Generation of optical soliton pulses smoothly tunable in a wide frequency range in silica fibers with variable dispersion

Amplification of frequency-modulated soliton-like pulses in inhomogeneous optical waveguides with normal dispersion

“…At the same time, the use of long waveguides (more than 100 m) with small amplification increments leads to an accumulation of noises and decay of the soliton like wave packet as a whole [1][2][3][4][5][6]; pulses with initial energies less than 10 pJ cannot be amplified to ener gies exceeding 0.1 nJ. In connection with this, we believe that, as an alternative to the regimes proposed above and considered in [6][7][8][9], a regime with the use of inhomogeneous waveguides with a length of not more than 10 m and with relatively large values of the amplification increment ( m -1 ) and an increas ing normal GVD is the most effective regime of FMP amplification. Note also that the influence of high order dispersion effects (beginning from the third order) can be considered very insignificant in the case of the proposed quick amplification of chirped pulses.…”

“…With allowance for the aforesaid values of the parame ters γ and and in correspondence with the condition of amplification of a similariton type FMP in waveguides with a homogeneous or smoothly decreas ing dispersion [3][4][5][6], the amplification increment must be no more than m -1 . In this case, to increase the pulse energy by more than an order of magnitude, the waveguide length must considerably exceed 100 m. As was shown by experiments with erbium and bismuth doped waveguides [8,9] and by numerical simulation [10,11], self similar FMPs are − ≈ × 26 3 10 D D 1 0.0 γ ≈ very sensitive to fluctuations of the amplification increment and variations of the diameter of the ampli fying waveguide. By virtue of this fact, it seems very difficult to use long (more than 100 m) active waveguides to increase the pulse energy considerably.…”

“…The function specifies the shape of the parabolic pulse and is defined by the expression (7) where is the pulse duration. Equation (4) has an exact solution in the form of a parabolic FMP in the case in which the condition (8) is satisfied, i.e., at a constant (with respect to the vari able ) effective amplification increment [6][7][8][9]. In the case of a homogeneous active waveguide, the condi tion of formation of a stable similariton, i.e., condition (8), can be written in an ultimately simple form, .…”

“…Here, it is important to note that the available sources of picosecond pulses that can be used for obtaining similariton FMPs, as a rule, ensure (after passing through additional dispersive elements) a frequency modulation (FM) rate of no more than α~ 10 23 -10 24 s -2 . Moreover, for really used amplifying waveguides (e.g., doped by Er 3+ ), GVD does not exceed the value s 2 /m as a rule [6][7][8]. With allowance for the aforesaid values of the parame ters γ and and in correspondence with the condition of amplification of a similariton type FMP in waveguides with a homogeneous or smoothly decreas ing dispersion [3][4][5][6], the amplification increment must be no more than m -1 .…”

Soliton Self-Frequency Shift: Experimental Demonstrations and Applications

“…Many other groups have shown SSFS in PM SMF in between these wavelength ranges [20], [34]- [36]. Other efforts include demonstrations in doped fiber amplifiers [37], highly nonlinear fiber [38], birefringent fiber [39], [40], fiber with length-variable dispersion [41], as well as non-PM fibers [34], [42], [43].…”