulses that have different wavelengths but are derived from a common mode-locked oscillator. A measurement is presented in which 4.0-mum mid-IR pulses from a synchronously pumped femtosecond optical parametric oscillator (OPO) are characterized by mixing with the 770-nm OPO pump pulses. Details of the pulse-retrieval algorithm are included, together with examples of pulse data retrieved from the experimentally measured XFROG trace.

Amplification of femtosecond pulses over by 18 dB in a quantum-dot semiconductor optical amplifier

We demonstrate amplification (> 18 dB) of 200-fs pulses in a quantum-dot (QD) semiconductor amplifier. Our measurements have shown that such QD devices can provide amplification of femtosecond pulses over a spectral range that exceeds 100 nm.

Simultaneous femtosecond-pulse compression and second-harmonic generation in aperiodically poled KTiOPO 4

We report both extracavity and intracavity simultaneous second-harmonic generation and compression of pulses at 1.25 mum from a synchronously pumped RbTiOAsO(4) -based optical parametric oscillator, using an aperiodically poled crystal of KTiOPO(4) . The 290-fs input pulses were temporally compressed to 120 fs, with average output powers as great as 120 mW. The experimental results are compared with a numerical model that uses data obtained by characterization of the input pulses by use of the frequency-resolved optical gating technique.

Femtosecond second-harmonic pulse compression in aperiodically poled lithium niobate: a systematic comparison of experiment and theory

We present detailed experimental results of simultaneous frequency doubling and pulse compression of chirped pulses from a femtosecond optical parametric oscillator using a second-harmonic crystal of aperiodically poled lithium niobate comprising eight different linearly chirped gratings. Our results are compared with a numerical model that incorporates the complex amplitude of the input pulse determined with frequency-resolved optical gating. We use the results of this model to analyze and discuss several aspects of the pulse-generation process.

Simultaneous second-harmonic generation and femtosecond-pulse compression in aperiodically poled KTiOPO 4 with a RbTiOAsO 4 -based optical parametric oscillator

We have obtained both extracavity and intracavity simultaneous second-harmonic generation and compression of signal pulses at 1.25 µm from a synchronously pumped RbTiOAsO4-based optical parametric oscillator with an aperiodically poled crystal of KTiOPO4. The 290-fs input pulses yield temporally compressed frequency-doubled pulses with durations of 120 fs and average output powers of as much as 120 mW. Experimental results are compared with a numerical model in which the temporal and spectral pulse shape and phase of the second-harmonic pulses are calculated with data obtained by characterization of the input pulses by use of the frequency-resolved optical gating technique. We also used the model to optimize the crystal parameters that would result in higher conversion efficiencies and that would enhance pulse compression.

All-solid-state mid-infrared femtosecond optical parametric oscillator based on periodically-poled lithium niobate

We describe an all-solid-state collinearly-pumped femtosecond optical parametric oscillator based on periodically-poled lithium niobate and tunable in the infrared from 996 nm to 1.22 μm (signal) and 2.6 to 4.98 μm (idler). Maximum output powers of 240 mW for the signal and 106 mW for the idler are recorded with 25 mW of average power measured at 4.88 μm. An overall conversion efficiency of 35% and slope efficiencies for the signal of 40% at a wavelength of 1.04 μm and 70% at 1.1 μm are measured. Using dispersion compensation, interferometric autocorrelations at signal and idler wavelengths of 1.0 and 4.88 μm, implying pulse durations of 210 and 190 fs, respectively, have been obtained.

Strong amplification of femtosecond pulses in quantum dot semiconductor optical amplifier

We demonstrate strong amplification (>21 dB) of 200 fs pulses in a quantum-dot semiconductor amplifier. Our measurements have shown that such quantum-dot devices can amplify of femtosecond pulses in a spectral range exceeding 100 nm.

Periodically poled RbTiOAsO/sub 4/ femtosecond optical parametric oscillator tunable from 1.38 to 1.58 /spl mu/m

The OPO described operates at room temperature and is continuously tunable over 200 nm from 1.375 to 1.575 /spl mu/m using only a single-cavity mirror set. The OPO is based on periodically poled RbTiOAsO/sub 4/ (PPRTA). The crystal used had a grating period of 30 /spl mu/m and was 5 mm long, 0.5 mm wide, and 5 mm high. The crystal was antireflection coated for a wavelength of 1.1 /spl mu/m, and we estimate the loss of each surface at a wavelength of 1.5 /spl mu/m to be /spl sim/1%. The OPO was synchronously pumped by a mode-locked Ti:sapphire laser at a repetition rate of 84 MHz, with output pulses of 100 fs duration and centered at a wavelength of 850 nm. We used a 90-mm focal-length lens to focus the pump beam into the PPRTA crystal. The polarization of the pump, signal, and idler wavelengths were all horizontal in the cavity and parallel to the poling direction.

Simple experimental technique for analytically characterizing ultrashort laser pulses

In this paper we will describe general methodology that allows the phase of an unknown pulse to be analytically obtained. This technique brings together time-frequency and interferometric techniques while at the same time it maintains robust error checking capabilities. Besides, it does not rely on the use of iterative retrieval algorithms and does rely on Fourier analysis. Our methodology only requires a simple collinear autocorrelator whose output is spectrally resolved as a function of delay. We call this technique Measurement of Electric Field by Interferometric Spectral Trace Observation (MEFISTO).

The use of a spectrally resolved interferometric correlation to analytically determine the phase of two unknown ultrashort laser pulses

In this paper we will describe a new technique that allows, for the first time, an analytical determination of the complex electric fields of two different pulses which have the same central frequency. This is done by performing a spectrally resolved analysis, in the Fourier domain, of a collinear cross-correlation. Blind-MEFISTO has the additional advantages in that it enables a simple extraction of pulse information without the need of an iterative retrieval algorithm and without having some of the ambiguities that are present in other techniques.