JPS6022638Y2 - High power optical pulse generator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a high-output optical pulse generator capable of obtaining high output by amplifying the output light of a semiconductor laser.

Semiconductor lasers such as InGaAsP/InP can oscillate in the wavelength band of 1.2 to 1.6 μm, which allows ultra-low loss optical fibers to be obtained, and are used as light sources for optical fiber communications.

In optical fiber communications, high-power optical pulses in the oscillation wavelength range of semiconductor lasers are required for inspection and diagnosis purposes such as detection of break points in optical fiber transmission lines.

However, since the active region of a semiconductor laser is extremely small, the laser output that can be used without optical damage is small, so the optical pulse obtained from the semiconductor laser alone is
The output is often insufficient for inspection and diagnosis of optical fiber transmission lines, etc.

On the other hand, a pulsed solid-state laser such as a Q-switched Nd:YAG laser can achieve a high peak output of several tens of kilowatts or more, but this oscillation line is, for example, 1.06 KW or more.
There are only a few discrete fibers in the μm band and 1.3 μm band, and the 1.2 to 1.6 μm required for optical fiber communication.
It is not possible to sufficiently cover the wide wavelength range of the m band.

By the way, recently, a single mode optical fiber has been used to
A method has been developed in which stimulated Raman scattered light is generated by excitation with a switched YAG laser, and optical pulses are generated in a wide wavelength range on the long wavelength side of the excitation wavelength.

Regarding the configuration and performance of this type of optical pulse generator,
For example, the technical magazine Optics Communications (O
PTIC3 COMMUNICAT1ONS) 2nd call, 426-42
CHINLON LIN on page 8
“Near-infrared light source in the 1-1.3 μm region using highly efficient stimulated Raman scattering in glass fiber” by Mr. et al.
It is discussed in detail in the paper titled.

However, the stimulated Raman scattered light obtained from this optical fiber has a wide spectrum, so if only the desired wavelength is selected by spectroscopy, the optical output will be extremely small, making it difficult to obtain high-output optical pulses. There was a drawback.

The object of this invention is to eliminate the drawbacks of the conventional optical pulse generators described above and provide a high-output optical pulse generator that can obtain high output at a desired wavelength.

The principle of this invention is to irradiate an optical fiber with pulsed solid-state laser light to generate stimulated Raman amplification gain in the optical fiber.
Further, the output light of the semiconductor laser having an oscillation wavelength within a certain band of amplification gain is used as the input signal light to the optical fiber, and this is selectively amplified.

In the conventional stimulated Raman scattering method, spontaneously emitted Stokes Raman light is used as a signal source, and this is amplified.In contrast, in this invention, the oscillation light of a semiconductor laser is used as a signal source, and this is used as a signal light source from outside. As a result, a much more monochromatic and stronger optical signal input than before can be obtained as an initial condition, and as a result,
Optical fibers produce monochromatic, strongly amplified, and high-power light pulses.

The stimulated Raman amplification effect using optical fiber is 400-10
Since it has a wide gain band of 0100O', by selecting one of the discrete oscillation wavelengths of a solid-state laser and combining this with the stimulated Raman amplification effect, 1.
．． It is possible to amplify the wavelength of a semiconductor laser with a desired wavelength between 2 and 1.6 μm.

SiO2 doped with GeO2 is usually used as the core of an optical fiber, but in addition to such a glassy core, a liquid such as benzene can also be used as the core.

Since the Stokes shift of benzene is larger than that of α0□-3in2 glass, it is possible to further expand the amplifiable gain band by using such a liquid core.

Next, the high-power optical pulse generator of the present invention will be explained in detail with reference to the drawings.

The figure is a layout configuration diagram showing the configuration of an embodiment of the present invention.

In the figure, 1 is a pulsed solid-state laser, 2 is a semiconductor laser, 3 is a multiplexer, 4 is an optical fiber, and 5 is a demultiplexer.

In the embodiment of the present invention, an Nd:YAG laser whose oscillation line can be selected is used as the pulsed solid-state laser 1, and the Q
By operating the switch, the wavelength is 1.06μm, 1
．． It is attempted to obtain a peak laser output of IK-W or more at any wavelength such as 12 μm, 1.32 μm, or 1.34 μm.

The oscillation wavelength of the semiconductor laser device 2 is λ5, which is the oscillation wavelength of the pulsed solid-state laser, and is converted into a wave number of 100 to 100.
It can be freely selected within a range on the long wavelength side of about 0 cm-1.

In the embodiment of the present invention, the semiconductor laser 2 is made of InGaAs.
By using a P/InP laser and oscillating the laser in a pulsed manner in synchronization with the oscillation of the pulsed solid-state laser 1, the peak output of the semiconductor laser is increased.

As the optical fiber 4, a single mode optical fiber with a GeO2-3iO2 core is used.

The length may be about 10m.

As the optical fiber 4, a single fiber having a core made of a liquid such as benzene can be used.

In this case, the wavelength difference between the two wavelengths λ5 and the input wavelength described above can be selected to be large.

The pulse outputs of the pulsed solid-state laser and the semiconductor laser are multiplexed by the multiplexer 3 and optically coupled to the optical fiber 4 .

When the output light of the pulsed solid-state laser 1 enters the optical fiber 4, a stimulated Raman amplification gain is generated in the optical fiber 4 due to its high peak output. S) output from 20 to 4Ck
It can be amplified by about iB.

A demultiplexer 5 provided on the output end side of the optical fiber 4 separates the optical output of the input wavelength amplified in the optical fiber 4 from the transmitted light of the excitation wavelength, so that it can be used as an output. ing.

Reference numeral 6 denotes a light shielding plate, which has the role of shielding light from the excitation wavelength.

A photodetector may be used as the light-shielding plate 6, and in this case, it can also serve as a monitor of the excitation light, thus killing two birds with one stone.

If the length of the optical fiber 4 is too long or the light of the pulsed solid-state laser 1 used for excitation is too strong,
Naturally emitted Stokes Raman scattered light is amplified,
Stimulated Raman scattering with a wide emission spectral band occurs,
This may reduce the S/N.

However, if the length of the optical fiber 4 and the output intensity of the pulsed solid-state laser 1 are selected appropriately, the output of the semiconductor laser can be increased from 20 to 49.
It is relatively easy to amplify by about dB and obtain a peak output of about several +W.

As described above, according to the present invention, by amplifying the output of a semiconductor laser, it is possible to obtain a high-output pulse generator that can obtain high output at a desired wavelength.

Although one embodiment of the present invention has been described above, it goes without saying that various substitutions, modifications, etc. of the constituent elements are possible without departing from the purpose of the present invention.

For example, it goes without saying that the pulsed solid-state laser 1 may be a continuous excitation laser or a pulsed excitation laser.
Instead of the Nd:YAG laser, it is also possible to use a solid-state laser that oscillates at a different wavelength from the Nd:YAG laser, such as an Er:YLF laser or an Er Niglass laser.

Further, for example, various elements such as a prism, a diffraction grating, and an interference filter can be used as the demultiplexer used in this invention.

[Brief explanation of the drawing]

The figure is a layout configuration diagram showing the configuration of an embodiment of the present invention, 1...Pulse solid-state laser, 2...Semiconductor laser, 3...Multiplexer, 4... Optical fiber, 5... Duplexer, 6... Light shielding plate.

Claims (1)

[Scope of utility model registration request] An optical fiber for stimulated Raman amplification, a pulsed solid-state laser for pumping the optical fiber, a semiconductor laser device having an oscillation wavelength within the amplification gain band of the optical fiber, and output light from the pulsed solid-state laser and the semiconductor laser device. a multiplexer for superimposing the output light from the semiconductor laser device and inputting the same into the optical fiber, and a demultiplexer for taking out the output light from the semiconductor laser device that is amplified in the optical fiber. Output light pulse generator.