TW558653B - A 1.3 mum broadband optical amplifier and wavelength tunable fiber laser with non-symmetric resonant cavity - Google Patents

Abstract

A new broadband optical light source is achieved by cascading a praseodymium-doped fiber amplifier (PDFA) and a multiple quantum well semiconductor optical amplifier (MQW-SOA). The PDFA is pumped by Nd:YLF high power laser and the MQW-SOA is pumped by injecting current for generating light amplification effect. The band of light amplification is combined with the two amplified bands of PDFA and MQW-SOA. The bandwidth thereof can reach 100 nm from 1280 nm to 1380 nm with driving current 50 mA and pumping power 885 mW of MQW-SOA and PDFA respectively. Besides, a new wavelength tunable laser is achieved by using a tunable optical filter, PDFA, MQW-SOA and an active fiber loop mirror in this invention. The nonsymmetrical cavity includes a wavelength tunable filter and a fiber loop mirror. A narrow line width 1.3 mum fiber laser with tunable range about 30 nm is therefore obtained, and can be applied in fiber optical industry testing and communication.

Description

558653 V. Description of the invention (l) Field of the invention The present invention relates to a wide-band optical amplifier used in the 1 · 3 // m band, in particular to a erbium-doped fiber amplifier (Praseodymium-Doped 卩 1 『6" eight 11 ^ 11 A new type of wide-band optical amplifier formed by serially connecting 61 ',? 0? 8) and Multiple Quantum Well Semiconductor Optical Amplifier (MQW-SOA)

Device. By using the wide-band optical amplifier of the present invention, in combination with a fiber loop equivalent mirror and a wavelength-tunable optical filter, an asymmetric resonance cavity is formed, so that a laser light source with a wavelength that can be adjusted can be generated. BACKGROUND OF THE INVENTION In the early 1980s, a wavelength of 1310 nm was used in single-mode fiber systems. It is technically more mature than 1 550 nm, and its bandwidth characteristics are also better-with better dispersion. But Erbium-Doped Fiber Amplifiers

After the introduction of Fiber Amplifier (EDFA), it fell into the I 550nm low-loss _ loss band, and in recent years, EDFA broadband amplifiers such as C-band, L-band, etc. have been introduced, making manufacturers turn to 1 550nm development. Although the 1 550 nm amplifier has many benefits, its optical communication loss in the 1 3 1 Onm band is greater. At present, the broadband erbium-doped fiber amplifier in the 1 · 5 // m band. If the early-developed C-band amplifier is added to the L-band amplifier currently under development, the optical signal amplification bandwidth can be increased to 70nm-80nm. . But in LAN WDM (Wavelength Division

Multiplexing (division multiplexing) technology requirements 128Onm-165Onm full spectrum Optical transmission will require 1280 nm-1380 nm optical amplifier and broadband

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The optical communication loss of the optical fiber in the 1310nm band is higher than that in the i 550nm band =: Therefore, the demand for the optical amplifier and light source in the 1310nm band is significantly pursued. 'In addition, lasers have the characteristics of high spectral purity and high brightness. Laser tunability can be divided into fixed-wavelength lasers and adjustable-wavelength lasers. Only adjustable-wavelength lasers can be used for conversion. Wavelength tunable WDM systems // In recent years in fiber optic communication systems, multiplexed wavelength tunable laser = research is very popular, traditional tunable wavelength lasers mostly use the distributed Bragg Reflector (DBR) ) Laser R & D technology 'But the adjustable range of this laser is only about 5 ~ 10ηη. The invention i σ therefore the present invention proposes a broadband optical amplifier used in the 1 · 3 // m band 'using an erbium-doped fiber amplifier (prase〇dymium-Doped Fiber Amplifler (pDF A)) and a quantum well semiconductor optical amplifier Quantum Well Semiconductor Optical Amplifier (MQW-SOA), and the use of two sets of amplifier optical gain spectral superposition technology to achieve the effect of wideband optical signal amplification, can be used in various fiber optic # systems in the 3 V m band, the network as light Amplifier. And using this broadband optical amplifier, a wavelength-tunable laser light source is proposed, which is combined with a fiber loop equivalent mirror and a wavelength-tunable optical filter to form an asymmetric resonant cavity, so a wavelength-tunable laser light source is produced. The invention can be applied to a demultiplexed optical fiber network, an optical fiber sensing system, and a precision photoelectric one measurement system.

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558653

It is clearly explained that the present invention uses two different optical amplifier series connection modes, and a broadband optical amplifier structure is provided. The block diagram is shown in FIG. 1. The broadband optical amplifier of the present invention is composed of a group of quantum well-semiconductor optical amplifiers and a group of erbium-doped fiber amplifiers 2 connected in series. The internal structure is shown in FIG. 2. The quantum well semiconductor optical amplifier 1 contains a quantum well semiconductor optical amplifier diode 11, a bias current source circuit 12, a temperature control circuit 13, a silicon dioxide fiber 14 and a silicon dioxide fiber 15 inside. The quantum well semiconductor optical amplifier 1 uses a temperature control circuit 13 to control an appropriate temperature, and uses a bias current source 鬌 H circuit 12 to excite the spectrum of the quantum well semiconductor optical amplifier 1. Erbium-doped fiber amplifier 2 contains erbium-doped fiber PDFF (Praseodymium-Doped Fluoride Fiber) 21, and split-wave multiplexed optical fiber! § (λρ /; ls) 22. Pump laser λ p 2 3. The erbium-doped fiber amplifier 2 uses a group of pump lasers 23 to achieve population inversion to generate the optical amplification function, and the demultiplexing multiplexed fiber coupler 22 can pump a laser at a wavelength of 1047 nm. 23 and 1300 nm wavelength signals are coupled into the erbium-doped fiber PDFF (Praseodymium Doped Fluoride Fiber) 21 at the same time, with two sets of different amplifiers in different bands of ASE (stimulated spontaneous, radiated,

Amplified Spontaneous Emission) spectral superposition technology can obtain the effect of wideband optical signal amplification at the band, and it is used as a 1.3μm band optical amplifier. In addition, as shown in Fig. 6, the present invention and design a wide-band wavelength can be iraHi irann page 8 558653

Mode laser, a series of quantum well semiconductor optical amplifiers 丨 and a group of erbium-doped fiber amplifiers 2 are connected in series, and a fiber loop equivalent mirror (〇pUcal Fi ^ r Loop Mirror) 4 is connected to the quantum well semiconductor optical amplifier !! An output end of the erbium-doped fiber amplifier 2 is connected to an optical wavelength tunable filter (Optical Tunable Filter) 3 to form a mirror surface of an asymmetric resonant cavity to adjust the output wavelength of the laser of the present invention , To achieve the effect of laser wavelength adjustable output. The experimental results show that: In order to verify the feasibility of the present invention, the measurement experiment 4 values of the actual instrument are used to analyze and confirm the output spectrum of each part of the broadband optical amplifier element of the present invention. In the experiment, we used a spectrum analyzer to actually measure the ASE spectrum of the 1.3 // m-band broadband optical amplifier of the present invention in its ι · 3 " claw band, and adjust the characteristics exhibited by parameters such as bias current and pump laser The change. -First, we measured the characteristics of the quantum well semiconductor optical amplifier 1. The experimental architecture is shown in Figure 3. The temperature control circuit 13 is controlled at room temperature. At C, the bias current circuit 12 is used to excite its ASE spectrum, and the measurement end technology and measurement end b are measured by a spectrum analyzer to analyze and obtain the correlation between the bias current and the ASE spectrum. In addition, the white light is used as the light source to pass through the spectrum analyzer to measure the multiplexed spectrum of the multiplexed fiber χ fiber coupler 22. The experimental architecture is shown in Figure (4). In terms of erbium-doped fiber amplifier 2, the previous multiplexed optical fiber coupler 22 was used in conjunction with a set of pump lasers 23 to excite the ASE light of PDFF (Praseodymium Doped F1uoride Fib6r) 21 ~

Page 9 558653 Description of the five inventions (5) 碏 'The measurement experiment structure using a spectrum analyzer at measurement end e and measurement end f is shown in Figure (5) to obtain the pump laser 23 and ASE spectra. Interrelationship 'The following is a description of the experimental measurement data of the Qi. FIG. 7 is a record of the quantum well semiconductor optical amplifier 1 in the measurement end a of the experimental architecture of FIG. 3 as the bias current increases from the με spectrum at the center wavelength of 1.34, and FIG. 8 is the experimental architecture of FIG. 3 Corresponding graph of the bias current of the quantum well semiconductor optical amplifier 1 at the measurement terminal a to the peak power of the ASE spectrum. This curve shows how to adjust the power of the ASE spectrum of the present invention.

Fig. 9 is a recording of the change in the ASE spectrum of the quantum well semiconductor optical amplifier 1 in the measurement end b of the experimental architecture of Fig. 3 in the center wavelength 1.34 // m band with increasing bias current. Fig. 10 is a corresponding curve of the peak value of the ASE spectral power and the bias current in the measurement terminal b of the experimental structure of Fig. 3, so that the output spectral characteristics of the quantum well semiconductor optical amplifier 1 can be adjusted based on this data. FIG. 11 is a result of spectral measurement of a white light source based on the experimental structure of FIG. 4. Fig. 12 is a record of the passband spectrum of the measurement end c of the experimental architecture of Fig. 4; Fig. 13 is a record of the passband spectrum of the measurement end d of the experimental architecture of Fig. 4;

Fig. 13 shows the spectral transmission of the multiplexed optical fiber coupler 22. Fig. 14 is the measurement end e of the experimental structure of Fig. 5. The measurement and erbium-doped fiber amplifier 2 changes with the input power of the pump laser 23 and changes in the ASE spectrum around the center wavelength. Fig. 15 shows the experiment in Fig. 5 Correspondence curve of peak e, ASE spectral power versus input power of Erbium-doped fiber amplifier 2

Page 10 558653 V. Description of the invention (6) Figure 16 shows the experimental structure of Figure 5: Erbium-doped fiber amplifier 2 Measurement end f at the wavelength 1.32 " in band The ASE spectrum increases with the pump laser 23 input power Changing circumstances. FIG. 17B is the corresponding curve of the ASE spectral power peak against the input power of the pump laser 23 in the measurement terminal f of the erbium-doped fiber amplifier 2 experimental architecture of FIG. 5, and the graph shows how to control the output spectrum of the erbium-doped fiber amplifier 2. Characteristics

Figure 18 shows the measured ASE spectrum of the quantum well semiconductor optical amplifier 1 when the bias current is 50 mA and the temperature is controlled at 20 ° C. Figure 19 shows the spectrum of the erbium-doped fiber amplifier 2 at the pump laser 23 The measurement results of the ASE spectrum at an input power of 885mW. Finally, the two optical amplifiers are connected in series as shown in Figure 1. The final output spectrum is shown in Figure 2. From the experimental results, the amplifier's The effect of increased bandwidth.

In addition, the characteristics of the ASE spectrum of the "asymmetric resonant cavity wavelength tunable optical fiber laser" of the present invention in the 1 · 3 band measured by a spectrum analyzer, and the characteristics exhibited by adjusting the bias voltage and the excitation laser are shown. Variety. First set the bias current of Chizijing Semiconductor Optical Amplifier 1 to 50mA, control the temperature at 20 ° C, and set the erbium-doped fiber amplifier 2 spectrum setting pump laser 23 input power to 800mW, then these two optical amplifier strings The subsequent output spectrum is shown in Figure 2O. The bias current is set to 50 mA, and the pumped laser power for 23 rounds is set to 800 mff ^ in order to obtain the best single-mode output effect of the asymmetric resonant cavity wavelength tunable fiber laser. That is to say, it is a single-mode output. Figure ^ The spectrum of the dynamic adjustment of the asymmetric resonator-type wavelength-tunable optical fiber laser according to the present invention can clearly see the range of wavelength adjustment and the size of each peak. 558653

V. Description of the invention (7) In addition, an optical isolator 5 may be placed between the multiple quantum well semiconductor amplifier and the erbium-doped fiber amplifier to make a unidirectional optical amplifier, so that the signal is amplified in only one direction. As shown in Figure 23. An optical equalizer 6 may be placed between the quantum well semiconductor amplifier 1 and the erbium-doped fiber amplifier 2 to flatten the bandwidth of the wideband amplifier or the bandwidth of the light source, as shown in FIG. 24. An optical filter may be placed between the quantum well semiconductor amplifier 1 and the erbium-doped fiber amplifier 2 so that the amplified optical amplifier bandwidth can be penetrated in certain specific bands' as shown in FIG. 25. The invention can be combined with the demultiplexer 8 to produce a 13 / zm band multi-channel light source and a broadband light source, as shown in FIG.

In the asymmetric resonator-type wavelength-tunable optical fiber laser of the present invention, a 2x2 photocoupler can be used instead of the equivalent lens of the optical fiber loop to control the output optical power f. Add optical isolator 9 to the loop of the equivalent loop 4 of the optical fiber loop to make a unidirectional tunable wavelength laser, so that the laser light with a higher power is output from the direction of the tunable optical filter, as shown in Figure 27 As shown. A laser-absorptive photoelectric switch 10 is built in the laser resonance cavity for laser light power modulation or mode-locked laser, as shown in Figure 28. The fiber loop equivalent mirror 4 can be replaced by a demultiplexer 丨 丨 and optionally two or more optical fibers can be connected on the side of the demultiplexer 11

The loop is synthesized to form a new type of asymmetric resonance cavity, which generates laser light output, as shown in Figure 29. Features and effects: The present invention is characterized in that two different amplifiers of quantum well semiconductor optical amplifier 1 and erbium-doped optical fiber amplifier 2 are connected in series to form a new type of broadband optical amplifier. The biggest feature of this optical amplifier is that it is used in the l3vm band.

Page 12 558653 V. Description of the invention (8) And the power is much stronger than ordinary light sources.咴 诒, 埶, / 故 入 牡 牡 1 · 5 Z / m wave band WDM research has been reported, and will inevitably integrate the 1 · 3 μ m band, ▲ development, so \ road towards WDM ultra-broadband optical fiber communication 15 band The characteristics of optical signal amplification The present invention patent is different from the current one. In addition, the device of the present invention can be used as an ancient! 〇aau * F is a smart power broadband light source for 1 · 3 // m-band optical fiber communication optical frequency @@ ϋ μ-μ should be used as a light source. In addition to the application of WDM fiber optic "system components to test the Chi Chi-Ding Xinli or optical signal amplification, can also be used in fiber optic gyroscope and other sensing systems, and its use. ,, ^ You use a single frequency laser Compared with the fiber-optic gyroscope, it can provide more precise measurement resolution. 1 · A new type of asymmetric resonant cavity has been developed by using a wavelength-tunable optical filter and an equivalent fiber-optic loop mirror. 2. Using a quantum well The semiconductor optical amplifier and the erbium-doped fiber amplifier are connected in series to form a broadband optical gain element. = 3 · The biggest feature of the asymmetric resonant cavity wavelength tunable optical fiber laser of the present invention is that it is used in the 1 · 3 μm band 4. Simple structure, it is not necessary to adjust the grating angle mechanically as in the early adjustable wavelength laser. 5 Wide range of adjustable wavelength. The effect of the present invention is as follows: The paste of the present invention is composed of two sets of optical amplifiers, which The bandwidth or gain range of the light source can be adjusted by controlling the bias current of the MQW-SOA and the pump laser power of the PDFF, and it has a higher gain than a single optical amplifier. Member, such as can-modulation optical filter, polarization control

Page 13 558653 V. Description of the invention (9) devices, optocouplers, etc., can develop many systems and applications, 5 has a considerable applicability for the 1. 3 // m wideband photoelectric technology. 1. Wavelength adjustable function 2. Can be used in WDM branched multiplex optical fiber communication system 3. Can be used in fiber optic sensor 4. Can be used in the development of new precision photoelectric measuring instruments The spirit and scope of the present invention are only limited by Limited to the scope of patent application below

Page 14 558653 Brief description of the drawings Figure 1 is a block diagram of the composition of a broadband optical amplifier. Figure 2 shows the structure of a 1 · 3 μm-band broadband optical amplifier. Figure 3 shows the experimental architecture of a quantum well semiconductor optical amplifier. · Figure 4 is the experimental measurement diagram of the characteristics of the split-wave multiplexing coupler. FIG. 5 is a diagram of the spectrum structure of an erbium-doped amplifier. FIG. 6 is a structural diagram of an asymmetric resonator-type wavelength-tunable fiber laser. Figure 7 shows the measurement results of the quantum well semiconductor optical amplifier's stimulated spontaneous emission (Amplified Spontaneous Emission; ASE) spectrum measurement terminal 3. Figure 8 is a graph of the peak power versus bias current of the quantum well semiconductor optical amplifier ASE spectrum measurement terminal a. Fig. 9 shows the measurement results of the quantum well semiconductor optical amplifier ASE spectrum measurement. Figure 10 is a graph of the peak power vs. bias current of the quantum well semiconductor optical amplifier ASE spectrum measurement terminal b. FIG. 11 is a spectrum measurement result of a white light source. Figure 12 shows the measurement results of the measurement terminal c of the demultiplexing multiplexing coupler. Figure 13 shows the measurement results of the measurement terminal d of the demultiplexing multiplexing coupler.

FIG. 14 shows the measurement results of the ASE spectrum measurement terminal e of the erbium-doped fiber amplifier. Figure 15 shows the peak power versus wheel-in power curve of the ASE spectral measurement terminal e of the Erbium-doped fiber amplifier. FIG. 16 shows the measurement results of the ase spectrum measurement terminal f of the erbium-doped fiber amplifier. Figure 17 shows the peak power input curve of the erbium-doped fiber amplifier ASE spectrum measurement terminal f.

Page 15 558653 Brief description of the figure Figure 18 shows the measurement results of the spectral characteristics of the quantum well semiconductor optical amplifier ASE (Ib = 50mA, T = 20.c). Figure 19 shows the measurement results of ASE spectral characteristics of erbium-doped fiber amplifiers (Pp = 0 · 885W). Figure 2G shows the measurement results of ASE spectral superposition of pdfa and MQW-SOA optical amplifiers in series. Figure 21 shows the laser spectrum measurement results of the output wavelength of an asymmetric resonator-type tunable optical fiber laser. FIG. 22 is an output laser continuous-wavelength wavelength spectrum chart of an asymmetric resonator-type wavelength-tunable optical fiber laser. 2 3 to 29 are schematic diagrams of other embodiments of the present invention. Description of drawing number 1 MQW-SOA (Multiple Quantum Well Semiconductor Optical Amplifier) quantum well semiconductor optical amplifier 11 quantum well semiconductor optical amplifier diode 1 2 bias current source circuit 1 3 temperature control circuit 1 4 silicon dioxide optical fiber 1 5 2 Silica fiber 2 PDFA (Praseodymium-Doped Fluoride Fiber Ampl if ier) Erbium-doped fiber amplifier 21 Erbium-doped fiber PDFF (Praseodymium Doped Fluoride Fiber)

Page 16 558653 Brief description of the diagram 22 Split-wave multiplex fiber 1¾ coupler (λρ / As) 23 Pump laser λρ 3 Wavelength tunable optical filter and wave filter (Opt ica 1 Tunable F i 1 ter) 4 Loop Mirror wi th Optical Coupler 41 2x2 Fiber Optic Coupler 4 2 Silicon Dioxide Fiber 5 Optical Isolator% 6 Optical Equalizer 7 Optical Filter 8 Splitter Multiplexer 9 Optical Isolation 10 Photo-absorptive photoelectric switch 11 Split-wave multiplexer Η Page 17

Claims (1)

558653 6. Scope of patent application 1. A 1 · 3μηη wideband optical amplifier, including an erbium-doped fiber amplifier, a multiple quantum well semiconductor optical amplifier, and the excited self-emission (ASE) frequency harmonic center of the two amplifiers The frequency and the optical signal amplification frequency band fall on different frequencies. After being connected in series, the stimulated spontaneous emission spectrum and the optical signal amplification spectrum can cover a wider frequency range. 2 · The wideband optical amplifier according to item 1 of the patent application, wherein the erbium-doped fiber amplifier includes a 1047 nm pump laser, a component multiplexed fiber coupler and an erbium-doped fiber, of which the multiplexed duplex fiber coupler The two wavebands are 1047nm and 1300nin. The 1047nm band is used for pump laser source to pass through. It is used to excite trout-doped fiber. At the same time, the ASE spectrum of erbium-doped fiber amplifier can be changed by adjusting the pump laser. The band is used to carry the carrier signal. 3. The broadband optical amplifier according to item 1 of the patent application scope, wherein the multiple quantum well semi-V bulk optical amplifier is a combination of a multiple quantum well semiconductor optical amplifier diode with a temperature control circuit and a forward bias current source circuit. The temperature control circuit is used to stabilize the temperature of the multiple quantum well semiconductor optical amplifier diode, and by changing the bias current of the forward bias current source circuit, the stimulated spontaneity of the Chitsui semiconductor optical amplifier can be changed. The radiation spectrum and the gain spectrum are both light-coupled by silicon dioxide fiber. 4. · As claimed, the wideband optical amplifier in the first item of the patent, in which an optical isolator can be placed between the erbium-doped optical amplifier, the multiple quantum well semiconductor optical amplifier, to make a unidirectional optical amplifier, so that the signal only Zoom in in one direction. 5. The broadband optical amplifier according to item 丨 of the If patent application, where an optical equalizer can be placed between the erbium-doped fiber amplifier and the quantum well semiconductor amplifier, so that 558653 6. Scope of patent application Flatten the bandwidth of the broadband optical amplifier or the bandwidth of the light source. 6. The wideband optical amplifier according to item 1 of the patent application, wherein an optical filter can be placed between the erbium-doped fiber amplifier and the quantum well semiconductor amplifier, so that the amplification bandwidth of the optical amplifier can be in certain specific bands. penetrate. 7. The wideband optical amplifier according to item 1 of the patent application range, wherein the present invention can be combined with a demultiplexer to make a 1. 3 m-band multi-channel light source and a broadband light source. ^ 8 · —An asymmetric cavity-wavelength tunable optical fiber laser used in the 1.3 band, including a wavelength-tunable optical filter, an erbium-doped fiber amplifier, a multiple quantum well semiconductor optical amplifier, and an optical fiber Loop equivalent mirror, in which the excited spontaneous light emission spectrum center frequency and optical signal amplification band of erbium-doped fiber amplifier and multiple quantum well semiconductor optical amplifier fall on different frequencies, so erbium-doped fiber amplifier and multiple quantum well semiconductor optical amplifier After being connected in series, the coverage of the stimulated spontaneous emission spectrum and the optical signal amplification spectrum can be wider. Then the wavelength selection characteristics of the wavelength-tunable optical filter are used to achieve the effect of the wavelength-tunable laser output. 9. The asymmetric resonator-type wavelength-tunable optical fiber laser according to item 8 of the patent application, where a 2x2 photocoupler can be used instead of an equivalent optical loop mirror to control the output optical power. I 〇 · If the asymmetric resonator-type wavelength-tunable optical fiber laser of item 8 of the patent application scope, an optical isolator is added to the equivalent mirror of the optical fiber loop to make a unidirectional tunable wavelength laser , So that the laser light with higher power is output from the direction of the wavelength-tunable optical filter. II · Asymmetric cavity-wavelength tunable optical fiber such as item 8 of the scope of patent application Η Page 19 558653 VI. Patent scope of laser light 'In which a light-absorptive photoelectric switch is built into the laser resonance cavity for lightning The light power is modulated or made into a mode-locked laser. 1 ^ · If the asymmetric resonant cavity-type wavelength tunable optical fiber in the eighth patent application scope of the patent, the f-fiber loop equivalent mirror can be replaced by a demultiplexer, and the demultiplexer can be divided into one: Jg | JJ ^ r -ra The new type of non-counter-whip fiber or two or more optical fibers are connected into a loop to form and turn the "vibration cavity", and a laser light wheel is generated. Page 20