Cook pasta according to package directions in a large pot of salted water until al-dente, strain reserving one and a half cups (or more - see notes) of the cooking water. The time for this will depend on the kind of pasta/noodles you use.
While the pasta is cooking, heat a cast iron pan, or other large sauté pan. Cut the salmon into 3-4 pieces to fit into your pan. Season with salt and pepper. Cook skin side up for 2 minutes, carefully turn over and cook another 3-4 minutes until just cooked and the skin can be easily removed. Set salmon aside and keep warm.
In a large sauté pan heat the butter and add the sliced garlic. Cook for 2 minutes, while stirring constantly. Add in the cream, half and half, vodka, lemon juice and zest. Bring to a simmer. Add in pasta water and cook until thickened slightly, about 4-5 minutes. Season with salt, pepper and red pepper flakes. Add in the cooked pasta and stir until pasta is coated well with sauce. Gently stir in the arugula. Cut the salmon into 2 inch sized pieces and gently stir into the pasta.
Divide into 4-6 servings. Top with parmesan, more red pepper flakes if desired and serve with a lemon wedge.