By means of the variational approximation and direct simulations we demonstrate the one-soliton state trapped in a channel has no existence threshold and is always stable.

• 通过数值方法直接求解非线性薛定格方程以及变分法近似求出了束缚于一个“凹槽”中的单个空间光孤子解，这种光孤子的存在没有阈值范围，且总是稳定传输的。