FM and AM mode locking of the homogeneous laser - Part I: Theory

Detuning effects of FM mode-locking in atmospheric CO2 lasers

“…We derive as a function of the detuned modulation frequency spectrum, pulse phase shift with respect to the modulation, the gain, and the shift of the centre modulation frequency of the pulse. The theoretical results are analogous to those obtained in the time domain approach [4]. The difference is that we start from the discrete set of oscillating modes and show that the amplitude and phase distribution of these modes satisfy a Gaussian form.…”

“…The pressure-broadened line profile of an atmospheric CO2 laser can be described by a Lorentzian line profile. For this case the single pass intensity gain for the nth mode with frequency con + q~ can be expressed by: These values are the same as those found [4] for a time domain solution of an optical pulse in a resonator.…”

“…The other situation, given by a negative value of 6, corresponds to the passage of the pulse at or close to the minimum of the phase perturbation. The pulse forming at these two different situations is sometimes called the positive and negative mode, respectively [4]. The two solutions give different values for al and as.…”

“…The problem of mode-locking and pulse forming by means of intracavity AM and FM modulation has been treated in the past by several authors [1][2][3][4][5][6][7][8]. For homogeneously broadened systems one may say that the problem has been approached from two different sides.…”

“…For homogeneously broadened systems one may say that the problem has been approached from two different sides. One way is to work completely in the time domain and to assume a Gaussian optical pulse inside the resonator [4,5]. The pulse parameters are then obtained from the requirement that after a complete round-trip through the resonator the pulse is unchanged.…”