2N\u22121 four-terminal phase-reversing switches are arranged in one or more columns of cascaded switches, wherein a frequency having a given relative phase \u03c6 is applied as an input of the top switch in a cascade. The delay interferometer has a free spectral range that is larger than a symbol rate of the phase modulated optical signal by an amount that improves receiver performance. The cookware may comprise a permanent magnet disposed on or in the base of the cookware. Through the monitor, service calls are received from the respective system under test.