A fluorescence detection system is provided. The fluorescence detection system includes a light source adapted to emit excitation light; a sample unit in which a sample is disposed; a first optical fiber adapted to connect the light source to the sample unit; an avalanche photodiode array detector adapted to receive fluorescent light generated by the sample when the sample is irradiated with the excitation light; and a second optical fiber adapted to connect the sample unit to the avalanche photodiode array detector, wherein the second optical fiber has a numerical aperture of equal to or greater than about 0.15 and the second optical fiber is positioned such that a longitudinal axis of the second optical fiber is orthogonal to a longitudinal axis of the first optical fiber. A method for detecting fluorescence and a computer-implemented method for detecting fluorescence are also provided.