The invention discloses a cutting assembly for use in a hair cutting device (100), the cutting assembly comprising an optical waveguide (102) having a sidewall, wherein a portion of the sidewall forms a cutting face for contacting a hair; and a movement mechanism (108) for effecting movement of the optical waveguide relative to the hair, in a direction substantially parallel to an optical axis of the optical waveguide (102). The invention also discloses a cutting assembly for use in a hair cutting device, the cutting assembly comprising an optical waveguide (102) having a sidewall, wherein a portion of the sidewall forms a cutting face for contacting a hair; a hair support for supporting the hair relative to the optical waveguide; and a movement mechanism (108) for effecting movement of the hair support relative to the optical waveguide (102), in a direction substantially parallel to an optical axis of the optical waveguide. A hair cutting device (100) is also disclosed.