Hi,
From my point of view you should not need to simulate the system for a full second, and in fact it will just not be possible. The time scale difference between gigahertz (10^-9 seconds) and even megahertz (10^-6 seconds) is just too gigantic. If you are looking at a transient part of the system you could just set the remote signal to be activated at say around 0.1 microsecond.
A time delay simulates the physical effect of time lag. In effect it will shift the optical signal right in the optical time domain visualizer. You could use it to model the estimated time it takes light to travel through a fiber or say through free space.
An optical delay on the other hand is a simulation tool used in bidirectional components. It aids in initializing bidirectional components. There is a better explanation of how bidirectional systems are simulated at:
Lesson 5: Bidirectional Simulation — Working with Multiple Iterations
Cheers