We fabricated an all-fiber, low implementation cost, coupler type wavelength selective optical add/drop filter for dense wavelength division multiplexing (DWDM) applications. We saw that grating strength was dependent on the coupling length of the 2x2 fused optical fiber coupler. Reflection and transmission spectra of the grating on the coupler were measured using amplified spontaneous emission (ASE) of the erbium doped fiber amplifier (EDFA) and an optical spectrum analyzer (OSA). The measurements at the drop port showed insertion losses of 17 dB and 22 dB for coupling lengths of 8.5 mm and 17.9 mm, respectively. And -1 dB bandwidths for those losses were 0.74 and 0.2 nm, respectively. Measurements at the output port show 8 dB and 0.3 dB of transmitted channel extinction ratios at the same Bragg wavelengths as the above.
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