Applied Fiber Optics, Inc.

Peter Zupei Chen

A structure and method are provided to compensate for temperature changes on wavelength shifting in DWDM by reducing tension in a fused-fiber DWDM when temperature increases and increasing tension when temperature decreases, thereby stabilizing wavelength shifts throughout the range of operating temperatures. The DWDM, which is enclosed by a protective package in some embodiments, is connected to substrates of different thermal expansion coefficients, such that the fused-fiber portion of the DWDM exhibits negative thermal expansion, i.e. contracts when temperature increases and expands when temperature decreases. As a result, temperature-induced wavelength shifts are minimized due to a passive thermal compensation, which can be easily adjusted. In other embodiments, twisting the fused-fiber portion of the DWDM to obtain optimum phase matching minimizes the polarization-dependent losses in the incoming light.

Thermal compensated fused-fiber dense wavelength division multiplexer

A structure and method are provided to improve stability and performance of multiplexers in dense WDM applications. A wavelength division multiplexer (WDM) utilizing an unbalanced Mach-Zehnder Interferometer has first and second fused-fiber couplers cascaded together by two optical connecting fibers having different optical path lengths. The different path lengths can be attained with connecting fibers of two different lengths or two different refractive indexes. In some embodiments, a portion of a fiber with a different refractive index than either or both connecting fibers is fuse-spliced between a connecting fiber to provide the path length difference. Tension can be applied to the fused-fiber multi-window WDM to obtain the desired passband prior to mounting the WDM within a supporting substrate for protection. A passive thermal compensation technique can be used to minimize the thermal effect on the passband wavelengths for dense WDM applications.

Fused-fiber multi-window wavelength division multiplexer using an

The present invention relates to an apparatus and method of making a Dense Wavelength-Division Multiplexer (DWDM) using a Fused-Biconical Taper ('FBT') technique. The DWDM according to the present invention comprises a multiple of Multi-window Wavelength-Division Multiplexers ('MWDMs') which cascade together in several stages, each stage has several MWDMs having an identical window spacing. For a N-channel DWDM, there are 2.sup.m-1 MWDMs cascaded in m-th stage, and the window spacing of the m-th stage MWDMs is 2.sup.m-1 .DELTA..lambda., where m is from 1 to (logN/log2), for example, the first stage(m=1) having 1 MWDM and the window spacing is .DELTA..lambda., the second stage(m=2) having 2 MWDMs and the window spacing is 2.DELTA..lambda., the third stage(m=3) having 4 MWDMs and the window spacing is 4.DELTA..lambda., etc., and the (logN/log2)-th stage has (N/2) MWDMs with a window spacing (N/2).DELTA..lambda.. The number N could be 2, 4, 8, 16 or more.

Apparatus and method of making a fused dense wavelength-division

The present invention relates to an apparatus and method of making a Dense Wavelength-Division Multiplexer (DWDM) using a Fused-Biconical Taper ('FBT') technique. The DWDM according to the present invention comprises a multiple of Multi-window Wavelength-Division Multiplexers ('MWDMs') which cascade together in several stages, each stage has several MWDMs having an identical window spacing. For a N-channel DWDM, there are 2.sup.m-1 MWDMs cascaded in m-th stage, and the window spacing of the m-th stage MWDMs is 2.sup.m-1 .DELTA..lambda., where m is from 1 to (logN/log2), for example, the first stage (m=1) having 1 MWDM and the window spacing is .DELTA..lambda., the second stage (m=2) having 2 MWDMs and the window spacing is 2 .DELTA..lambda., the third stage(m=3) having 4 MWDMs and the window spacing is 4.DELTA..lambda., etc., and the (logN/log2)-th stage has (N/2) MWDMs with a window spacing (N/2).DELTA..lambda.. The number N could be 2, 4, 8, 16 or more.

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Fremont, CA, United States of America

Peter Zupei Chen