Importance

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Abstract

A method and apparatus are presented for a tunable device for measuring the optical spectrum of a DWDM signal on a per channel basis. The device is an InP-semiconductor based tunable ring resonator. In a preferred embodiment the typical size of the chip is approximately 250.mu.m.times.250.mu.m. The three main sections of the device comprise a straight input passive waveguide, a straight output absorbing waveguide, and a tunable ring resonator. The ring resonator sets up a wavelength selective resonant cavity, allowing measurement of OP and OSNR across the free spectral range of the device, centered at a nominal service wavelength. In the preferred embodiment, the device can measure the OP and OSNR of an arbitrary demultiplexed DWDM signal, with a measurement time of approximately 225 microseconds. Inasmuch as the device is simply measuring optical performance parameters within a particular frequency (i.e. wavelength) range, the bit rate, format, and any other protocol based or organizational structures are irrelevant to the spectrum analysis. Thus the invention is fully bit-rate and format insensitive, allowing repeated use of the same device throughout the network, including in parallel arrays.

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First Claim