A polarization independent electrooptic add/drop tunable filter fabricated on a
LiNbO3 substrate with a narrow -3 dB bandwidth (FWHM) of 1.56 nm operating in the
1.55 üm wavelength regime has been developed to meet the demands of fast tuning
speed and increased channel capacity for dense wavelength division multiplexed
(WDM) networks. The operation of the filter is based on passive polarization beam
splitters and strain-induced phase-matched TEâÂÂTM polarization mode converters.
Extinction ratios as high as 20 dB for polarization beam splitters were achieved using
zero-gap two-mode interference directional couplers with an opening angle of 0.55ð. A
tunable TEâÂÂTM polarization mode converter with 98.2 % conversion efficiency was
obtained using a strain-induced refractive index grating consisting of 765 parallel strips
10.5 üm wide in a strained SiO2 surface film with a spatial period of 21 üm. Thermal and
electrooptic tuning of the polarization mode converters were examined. A polarization
independent electrooptic add/drop tunable filter in which the fabrication parameters of
the splitter and the mode converter were optimized was produced. Fiber-to-fiber
insertion loss less than 6.3 dB was measured on a 62 mm long filter device. The spectral characteristics reveal a -3 dB bandwidth of 1.56 nm and nearest sidelobes about 12 dB
below the center peak. A thermal tuning rate of -0.903 nm/ðC was realized. Electrooptic
tuning was also demonstrated. A tuning range of 14.08 nm with applied DC voltages
from -80 V to +80 V was achieved indicating an electrooptic tuning rate of 0.086 nm/V.
The filter performance for both TE and TM modes was examined and polarization
independence of the spectral characteristics was confirmed.
| Identifer | oai:union.ndltd.org:tamu.edu/oai:repository.tamu.edu:1969.1/5858 |
| Date | 17 September 2007 |
| Creators | Kuo, Hsin-Hui |
| Contributors | Taylor, Henry F. |
| Publisher | Texas A&M University |
| Source Sets | Texas A and M University |
| Language | en_US |
| Detected Language | English |
| Type | Book, Thesis, Electronic Dissertation, text |
| Format | 1128895 bytes, electronic, application/pdf, born digital |
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