| In recent years there has been great interest in short pulsed lasers for applications in communication, fast temporally resolved measurements (electro-optic sampling), and as a means for obtaining higher peak powers. In contrast to argon ion pumped mode-locked Ti:sapphire lasers, there is a need for compact, economical, low-noise, diode-pumped, infrared wavelength short-pulsed sources. This need is addressed in the first part of the thesis, where a 20 GHz dielectric resonator/optical modulator (DROM) is introduced and developed for harmonic mode-locking of a diode pumped Nd:BEL laser. Depending on the mode-locker drive frequency, two distinct regimes of mode-locking were observed: (1) 2.9 psec pulses at the cavity repetition-rate of 238 MH, (2) 3.9 psec pulses at the repetition-rate of 20 GHz. These are the shortest pulses yet reported for active mode-locking of a Nd laser. After the short pulses are created, it is desirable to have a means for controlling them. This leads to the concept of temporal imaging and time-lenses. There is an interesting analogy between the spatial problem of Fresnel diffraction and the temporal problem of first order dispersion. This can be extended to introduce the idea of a time-lens as a dual of a spatial lens (regular lens). The time-lens is simply a quadratic optical phase modulator in time, which is approximated by a portion of a sinusoidal phase modulator. Thus, by using phase modulators as lenses and grating pairs as dispersive elements, complete temporal imaging systems can be constructed in exact duality with spatial imaging systems. A resonant microwave optical phase modulator in LiNbO... |
