CN111211473A

CN111211473A - Full-optical fiber Raman pulse laser with high peak power and narrow linewidth

Info

Publication number: CN111211473A
Application number: CN202010023983.6A
Authority: CN
Inventors: 何赛灵; 尹韬策; 戚章泥
Original assignee: Zhejiang University ZJU
Current assignee: Zhejiang University ZJU
Priority date: 2020-01-09
Filing date: 2020-01-09
Publication date: 2020-05-29

Abstract

The invention discloses an all-fiber high peak power and narrow linewidth Raman pulse laser, comprising a Raman pumping laser, a circulator, a signal generator, a reflective semiconductor optical amplifier, an erbium-doped fiber pre-amplifier, and an erbium-ytterbium co-doped fiber. Main amplifiers, wavelength division multiplexers, isolators, Raman laser seeds and highly doped germanium dioxide fibers. The Raman-pumped laser is modulated into a pulsed laser by a reflective semiconductor optical amplifier, which is then sequentially amplified by an erbium-doped fiber pre-amplifier and an erbium-ytterbium co-doped fiber main amplifier. The amplified Raman-pumped pulsed laser enters the high-doped germanium dioxide fiber through the wavelength division multiplexer, and the Raman laser seed on the other side enters the high-doped germanium dioxide fiber through the isolator and the wavelength division multiplexer to be Raman pumped The pulsed laser is modulated and amplified simultaneously. The all-fiber high peak power narrow linewidth Raman pulse laser of the invention has the advantages of simple fabrication, easy integration and compact structure, and can be used in the field of laser gas sensing.

Description

Full-optical fiber Raman pulse laser with high peak power and narrow linewidth

Technical Field

The invention relates to an all-fiber high-peak-power narrow-linewidth Raman pulse laser.

Background

Methane is a greenhouse gas second only to carbon dioxide and is also the main component of natural gas, biogas and gas. In some special scenes, methane may leak or gather, and when the methane in the air reaches a certain concentration, people may be suffocated or even explode. Therefore, it is very important to accurately detect the methane gas concentration. A laser with the emission wavelength near 1653 nanometers can effectively detect the concentration of methane, but the power of the current light source is low, and the remote high-precision detection capability is not realized. Conventional rare earth doped fibers such as erbium doped fibers are insufficient at 1653 nanometers to provide optical gain to amplify laser power. The raman effect can be simply explained by a beam of light impinging on a substance, molecules in the substance absorbing part of the energy, vibrating in different ways and degrees, and then scattering out the light at a lower frequency. The high-frequency laser is used for amplifying the low-frequency laser by utilizing the Raman effect, and the laser is called stimulated Raman amplification, so that a gain gap of the rare earth doped optical fiber can be bypassed.

Disclosure of Invention

In order to overcome the defects of the prior art, the invention mainly aims to provide an all-fiber high-peak-power narrow-linewidth Raman pulse laser which has the advantages of good optical quality, low cost, good temperature stability and compact structure.

A full optical fiber Raman pulse laser with high peak power and narrow linewidth comprises a Raman pump laser, a circulator, a signal generator, a reflective semiconductor optical amplifier, an erbium-doped optical fiber preamplifier, an erbium-ytterbium co-doped optical fiber main amplifier, a wavelength division multiplexer, a high-doped germanium dioxide optical fiber, a wavelength division multiplexer, an isolator and a Raman laser seed;

the Raman pump laser, the circulator, the erbium-doped fiber preamplifier, the erbium-ytterbium co-doped fiber main amplifier, the wavelength division multiplexer, the high-doped germanium dioxide fiber, the wavelength division multiplexer, the isolator and the Raman laser seed are sequentially connected through fiber fusion;

the circulator is provided with three ports a, b and c, the Raman pump laser is connected with the port a of the circulator, and the port c of the circulator is connected with the erbium-doped fiber preamplifier; the port b of the circulator is sequentially connected with the reflective semiconductor optical amplifier and the signal generator through optical fiber welding.

The Raman pump laser is a 1541 nanometer Raman pump laser;

the wavelength division multiplexer is an 1541/1653-nanometer wavelength division multiplexer;

the Raman laser seed is a 1653 nanometer distributed feedback laser.

The core diameter of the high-doped germanium dioxide optical fiber is 4-6 microns, the cladding is 125 microns, the doping concentration of the germanium dioxide is 50-75 mol%, and the length is 50-100 meters.

The repetition frequency of the periodic square wave voltage signal applied to the reflective semiconductor optical amplifier by the signal generator is 100-500 kHz, and the pulse width is 100-500 nanoseconds.

The invention has the beneficial effects that:

in order to realize the output of the 1653 nanometer pulse laser with full optical fiber and high peak power, the invention combines the stimulated Raman amplification mechanism, uses the corresponding pulse laser to modulate and amplify the existing 1653 nanometer laser seed, and simultaneously adopts the backward pumping mode to ensure a certain optical signal-to-noise ratio and line width, so as to reduce the noise transfer and polarization state influence between the two beams of light. The 1541 nanometer high-power pulse fiber laser backward pumps the high-doped germanium dioxide fiber to realize the full-fiber high-peak-power narrow-linewidth Raman pulse laser. The central wavelength of the Raman pulse laser is 1653 nm, the repetition frequency is 100 kHz, the pulse width is 31 ns, the optical signal to noise ratio is larger than 35 dB, the line width is smaller than 0.08 nm, and the peak power reaches 30W. The all-fiber high-peak-power narrow-linewidth Raman pulse laser has the advantages of simple manufacture, easy integration and compact structure, and can be used in the field of laser gas sensing.

Drawings

FIG. 1 is a schematic diagram of an all-fiber high peak power narrow linewidth Raman pulse laser;

in the figure, a Raman pump laser 11, a circulator 12, a signal generator 13, a reflective semiconductor optical amplifier 14, an erbium-doped fiber preamplifier 15, an erbium-ytterbium co-doped fiber main amplifier 16, a wavelength division multiplexer 17, a high-doped germanium dioxide fiber 18, a wavelength division multiplexer 19, an isolator 110 and a Raman laser seed 111;

FIG. 2 is a spectrum of a Raman pulsed laser at the highest average output power;

FIG. 3A is a waveform diagram of a single pulse in the time domain of a Raman pulsed laser;

fig. 3B is a timing diagram of a single pulse in the time domain of the raman pulsed laser.

Detailed Description

The invention is further elucidated with reference to the figures and embodiments.

Example 1

As shown in fig. 1, the all-fiber high peak power narrow linewidth raman pulse laser provided by the present invention includes: a raman pump laser 11 for providing energy, a reflective semiconductor optical amplifier 14 for modulating the pump laser, a circulator 12 for introducing the pump laser into the reflective semiconductor optical amplifier, a signal generator 13 for driving the modulated reflective semiconductor optical amplifier, an erbium-doped fiber preamplifier 15 for pre-amplifying the pump laser, an erbium-ytterbium co-doped fiber main amplifier 16 for amplifying the pump laser power, a raman laser seed 111 for generating 1653 nm laser, an isolator 110 for protecting the 1653 nm laser seed, a highly doped germanium dioxide fiber 18 for providing raman gain and energy transfer, a wavelength division multiplexer 17/19 for introducing and extracting the pump laser and the 1653 nm laser into and out of the highly doped germanium dioxide fiber. All the optical fiber devices are connected through optical fiber fusion, and a Raman pump laser 11, a circulator 12, an erbium-doped fiber preamplifier 15, an erbium-ytterbium co-doped fiber main amplifier 16, a wavelength division multiplexer 17, a high-doped germanium dioxide optical fiber 18, a wavelength division multiplexer 19, an isolator 110 and a Raman laser seed 111 are connected in sequence. The port b of the circulator 12 is connected to the reflective semiconductor optical amplifier 14 and the signal generator 13 in this order. The raman pump laser 11 is first modulated into pulsed laser by a reflective semiconductor optical amplifier 14 driven by a signal generator 13 through a circulator 12, and then power amplified sequentially by an erbium-doped fiber preamplifier 15 and an erbium-ytterbium co-doped fiber main amplifier 16. The amplified raman pump pulse laser enters the highly doped germanium dioxide optical fiber 18 through the wavelength division multiplexer 17, and the raman laser seed 111 on the other side enters the highly doped germanium dioxide optical fiber 18 through the isolator 110 and the wavelength division multiplexer 17 and travels in the same direction as the raman pump pulse laser. The raman laser seeds 111 are simultaneously modulated and amplified by the raman pump pulsed laser in the highly doped germanium dioxide fiber 18.

The raman pump laser 11 is a 1541 nm continuous fiber laser. The diameter of the highly doped germanium dioxide optical fiber 18 core is 4 microns, the doping concentration of the germanium dioxide is 75 mol%, and the length is 50 meters. The

wavelength division multiplexers

17 and 19 are 1541/1653 nm wavelength division multiplexers. The raman laser seed 111 is a 1653 nanometer distributed feedback laser. The repetition frequency of the periodic square wave voltage signal applied to the reflective semiconductor optical amplifier 14 by the signal generator 13 is 100 kHz, and the pulse width is 100 nanoseconds.

Fig. 2 is a spectral diagram of a raman pulsed laser at the highest average output power. At the moment, the central wavelength of the Raman pulse laser is 1653 nanometers, the highest average output power is 98.45 mW, the optical signal to noise ratio is at least larger than 35 dB, and the line width is smaller than 0.08 nanometer.

Fig. 3A and 3B are waveform diagrams and timing charts of a single pulse of the raman pulse laser, respectively. The repetition frequency of the raman pulse laser is 100 kHz, the period corresponds to 10 microseconds, the single pulse width is about 31 nanoseconds, and the estimated maximum peak power is 30 watts.

The embodiments in the above description can be further combined or replaced, and the embodiments are only described as preferred examples of the present invention, and do not limit the concept and scope of the present invention, and various changes and modifications made to the technical solution of the present invention by those skilled in the art without departing from the design concept of the present invention belong to the protection scope of the present invention. The scope of the invention is given by the appended claims and any equivalents thereof.

Claims

1. An all-fiber high peak power narrow linewidth Raman pulsed laser, characterized in that: comprising a Raman pumped laser (11), a circulator (12), a signal generator (13), a reflective semiconductor optical amplifier ( 14), erbium-doped fiber preamplifier (15), erbium-ytterbium co-doped fiber main amplifier (16), wavelength division multiplexer (17), highly doped germanium dioxide fiber (18), wavelength division multiplexer (19) , an isolator (110), a Raman laser seed (111);

Among them, Raman pump laser (11), circulator (12), erbium-doped fiber pre-amplifier (15), erbium-ytterbium co-doped fiber main amplifier (16), wavelength division multiplexer (17), highly doped dioxide The germanium fiber (18), the wavelength division multiplexer (19), the isolator (110), and the Raman laser seed (111) are sequentially connected by fiber fusion;

The circulator (12) is provided with three ports a, b and c, the Raman pump laser (11) is connected to the a port of the circulator (12), and the c port of the circulator (12) is connected to the erbium-doped fiber The preamplifier (15) is connected; the b port of the circulator (12) is connected to the reflective semiconductor optical amplifier (14) and the signal generator (13) in sequence through optical fiber fusion.

2. The all-fiber high peak power narrow linewidth Raman pulsed laser according to claim 1, wherein the Raman pumped laser (11) is a 1541 nm Raman pumped laser;

The wavelength division multiplexer (17) is a 1541/1653 nanometer wavelength division multiplexer;

The Raman laser seed (111) is a 1653 nm distributed feedback laser.

3. The all-fiber high-peak power narrow-linewidth Raman pulsed laser according to claim 1, characterized in that: the core diameter of the high-doped germanium dioxide fiber (18) is 4-6 microns, and the cladding is 125 microns. Micron, the doping concentration of germanium dioxide is 50-75mol.%, and the length is 50-100 meters.

4. The all-fiber high peak power narrow linewidth Raman pulsed laser according to claim 1, wherein the signal generator (13) is added to the periodic square wave of the reflective semiconductor optical amplifier (14). The repetition rate of the voltage signal is 100-500 kHz and the pulse width is 100-500 nanoseconds.