Appeal No. 2007-0400
Application 10/788,054
(col. 6, ll. 54-58), while a “Detector 2” (114) provides the control input for the grid
positioning control loop 226 (col. 7, ll. 5-7). Figure 3 shows a transmitter having
“n” lasers and a pair of such detectors for each laser. Specifically, this figure
shows a common etalon (312), a common gas-filled reference cell (308), a plurality
of lasers (#1 to #n), and, associated with each laser, a pair of photodiodes (314,
332) corresponding to detectors 114 and 132 of Figure 1.
Figure 5 is a flow chart showing the operation of the control of the laser path
through its optical components (col. 9, ll. 34-35). When an active laser 502 fails,
the detector 514 senses the failure and notifies the microprocessor/controller 530 of
the failed comb number (col. 11, ll. 9-11). The microprocessor/controller then
initializes a spare laser 504 to the properties of the failed laser 502, which are
found in a lookup table (col. 11, ll. 13-15). The spare laser 504 is then tuned to the
wavelength of the failed channel 502 and the modulated signal is vectored to the
spare laser (col. 11, ll. 15-18). This can be accomplished by switching the laser
modulation signal electronically to modulate the spare laser instead of the failed
laser (col. 13, ll. 34-36).
Figure 6 shows a low-cost implementation using discrete optical elements
mounted on a silicon optical micro-board 642 (col. 11, ll. 47-49). Gas cell 608 and
etalon plate 612 correspond to elements 208 and 212 in Figure 2 and are common
to all of the lasers, of which only one is depicted in Figure 6 together with its
associated lenses 606 and 620 (col. 11, ll. 49-50).2 Likewise, the only photodiodes
2 The reference appears to be incorrect in stating that “[g]as cell 608 and
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