Superluminescent Diode Research Articles

On the detection of nanoparticle cloud migration by a resonant photonic surface signal towards sedimentation velocity measurements

Migration and sedimentation of solid particles in a liquid are physical phenomena involving accumulation of soft matter or decantation of fragmented matter. A thorough understanding together with relevant measurements are prerequisites regarding many fields, including medicine, galenic pharmacology, food processing, and the cosmetics industry. In this paper, we investigate the feasibility of monitoring and detecting the migration of a nanoparticle cloud with a resonant light probe. For this purpose, hybrid silicon/silica/UV210 organic integrated photonic racetrack resonators were patterned by thin film processes to be used as sensors measuring the outcome of the impact of a cloud of nanoparticles, the dynamic migration plus sedimentation phenomenon of the nanoparticle cloud in water. A broadband superluminescent diode has been used for the excitation. Then, the spectral characteristics of the resonant guided modes have been analyzed, considering the observed changes while tracking the free spectral range of the transduced comb spectra as a function of time. The way to operate can be summarized as follows: Solutions based on spherical silica nanoparticles of fixed size are prepared and subjected to rheological measurements to obtain their respective viscosities. Next, a millimeter tank filled with water is conveniently placed on the active surface of the sensing chip, prior to the addition of one of the previously mentioned solutions. The series of spectra are acquired during the whole migration sequence and the transduced optical signal is then directly processed and treated by a specific code operated in real time by way of Lagrange interpolation polynomials. Collected data are then compared to a simple theoretical model describing the sedimentation of a spherical particle in water (Stokes' law). Eventually, the implementation of the device in a characterization platform and the development of a specific protocol allows a global treatment, whose description is followed by discussions on measurements and data. Consequently, after the impact of the drop containing the nanoparticles, the monitoring of a first phase regarding their fast cloud migration into the global study volume (with flow of matter plus vortex) eventually followed by their slow sedimentation, can be detected using such a resonant light probe. The overall duration of the first phase associated with sedimentation velocities is in the order of a few tens of µm/min for particles with submicron diameters (several hundreds of nanometers); a first attempt of comparison of this first phase with the results of the classic Stokes model would give a convergence of the values reaching between 9 and 19% for the sedimentation rates.

High-Power Heterogeneously Integrated III-V/Silicon Superluminescent Diode

We demonstrate heterogeneously integrated O-band superluminescent diodes (SLDs) emitting 10 mW of continuous-wave output power at a device temperature of up to 65 °C. At 10 mW output power, the SLD has a wall-plug efficiency of 3.1% at 25 °C and 1.3% at 65 °C; a 3-dB optical bandwidth of 20-30 nm; and spectral modulation (ripple amplitude) of 0.13 (1.1 dB) at 25 °C and 0.09 (0.8 dB) at 65 °C. This is the highest reported output power and efficiency for a SLD integrated with silicon by more than one order of magnitude, which opens up new applications for cheaper and more compact SLD-based photonics integrated circuits.

Application of spectral-domain optical coherence tomography technique to in-process measure hole depth during femtosecond laser drilling in different alloys

In this paper, a real-time diagnostic based on the spectral-domain optical coherence technique has been developed to measure the hole depth during femtosecond laser drilling. This diagnostic borrows the idea of a fiber interferometer, and the hole is integrated as a part of the sample arm. By means of investigating the interference fringes detected by the line camera, the hole depth can be extracted. This diagnostic utilizes a broadband small-volume super-luminescent diode as the coherent light source, which has a central wavelength of 833 nm and a full width at half maximum of 24 nm. It has a temporal resolution of 50 µs and a maximal theoretic depth resolution of 12.8 µm. Three kinds of metal samples have been tested, confirming the ability of depth measurement. Copper has been proven to have the best-normalized reflectivity during drilling compared with aluminum alloy and stainless steel.

Real-Time Compensation for SLD Light-Power Fluctuation in an Interferometric Fiber-Optic Gyroscope.

An interferometric fiber-optic gyroscope (IFOG) demodulates a rotation signal via interferometric light intensity. However, the working environments of IFOGs typically involve great uncertainty. Fluctuations in temperature, air pressure, electromagnetic field, and the power system all cause the power of the superluminescent diode (SLD) light source to fluctuate as well. In this invited paper, we studied the effects of SLD power fluctuation on the dynamic and static performance characteristics of a gyro system through the use of a light-power feedback loop. Fluctuations of 0.5 mA, 1 mA, and 5 mA in the SLD source entering the IFOG caused zero-bias stability to be 69, 135, and 679 times worse. We established an effective method to monitor power fluctuations of SLD light sources and to compensate for their effects without increasing hardware complexity or system cost. In brief, we established a real-time power-sensing and -compensating system. Experimental results showed that for every 0.1 mA increase in the fluctuation amplitude of the driving current, the zero-bias stability became 4 to 7 times worse, which could be reduced about 95% through the use of SLD power compensation.

Measurement of the motional heating of a levitated nanoparticle by thermal light

We report on measurements of the photon-induced heating of silica nanospheres levitated in a vacuum by a thermal light source formed by a superluminescent diode. Heating of the nanospheres motion along the three trap axes was measured as a function of gas pressure for two particle sizes and recoil heating was shown to dominate other heating mechanisms due to relative intensity noise and beam pointing fluctuations. Heating rates were also compared with the much lower reheating of the same sphere when levitated by a laser.

Extreme temperature operation for broad bandwidth quantum-dot based superluminescent diodes

The high-temperature resilience of quantum-dot (QD) laser materials is exploited to realize a broad spectral bandwidth emitter in the near infrared. For an InAs/GaAs-based QD-superluminescent light emitting diode (SLEDs), we introduced a 2000 μm long, 5 μm width ridge waveguide that is tilted by 7° and composed of eight multi-sections. With increased temperature operation over 160 °C, the spectral bandwidth is dramatically increased by thermally excited carrier transition in ES1 and ES2. Additionally, the positive net-modal gain is demonstrated at the high operating temperatures, and this is exploited in the QD-SLEDs operating at 180 °C, which exhibit a −3 dB linewidth of 270 nm and a power of 0.34 mW. The simplicity of this approach, utilizing heat alone, is contrasted with other approaches for the extremely broad spectral bandwidth emitter.

Широкополосное излучение суперлюминесцентных диодов на основе многослойных структур с квантовыми яма-точками InGaAs/GaAs

We have studied superluminescent diodes with simplified design and active region based on 5 or 7 layers of InGaAs/GaAs quantum well-dots (QWDs). Emission peaks of the individual QWD layers are shifted with respect to each other by 15-35 nm to provide as wide as possible emission line in a superluminescent mode with central wavelength of about 1 µm without significant spectral dips. For superluminescent diodes with the active region based on 5 and 7 QWD layers, the maximal value of full width at half maximum of emission spectrum was 92 and 103 nm respectively.

Design and Fabrication of Antireflective Film for Weak Ripple Superluminescent Diode

Design and Fabrication of Antireflective Film for Weak Ripple Superluminescent Diode

Design of ultracompact broadband focusing spectrometers based on diffractive optical networks.

We propose the inverse design of ultracompact, broadband focusing spectrometers based on adaptive diffractive optical networks (a-DONs). Specifically, we introduce and characterize two-layer diffractive devices with engineered angular dispersion that focus and steer broadband incident radiation along predefined focal trajectories with the desired bandwidth and nanometer spectral resolution. Moreover, we systematically study the focusing efficiency of two-layer devices with side length L=100μ m and focal length f=300μ m across the visible spectrum and demonstrate accurate reconstruction of the emission spectrum from a commercial superluminescent diode. The proposed a-DONs design method extends the capabilities of efficient multi-focal diffractive optical devices to include single-shot focusing spectrometers with customized focal trajectories for applications to ultracompact spectroscopic imaging and lensless microscopy.

Superluminescent diode integrated with monitor photodiode

Superluminescent diode integrated with monitor photodiode

Reliability Evaluation of Superluminescent Diodes in Space Environment Based on Bayesian Networks

Reliability evaluation of electronic systems in space environment is a critical issue. In this work, reliability evaluation of superluminescent diode (SLD) systems, which are sensitive to both displacement damage effects and charge–discharge effects, was investigated by the Bayesian network model. Displacement equivalence model of the SLDs is verified by the irradiation results of 5-MeV protons and 1-MeV electrons. Charge–discharge effects of SLDs are induced by 110-keV electrons. Orbital energy spectra and cumulative distribution functions for the equivalent irradiation fluence are calculated by self-built software. Based on the experimental and calculated results, the Bayesian networks under various conditions are established. The probabilities of the type of faults prone in the system under each condition can then be analyzed and quantified. The proposed method provides a good idea for on-orbit reliability evaluation of complex systems.

Communication wavelength investigation of bound states in the continuum of one-dimensional two-material periodic ring optical waveguide network.

In this study, a one-dimensional (1D) two-material period ring optical waveguide network (TMPROWN) was designed, and its optical properties were investigated. The key characteristics observed in the 1D TMPROWN include the following: (1) Bound states in continuum (BICs) can be generated in the optical waveguide network. (2) In contrast to the BICs previously reported in optical structures, the range of the BICs generated by the 1D TMPROWN is not only larger, but also continuous. This feature makes it possible for us to further study the electromagnetic wave characteristics in the range of the BICs. In addition, we analyzed the physical mechanisms of the BICs generated in the 1D TMPROWN. The 1D TMPROWN is simple in structure, demonstrates flexibility with respect to adjusting the frequency band of the BICs, and offers easy measurement of the amplitude and phase of electromagnetic waves. Hence, further research on high-power super luminescent diodes, optical switches, efficient photonic energy storage, and other optical devices based on the 1D TMPROWN designed in this study is likely to have implications in a broad range of applications.

Flattening laser frequency comb spectra with a high dynamic range, broadband spectral shaper on-a-chip.

Spectral shaping is critical to many fields of science. In astronomy for example, the detection of exoplanets via the Doppler effect hinges on the ability to calibrate a high resolution spectrograph. Laser frequency combs can be used for this, but the wildly varying intensity across the spectrum can make it impossible to optimally utilize the entire comb, leading to a reduced overall precision of calibration. To circumvent this, astronomical applications of laser frequency combs rely on a bulk optic setup which can flatten the output spectrum before sending it to the spectrograph. Such flatteners require complex and expensive optical elements like spatial light modulators and have non-negligible bench top footprints. Here we present an alternative in the form of an all-photonic spectral shaper that can be used to flatten the spectrum of a laser frequency comb. The device consists of a circuit etched into a silicon nitride wafer that supports an arrayed-waveguide grating to disperse the light over hundreds of nanometers in wavelength, followed by Mach-Zehnder interferometers to control the amplitude of each channel, thermo-optic phase modulators to phase the channels and a second arrayed-waveguide grating to recombine the spectrum. The demonstrator device operates from 1400 to 1800 nm (covering the astronomical H band), with twenty 20 nm wide channels. The device allows for nearly 40 dBs of dynamic modulation of the spectrum via the Mach-Zehnders , which is greater than that offered by most spatial light modulators. With a smooth spectrum light source (superluminescent diode), we reduced the static spectral variation to ∼3 dB, limited by the properties of the components used in the circuit. On a laser frequency comb which had strong spectral modulations, and some at high spatial frequencies, we nevertheless managed to reduce the modulation to ∼5 dBs, sufficient for astronomical applications. The size of the device is of the order of a US quarter, significantly cheaper than their bulk optic counter parts and will be beneficial to any area of science that requires spectral shaping over a broad range, with high dynamic range, including exoplanet detection.

Short-wave infrared computed tomography.

We demonstrate a short-wave infrared computed tomography method. It uses a fiber-coupled 1.44µm super-luminescent diode as light source, a PbSe photodiode as infrared detector, and an electronically controlled rotation and translation stage for high-speed Radon scanning. It is a safe and low power nondestructive testing method that can be used for the detection of plastic polymers, biological tissue and other materials that visible light cannot penetrate. We analyze the theoretical resolution of the method and build a short-wave infrared computed tomography system, which realizes the tomography and 3D reconstruction of black plastic bottles and artificial blood vessels. The measured resolution reaches10µm.

High-Precision Cavity Length Demodulation Method for Fiber-Optic Fabry-Perot Sensors Based on Dual Superluminescent Diodes.

A high-precision cross-correlation cavity length demodulation method for fiber-optic Fabry–Perot (F–P) sensors based on two different wavelength superluminescent diodes (SLDs) was proposed. This method can solve the problem of low demodulation accuracy caused by the difficulty in identifying the maximum cross-correlation coefficient when the cavity length of the fiber-optic F–P fiber sensor is too short, or when the spectral bandwidth of the illuminating single-light source is too narrow. This demodulation method is based on the principle that the two main peaks of the two cross-correlation curves corresponding to two different spectral ranges should match, and the average value of the two calculated cavity lengths corresponding to the two matched peaks is determined as the real cavity length. The cavity length demodulation of fiber-optic F–P sensors in the range of 20–200 μm shows a maximum measurement deviation of 0.008 μm, which is significantly smaller than the demodulation result obtained with a single light source, and the standard deviation of the measurement results is only approximately 0.0005 μm, indicating the high precision and stability of a dual SLD cross-correlation demodulation method.

Bessel-Beam Interferometry for Turbidity With Refractive Index, Attenuation Coefficient, and Loss

This letter demonstrates a quasi-Bessel beam optical interferometry and fast Fourier transform (FFT) to estimate turbidity of liquid samples in terms of the refractive index (RI), optical attenuation coefficient, and loss. The device comprises a broadband superluminescent diode (SLD) source and a packaged deep-seated optical fiber negative axicon (DSNA) probe connected to the SLD source guiding light to the liquid sample trapped in between DSNA probe head and a glass slide. It generates a low-coherence interference spectrum as recorded in a spectrometer via an optical circulator. The FFT of the said spectrum gives power spectrum corresponding to the respective interfaces of the trapped sample. The power spectrum is used wisely to estimate turbidity in terms of RI, optical attenuation, and optical loss. The design is able to measure as low as 5 NTU (nephelometric turbidity units). This sensing platform may be useful in environmental protection, pharma, and processing industries.

Multicore Fiber Bending Sensors with High Sensitivity Based on Asymmetric Excitation Scheme.

Bending sensing was realized by constructing a tapered four-core optical fiber (TFCF) sensor. The four-core fiber (FCF) between the fan-in and fan-out couplers was tapered and the diameter became smaller, so that the distance between the four cores arranged in a square became gradually smaller to produce supermodes. The two ends of the TFCF were respectively connected to the fan-in and fan-out couplers so that the individual cores in the FCF could link to the separate single-mode fibers. A broadband light source (superluminescent diodes (SLD)) spanning 1250–1650 nm was injected into any one of the four cores, and the orientation was thus determined. In the tapering process, the remaining three cores gradually approached the excitation core in space to excite several supermodes based on the tri-core structure first, and then transited to the quadruple-core structure. The field distributions of the excited supermodes were asymmetric due to the corner-core excitation scheme, and the interference thus resulted in a higher measurement sensitivity. When the diameter of the TFCF was 7.5 μm and the tapered length was 2.21 mm, the sensitivity of the bending sensor could reach 16.12 nm/m−1.

Effect of temperature change on refractive index of an egg white and yolk: a preliminary study

In this article, the refractive index of an egg white and yolk depending on temperature in range 30 - 47 °C over 1550 nm was determined. The measurement head was constructed as fiber optic Fabry-Perot interferometer with interference between polished fiber end-face and aluminum weighing dish. The measurement setup has been made of an optical spectrum analyzer, a superluminescent diode with a central wevelength of 1550 nm, 2:1 fiber coupler and heat plate. Full Text: PDF ReferencesP. Magdelaine, "Egg and egg product production and consumption in Europe and the rest of the world, Improving the Safety and Quality of Eggs and Egg Products", Egg Chemistry, Production and Consumption, 3 (2011). CrossRef H. Kuang, F. Yang, Y. Zhang, T. Wang, and G. Chen, "The Impact of Egg Nutrient Composition and Its Consumption on Cholesterol Homeostasis", Cholesterol (2018). CrossRef J. Gienger, K. Smuda, R. Müller, M. Bär, and J. Neukammer, "Refractive index of human red blood cells between 290 nm and 1100 nm determined by optical extinction measurements", Sci. Rep. 9, 1 (2019). CrossRef P. Listewnik, M. Hirsch, P. Struk, M. Weber, M. Bechelany, and M. Jędrzejewska-Szczerska, "Preparation and Characterization of Microsphere ZnO ALD Coating Dedicated for the Fiber-Optic Refractive Index Sensor", Nanomaterials 9, 2 (2019) CrossRef Y. Wu, Y. Zhang, J. Wu, and P. Yuan, "Fiber-Optic Hybrid Structured Fabry-Perot Interferometer Based On Large Lateral Offset Splicing for Simultaneous Measurement of Strain and Temperature", J. Lightwave Technol., 35, 19 (2017). CrossRef M. Islam, M. Mahmood, M Lai, K. Lim, and H. Ahmad, "Chronology of Fabry-Perot Interferometer Fiber-Optic Sensors and Their Applications: A Review", Sensors 14, 4 (2014). CrossRef K. Karpienko, M. Wróbel, and M. Jędrzejewska-Szczerska, "Determination of refractive index dispersion using fiber-optic low coherence Fabry-Perot interferometer: implementation and validation", Opt. Eng. 53, 7 (2014). CrossRef M. Kosowska, D. Majchrowicz, K. Sankaran, M. Ficek, K. Haenen, and M. Szczerska, "Doped Nanocrystalline Diamond Films as Reflective Layers for Fiber-Optic Sensors of Refractive Index of Liquids", Materials 12, 13 (2019). CrossRef G. Xiao, A. Adnet, Z. Zhang, F. Sun, and C. Grover, "Monitoring changes in the refractive index of gases by means of a fiber optic Fabry-Perot interferometer sensor", Sensors and Actuators 118, 2 (2005). CrossRef

High-Sensitivity Fiber-Optic Low-Frequency Acoustic Detector Based on Cross-Correlation Demodulation

Fiber-optic acoustic sensors based on Fabry-Perot (F-P) interference structure have advantages of compact structure, high sensitivity, convenience to manufacture and immunity to electromagnetic interference. To simplify the demodulation system of the fiber-optic F-P sensor and reduce the demodulation cost, a low-frequency acoustic detector based on the principle of optical cross-correlation (OCC) demodulation is proposed. A fiber-optic F-P interference sensor based on the phenylene sulfide (PPS) diaphragm is used as a low-frequency acoustic detection unit. The OCC demodulation system of the F-P acoustic sensors mainly includes a superluminescent diode (SLED), a flat glass wafer and single-mode fibers. The flat glass wafer is used as the static correlation reference cavity of the PPS diaphragm-based F-P acoustic sensor. The experimental results show that the detector is responsive to low-frequency acoustic waves from below 20 Hz to 250 Hz. For the acoustic waves with a frequency of 20 Hz, the minimum detection limit (MDL) of sound pressure is 0.65 mPa. The detector has the potential for low-cost and high-sensitivity acoustic detection for applications such as infrasonic detection and photoacoustic gas detection.

A Panda fiber temperature sensor up to 900°C

The use of Panda-type polarization-maintaining (PM) fiber for the localized sensing of high temperatures was analyzed with simulations and experiments up to 900°C. Accuracy and repeatability of the results started to decline above 800°C. Fused silica optical fiber melts at 1700°C, which sets an ultimate limit for measurable temperatures. In practice, optical fiber birefringence restricts the maximum temperature to 1060°C where PM fiber loses its ability to maintain polarization. Three sensor fibers (4, 5 and 10 cm long) were spliced at 45° angles to input/output fibers and calibrated in an oven from room temperature to 850–900°C temperature range. Two superluminescent light-emitting diodes (SLEDs) were coupled together as a broadband light source. Birefringence-induced change of the polarization in the sensor fiber was measured with a polarization splitter and an optical spectrum analyzer (OSA) as a function of the wavelength. Temperature-dependent birefringence generates a sinusoidal reflection spectrum from the input polarization mode to the orthogonal output polarization mode. Temperature changes could be concluded from variations in these spectra. Finally, a small fusion device, NORTH, at DTU, Denmark was successfully used as a testbed to make sure that the sensors can handle transportation and the instrumentation required for vacuum operation and still produce sensible data from a harsh environment.