Wavelength Division Multiplexed (WDM) based broadband fiber optic networks offer an attractive approach to achieve extremely high throughputs while employing moderate speed electronics. Passive optical filters play a crucial role in such networks serving the function of combining and separating multiple wavelengths. Single and multiple cavity F-P filters are analyzed with particular emphasis on their bandwidth and tuning range. Fabry-Perot (F-P) filter tuning commonly employs piezoelectric techniques. A new tuning technique based on a F-P filter fabricated with a fiber having an electro-optic cladding is proposed. A novel F-P filter structure employing optical feedback is proposed and analyzed. The application of F-P filters in an incoherent multiwavelength star network and the associated concerns involving crosstalk and dispersion are evaluated. A comparative error performance analysis of one and two F-P filter receivers in a BFSK transmission system is performed. An overview of numerous multiwavelength network and switch proposals along with their associated merits and demerits is given.