Pulsed laser device

Patent metadata

Field	Value
Publication number	US-10534128-B2
Application number	US-201715836023-A
Country	US
Kind code	B2
Filing date	Dec 8, 2017
Priority date	Jun 10, 2015
Publication date	Jan 14, 2020
Grant date	Jan 14, 2020

Abstract

A pulsed laser device includes: a semiconductor laser device that outputs laser light having a single wavelength; a semiconductor optical amplifier that receives the laser light output from the semiconductor laser device and amplifies the laser light to output; and a semiconductor-optical-amplifier driver that supplies a pulse-modulated semiconductor-optical-amplifier driving current to the semiconductor optical amplifier.

First claim

The invention claimed is:

1. A pulsed laser device comprising:
a semiconductor laser device that outputs laser light having a single wavelength;
a semiconductor optical amplifier that receives the laser light output from the semiconductor laser device and amplifies the laser light to output; and
processing circuitry configured to:
supply a pulse-modulated semiconductor-optical-amplifier driving current to the semiconductor optical amplifier by a semiconductor-optical-amplifier driver,
supply a pulse-modulated semiconductor-laser-device driving current to the semiconductor laser device, and the semiconductor-optical-amplifier driver, and
synchronize the pulse modulation of the semiconductor-laser-device driving current with the pulse modulation of the semiconductor-optical-amplifier driving current, by generating time waveforms for the pulse-modulated semiconductor-optical-amplifier driving current and the pulse-modulated semiconductor-laser-device driving current, wherein

a cycle of an ON state and an OFF state of the pulse-modulated semiconductor-optical-amplifier driving current and the pulse-modulated semiconductor-laser-device driving current are matched with each other, and the phase of the pulse modulation currents is such that when pulsed laser light output by the semiconductor laser device is input to the semiconductor optical amplifier, the driving current for the semiconductor optical amplifier in the ON state is supplied to the semiconductor optical amplifier, wherein
the pulse width is equal to or greater than 0.1 ns and less than 1 μs, and
the synchronization is performed by substantially matching temporal centers of the pulse widths.

2. The pulsed laser device according to claim 1 , wherein
a modulation pulse width of the semiconductor-laser-device driving current is greater than a modulation pulse width of the semiconductor-optical-amplifier driving current.

3. The pulsed laser device according to claim 1 , further comprising:
an optical fiber amplifier that receives the laser light output from the semiconductor optical amplifier and amplifies the laser light to output, wherein
the optical fiber amplifier includes an optical amplification fiber that has an optical amplification effect by simulated emission, and a pumping source that outputs pumping light to be supplied to the optical amplification fiber, and
the processing circuitry is further configured to supply a pulse modulated pumping-source driving current to the pumping source, synchronize the pulse modulation of the semiconductor-laser-device driving current, the pulse modulation of the semiconductor-optical-amplifier driving current, with pulse modulation of the pumping-source driving current.

4. The pulsed laser device according to claim 3 , wherein
a modulation pulse width of the pumping-source driving current is greater than the modulation pulse width of the semiconductor-laser-device driving current and the modulation pulse width of the semiconductor-optical-amplifier driving current.

5. The pulsed laser device according to claim 3 , wherein
the processing circuitry is further configured to synchronize the pulse modulation of the semiconductor-optical-amplifier driving current with the pulse modulation of the pumping-source driving current such that pulsed laser light output from the semiconductor optical amplifier is input to the optical fiber amplifier in a latter half of a period of a pumped state in the optical fiber amplifier.

6. The pulsed laser device according to claim 3 , wherein
the processing circuitry is further configured to synchronize the pulse modulation of the semiconductor-optical-amplifier driving current with the pulse modulation of the pumping-source driving current such that a pumped state in the optical fiber amplifier is turned into an OFF state at substantially a same time when a state of pulsed laser light output from the semiconductor optical amplifier becomes an OFF state.

7. The pulsed laser device according to claim 3 , wherein
the processing circuitry is further configured to perform control such that the modulation pulse width of the pumping-source driving current is longer than a relaxation time of the optical fiber amplifier.

8. The pulsed laser device according to claim 3 , wherein
the processing circuitry is further configured to perform control such that as the modulation pulse width of the pumping-source driving current decreases, the pumping-source driving current increases.

9. The pulsed laser device according to claim 3 , wherein
the processing circuitry is further configured to perform control such that when relaxation time of the optical fiber amplifier is longer than a period of an OFF state in pulses of the pumping-source driving current, a pumping-source driver supplies a pumping-source driving current of a direct current of a predetermined value to the pumping source.

10. The pulsed laser device according to claim 3 , further comprising:
an optical bandpass filter that is disposed in a subsequent stage of the optical fiber amplifier, and that selectively passes light having a wavelength of the laser light output from the semiconductor laser device.

11. The pulsed laser device according to claim 1 , further comprising:
an optical fiber amplifier that receives the laser light output from the semiconductor optical amplifier and amplifies the laser light to output.

12. The pulsed laser device according to claim 3 , further comprising:
a booster optical-fiber amplifier that is disposed in a subsequent stage of the optical fiber amplifier, and that receives the laser light output from the optical fiber amplifier and amplifies the laser light to output.

13. The pulsed laser device according to claim 12 , wherein
the booster optical-fiber amplifier includes an effective-mode cross-section expander that expands an effective-mode cross-sectional area of the received laser light, and an effective-mode cross-section expanding optical-amplification fiber that amplifies laser light that is expanded the effective-mode cross-section area, while propagating in a single mode in a state that the effective-mode cross-sectional area has been expanded.

14. The pulsed laser device according to claim 13 , wherein
the effective-mode cross-section expander converts a propagation mode of the received laser light propagated in a fundamental mode into a higher order mode, and the effective-mode cross-section expanding optical-amplification fiber amplifies the laser light in the higher order mode while propagating in the single mode.

15. The pulsed laser device according to claim 14 , wherein
the booster optical-fiber amplifier further includes an effective-mode cross-section reducer that converts the propagation mode of the laser light in the higher order mode that has been amplified by the effective-mode cross-section expanding optical-amplification fiber into the fundamental mode.

16. The pulsed laser device according to claim 13 , wherein
the effective-mode cross-section expander converts a propagation mode of the received laser light propagated in a fundamental mode of the optical fiber into a multimode, and
the effective-mode cross-section expanding optical-amplification fiber leaks components of a higher order mode out of the laser light in the multimode, and amplifies components of the fundamental mode while propagating in the single mode.

17. The pulsed laser device according to claim 1 , further comprising:
a plurality of semiconductor laser devices that output laser light beams having wavelengths different from each other; and

Assignees

• Furukawa Electric Co Ltd

Inventors

• Otani Eisuke

Classifications

• H01S3/1024

  for pulse generation · CPC title

• H01S3/0677

  L-band amplifiers, i.e. amplification in the range of about 1560 nm to 1610 nm · CPC title

• H01S5/4031

  Edge-emitting structures · CPC title

• H01S5/4012

  Beam combining, e.g. by the use of fibres, gratings, polarisers, prisms · CPC title

• H01S3/06758

  Tandem amplifiers · CPC title