A broadband light source device (100) for creating broadband light pulses (1) comprises a hollow-core fiber (10) of non-bandgap type including a filling gas and being arranged for creating the broadband light pulses (1) by an optical nonlinear broadening of pump laser pulses (2), wherein the hollow-core fiber (10) has an axial hollow light guiding fiber core (11), which supports core modes of a guided light field, and an inner fiber structure (12), which surrounds the fiber core (11) and which supports transverse wall modes of the guided light field, and a pump laser source device (20) being arranged for creating and providing the pump laser pulses (2) at an input side (13) of the hollow-core fiber (10), wherein the transverse wall modes include a fundamental transverse wall mode and second and higher order transverse wall modes, the broadband light pulses (1) have a core mode spectrum being determined by a fiber length, a fiber core diameter, at least one pump pulse and/or beam parameter of the pump laser pulses (2) and at least one gas parameter of the filling gas, and the inner fiber structure (12) of the hollow-core fiber (10) is configured such that at least the second and higher order transverse wall modes and the core mode spectrum have a spectral displacement relative to each other. Furthermore, a method of creating broadband light pulses is described.