Abstract: Exemplary methods for detecting substrate slippage include sweeping a first sensor and a second sensor of an in-situ monitoring system across the substrate as the substrate undergoes polishing with a rotatable platen. A first sequence of signal values from the first sensor and a second sequence of signal values from the second sensor include a signal strength relative to the thickness of the layer. For each signal value of at least some of the first sequence of signal values and second sequence of signal values, the method may include determining a first and second position on the substrate respective. The method may also include activating a slippage alert if: the signal strength varies by 30% or more from the first sequence of signal values to the second sequence of signal values, a position on the substrate for the second signal value cannot be determined, or a combination thereof.

Abstract: A wavelength division multiplexer (WDM) includes one or more lenses, a WDM filter, and multiple common, multiple reflected and multiple transmit optical fibers optically coupled to the one or more lenses. Light at a first wavelength propagates in either direction between one common optical fiber and one reflected optical fiber via the one or more lenses and the WDM filter, wherein the WDM filter reflects the light at a first wavelength during propagation in either direction between the common optical fiber and the reflected optical fiber. Light at a second wavelength propagates in either direction between the common optical fiber and one transmit optical fiber via the one or more lenses and the WDM filter, wherein the WDM filter passes the light at a second wavelength during propagation in either direction between the common optical fiber and the transmit optical fiber.

Abstract: An optical switch includes an array of optical fibers to conduct optical signals. A biconvex lens has a front convex surface facing the fibers' tips and has a back convex surface facing a microelectromechanical (MEMS) mirror. The MEMS mirror can be selectively oriented to reflect the optical signals incident to the MEMS mirror so the optical signal input from one fiber can be selectively routed to another of the fibers.

Abstract: A tunable laser comprising: a foundation including a first side and an oppositely facing second side and including a hole extending from the first side to the second side; a tuning assembly including a base, a fine tuning arm and a rotational flex bearing disposed adjacent the first side of the foundation; wherein the base is disposed adjacent to the first side of the foundation; wherein one end of the flex bearing is secured to the base; wherein the other end of the flex bearing is secured to the fine tuning arm; wherein a portion of the fine tuning arm extends at least partially into the hole; an external cavity laser including a gain medium, a dispersion medium and a reflective member disposed adjacent to the second side of the foundation; wherein the gain medium and the dispersion medium grating are secured in a fixed relation relative to the each other; wherein the reflective member is secured to the portion of the arm extending into the hole; and a piezoelectric device with one end secured to the base a