Bismuth-doped fiber amplifier

Abstract

A bismuth-doped (BI) fiber (BIDF) and a bismuth-doped fiber amplifier (BIDFA) are shown and described. The BiDF includes a gain band and an auxiliary band. The gain band has a first center wavelength (λ1) and a first six decibel (6 dB) gain bandwidth. The auxiliary band has a second center wavelength (λ2), λ2<λ1. The system also includes a signal source and a pump source optically coupled to the BiDF. The signal source provides an optical signal at λ1, and the pump source provides pump light at a pump wavelength (λ3).

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims the benefit of U.S. Provisional Patent Application Serial No. 62 / 730,766, filed by DiGiovanni on September 13, 2018, entitled “Bismuth Doped Fiber Amplifier to Extend O-Band,” and is incorporated herein by reference. Technical Field

[0003] The present invention relates generally to optical devices and, more particularly, to optical fiber amplifiers. Background Art

[0004] The O-band (referring to the original band) in fiber optic communication systems operates between the wavelength (λ) range from about 1260 nanometers (-1260 nm) to 1360 nm. One advantage of operating in the O-band is that the transmitter wavelength is located near the zero dispersion wavelength (λ0). Therefore, neither optical nor electronic dispersion compensation is usually required. Due to these and other advantages, efforts are being made to improve fiber optic systems and processes that operate in the O-band. Summary of the invention

[0005] The present disclosure provides an optical system using bismuth (Bi)-doped optical fiber. One embodiment of the system includes a Bi-doped optical fiber (or Bi-doped fiber (BiDF)), which includes a gain band and an auxiliary band. The gain band has a first center wavelength (λ1) and a first six decibel (6dB) gain bandwidth. The auxiliary band has a second center wavelength (λ2). The system also includes a signal source optically coupled to the BiDF. The signal source provides an optical signal within the gain band to the BiDF. In addition, a pump source is optically coupled to the BiDF. The pump source provides pump light of a pump wavelength (λ3) to the BiDF. For some embodiments, multiple pump sources provide pump light of multiple wavelengths to the BiDF.

[0006] After studying the following drawings and detailed description, other systems, devices, methods, features and advantages will be or will become apparent to those skilled in the art. All these additional systems, methods, features and advantages are intended to be included in this description, within the scope of the present disclosure, and protected by the accompanying claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Many aspects of the present disclosure may be better understood with reference to the following drawings. The components in the drawings are not necessarily drawn to scale, but emphasis is placed on clearly illustrating the principles of the present disclosure. In addition, in the drawings, the same reference numerals represent corresponding parts in multiple drawings.

[0008] Figure 1Ais a schematic diagram illustrating one embodiment of a system including a bismuth (Bi)-doped fiber (or a Bi-doped gain fiber or a truncated Bi-doped fiber (BiDF)).

[0009] Figure 1B It is shown Figure 1A Graphs of amplified spontaneous emission (ASE) in a system of FIG. 1 for pump lasers having center wavelengths (λ) of approximately 1155 nanometers (˜1155 nm), ˜1175 nm, ˜1195 nm, ˜1215 nm, and ˜1235 nm.

[0010] Figure 1C It shows that for Figure 1A Plots of the dependence of gain (G), peak gain in micrometers (μm), and power conversion efficiency (PCE) on pump λ for a system with a power density of 1000 W.

[0011] Figure 1D is shown for a pump λ of ~1195 nm, Figure 1A Plot of the input and output spectra of the system.

[0012] Figure 1E is shown for a pump λ of ~1235 nm, Figure 1A Plot of the input and output spectra of the system.

[0013] Figure 2A is a graph showing G and noise figure at -500 milliwatt (mW) pump power for one embodiment of a reversely pumped Bi-doped fiber amplifier (BiDFA) system.

[0014] Figure 2B is shown for obtaining Figure 2A Plot of G and noise figure for a reverse-pumped BiDFA system at a pump power of ~750 mW.

[0015] Figure 3A is a graph illustrating the optical spectrum of one embodiment of a BiDFA system, with optical spectra representing the transmitter output, the BiDF input and the amplifier output after 40 kilometers (km) transmission.

[0016] Figure 3B It is shown that for obtaining Figure 3A Graph of the average bit error rate (BER) versus signal power for a BiDFA system, G.652 transmission fiber and variable optical attenuator (VOA) for a 40km link compared to back-to-back performance.

[0017] Figure 3C It is shown Figure 3A Table of BER of different wavelength channels in BiDFA system.

[0018] Figure 3D It shows that for Figure 3A Figure 3. BER degradation versus optical signal-to-noise ratio (OSNR) for a BiDFA system.

[0019] Figure 3E It is shown that the use Figure 3A Figure 3. BER curves of the BiDFA system at various transmission distances.

[0020] Figure 4A is a graph showing a spectrum of another embodiment of a BiDFA system in which the signal is pre-amplified with another BiDFA, the spectrum representing the transmitter output, BiDF input, and amplifier output.

[0021] Figure 4B It is shown that the use Figure 4A Figure 3. BER curves of the BiDFA system at various transmission distances.

[0022] Figure 4C It is shown Figure 4A Table of BER for different wavelength channels in the BiDFA system.

[0023] Figure 5 is a schematic diagram illustrating one embodiment of a BiDFA system with cascaded amplification stages.

[0024] Figure 6 is a schematic diagram illustrating one embodiment of a BiDFA with an additional light source.

[0025] Figure 7 It is shown Figure 6 A graph of the improvement in optical loss of the BiDFA. DETAILED DESCRIPTION

[0026] Recently, the total O-band transponder rate has been increased to 425 Gigabits per second (Gb / s) by using, for example, eight (8) local area network (LAN) wavelength division multiplexing (WDM) channels modulated by a four-level pulse intensity modulation (PAM-4) signal at approximately 26.6 Gbaud per second (-26.6 Gbaud / s). The use of LAN WDM and complex modulation formats reduces the per-channel power available at the receiver and the receiver sensitivity, making optical amplification desirable. Although semiconductor optical amplifiers can be used to boost O-band signals, semiconductor optical amplifiers introduce distortion due to self-gain modulation and cross-gain modulation. Therefore, semiconductor optical amplifiers are not suitable for WDM transmission of complex intensity modulation formats (such as PAM-4).

[0027] In some O-band applications, praseodymium doped fiber amplifiers (PrDFA) with a gain bandwidth between about 1280 nanometers (-1280 nm) and -1320 nm are used. However, PrDFAs require a non-silica host glass, making PrDFAs expensive and complex.

[0028] To address these shortcomings, the present disclosure teaches a silica-based bismuth (Bi) doped fiber amplifier (BiDFA) that allows for extended O-band transmission range and O-band transmission capacity. The silica-based BiDFA disclosed in the present invention has a six decibel (6dB) gain bandwidth greater than ~60nm. The center of the gain band depends on the pump wavelength and can be flexibly centered between ~1305nm and ~1325nm. The BiDFA uses optical fiber that is essentially free of erbium (Er) while exhibiting parameters comparable to Er-doped fiber amplifier (ErDFA) systems. The disclosed embodiments are capable of extending 400GBASE-LR-8 transmission distances to approximately forty kilometers (~40km) over optical fiber that complies with the ITU-TG.652 industry standard.

[0029] Having provided a general technical solution to the technical problem, now detailed reference is made to the description of the embodiments as shown in the accompanying drawings. Although several embodiments are described in conjunction with these drawings, it is not intended to limit the present disclosure to one or more embodiments disclosed herein. On the contrary, it is intended to cover all alternatives, modifications and equivalents.

[0030] Figure 1A is a diagram showing an embodiment of a system including a bismuth (Bi)-doped optical fiber (or Bi-doped fiber (BiDF)). Specifically, Figure 1A An optical amplifier system is shown having a signal input 105, a first optical isolator 110 coupled to the signal input 105, and a BiDF 115 optically coupled to the first optical isolator 110. The BiDF 115 is optically coupled to a broadband three-decibel (3dB) coupler 120, which allows the introduction of pump light by a reverse pump light source 125. It should be understood that the BiDF 115 can also be pumped with a co-directional pumping scheme or a combination of co-directional pumping and reverse pumping schemes. In the case where the co-directional pumping and reverse pumping schemes are known in the art, further discussion of the co-directional pumping and reverse pumping schemes is omitted herein. The output transmission fiber 130 transmits the signal from the 3dB coupler 120 to the second optical isolator 135 and then to the signal output 140.

[0031] exist Figure 1AIn an embodiment, the BiDF 115 includes a Bi-doped core of phosphosilicate glass having a Bi concentration of less than about 0.01 mole percent (<0.01 mol%). As is known in the art, a manufacturing process such as modified chemical vapor deposition (MCVD) or using a glass tube to form a cladding of a preform while depositing the components of the core (e.g., a compound of silicon (Si), phosphorus (P), and Bi) from the vapor phase.

[0032] Other fabrication methods known in the art can produce BiDF 115 .

[0033] When manufactured, BiDF 115 has a core diameter of about seven microns (-7 μm), a refractive index difference of about 6e-3 (-0.006) between the core and cladding, and a cutoff wavelength of -1100 nm. The core diameter of -7 μm allows for good splice matching with other silica-based optical fibers. Further discussion of the optical fiber manufacturing process is omitted here as long as they are within the scope of MCVD and other BiDF manufacturing processes understood by those of ordinary skill in the art.

[0034] like Figure 1A As specifically shown in FIG. 1 , the system includes a BiDF 115 having a length of about eighty meters (-80 m) that is counter-pumped by one or more pump sources 125 having a central wavelength (λ3) between -1155 nm and -1255 nm. Specifically, Figure 1A The embodiment uses one (1) pump to select five (5) different center wavelengths, ˜1155 nm, ˜1175 nm, ˜1195 nm, ˜1215 nm, and ˜1235 nm. In addition, for Figure 1A In an embodiment, the signal input 105 comprises a distributed feedback (DFB) laser operating at ∼1310 nm, and an eight-channel comb is used to measure the fiber gain (G), saturated output power, and power conversion efficiency (PCE) from the output of the 400GBASE-LR8 transceiver in the wavelength range of ∼1272 nm to ∼1310 nm, all at Figure 1C Shown in.

[0035] The transmission fiber and BiDF 115 are spliced ​​using standard splicers and automated splicing procedures known to those skilled in the art. Figure 1A 1 shows that one (1) of five (5) pump sources 125 may be used, but alternative embodiments may allow any number of pump sources to be used in any combination. Such embodiments may be used to widen the gain bandwidth.

[0036] Figure 1B The amplified spontaneous emission (ASE) spectra for all five (5) pump wavelengths at a pump power of about 275 milliwatts (-275 mW) are shown. Figure 1BAs shown, there is a 0.5 nm shift in the ASE intensity peak for every 1 nm of pumping. In addition, the ASE spectrum exhibits a bell-shaped curve with a 3 dB bandwidth of 60 nm and a 6 dB bandwidth of 85 nm.

[0037] At an input power of approximately -2 decibel milliwatts (-2dBm), Figure 1C The dependence of G, power and PCE on the pump wavelength (λ3) is shown in FIG. Figure 1A In an embodiment, the amplifier system produces a G of ∼15dB to ∼18dB, a power of ∼20dBm, and a PCE of ∼23% to ∼27% for λ3 of ∼1195nm to ∼1235nm. For shorter λ3 (at ∼400mW pump power), all parameters decay dramatically. It should be appreciated that the input signal range of ∼1272nm to ∼1380nm is covered by using a combination of an LR-8 transceiver with three (3) Fabry-Perot lasers. The input (about -6dBm total signal power) spectrum for 400mW pump power and the output spectra at ∼1195nm and ∼1235nm are ∼100nm and 100nm, respectively. Figure 1D and Figure 1E The gain peak is consistent with the ASE peak wavelength, and the 6dB gain bandwidth is at least ~80nm in the λ3 range of ~1195nm to ~1235nm. Figures 1B to 1E , Figure 1A The optical amplifier system exhibits a gain of at least ˜16 dB for a gain fiber length of ˜80 m. For the same length, the system exhibits a PCE of at least ˜20% and an output power of at least ˜16 dBm.

[0038] For another embodiment, the second optical isolator 135 is removed (to simplify design and improve performance), and the 3dB coupler 120 is replaced by a fused fiber wavelength division multiplexer (WDM) that transmits light in the wavelength range covering the signal and pump (where the induced loss may be as high as ~4dB). The gain of the short wavelength channel increases for λ3 of ~1195nm. For the WDM embodiment, Figure 2A A graph of G and noise figure (NF) for a pump power of 500 mW is shown in FIG. Figure 2B The graphs of G and NF at a pump power of 750 mW are shown in FIG. Figure 2A and Figure 2B As shown, in the wavelength range of ˜1272 nm to ˜1310 nm, the amplifier system has a maximum G of ˜18 dB with a gain flatness of ˜2 dB and a typical NF of ˜5 dB, and the highest NF is ˜5.5 dB at ˜1272 nm.

[0039] The BiDFA performance was tested using a 400GBASE-LR8 transceiver and an ONT604 tester. The tester generates 16 × 26.6 Gigabits per second (Gb / s) of 2 31 -1 pseudo-random binary sequence (PRBS) on-off keying (OOK) data channels, while detecting the individual bit error rate (BER) of each of the 16 receiver-side channels. The 400GBASE-LR8 transceiver combines the 16 OOK data channels into 8×26.6Gbaud / s pulse intensity modulated PAM-4 channels and transmits them using a set of eight (8) directly modulated lasers. On the receiver side, the eight (8) WDM channels are demultiplexed (using filter widths greater than ~4nm), detected, and converted into 16 digital signal channels. The transceiver signal (at ~11.7dBm) is launched into ~40km to ~55km of fiber or a variable optical attenuator (VOA) and amplified by the BiDFA. To control the received power, another VOA is placed between the BiDFA and the transmission fiber (which complies with G.652, meaning the transmission center wavelength is ~1312nm with a loss of ~0.33dB at ~1310nm).

[0040] Figure 3A The optical spectrum after transmission is shown (G.652 fiber and BiDFA). Figure 3A The transmitter output, the BiDF input after ~40 km, and the BiDFA output are shown. Figure 3A In the example above, a wavelength offset was added to increase visibility. The system exhibited an average fiber loss of ~14.6 dB (including connectors), with the short wavelength channels experiencing up to ~2 dB higher losses than the long wavelength channels. For practical purposes, the pump power was limited to ~500 mW.

[0041] Using these parameters, the average bit error rate (BER) as a function of signal power over ~40 km of transmission fiber and 14.6 dB VOA was calculated at Figure 3B The power penalty at 1e-5 BER is less than 2 dB for both VOA and transmission fiber, while the long term BER (greater than 8 hours) is 5e-6 for amplified transmission over 40 km distance.

[0042] Figure 3C It shows Figure 3A The BER table of different wavelength channels in the BiDFA system is shown in Figure 1. Figure 3CAs shown, short wavelength channels have higher BER and the channel BER decreases with wavelength. This wavelength dependence can be attributed to the higher accumulated dispersion in short wavelength channels (compared to long wavelength channels) as well as the ~3 dB lower received power and ~2 dB lower optical signal-to-noise ratio (OSNR).

[0043] Inserting a VOA between the G.652 fiber and the BiDFA keeps the received power at ~6dBm and the difference between the best and worst channels at ~3dB, allowing investigation of BER degradation from OSNR due to ASE noise generated by the amplifiers and also allowing estimation of link loss tolerance. Figure 3D For a transmitter power of ~11.7 dBm and a ~40 km fiber span with ~14.6 dB loss, up to ~1.8 dB of loss can be added before a BER of 1e-5 is reached. Figure 3E As shown, the BER can also be measured on all channels for distances up to 55 km. However, as the distance increases, the error floor gradually increases to 1.3e-4.

[0044] Figure 4A is a graph showing the spectrum of another embodiment of a BiDFA system, where in addition to the receiver post-amplification (Amp II), another BiDFA (Amp I) is used to pre-amplify the signal. The spectrum shown represents the transmitter output, BiDF input, and BiDFA output. Specifically, the system has a total output power of ~20.8dBm (λ3 at ~1215nm and 750mW pump power). Although channels 1 to 4 continue to transmit, Figure 4C Only BER data from channels 8 to 15 are shown in FIG. Figure 4B The BER of G.652 fiber with transmission lengths of 70 km, 81.5 km and 85 km is shown in FIG. Figure 4A , Figure 4B and Figure 4C As shown and specifically by a long-term error floor of 3e-5 in a transmission length of ˜81.5 km, the short wavelength channel limits the transmission distance. Furthermore, for some embodiments, the amplifier system exhibits a bleaching effect, where the amplifier signal PCE increases with input signal power.

[0045] For some embodiments, the amplification stages used for the BiDFA may be cascaded. Figure 5 One such embodiment is shown. Specifically, Figure 5 The embodiment includes a first amplifier stage 510 and a second amplifier stage 550, which are optically coupled together via a connecting optical fiber 555. It should be understood that additional amplifier stages can be cascaded as needed. Figure 5As shown, the first stage 510 includes a signal input 515, a first pump source 520, and a first WDM 525 that combines the signal with the pump in a co-directional pumping configuration (or scheme). The first stage 510 also includes a first BiDF 530 optically coupled to the output of the first WDM 525. The first stage 510 also includes a second pump source 540 and a second WDM 535 that couples pump light from the second pump source 540 to the first BiDF 530 in a counter-directional pumping configuration (or scheme).

[0046] The second stage 550 includes a signal input 515, a third pump source 560, and a third WDM 565 that combines the signal with the pump in a co-directional pumping configuration (or scheme). The second stage 550 also includes a second BiDF 570 optically coupled to the output of the third WDM 565. The second stage 550 also includes a fourth pump source 580 and a fourth WDM 575 that couples pump light from the fourth pump source 580 to the second BiDF 570 in a counter-directional pumping configuration (or scheme). The fourth WDM 575 is optically coupled to a signal output terminal 585.

[0047] It should also be understood that for some embodiments, the bleaching of the first amplifier stage 510 is different from the bleaching of the second amplifier stage 550, while for other embodiments, the bleaching of the two stages 510, 550 is the same. The difference in bleaching is achieved by, for example, changing the concentration of Bi in the gain fiber. Therefore, by improving certain parameters (e.g., gain, bleaching level, etc.) at each amplifier stage 510, 550, certain parameters of the entire cascade system (e.g., total system gain, output power, etc.) are improved. In addition, it should be understood that some pumps are redundant and therefore can be omitted (e.g., a co-directional pumping-only scheme can be used, a counter-directional pumping-only scheme can be used, or a combination of a co-directional pumping scheme and a counter-directional pumping scheme can be used (e.g., Figure 5 ) and so on). Moreover, each additional stage can be configured with one or more different types of gain fibers (e.g., Bi-doped, Er-doped, etc.). In addition, each pump can be configured with a single pump wavelength or multiple pump wavelengths as needed. In addition, each pump source can operate at the same wavelength as other pump sources, or at a different wavelength from other pump sources.

[0048] Now go to Figure 6 , shows another embodiment of the BiDFA system. Specifically, Figure 6The embodiment of FIG. 1 shows a BiDFA system, which includes a signal source 610 operating at a central wavelength λS, a pump source 620, and a light source 630 operating at a central wavelength λA. The pump source 620 can be a single pump wavelength source with a central wavelength of λ3, or a collection of more than one pump sources. In an alternative, an additional pump source with a central wavelength λ4 can be added to the Figure 6 in the configuration.

[0049] For some embodiments, multiple pump wavelengths can be multiplexed together to present many different center wavelengths (λ3), each corresponding to its respective pump source. In some embodiments, λ3 (or λ4, depending on the configuration) is between ˜1155 nm and ˜1255 nm. Specifically, for some embodiments, λ3 (or λ4, depending on the configuration) includes wavelengths of ˜1155 nm, ˜1175 nm, ˜1195 nm, ˜1215 nm, and ˜1235 nm. For multiple pump sources, the VOA balances the output power of λ3 (or λ4).

[0050] The signal source 610, the pump source 620 and the light source 630 are optically coupled to the BiDF 670. The BiDF 670 has a gain band and an auxiliary band. The gain band has a central wavelength λ1. For some embodiments, λ1 is between ~1305nm and ~1325nm. The auxiliary band has a central wavelength λ2, and the light source in the auxiliary band has a wavelength λA. For some embodiments, λA is ~1405nm. The gain band has a 6dB gain bandwidth of at least ~60nm. For some embodiments, the 6dB gain bandwidth and the central wavelength λ1 are dependent on λ3. Preferably, the BiDF 670 is substantially free of Er. Figure 6 The system also includes an optional optical signal analyzer (OSA) 690 or other signal output. According to some embodiments, λA may be in the range of ˜1360 nm to 1500 nm (λ2b), or in the range of ˜1240 nm to ˜1280 nm (λ2a).

[0051] The additional light source 630 improves amplifier efficiency by reducing signal loss at λS (or increasing signal gain at λS). Specifically, it is known that Bi has excitation and emission bands in the range of ~1200nm (λ2a), the range of ~1300nm (O-band), and the range of ~1400nm (λ2b). By adding optical power above a certain power level at λ2, signal excitation can be increased due to the reduction of bleaching. Therefore, exciting λA (in λ2a or λ2b) causes the signal gain in the gain band (e.g., ~1260nm to ~1360nm) to increase by a value between ~6dB and ~10dB. This is because gain and efficiency are sensitive to the competition between the ground state ion population and the excited state ion population. In particular, higher inversion levels are necessary for higher gain. However, at low input signal power (e.g., less than about -10 dBm), emission at out-of-band wavelengths (e.g., λA at ~1200 nm in range λ2a or λA at ~1400 nm in range λ2b) can shift power and reduce the inversion level. This shifting effect can be compensated to some extent by introducing out-of-band light at λ2. The relative positions of λS, λ2a, λ2b, and λ3 are summarized as follows: λS is located in the O-band (at ~1260 nm to ~1360 nm); λ3 is located below ~1240 nm (typically within ~1195 nm to 1240 nm); λ2a is located below the O-band; and λ2b is located above the O-band.

[0052] For example, for λA of ~1405nm and λS of ~1320nm, if a λA signal of lower power level (e.g., ~4dBm) is introduced into a small λS signal (e.g., about -10dBm) in the presence of a larger pump signal (e.g., greater than ~20dBm) at λ3, the excitation at λA will increase the amplification efficiency, thereby increasing the gain at λ1 by ~6dB to ~10dB. Figure 7 An example is shown. Specifically, Figure 7 is a graph comparing the loss of the λ1 signal in the 100 mBiDF. Specifically, the signal loss is compared when there is a light source 630 and when there is no light source 630. Figure 7 As shown, adding ~4.1 dBm at λA at ~1405 nm reduces the attenuation (loss) in BiDF670 from ~19 dB / 100 m to ~15.3 dB / 100 m, which is a ~3.7 dB reduction in signal loss, and if extended to both polarizations, this translates into a ~6 dB to ~10 dB increase in small signal gain. Thus, for communications where the data-bearing signal in the O-band is in the range of about 30 dBm to about +3 dBm, adding an additional light source 630 in the adjacent excitation band (λ2) increases amplifier efficiency. Note that the light source 630 can be a laser or a broadband light source.

[0053] Another way to improve amplifier efficiency, especially for small signals (e.g., less than -10 dBm), is to change the waveguide properties of the BiDF core. As mentioned above, inversion depends to some extent on the competition between the excited state and the ground state. Therefore, one way to increase the inversion level is to increase the intensity of the pump light (λ3).

[0054] The intensity of the pump light (at λ3) can be increased by reducing the mode field area (MFA) of the waveguide. The MFA of the waveguide can be reduced by increasing the core refractive index (e.g., by increasing the concentration of non-gain producing co-dopants in the core) and reducing the core diameter. Preferably, the non-gain producing co-dopants (e.g., lanthanum (La) or lutetium (Lu)) do not change the gain characteristics of Bi to be different from the desired P-doped silica glass. Alternatively, the MFA of the waveguide can be reduced by reducing the cladding refractive index, which can be achieved by doping with fluorine (F). Regardless of the method of reducing the MFA, a reduction in the MFA of the BiDF will produce a corresponding increase in the efficiency of the BiDFA. It should also be noted that the P-Bi-SiO2 core produces the desired gain at ~1300nm, but co-dopants of germanium (Ge) or aluminum (Al) (e.g., in a Ge-Bi-SiO2 core or an Al-Bi-SiO2 core) do not produce the equivalent desired gain.

[0055] Although exemplary embodiments have been shown and described, it will be apparent to those skilled in the art that many changes, modifications, or alterations may be made to the disclosed subject matter described. For example, although most values ​​are provided as approximations (using "~"), these approximations also include exact values, and therefore, the approximations reflect an error margin to the nearest significant figure. Therefore, all such changes, modifications, and alterations should be considered within the scope of the disclosed subject matter.

Claims

1. An optical system, comprising: Operating wavelength range between 1272nm and 1310nm; Bismuth-doped optical fiber without Erbium Er, the bismuth-doped optical fiber comprising: a six decibel (6 dB) gain band having a bandwidth greater than 60 nm, the six dB gain band centered within a wavelength range between 1305 nm and 1325 nm; a signal source, optically coupled to the bismuth-doped Bi optical fiber, the signal source being used to provide an optical signal within the six-decibel gain band to the bismuth-doped Bi optical fiber; and A pump source is optically coupled to the bismuth-doped Bi optical fiber, the pump source is used to provide pump light at a pump center wavelength to the bismuth-doped Bi optical fiber, the pump center wavelength is at least two wavelengths selected from the group consisting of: 1155nm; 1175nm; 1195nm; 1215nm; and 1235nm.

2. The system according to claim 1, wherein: The pump source provides pump light using a pump configuration selected from the group consisting of: Co-directional pumping configuration; A counter-pumping configuration; and A combination of co-pumping and counter-pumping configurations.

3. The system according to claim 1, wherein: The system has a gain of at least sixteen decibels (16 dB) at a distance of eighty meters (80 m).

4. The system according to claim 1, wherein: The system has a power conversion efficiency (PCE) of at least twenty percent (20%) over a distance of eighty meters (80 m).

5. The system according to claim 1, wherein: The system has a noise figure of less than 5.5 decibels (5.5 dB).

6. The system according to claim 1, wherein: The system has an output power of at least sixteen decibel milliwatts (16 dBm) at a distance of eighty meters (80 m).

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