Patent ID: 6385372
Filing Date: 2002-05-07
Classification: G02B

Abstract:
A method for producing a stable fiber optic coupler of two or more lines, the method comprising:positioning a selected section, having a selected length d, of at least two fiber optic lines, referred to as â€œFO linesâ€ , contiguous to each other and parallel to a selected alignment axis; heating a selected central section of the FO lines to a first temperature T1 within a selected first temperature range for a first time interval of selected temporal length &Dgr;t1; elongating the central section of the FO lines to a selected fractional elongation increment f lying in a selected fractional elongation range for a second time interval of a selected temporal length &Dgr;t2, where the first and second time intervals may overlap; providing a selected input signal having at least a first selected wavelength component &lgr;1 and a second wavelength component &lgr;2, and providing a measurement of signal power output in at least one of the FO lines in response to the input signal at each of the wavelengths &lgr;1 and &lgr;2, where &lgr;1 and &lgr;2 are chosen to approximately correspond to two consecutive local minima in signal power output, with &lgr;2>&lgr;1; where &lgr;1 is greater than a selected wavelength value &lgr;1 (ITU), performing at least one of the following processes: elongating the central section of the FO lines to a selected fraction elongation increment f1 for a third time interval of selected temporal length &Dgr;t3; and heating the central section of the FO lines to a selected second temperature T2 within a selected second temperature range for a fourth time interval of selected temporal length &Dgr;t4; where &lgr;1 is less than the selected wavelength value &lgr;1 (ITU), reducing the fractional elongation increment to a selected increment f25; and heating the central section of the FO lines to a selected third temperature T31 for a sixth time interval of selected temporal length &Dgr;t6, whereby the FO lines in at least part of the central section fuse to provide a fiber optic coupler having at least two output lines for electromagnetic signals.