| 摘要 |
The present invention provides a cost-effective method and apparatus for optical frequency modulation (FM) characterization of a laser source and provide a measure of laser chirp by using inexpensive equipment that is readily available. In order to measure the chirp, the invention makes use of interferometry without resorting to expensive and bulky equipment such as optical network or optical spectrum analyzers.In a preferred embodiment, the chirp characteristic of a laser source is measured by injecting an input signal at a particular modulation frequency into the laser source under test to generate an optical signal and passing the optical 15 signal generated into an asymmetrical Mach Zehnder interferometer (AMZI). Because the AMZI exhibits a cyclical wavelength to photo-current response, a number of high frequency ripples or interference ripples are introduced in the optical signal. According to the invention, the interference ripples introduced within a half modulation period of the laser input signal are counted to provide a measure of the approximate chirp amount on the modulated frequency.
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