I am not sure of your example exactly, but there are some oscillator (ring laser). you can start with some of them.
I think you should take care of oscillator fundamentals:
1. sometimes you need to use initializer component to push the input signal one time.
2. sometimes you can use iterations with delay components to make bidirectional components work.
please go through these example and customize your accordingly to make it works.
Hope that helps,
Mohamed
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