Light generator, in particular for conveying a microwave signal
AssigneeAlcatel
InventorsPatrick Brindel, Annaick Trotel
Life of this patent
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Abstract
A laser is biased in the vicinity of the bend in its characteristic curve. It also receives, in electrical form, a base wave applied to an input of the generator and a local wave provided by a local oscillator, and it mixes these waves by adding their frequencies so as to modulate the lightwave that it emits. The invention is particularly applicable to telecommunications systems.
Claims8
A light generator for conveying a microwave signal, the generator comprising a laser inside a package having a predetermined cut-off frequency, the laser being biased by a DC bias current close to a bend in a characteristic curve of the laser, the laser being controlled from outside the package by a plurality of AC control currents having respective individual frequencies which are lower than the predetermined cut-off frequency of the package, a linear combination of said individual frequencies establishing a transposed frequency higher than the cut-off frequency, the AC control currents being combined by the laser so as to modulate a lightwave emitted by the laser at the transposed frequency.
A light generator for conveying a microwave signal, said generator comprising:
- a semiconductor chip embodying a laser for emitting an amplitude modulated lightwave in response to bias and control currents, a characteristic curve of said laser defining the amplitude of said wave as a function of the sum of the currents applied thereto, said curve having a bend;
- a package for containing said chip, said package including electrical connection elements enabling said bias and control currents to be applied to said chip, said electrical connection elements having a package cutoff frequency beyond which the connection elements do not allow such a current to be applied;
- two AC control sources for simultaneously providing two individual electrical control currents at two individual frequencies, both of which are lower than said package cutoff frequency and each of which is applied to said chip via a respective electrical connection element of said package;
- and
- a DC bias source providing an electrical bias current that biases said laser to the vicinity of a bend in its characteristic curve, thereby giving the laser a non-linear characteristic whereby it mixes said two individual electrical control currents to modulate said lightwave with a transposed wave having a transposed frequency equal to a linear combination of the two individual frequencies.
Dependencies are inferred from the claim text.