We show that a crystalline lithium niobate (LiNbO3 : LN) grism and a hybrid grism made of a LN transmission grating and a zinc sulfide (ZnS) prism, in spite of their birefringent properties, can be used as new and powerful dispersing elements with high refractive indices to realize high spectral resolution for optical to near infrared astronomical spectrograph with transmission optics. We also show new fabricating methods for grisms and immersion gratings with high index material and deep grooves.