A spectral filter includes a curved filtering element including a concave surface forming a portion of a sphere. The concave surface may be positioned to receive light diverging from an output face of an optical fiber located at a first location proximate to a center of the sphere corresponding to the concave surface. The concave surface may transmit a first portion of a spectrum of the light. The concave surface may further reflect and focus a second portion of the spectrum to a second location proximate to the center of the sphere. The spectral filter may further include a collector to direct the second portion of the spectrum away from the output face of the optical fiber.