Influence of acoustic energy walk-off on acousto-optic diffraction characteristics

Dependences of ultrasonic modulation of coherent light on optical frequency shift and phase modulation

“…As shown in figure 1, a longitudinal US of cyclic frequency Ω is launched into an optically clear medium. Inside the medium, the US produces a phase grating with the optical refractive index obeying [9,10]…”

“…In this paper, only the RNd is involved. For RNd, the zero-order diffracted light travels along the Z direction and has no frequency shift [9,12]. Additionally, the first-order diffracted light can be approximated as traveling along the Z direction and is frequency-shifted by the US frequency [9,12].…”

“…For RNd, the zero-order diffracted light travels along the Z direction and has no frequency shift [9,12]. Additionally, the first-order diffracted light can be approximated as traveling along the Z direction and is frequency-shifted by the US frequency [9,12]. In this paper, our research object is only limited to the zero-and first-order diffracted light coming from a small region with center at position (0, y, 0) within the US field.…”

“…The optical phase modulation of the zero-order diffracted light, coming from the position (0, y, 0), can be written as klΔnsin Ω(t+y/v), where k is the optical wave vector in vacuum, l is the AO interaction length along the Z direction [9,10]. Additionally, the value of δ is much smaller than the US wavelength.…”

Дифракция Света На Ультразвуке В Пространственно Периодическом Акустическом Поле

“…В соответствии с этим введем углы ϕ 0,1 = θ 0,1 − α. Условие фазового синхронизма R = 0 определяет угол Брэгга: Выражение (11) говорит о том, что снос акустической энергии не оказывает влияния на условие фазового синхронизма. Однако выражения для Ŵ и R по-прежнему зависят от угла сноса α, что означает изменение диапазона АО взаимодействия и, следовательно, угловых, частотных и спектральных характеристик [17].…”