Apparatus for polarization-independent optical polarization scrambler and a method for use therein

A method for use in an optical scrambler (5) which scrambles a state of polarization (SOP) of light entering the scrambler, at an optical input (1), to yield a scrambled SOP of said light as it exits the scrambler at an optical output (9), the scrambler having:

• a plurality of optically cascaded piezoelectric tubes (PZTs) (10), wherein each of said tubes is optically interconnected to a next successive one of the tubes through a corresponding device (30a) that provides optical birefringence so as to define at least one corresponding device, such that the light serially propagates from the optical input through the associated fiber wrapped around each of said PZTs and the at least one corresponding device to said optical output, wherein each of the PZTs is driven by a corresponding electrical drive signal and has an associated optical fiber wound around said each PZT such that said each PZT exhibits time-varying physical displacement in response to the corresponding drive signal thereby inducing variable birefringence in the optical fiber wrapped around said each PZT;
• and
• first and second drive circuits (20) connected to first and second different corresponding ones of the PZTs for supplying first and second drive signals to the first and second PZTs, respectively;
• wherein the method comprises the steps of:
• generating through the first drive circuit (20a) a first-time varying signal, as the first drive signal, wherein the first drive signal comprises a modulated signal having both frequency and amplitude variations;
• and
• generating in the second drive circuit (20d), as the second drive signal, a second time-varying signal which is independent of the first drive signal, wherein the second drive signal comprises a substantially fixed frequency and a substantially fixed amplitude.

The method in claim 20 wherein one of the first drive signals exhibits either substantially the same or different frequency or amplitude variations as at least another one of the first drive signals.

• 22.The method in claim 21 further comprising the steps, in each of the first drive circuits, of:
• generating a fundamental frequency signal;
• and
• either:
• modulating the fundamental frequency by:
• frequency modulating the fundamental frequency so as to generate a frequency modulated (FM) signal;
• and
• amplitude modulating the frequency modulated signal so as to generate a resulting signal;
• or
• modulating the fundamental frequency by:
• amplitude modulating the fundamental frequency so as to generate an amplitude modulated signal;
• and
• frequency modulating the amplitude modulated signal to generate a resulting signal;
• and
• amplifying the resulting signal so as to yield the corresponding different one of the first drive signals.