Hollow-core　photonic　crystal　fiber　(HC-PCF)　has　been　proved　to　be　a　versatile　platform　for　lab-on-a-fiber　applications.　By　filling　the　fiber　with　various　gases,　liquids　or　solid　materials,　the　light-matter　interaction　could　be　greatly　enhanced.　Many　novel　optical　phenomena　that　are　unattainable　in　free-space　could　be　easily　identified　inside　the　fiber.　Such　a　platform　offers　a　promising　route　for　creating　compact,　integrable　and　biocompatible　all-fiber　multifunctional　optical　devices.　Here,　we　review　our　recent　progress　in　developing　a　novel　HC-PCF　coined　＂hollow-core　negative　curvature　fiber＂　(NCF)　that　could　provide　light　guidance　at　spectral　ranges　covering　from　UV,　visible,　NIR　to　MIR.　These　NCFs　show　attributes　of　low　transmission　loss,　octave-spanning　transmission　bandwidth,　high　damage　threshold　and　single　modeness.　As　a　proof-of-concept　demonstration　for　lab-on-a-fiber　applications,　we　filled　one　of　the　fibers　with　ethanol　(refractive　index　1.36)　to　form　a　liquid-core　anti-resonant　fiber.　At　a　low　volume　of　1　mu　L,　Raman　signal　from　ethanol　was　observed　at　a　pump　power　of　2　mW.　Such　a　high　performance　NCF　opens　a　window　for　applications　in　fiber-enhanced　spectroscopy,　biochemical　sensing　and　nano-plasmonics.