Bid 2♦ . Generally with a good, distributional hand you should choose to bid your second suit rather than rebid your first suit. You could certainly bid 3♠ (showing 15+ to 18- HCPs and 6+ spades), but then you have tossed out the opportunity to play hearts or diamonds. 2♦ shows 4+ diamonds and 12-17 HCPs.
Let’s look at what might happen over 2♦. If partner bids 3♦, you have a fabulous hand that might even make slam in diamonds. If partner bids 2♥, you can raise to 3♥ showing a heart fit and 16 to 18 HCPs. If partner preferences back to 2♠, you can raise to three spades showing 16-18 HCPs and six spades and four diamonds….much more descriptive than jumping to 3♠ initially.
Yes, Responder can pass 2♦, but if they do so, they probably have a singleton spade so you are probably better off in diamonds than spades anyway.
Shape is what can push a hand to games or slams, even when the HCPs are not there. Try to always bid out your shape (your pattern).