Forward volume wave microwave envelope solitons in yttrium iron garnet films: Propagation, decay, and collision

Abstract

Magnetostatic forward volume wave (FVW) microwave magnetic envelope solitons in 7.2 pm thick, single-crystal yttrium-iron garnet films have been studied at 5.6-6.0 GHz. Rectangular input pulses with peak powers up to 3 W and pulse widths 5-50 ns were used. Single soliton output pulses with a characteristic increase in amplitude and pulse narrowing are observed when the power or width of the rectangular input microwave pulse exceeds threshold levels. Above these levels, output pulse peak power versus input power or pulse width exhibits a nonlinear increase and shows saturation effects. Multiple peak output profiles are observed for pulse powers and widths well above threshold. Solitons could be formed for all frequencies within the usable, low transmission loss portion of the magnetostatic FVW band. The use of reflected pulses from the film edge made it possible to study soliton decay and soliton collisions. The soliton decay rate was found to be approximately twice the linear rate, as expected from theory. The collision of solitons was found to occur with no significant change in shape and velocity. The various characteristic times from theory for pulse decay, pulse dispersion, nonlinear response, and propagation are found to be consistent with the experimental results.

Magnetostatic wave dynamic magnetization response in yttrium iron garnet films

“…This amplitude, for example, has been a key factor in recent work on microwave magnetic envelope solitons. [1][2][3][4][5][6] In Refs. 3-6, for example, estimates of the dynamic microwave magnetization ͑DMM͒ amplitude response as a function of input power were needed in order to compare experimental data on magnetostatic wave solitons with the numerical modeling results obtained from the nonlinear Schrödinger equation.…”

Magnetostatic forward volume wave soliton in a microstrip line with YIG film substrate

“…In this case, the operating point is in the region where the phase constant k y is small near the cutoff frequency on the dispersion curve of the YIG thin film microstrip line. This operating point is within the bandwidth in which the MSFVW soliton appears [6]. When the power of the input signal is small, a waveform similar to that of the input signal is observed with a time delay as the output signal.…”

“…In the case of MSFVW, the variation of the dispersion owing to nonlinearity depends on the demagnetization effect of the z component M z of the magnetization. When M z is expressed in terms of the saturation magnetization M 0 of YIG, Hence, the dispersion relationship in nonlinear operation is as follows, taking account of |M| 2 , which expresses the demagnetization effect of M z [2,6] When Eq. (3) …”

“…Also, as described earlier, the MSFVW soliton is generated in the region with a small phase constant k y . Hence, the variations of the high frequency magnetizations m x and m y in the film thickness direction are small and can be considered uniform [6].…”

“…(5) is the definition of the amplitude given by Eq. (2) [2,6]. The high frequency magnetizations m x 2 and m y 2 are evaluated from the average integrated field distributions of the MSFVW in the film thickness direction and the Poynting power.…”