Investigation of the dependence of the pass band of a multimode fiber waveguide on the excitation conditions

An investigation is made of the dependence of the pass band of a waveguide on the excitation conditions. Approximate equations which express the dependence of the waveguide pass band on the excitation conditions are derived using an analytic expression for the transfer function of a waveguide having a step refractive index profile. An experimental investigation was made of this dependence. This technique can be used to measure the pass band of graded-index waveguides.