Method and apparatus for determining transmission wavelengths for lasers in a dense wavelength division multiplexer

A system for calibrating a laser comprising:

• means for routing an output beam from the laser through an etalon while tuning the laser through a range of discrete laser tuning parameters where said laser tuned parameters are selected from the group consisting of current, voltage, and temperature to produce an etalon transmission spectrum;
• means for routing an output beam from the laser through a gas cell having a gas absorption spectrum of a gas of known light absorbing characteristics while tuning the laser through the range of discrete laser tuning parameters to produce a gas absorption spectrum;
• means for detecting and storing peaks of the etalon transmission spectrum and the gas absorption spectrum;
• and
• means for comparing the stored detected etalon transmission spectrum with the detected gas absorption spectrum to determine the absolute transmission wavelength of the laser, thereby providing references for precisely tuning the laser.

A system for calibrating a laser, the system comprising:

• an etalon;
• a gas absorption cell containing a gas of known light absorption characteristics;
• a waveguide for routing an output beam from the laser through the etalon and through the gas cell;
• a control unit tuning the laser through a range of discrete laser tuning parameters where said laser tuned parameters are selected from the group consisting of current, voltage, and temperature while the output beam from the laser is routed through the etalon and through the gas cell to produce an etalon transmission spectrum and to produce a gas absorption spectrum;
• a detector for detecting and storing peaks of the etalon transmission spectrum and the gas absorption spectrum;
• and
• an absolute transmission wavelength determination unit operative to compare the stored detected etalon transmission spectrum with the stored detected gas absorption spectrum to determine the absolute transmission wavelength of the laser as a function of the laser tuning parameters, thereby providing references for precisely tuning the laser.

A method for calibrating a laser using an automatically-tunable etalon and a gas cell having a known gas, said method comprising the steps of:

• calibrating absolute transmission wavelengths of the laser using etalon transmission lines of the automatically-tunable etalon and gas absorption lines for the known gas in the gas cell;
• tuning the laser to align a selected transmission wavelength of the laser to a known telecommunications transmission wavelength;
• tuning the etalon with a microcontroller to align a transmission line of the etalon to the selected transmission wavelength;
• detecting any drift between the tuned etalon transmission line and the selected transmission wavelength;
• and
• re-tuning the laser to compensate for any drift between the tuned etalon transmission line and the selected transmission wavelength to thereby lock a wavelength of an output beam of the laser to the selected transmission wavelength.