Apparatus and method for wavelength-locked loops for systems and applications employing electromagnetic signals

A wavelength-locked loop servo-control circuit that enables real time mutual alignment of an electromagnetic signal having a peaked spectrum function including a center wavelength and a tunable wavelength selective device implementing a peaked passband function including a center wavelength, in a system employing electromagnetic waves, said circuit comprising:

• mechanism for applying a dither modulation signal at a dither modulation frequency to said tunable wavelength selective device, said tunable wavelength selective device further receiving an electromagnetic signal having a center wavelength and generating a dither modulated optical signal for output thereof;
• mechanism for converting a portion of said dither modulated electromagnetic signal to an electric feedback signal;
• mechanism for continuously comparing said feedback signal with said dither modulation signal and generating an error signal representing a difference between a frequency characteristic of said feedback signal and a dither modulation frequency;
• and
• mechanism for adjusting a passband center wavelength of said tunable wavelength selective device according to said error signal, wherein said center wavelength of said electromagnetic signal and said tunable wavelength selective device center wavelength become aligned when said frequency characteristic of said feedback signal is two times said dither modulation frequency.

A method for mutually aligning a center wavelength of an electromagnetic signal of having a peaked spectrum function with a center wavelength of a wavelength selective device implementing a peaked passband function, in a system employing electromagnetic waves, said method comprising the steps of:

• a) applying a dither modulation signal at a dither modulation frequency to said electromagnetic signal operating at a specific wavelength, and inputting said dither modulated electromagnetic signal to said wavelength selective device having a peak frequency response at a desired wavelength;
• b) converting a portion of said dither modulated electromagnetic signal to an electric feedback signal;
• c) continuously comparing said feedback signal with said dither modulation signal and generating an error signal representing a difference between a frequency characteristic of said feedback signal and a dither modulation frequency;
• and
• d) adjusting the peak spectrum function of said electromagnetic signal according to said error signal, wherein said center wavelength of said electromagnetic signal and said wavelength selective device center wavelength become aligned when said frequency characteristic of said feedback signal is two times said dither modulation frequency.

A method for mutually aligning a center wavelength of an electromagnetic signal of having a peaked spectrum function with a center wavelength of a wavelength selective device implementing a peaked passband function, in a system employing electromagnetic waves, said method comprising the steps of:

• a) applying a dither modulation signal at a dither modulation frequency to said tunable wavelength selective device, said tunable wavelength selective device further receiving an electromagnetic signal having a center wavelength and generating a dither modulated electromagnetic signal for output thereof;
• b) converting a portion of said dither modulated electromagnetic signal to an electric feedback signal;
• c) continuously comparing said feedback signal with said dither modulation signal and generating an error signal representing a difference between a frequency characteristic of said feedback signal and a dither modulation frequency;
• and
• d) adjusting a passband center wavelength of said tunable wavelength selective device according to said error signal, wherein said center wavelength of said electromagnetic signal and said tunable wavelength selective device center wavelength become aligned when said frequency characteristic of said feedback signal is two times said dither modulation frequency.

A servo-control circuit for tuning a laser signal generator providing an optical signal at a specified wavelength in an optical system, said optical system including a bandpass filter device for receiving and transmitting optical signals in said optical system at a desired wavelength, said servo-control system comprising:

• device for applying a bias signal to said laser signal generator for tuning said optical signal to a specific wavelength;
• device for applying a dither modulation to said bias signal to produce a dither modulated optical signal, said dither modulated optic signal being input to said bandpass filter device;
• detector device for receiving said dither modulated optical signal output from said bandpass filter device and converting said received optical signal into an electrical feedback signal;
• and,
• device for continuously comparing frequency characteristics of said converted feedback signal against frequency characteristic of a dither modulation signal and generating an error signal therefore, said error signal responsively modifying the bias signal until a predetermined relation exists between a frequency characteristic of said converted feedback signal and a dither modulation frequency, whereby when said predetermined relation exists, said wavelength of said optical signal exactly matches the desired wavelength of said wavelength selective device.

A servo-control circuit for tuning a tunable wavelength selective device capable of receiving and transmitting optical signals of a desired wavelength in an optical system, said servo-control system comprising:

• mechanism for applying a dither modulation signal at a dither modulation frequency to said tunable wavelength selective device, said tunable wavelength selective device further receiving said optical signal having a center wavelength and generating a dither modulated optical signal for output thereof;
• mechanism for converting a portion of said dither modulated optical signal to an electric feedback signal;
• mechanism for continuously comparing said feedback signal with said dither modulation signal and generating an error signal representing a difference between a frequency characteristic of said feedback signal and a dither modulation frequency;
• and
• mechanism for adjusting a passband center wavelength of said tunable wavelength selective device according to said error signal until a predetermined relation exists between a frequency characteristic of said converted feedback signal and said dither modulation frequency, whereby when said predetermined relation exists, said desired wavelength of said wavelength selective device exactly matches a wavelength of said input optical signal.

A method for tuning a laser signal generator providing an optical signal at a specified wavelength in an optical system, said optical system including a bandpass filter device for receiving and transmitting optical signals in said optical system at a desired wavelength, said method comprising the steps of:

• a) applying a bias signal to said laser signal generator for tuning said optical signal to a specific wavelength;
• b) applying a dither modulation to said bias signal to produce a dither modulated optical signal, said dither modulated optic signal being input to said bandpass filter device;
• c) converting said received optical signal into an electrical feedback signal;
• and,
• d) continuously comparing frequency characteristics of said converted feedback signal against a frequency characteristic of a dither modulation signal and generating an error signal therefore, said error signal responsively modifying the bias signal until a predetermined relation exists between a frequency characteristic of said converted feedback signal and dither modulation frequency, whereby when said predetermined relation exists, said wavelength of said optical signal exactly matches the desired wavelength of said wavelength selective device.