According to one embodiment, an optical filter has a polarization rotator and two instances of an optical bandpass filter (OBPF). The first instance of the OBPF processes a TE-polarized component of an optical input signal to produce a first filtered signal. The polarization rotator then transforms the TE polarization of the first filtered signal into the TM polarization. The polarization rotator also transforms the polarization of a TM-polarized component of the optical input signal into the TE polarization. The second instance of the OBPF processes the resulting TE-polarized signal to produce a second filtered signal. The first and second filtered signals having TM and TE polarizations, respectively, are then combined to produce a filtered output signal.