A method for measuring the damping coefficient of vibrating target based on Fourier transform of self-mixing interference signal is presented. Theoretical researches indicate, the dominant harmonic order of the laser self-mixing signal is proportional to the amplitude of vibration. Based on this theory, damping efficient can be extracted from the ratio between the amplitudes of the vibration target at different moments. The error of the damping coefficient is about 4%.This method characterized by simple structure, non-contact measurement and high accuracy, can be extensively applied in measurement of industrial harmonic damping vibration.
We investigate a high-pumping-efficiency and linewidth-broadening, L-band, erbium-doped, superfluorescent fiber source (SFS) using a cascaded dual-backward-pumped configuration. With optimized structural parameters, the design provides an L-band SFS with a mean wavelength of 1578.2 nm, an output power of 132.8 mW, and a spectral linewidth of 52.6 nm without using any external spectral filters under 265-mW pump power. The high pumping efficiency of 50.1% is achieved experimentally. The design relaxes the danger in resonant lasing while enhancing the pumping efficiency and broadening the linewidth.
We present a wideband and high pumping-efficiency L-band erbium-doped fiber (EDF) amplified spontaneous emission
(ASE) source using a two-stage double pass backward (DPB) pumping configuration.DPB configuration has been proved
to have a high pumping-efficiency. In this paper we use a two-stage DPB pumping configuration to generate a stable
L-band ASE source for the first time. The source consists of two sections of EDF, a 1480nm pumping laser diode (LD)
which is divided into two portions to pump two sections of EDF separately. By using a power splitter, the pumping
power of two stages can be adjusted proportionally. The effects of EDF length and pump power arrangement on the
output characteristics of L-band ASE spectrum, output power and mean wavelength are theoretically investigated. The
results show that the pumping-conversion efficiency and the linewidth can be improved significantly by optimizing the
fiber length ratio and pump ratio of the two-stage DPB configuration. Based on former work, the total fiber length is
chosen at 19m in this paper. With the total fiber length fixed, the proposed source has a high pumping efficiency of 53%,
an output power of 111mW, and a broadening linewidth of 49nm with the mean wavelength at 1580.18nm under the
optimizing fiber ratio of 0.842 and pump power ratio of 0.5.
We first demonstrate that by inserting an appropriate section of unpumped erbium-doped fiber (EDF) in an erbium-doped superfluorescent fiber source (SFS) of double-pass backward configuration, a stable L-band SFS can be achieved. The fiber-length arrangement of unpumped fiber are shown to have significant effects on the output properties of the L-band SFS. The spectral linewidth is broadened, and the variation of mean wavelength versus pump power is eliminated to achieve a wideband and mean wavelength stable L-band SFS by optimizing the fiber-length ratio of the pumped fiber length to the total fiber length. For a 19-m-long total EDF with fiber-length ratio of 0.84, a mean wavelength stable L-band SFS with a spectral linewidth of 49.6 nm, an output power of 46.3 mW, and a mean wavelength of 1583.20 nm was experimentally achieved.
In this paper, a simple single-backward configuration with a section of un-pump fiber is presented to achieve a stable
L-band superfluorescent fiber source (SFS). The effects of the structural parameters on the output characteristics of the
L-band SFS in terms of output spectrum, mean wavelength, and linewidth are theoretically examined. By selecting
suitable structure parameters, an L-band SFS with mean wavelength insensitive to pump power is achieved under a
pump power of 190mW, corresponding to a mean wavelength of 1583.20nm, an output power of 47mW, and a spectral
linewidth of 49.6nm. The proposed L-band SFS design shows its tremendous advantages as simple structure and good
performances that make it be useful in WDM system, fiber optic gyroscopes and fiber sensor systems applications.
We have experimentally investigated a new two-stage C+L-band (1525 to 1605-nm) amplified spontaneous emission (ASE) fiber source using a dual forward pumping configuration. The proposed source offers a high pumping efficiency of 24.6%, output power of about 52 mW, and a wide bandwidth of 80 nm. Without using any external spectral filters, the source has a low spectral ripple between 2.4 and 2.9 dB for different pumping power levels. This designed configuration is also suitable for high-efficiency L-band ASE. The obtained source will be useful in characteristic measurement for wavelength-division multiplexing components and spectrum-sliced multiwavelength fiber sources for local access networks.
Theoretical design optimization of the first-order P-doped fiber Raman laser (FRL) by an explicit approach was
investigated. The authors derived an explicit expression for the output power of the laser without using the depleted-pump
approximation. The proposed solution shows excellent agreement with numerical simulation. According to the
explicit solution, one can clearly know the effects of fiber length, reflectivity of output fiber Bragg grating (FBG),
Raman gain and loss of the P-doped fiber and extra losses on the output power. The solution also present a criteria by
which one can determine whether the depleted-pump approximation is valid or not. It is very fast and convenient to
optimize the output power of the FRL using the proposed explicit solution. The optimal values of fiber length,
reflectivity of output FBG and conversion efficiency are obtained under different pump power. While increasing pump
power, the optimal fiber length and reflectivity of output FBG decrease and the optimal conversion efficiency increase.
There exists a certain tolerance of the optimal parameters, in which the conversion efficiency decreases only slightly.
The results provide us an intuitive physical understanding to the laser and are instructive to experimental design of the
laser.
We present a two-stage dual-forward pumped configuration to achieve a wavelength stable L-band amplified
spontaneous emission (ASE) source. The effects of EDF length and pump power arrangements on the characteristics of
L-band ASE spectrum, output power, and mean wavelength are investigated. The results show that not only the pumping
conversion efficiency can be improved largely but also the pump power independent mean wavelength operation can be
achieved by optimizing the fiber length ratio and pump ratio of the dual-forward pumped configuration as comparing to
that of the conventional double-pass forward configuration.
Two kinds of configurations of L-band amplified spontaneous emission (ASE) source with two-stage EDF and dual
forward pumps are suggested for generating a high power L-band ASE spectrum. The characteristics are theoretically
compared in terms of the output power, pumping conversion efficiency, bandwidth, and mean wavelength stability for
these two configurations. The EDF length and pump power allotment are also optimized. An L-band ASE source of
76mW output power with about 36.2% pumping conversion efficiency are experimentally obtained.
A LD-single-end-pumped Nd:YVO4 CW all-solid-state laser with maximum output power 12.5W at 1064nm was
designed to pump the cascaded phosphosilicate fiber Raman laser. The Nd:YVO4 laser is lower in cost than Yb-doped
cladding fiber laser which is usually used as a pump for Raman fiber laser. However, it is inefficient to couple pump
beam into single mode fiber (SMF). The coupling efficiency from pump beam to SMF is largely affected by the beam
quality. Thus, a high coupling efficiency requires maintaining laser's operation in the TEM00 mode while scaling the
power. The beam quality and maximum output power of the Nd:YVO4 laser is restricted by the thermal lens and fracture
within the gain medium under high pump intensity conditions. The thermal effects was decreased by using a 3×3×
10mm3 Nd:YVO4 crystal with a low neodymium-doped concentration (0.3at%). Furthermore, a plane-plane resonant
cavity with large mode volume and a large pump size was also used to reduce the effects. The Nd:YVO4 laser with
maximum output power 12.5W and M2<1.2 was obtained. More power than 4W was injected into cascaded Raman
cavity at the maximum pump power and about 1W coherent second-order Stokes radiation at 1484nm was achieved.
Two novel methods are demonstrated to build up a band-selective amplified spontaneous emission (ASE) broadband light source that can operate in the selective conventional band (C-band, 1525~1565 nm) or long-wavelength band (L-band, 1565~1605 nm) region using a 1×2 optical switch. With the backward ASE feedback technique, an output power of 27.6 mW for the C-band ASE and 11.8 mW for the L-band ASE are obtained while with the compound pump technique, a power of 24.5 mW for L-band ASE and 27.2 mW for C-band ASE are obtained both with a fixed total pump power of 100 mW. The advantage of using the backward ASE feedback technique is that the ASE source design is simpler whereas the power of L-band ASE is lower, and the notable advantage of using the compound pump technique is that the output powers of the two selective bands (C- or L-band) are balanced though the configuration is a little complicated.
A scheme for generating multi-wavelength fiber source based on erbium-doped fiber amplified spontaneous emission and spectrum sliced technique is demonstrated for potential applications in the dense-wavelength division multiplexing (DWDM) communication systems. A spectrum sliced multi-wavelength fiber source of 140 channels (extinction ratios larger than 13 dB) with 0.57nm channel spacing covering C-band and L-band is obtained by optimizing the erbium-doped fiber length and the pumping ratio of the scheme.
In this paper, we investigate the 1480nm pumped L-band erbium doped fiber amplified spontaneous emission source of three major configurations: one-stage double-pass forward pump configuration,
two-stage with C-band ASE injection configuration, one-stage double- pass bi-directional pump configuration. The characteristics are compared in terms of the output power, pumping conversion efficiency, bandwidth, and mean wavelength stability. It is shown that the one- stage double-pass bi-directional pump configuration has a better performance than the other two configurations.
In this paper, a practical two-stage scheme is suggested for generating a C+L-band erbium-doped fiber amplified spontaneous emission (ASE) broadband light source. A considerable power increase of the L-band ASE spectrum is achieved by injecting the C-band ASE into the long section erbium-doped fiber. The C+L-band ASE source is obtained by combining the enhanced L-band ASE with the C-band ASE from two stages respectively. A spectrum flat ASE source with nearly 80nm bandwidth and about 15.9dBm output power is obtained with a total pump power of 180mW. Namely, the pump conversion efficiency is about 21.6%. Such a broadband incoherent light source is desirable for various applications in some areas like sliced wavelength- division multiplexed local-access networks, characteristic measurement for dense wavelength-division multiplexed components, and fiber-optic sensor systems etc.
In this paper, a novel scheme for band selection in an amplified spontaneous emission source (ASE) based on erbium-doped fiber is demonstrated. C-band operation is obtained without backward ASE feedback whereas L-band operation is obtained with backward ASE feedback with the used of a 1X2 optical switch. A selective ASE source with an output power of 27.6mW for the C-band and 11.8mW for the L-band is obtained experimentally with a total pump power of 100mW of 1480nm laser diode. This band selective ASE source convenience the users select the necessary band when needed without any form of upgrading or additional module attachment therefore has the potential use for the dual-band DWDM device characterization and metro networks.
A new bidirectional pumped configuration for an L-band erbium-doped superfluorescent fiber source is demonstrated. Data are presented showing that with this configuration, the mean wavelength variation with the pump power can be reduced to zero by optimizing the fiber length and the pumping ratio of forward to total pump power.
A new spectrum sliced multi-wavelength fiber source (MWFS) with no power loss is presented in this paper. The source is composed by a reflection Mach-Zehnder filter (RMZF) with double-pass backward superfluorescent fiber source (DPB SFS) configuration. The RMZF not only provides spectrum filtering but also provides the double-pass function. Multi-wavelength source with extinction ratios larger than 15 dB can easily be obtained over the total conventional band gain region with appropriate erbium-doped fiber (EDF) length and pump power. There is no power loss with the MWFS as compared to the original DPB SFS owning to the RMZF also provides the double-pass function. More than 50 channels of 0.57nm wavelength spacing between 1530nm-1560nm are obtained.
A novel one-stage configuration for high stability L-band (1565-1605nm) erbium-doped superfluorescent fiber source (SFS) is designed and investigated. The superfluorescent source is realized in a 19m erbium-doped fiber with double-pass bi-directional pumping configuration. High pumping conversion efficiency and pump power insensitive mean wavelength characteristic due to the bi-directional pumping configuration. Pumping conversion efficiency about 60% and flat spectral linewidth over 30 nm is obtained by the proposed SFS.
A temperature-tunable polarization interference filter (PIF) made of YVO4 crystal has been presented and applied for wavelength monitoring of a distributed feedback (DFB) laser in a dense wavelength-division-multiplexing (DWDM) optical communication system. This novel device offers a flexible way to monitor the operating wavelength of the transmitter over a wide capture range. Monitoring resolution of 0.02 nm can be obtained by measuring the temperature variation of the filter while its transmission value is kept at a constant value.
The self-injection locking single frequency Yb-doped fiber ring laser is reported. The system shows compact, stable and tunable. In the primary experiment, the Self-injection locking single frequency fiber ring laser with wavelength 1.05325)mum, power exceeding 3.5mW,line-width less than 36 MHz was manufactured. The laser shows stability, low threshold and high power. No mode-hopping was observed within 2 hours. The single polarization output can be obtained when use single polarization fiber.
A diode-pumped, compact, wavelength tunable, single frequency Er3+:Yb3+ codoped DBR fiber laser is reported. An output power of 2.4mW for 75mW of 980nm diode pump power and a slope efficiency of 6% at 1557.05nm were obtained. Linewidth of the laser was estimated at 1557.05nm to be less than 1MHz. Also, the laser can be tuned to wavelengths between 1557nm to 1561nm and operates single mode throughout this range.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.