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US 9,853,411 B2Granted
Pulsed bias current for gain switched semiconductor lasers for amplified spontaneous emission reduction
AssigneenLIGHT, Inc.
InventorsTimothy S. McComb, Dennis McCal
Life of this patent
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Abstract
Gain switched laser diode pulses are used as seed pulses for optical pulse generation. ASE is reduced by applying a prebias to the laser diodes at an amplitude less than that associated with a laser diode threshold. An electrical seed pulse having an amplitude larger than that associated with laser threshold is applied within about 10-100 ns of the prebias pulse. The resulting laser diode pulse can be amplified in a pumped, rare earth doped optical fiber, with reduced ASE.
Claims19
A seed laser source, comprising:
- a laser diode;
- and
- a laser diode driver configured to apply a pulsed laser drive signal to the laser diode, wherein the laser drive signal is coupled to provide:
- a seed signal comprising a first seed pulse to the laser diode, the first seed pulse having an amplitude greater than a laser diode threshold amplitude, and
- a corresponding prebias signal comprising a first prebias pulse having a duration in excess of 2 ns and an amplitude less than the laser diode threshold throughout the duration, and that is applied within about 50 ns of the first seed pulse, and wherein:
- the amplitude of the first seed pulse is at least 10 times the laser diode threshold amplitude, and
- the laser diode driver is configured so that the first prebias pulse terminates prior to the first seed pulse, such that the first seed pulse is not applied during the duration of the first prebias pulse.
4 more elements
A method, comprising:
- establishing optical gain in a laser gain medium;
- producing an optical seed pulse by applying a prebias pulse signal to a laser diode, and a corresponding seed pulse signal to the prebiased laser diode, wherein the prebias pulse signal has a duration of at least 100 ns, and an amplitude that is less than 0.5 times a laser diode threshold throughout the duration and terminates prior to the application of the corresponding seed pulse signal, such that the seed pulse signal is not applied during the duration of any preceding prebias pulse signal;
- and
- producing at least one optical pulse from the laser gain medium in response to the optical seed pulse.
1 more element
A system for producing optical pulses, comprising:
- a laser diode;
- a laser diode drive source configured to repetitively apply a prebias pulse signal and a corresponding seed pulse signal to the laser diode to produce a seed laser pulse, wherein the prebias pulse signal has a duration in excess of 2 ns and an amplitude that is less than a laser diode threshold throughout the duration, and wherein the prebias pulse signal terminates prior to application of the corresponding seed pulse signal, such that the seed pulse signal is not applied during the duration of any preceding prebias pulse signal;
- a doped optical fiber situated to receive the seed laser pulse;
- and
- at least one pump laser configured to couple a pump laser beam to the doped optical fiber so as to produce optical gain in the doped optical fiber.
2 more elements
A method, comprising:
- repetitively applying a seed signal to a seed laser diode so as to produce seed pulses;
- amplifying the seed pulses with a fiber amplifier;
- repetitively applying a prebias pulse signal to the seed laser diode prior to application of the seed signals, wherein a duration and amplitude of the prebias pulse signal are selected so as to control amplified spontaneous emission, wherein the prebias pulse signal is modulated between zero and an amplitude that is less than a seed laser diode threshold, and wherein each application of the prebias pulse signal terminates prior to the next application of the seed signal such that a given seed pulse is not produced during the duration of a prior application of the prebias pulse signal.
Dependencies are inferred from the claim text.