Amplified Spontaneous Emission Light Research Articles

All-optical tuning of the frequency of Yb3+/Er3+ co-doped microsphere WGM laser pumped by 1 µm ASE light source

In this paper, the laser generated by Yb3+/Er3+ co-doped silica microspheres excited and tuned by amplified spontaneous emission (ASE) light source was studied. The adoption of ASE light avoids the synchronous adjustment of the coupling condition of the microcavity during broadband tuning process, and facilitates the actual application of the microcavity-based tunable laser. The stable single-mode laser at approximate 1595 nm was generated in the Yb3+/Er3+ co-doped silica microsphere due to the polarization insensitivity of the ASE light source with a center wavelength of 1 µm. For the all-optical modulation of laser mode, a thin layer of copper film was coated on the spherical crown of the microsphere by magnetron sputtering. Controllable heating of the microsphere and linear tuning of laser mode were realized through the absorption of ASE light by the copper film injecting from the stem of the microsphere. The tuning range reached 190 GHz.

Passive IoT Optical Fiber Sensor Network for Water Level Monitoring with Signal Processing of Feature Extraction

This paper presents a real-time remote water level monitoring system based on dense wavelength division multiplexing (DWDM)-passive optical fiber sensor (OFS) network for the application of the Internet of Things (IoT). This network employs a broadband light source based on amplified spontaneous emission (ASE) as a seed light. This ASE light is spectrum-sliced by an athermal type arrayed waveguide grating (200 GHz × 16 channel), then distributed towards multiple sensing units (SU). Here, 16 SUs are installed vertically at the specified height in the water pool according to the design specification (i.e., spatial resolution). Then, each SU reflects an optical spectrum having a different reflection coefficient depending on the surrounding medium (e.g., air or water). By measuring these reflected optical spectra with an optical spectrum analyzer, the water level can be easily recognized in real time. However, as the sensing distance increases, system performance is severely degraded due to the Rayleigh Back-Scattering of the ASE light. As a result, the remote sensing capability is limited at a short distance (i.e., <10 km). To overcome this limitation, we propose a simple signal processing technique based on feature extraction of received optical spectra, which includes embedding a peak detection algorithm with a signal validation check. For the specific, the proposed signal processing performs the peak power detection, signal quality monitoring, and determination/display of the actual water level through three function modules, i.e., data save/load module, signal processing module, and Human–Machine Interface display module. In particular, the signal quality of the remote sensing network can be easily monitored through several factors, such as the number of spectral peaks, the wavelength spacing between neighboring peaks and the pattern of detected peak power. Moreover, by using this validation check algorithm, it is also possible to diagnose various error types (such as peak detection error, loss of data and so on) according to the pattern of measured optical spectra. As a result, the IoT sensor network can recognize 17 different level statuses for the water level measurement from a distance of about 25 km away without active devices such as optical amplifiers (i.e., passive remote sensing).

Light‐Emitting Device Based on Amplified Spontaneous Emission

AbstractIn recent years, with the rapid development of military, optical communication, biological imaging, and other fields, practical engineering applications such as fiber‐optic gyroscope, wavelength division multiplexing, and optical coherence tomography have put forward higher requirements on light sources. Amplified spontaneous emission (ASE) light source has become an excellent candidate due to its advantages such as suitable bandwidth, low coherence, and high power. Although the ASE light source is developed to a certain extent, there is still great room for improvement in the choice of gain medium and device structure. In order to accelerate the development and practical engineering application of ASE optoelectronic devices, it is of great significance to grasp the basic characteristics of the gain materials and the design of the device structure. In this review, the principle of the ASE effect and its difference with the generation of lasing are analyzed. Then, the optical gain properties of various gain materials, together with different structural types of electrically pumped ASE devices and their practical engineering applications, are summarized. Finally, the new ASE light‐emitting devices integrated with high‐gain materials and low‐cost structures are prospected to provide more ideas for their development.

Optical stealth communication based on quantum noise stream ciphered amplified spontaneous emission light.

Amplified spontaneous emission (ASE) light is the most natural optical carrier to hide a message in the existing optical networks at photonic layer. To enhance the anti-intercept ability of the ASE-carried stealth channel, a novel optical stealth communication scheme based on quantum noise stream cipher is proposed. The ASE light is intensity modulated by the cipher-text according to Y-00 protocol, and then transmitted under public optical noise after power attenuation. The expression of quantum noise stream ciphered ASE signal is derived, and numerical simulation is carried out. A proof-of-concept experiment is set up to demonstrate the feasibility of the proposed scheme. The experiment results show that the quantum noise stream ciphered stealth signals can be transmitted over a 25 km single-mode fiber span error-free.

2 μm Laser generation and amplification based on dual Tm3+-doped high-Q silica microsphere using an ASE light source for pumping

A dual Tm3+-doped silica microsphere-tapered optical fiber (TDSM-TOF) structure was proposed to excite 2 μm whispering gallery mode (WGM) laser generation and amplification. A C-band amplified spontaneous emission (ASE) light source was employed as the pumping source of TDSMs. The absorption spectra and the laser spectra of TDSM1 and TDSM2 and their concatenations were measured respectively. The ASE source has polarized light in any direction to satisfy the resonance of the microsphere cavity, the laser longitudinal mode distributions can counteract the influence of polarization variation because of environmental vibration. Meanwhile, six photons up-conversion fluorescence could also be observed.

Efficient second harmonic generation of a Yb fiber-based amplified stimulated emission source

Efficient second harmonic generation (SHG) of ytterbium (Yb)-doped fiber-based amplified spontaneous emission (ASE) light with temporally low coherence is reported. A Yb-fiber ASE light with a tunable bandwidth was amplified in two power amplifier stages and was frequency-converted by a periodically-poled lithium tantalite waveguide. The second harmonic conversion efficiency of the ASE light achieved in the experiment was inversely proportional to the bandwidth, which was in very good agreement with theoretically calculated value using the self-convolution relationship of the power spectral density for nonlinear frequency conversion of low coherent light. The prospects for further improvement in nonlinear frequency conversion of the fiber ASE source will be discussed.

A Stable 1550nm WGM Laser Generated by Yb3+/Er3+ Co-doped Silica Microspheres under μm ASE Source Pumping

The amplified spontaneous emission (ASE) light source at 1 μm was used to excite Yb3+/Er3+ co-doped silica (YEDS) microspheres by evanescent-wave coupling through a taper optical fiber (TOF) to generate a stable 1550 nm laser. Inevitably, the experimental process was accompanied by a frequency up-conversion luminescence whose fluorescence spectrum was collected and analyzed. Pumped by the ASE light source with different power, the system of YEDS microsphere and TOF also generated single-mode laser and multi-longitudinal mode laser. Their peak wavelength, output power of the peak laser, full width at half maximum (FWHM), and side mode suppression ratio (SMSR) were respectively measured. Moreover, the characteristics of a 1550 nm whispering gallery mode (WGM) laser excited by a 1 μm ASE pumping and a tunable laser (TLS) pumping were compared under different variable conditions. It was demonstrated that the ASE pump source has polarization in all directions to excite WGMs in the microsphere cavity, which was different from and superior to the TLS. Therefore, the laser generated by the ASE pump source as an excitation source was not affected by vibration and temperature change. The results show that the 1550 nm laser pumped by ASE can stably output the microsphere WGM mode laser under the interference of vibration and temperature change, which is more suitable for the actual application environment.

Broadband mid-infrared amplified spontaneous emission from Er/Dy co-doped fluoride fiber with a simple diode-pumped configuration

Er3+/Dy3+ co-doped double-clad ZBLAN optical fiber has been used to obtain amplified spontaneous emission (ASE) broadband light sources cladding-pumped by 980-nm multimode laser diode (LD) sources. It has been demonstrated that mid-infrared broadband emission extending from 2515 to 3735 nm was obtained by energy transfer between Er3+ and Dy3+. We experimentally investigated the optimum design of Er3+/Dy3+ co-doped ZBLAN fiber in terms of ion concentration, fiber length, pumping configuration, and pumping power. The ASE output power was more than 2.5 mW when the LD pump power was set at 5 W. To assess its potential for gas sensing applications, the fabricated ASE light source was used to successfully detect methane gas with concentrations at 1% and 5%. The simple and stable construction of our ASE light source is suitable for practical purposes.

Optical Based Humidity Sensor by Using Zinc Oxide-PVA In Micro Cavity

We demonstrate a simple optical based humidity sensor using a micro cavity. The micro cavity consists of single mode fiber (SMF-28e, Corning) and a reflective mirror coated with zinc oxide (ZnO) which is embedded in polyvinyl alcohol (PVA). A wideband amplified spontaneous emission (ASE) source, ranging from 1530-1610 nm was injected into the micro cavity. The water molecules from the surface of the ZnO-PVA changed the refractive index of the micro cavity which subsequently modified the phase of ASE light that was reflected from the coated mirror. The change of phase in the reflected light from the coated mirror was monitored with optical spectrum analyzer (OSA). The performance of our optical humidity sensor for non-coated mirror and ZnO-PVA coated mirror was recorded at 0.03 nm/RH% and 0.074 nm/RH%, respectively. This shows that optical humidity sensor with ZnO-PVA coated mirror is more sensitive to humidity changes.

3 kW high OSNR 1030 nm single-mode monolithic fiber amplifier with a 180 pm linewidth.

In this Letter, the amplified spontaneous emission (ASE) effect of a 1030 nm fiber laser is studied theoretically and, based on the theoretical results, a 3 kW high optical signal-to-noise ratio (OSNR) 1030 nm fiber amplifier with a 180 pm linewidth and near-diffraction-limited beam quality is achieved. A theoretical model, which takes simulate ASE light falling in the range of Raman light as the Raman seed, has been used to optimize the power scaling capability of 1030 nm fiber amplifiers. It shows that the SRS effect seeded by the ASE is the main limiting factor for the fiber amplifiers operating at 1030 nm, and >3kW output power with a high OSNR can be achieved by proper parameter designing of the fiber laser system. A 1030 nm monolithic narrow linewidth fiber amplifier, which delivers 3 kW output power with the OSNR being 37 dB and a 0.18 nm spectrum linewidth, has been demonstrated. At the maximum 3 kW output power, the SRS light peak is obviously higher than ASE light, which agrees with the theoretical predictions. Neither a stimulated Brillouin scattering effect nor a thermal-induced mode instability effect has been observed at ultimate power level, and the beam quality factor M2 is measured to be less than 1.2. To the best of our knowledge, this is the highest average power for a narrow linewidth single-channel fiber laser system reported so far operating at 1030 nm.

Continuous-variable random-number generation from an amplified spontaneous emission light source

An amplified spontaneous emission (ASE) light source using an Er-doped fiber is an ideal random-number source in principle because ASE originates from vacuum fluctuations. Interferometrically measured ASE light directly reflects vacuum fluctuations in phase space; the interferometer does not need to be stabilized because the phase is completely random, and measurable random numbers are a continuous variable because vacuum fluctuations are continuous. These characteristics make the random-number source practical and ideal. Evaluated randomness was sufficiently ideal at the accuracy level of measurements and evaluations.

2 [formula omitted] Tm[formula omitted] doped silica microsphere laser using amplified spontaneous emission light for pumping

Single wavelength laser sources used for pumping lasers demonstrate poor resistance to environmental factors. Therefore, a method for employing an amplified spontaneous emission (ASE) light source for pumping thulium ion (Tm3+) doped silica microsphere (TDSM) lasers is proposed. The ASE source emits non-polarized light with a broad bandwidth. When using ASE light, there is always a wavelength group that resonates with the high-Q microsphere to adaptively couple into TDSM and excite the Tm3+ ion. The ASE source resists the resonance wavelength mismatch owing to the variation of pump light polarization caused by vibration and the variation induced by temperature change. With ASE light pumping, we demonstrated the generation of 2 μm whispering gallery modes (WGMs) laser with a very low threshold.

High-energy pulsed operation of a Yb fibre master oscillator power amplifier with an amplified spontaneous emission light source

We report high-energy pulsed operation of an amplified spontaneous emission (ASE) light source at 1050 nm based on a Yb-doped fiber master oscillator power amplifier (MOPA). The ASE seed beam with a tailored spectral bandwidth was temporally modulated by an acousto-optic modulator and was amplified in three Yb fiber amplifier stages. The MOPA yielded 320.7 µJ and 415.0 µJ of the pulsed outputs at a 100 kHz repetition rate for the ASE seeds with 1 nm and 2 nm bandwidths, respectively. Investigation of stimulated Brillouin scattering (SBS) in Yb fibers showed that ASE light pulses could offer a higher pulse energy than laser pulses due to the higher SBS threshold. We will discuss the prospects of further power scaling in a fiber ASE light source with a broad bandwidth by overcoming the SBS limitation.

Semi-quantum noise randomized data encryption based on an amplified spontaneous emission light source.

The first semi-quantum noise randomized cipher based on amplified spontaneous emission (ASE) light source employing Y-00 protocol is proposed and demonstrated by a proof-of-principle experiment. As the signal carrier, ASE light can provide another fundamental uncertainty, namely, self-beating noise of ASE signal, which is much bigger than quantum shot noise of mesoscopic coherent state and also inevitable. By incorporating both the shot noise and beat noise of ASE signals, the security will be improved with a larger number of masked signals (NMS) under intrinsic noise. After formulating NMS and Q-factor in theory, we investigate the impacts of key system parameters on the security and transmission performances, respectively, in order to optimize the system design. To evidence the theoretical results, an experimental setup with balanced photodetector (BPD) as decoder is constructed. The local light modulated by M/2-ary running key is applied as optical threshold signal, which is fed into BPD together with the M-ary ASE signal, outputting the binary signal. Eventually, a 128-level Y-00 realization based on ASE source is realized at 2.5Gb/s over 100-km fiber. The experimental results agree with the theory in the trend, which indicate the validity and feasibility of the proposed scheme.

Measurement of Multimode Fiber Bandwidth by the Fourth-Order Spectra of Amplified Spontaneous Emission

We present a novel bandwidth measurement scheme for multimode optical fibers. Amplified spontaneous emission (ASE) radiation was utilized for a source of intrinsically modulated light with a wide modulation bandwidth. In our measurement scheme, the continuous-wave (CW) ASE light that passed through a multimode fiber (MMF) under test was analyzed by the fourth-order power with a high-speed photodetector and an electric spectrum analyzer. The modulation transfer function of the multimode fiber could be directly measured with the photoelectric spectra in the modulation frequency domain. The measurement result of our method was experimentally compared to that of the conventional measurement scheme based on the impulse response measurement. It has been found that our scheme provides a stable measurement means of MMF characterization that is suitable for the field testing due to the simplicity of the system.

Efficient generation of blue light in oligothiophene chromophores doped in polymer films and fiber

A conjugated oligothiophene chromophore with large linear and nonlinear absorption cross-sections that emits light in the blue region is studied. Here measurements of the one- and two-photon absorption and fluorescence of an oligothiophene chromophore doped in polymethyl-methacrylate (PMMA) polymer is presented. It was observed that oligothiophene/PMMA fluoresces strongly and through amplified spontaneous emission (ASE), is an efficient source of blue light around 460nm. Using these materials, a polymer fiber-based blue ASE light source is demonstrated. Blue emitting molecules (mainly in PMMA) are tabulated for comparison.

광대역 ASE 광원과 PI-RSOA를 이용한 WDM-PON 시스템에서의 방송 신호 전송

본 논문에서는 파장분할 다중방식의 수동형 광 가입자망(WDM-PON: Wavelength Division Multiplexing - Passive Optical Network)에서 매우 구조가 간단하고 저비용으로 구현 가능한 방송신호 전송 방법을 제안한다. 이는 하나의 광대역 증폭된 자발 광원(Amplified Spontaneous Emission: ASE)과 편광 독립 반사형 반도체 광 증폭기(Polarization Independent-Reflective Semiconductor Optical Amplifier: PI-RSOA) 만으로 구현이 가능하기 때문이다. 채널당 1.25 Gb/s 속도에서 24개의 가입자 채널에 대해 30 Km 이상의 방송 신호 전송 시, 무오류(error-free) 성능을 갖는 것을 실험적으로 증명하였다. In this paper, we propose a new method for broadcasting in a WDM-PON system which has the merits of a simple and cost effective structure. It can be constructed using only an ASE (Amplified Spontaneous Emission) light source and a PI-RSOA (Polarization Independent - Reflective Semiconductor Optical Amplifier). Error-free broadcast signal transmission over 30 Km for 24 channels at 1.25 Gb/s has been successfully demonstrated.

Single-shot tomography by means of VIPA and spatial phase modulator installed optical interferometer

A VIPA (virtually imaged phased array) installed optical interferometer has been proposed for scanless tomography. Also, a spatial phase modulator and a line-image sensor were installed into the interferometer to realize single-shot measurement by displaying the delay time on a line-image sensor. The correlation peak function was observed on the line-sensor at same time. The envelope of the peak was given by the inverse Fourier transformation of the light source spectrum. The peak position on the image-sensor reflects the sample structure. Furthermore, the correlation peaks are appeared repeatedly along the delay time of the interferometer. The repeated correlation function raise an alignment flexibility of the sample set position, which has been limited in the traditional time-domain interferometry involving the delay time to be zero. The flexibility was experimentally confirmed at 25 mm related to the VIPA coherency. The resolution was experimentally 52.5 μm when the ASE (amplified spontaneous emission) light source of the optical fiber amplifier was used. The single-shot measurement was realized by a line-image sensor of the 30 frames per second. The repeatability of the interfered peak position was 5 μm by the tunable mirror position. The one-dimensional scanless measurement was demonstrated by use of 3-layer glass plates.

A broadband ASE light source-based full-duplex FTTX/ROF transport system

A full-duplex fiber-to-the-X (FTTX)/radio-over-fiber (ROF) transport system based on a broadband amplified spontaneous emission (ASE) light source is proposed and demonstrated for rural wide-spread villages. Combining the concepts of long-transmission transmission and ring topology, a long-haul single-mode fiber (SMF) trunk is sharing with multiple rural villages. Externally modulated baseband (BB) (1.25 Gbps) and radio-frequency (RF) (622 Mbps/10 GHz) signals are successfully transmitted simultaneously. Good bit error rate (BER) performance was achieved to demonstrate the practice of providing wire/wireless connections for long-haul wide-spread rural villages. Since our proposed system uses only a broadband ASE light source to achieve multi-wavelengths transmissions, it also reveals an outstanding one with simpler and more economic advantages.

Full-duplex ROF transport systems based on a broadband ASE light source and nonlinear distortion suppression scheme

A full-duplex radio-over-fiber (ROF) transport system employing a broadband amplified spontaneous emission (ASE) light source and nonlinear distortion suppression scheme is proposed and demonstrated. A 10 GHz/70 Mbps data rate (compatible WiMAX format) signal is externally modulated and transmitted over a 120 km single-mode fiber (SMF) transmission both for down/up-link. Good bit error rate (BER) performance and a clear eye diagram were achieved in our proposed systems. Such a proposed full-duplex ROF transport system is suitable for long-haul microwave optical links.