Abstract:
L'invention a pour objet un procédé de mesure de la modulation de fréquence f(t) d'une source laser qui comprend les étapes suivantes : - modulation de la source laser selon une période T, par une commande de modulation, - au cours d'une même période T, réalisation de plusieurs mesures d'une intensité lumineuse de battement entre deux bras d'un interféromètre situé en aval de la source laser et apte à introduire un retard τ entre les deux bras, ces mesures étant synchronisées avec la commande de la modulation, - calcul de la fréquence f(t) à partir des mesures, - pendant chaque période T, f(t) varie mais le retard τ est considéré constant, - le retard τ évolue temporellement sur plusieurs périodes T, - les mesures effectuées à l'instant t i au cours d'une même période sont réitérées à t i +k T, avec k≥1 et en ce que le retard τ a évolué d'une itération à l'autre.
Abstract:
The present document relates to optical transmission systems. In particular, the present document relates to a system and method enabling the coexistence of tunable and non-tunable Optical Network Units (ONUs) in a passive optical network (PON), e.g. a wavelength division multiplexing (WDM) PON. A media access controller for a passive optical network (200) is described. The passive optical network (200) comprises a first optical line terminal (201) with a receiver for a first wavelength range; a second optical line terminal (202) with a receiver for a second wavelength range, adjacent to the first wavelength range; and an optical network unit (101) with a transmitter having a transmitter wavelength which drifts between the first and the second wavelength range. The media access controller is adapted to assign the optical network unit (101) to the first (201) and the second (202) optical line terminal, such that an optical burst transmitted by the optical network unit (101) is received by the first optical line terminal (201) and the second optical line terminal (202).
Abstract:
Method for calibrating a tunable semiconductor laser (121;10) comprising at least a phase section (12) and at least a first Bragg reflector section (14a,14b), through which sections a phase current and a first reflector current, respectively, is applied, which laser (121;10) is not actively temperature stabilized, said method comprising the steps of a)selecting a phase current;b)identifying a range (203) of reflector currents that achieves emission of light from the laser (121;10) within a desired frequency band of operation;c) scanning the reflector current or currents over the range (203) of reflector currents, for each of at least two different phase currents, and reading the relative output power of the laser (121;10) for each point scanned; d) identifying at least one stable operating point (302);e)identifying and storing into a memory at least one stable, continuous tuning line (305) as constructed by interpolating between neighboring stable operating points (302);f)calibrating the laser frequency by scanning along said identified tuning line (305) and observing a fed back signal (113) from a target (110) for the light emitted from the laser (121;10);g)measuring the temperature of the laser (121;10) when step f) was conducted; and h)storing into the memory the temperature of the laser (121;10) and at least one operating point along the tuning line (305) indicative of the target frequency range.
Abstract:
A structure and method that can be used to achieve selective etching in (Ga,A1,In,B)N laser diodes, comprising fabricating (Ga,A1,In,B)N laser diodes with one or more Al-containing etch stop layers.
Abstract:
In accordance with one embodiment of the present disclosure, a method of evaluating the operating characteristics of a DBR laser diode is provided. According to the method, a diagnostic electrical current (II)is injected into the wavelength tuning section of the DBR laser to generate amplified spontaneous emission (ASE) of light in the wavelength tuning section. Light emitted from the wavelength tuning section is absorbed by the gain section and photo current (ISAIN) generated by the light absorbed in the gain section is measured. The photo current (ISAIN) measured in the gain section can be correlated with an evaluation of the operating characteristics of the DBR laser diode. For example, the measured photo current (ISAIN) can be correlated with a substandard operating characteristic when it departs from a given photo current metric by more than an acceptable amount. Alternatively, the measured photo current (ISAIN) can be correlated with a certified operating characteristic when it departs from the given photo current metric by an acceptable amount. Additional embodiments are disclosed and claimed.
Abstract:
A system for controlling optical-power stability of emitting laser diodes (204), the laser diodes exhibiting temperature changes at the laser diode junctions (312), the temperature changes are predicted according to the laser diodes duty cycle. The system includes, a laser diodes arranged to emit light on a target (14); a data stream analyzer (408) configured to receive incoming data stream (324) analyze the data and produce an image data occurrence factor of larger than zero values (424) representing the data in the incoming data stream (324); and an optical power stabilizer (412) configured to control current intensity (428) applied on a laser diode according to the image data occurrence factor (424).