You're not going to come up with an optical filter that'll radically attenuate all but your desired narrow green wavelength. (Not inexpensively so, anyway.)It's possible that you could considerably attenuate, with mylar tape or something, all light (wavelengths) such that only a laser's intensity could get through.
Well the actual sensor will be covered, but I do wonder if I could just get a strip of the material that's made out of, just to block out all the light that could get in...Or maybe just get a strip of black fabric that could be stapled in between the laser and the sensor, and the rest enclosed. Then the intensity of the laser could get through, but very little other light