What is a key challenge when using an elliptical laser diode (LD)?

The challenge associated with using an elliptical laser diode primarily lies in the difficulty of focusing the energy it emits onto optical fibers. Elliptical laser diodes have an intrinsic beam shape that can make it complicated to couple the emitted light efficiently into the core of a fiber optic cable. This is particularly significant because the light must be precisely aligned and focused to maximize the amount of energy entering the fiber, which directly affects performance. If the beam shape diverges from the required profile, then less light can enter the fiber, leading to energy loss and less effective data transmission.

The incorrect options highlight different characteristics that do not accurately represent the challenges presented by elliptical laser diodes. Therefore, the focus on energy coupling efficiency underscores the key difficulty faced in practical applications of elliptical laser diodes.