Low-cost Semiconductor Laser Research Articles

Cladding pumped bismuth-doped fiber amplifiers operating in O-, E-, and S-telecom bands.

Bismuth-doped fibers (BDFs) are considered nowadays as an essential part of the development of novel optical amplifiers, which can provide a significant upgrade to existing fiber optic telecommunication systems, securing multiband data transmission. In this paper, a series of BDF amplifiers (BDFAs) for O-, E-, and S-telecom bands based on a cladding pumping scheme using low-cost multimode semiconductor laser diodes at a wavelength of 0.7-0.8 µm were demonstrated for, it is understood, the first time. The developed BDFAs are characterized by a high peak gain of >25-30 dB in the corresponding telecom bands and a relatively low noise figure of 5-6 dB. Comparative analysis shows that most of the parameters of cladding pumped BDFAs are close to those of the best core pumped ones. This research opens up new opportunities for utilizing Bi-doped fibers as a key element of cost-effective and ready-to-work BDFAs for various practical applications.

Development of Solution-Processed Perovskite Semiconductors Lasers

Lead halide perovskite is a new photovoltaic material with excellent material characteristics, such as high optical absorption coefficient, long carrier transmission length, long carrier lifetime and low defect state density. At present, the steady-state photoelectric conversion efficiency of all-perovskite laminated cells is as high as 28.0%, which has surpassed the highest efficiency of monocrystalline silicon cells (26.7%). In addition to its excellent photovoltaic properties, perovskite is also a type of direct bandgap semiconductor with low cost, solubilization, high fluorescence quantum efficiency and tunable radiation wavelength, which brings hope for the realization of electrically pumped low-cost semiconductor lasers. In recent years, a variety of perovskite lasers have emerged, ranging from the type of resonator, the wavelength and pulse width of the pump source, and the preparation process. However, the current research on perovskite lasers is only about the type of resonator, the type of perovskite and the pump wavelength, but the performance of the laser itself and the practical application of perovskite lasers are still in the initial stages. In this review, we summarize the recent developments and progress of solution-processed perovskite semiconductors lasers. We discuss the merit of solution-processed perovskite semiconductors as lasing gain materials and summarized the characteristics of a variety of perovskite lasers. In addition, in view of the issues of poor stability and high current density required to achieve electrically pumped lasers in perovskite lasers, the development trend of perovskite lasers in the future is prospected.

A Directly Modulated Laterally Coupled Distributed Feedback Laser Array Based on SiO2 Planarization Process

Low-cost and high-speed single-mode semiconductor lasers are increasingly required as wide-band access fiber communication expands in recent years. Here, a high-speed laterally coupled distributed feedback (LC-DFB) laser array is achieved based on a SiO2 planarization process. The device exhibits low threshold currents of about 12 mA and high slope efficiencies over 0.26 W/A. Stable single mode operation and high-speed performance are realized with side mode suppression ratios (SMSR) over 45 dB, and 3-dBe bandwidths exceed 14 GHz for all four channels. Such a high-speed and process simple LC-DFB laser array shows great potential to the low-cost fiber communication networks.

Infrared light induced deep ultraviolet internal light centers for novel cost-effective 3D printing

We report a novel and cost-effective 3D printing technology by using NaYF4:Yb3+/Tm3+ up-conversion microcrystals to produce internal deep ultraviolet (UV) light centers as a light curing source in the polymer matrix by near infrared light excitation. Excellent up-conversion emission from NaYF4:Yb3+/Tm3+ microcrystals is demonstrated by using microcrystals as gain medium to realize up-conversion lasing emission centered at 291, 346 and 364 nm. This 3D printing technique, in which a low cost semiconductor laser is used, is potential to print large structures at high printing efficiency.

Evaluation method for the optical feedback factor and linewidth enhancement factor using phase discontinuities in self-mixing interferometry signals.

Self-mixing interferometry (SMI) is a reliable method that has been applied to measuring displacements, absolute distances, and velocities of remote targets. Evaluating the optical feedback factor C and the linewidth enhancement factor α is a vital step in calculating laser diode parameters and in processing SMI signals using phase unwrapping. This paper proposes an evaluation method for the optical feedback factor and the linewidth enhancement factor of arbitrary waveforms by investigating the slopes of phase discontinuity distribution in the optical feedback regime of 1<C. First of all, the effects that the slope of phase discontinuity distribution has on the prediction of the optical feedback factor and the linewidth enhancement factor are clarified. Next, an algorithm is proposed to evaluate the optical feedback factor and the linewidth enhancement factor using the slope variation of phase discontinuity distribution, along with a method to select discontinuities in order to improve measurement accuracy using the cumulative effect of discontinuity distribution. The proposed method is verified through simulations as well as experiments with a low-cost semiconductor laser.

Highly stable enhanced near-infrared amplified spontaneous emission in solution-processed perovskite films by employing polymer and gold nanorods.

Solution-processed organo-lead halide perovskites have emerged as promising optical gain media for tunable coherent light sources. The lasing performance is generally determined by the as-synthesized crystal quality. Noble metal nanostructures have been widely utilized to enhance optical responses due to their unique property of localized surface plasmon resonance. Herein, we report a simple method to enhance the near-infrared amplified spontaneous emission (ASE) performance of MAPbI3 polycrystalline films by solution-processing a PMMA spacer layer and an Au NR-doped PMMA top layer on perovskite thin films. As a result, the ASE threshold of the triple-layer perovskite film was significantly reduced by around 36% and the ASE intensity increased by 13.9-fold, compared to the pristine film. The underlying mechanism was attributed to the combined effects of surface passivation by PMMA and plasmon resonance enhancement of Au NRs. The passivation effect results in suppressing the nonradiative recombination and prolonging excited state decay, which have been investigated by transient absorption and pump-probe measurements. The plasmon effect is systematically studied through distance-dependent and spectra-dependent plasmon enhanced emission. The perovskite films with PMMA and Au NR coating showed great stability for 180 min under intense pulse laser continuous irradiation. The improved ASE performance still remained after leaving the film under the atmosphere for more than one month. We have successfully demonstrated a highly stable and sustained ASE output from MAPbI3 films under pulse laser excitation. This study provides a general approach for exploring plasmonic nanostructures in combination with polymers in the development and application of low-cost solution-processed semiconductor lasers.

Development and characterization of a laboratory setup for photoacoustic NO2 determination based on the excitation of electronic 2B2 and 2B1 states using a low-cost semiconductor laser

This work gives a detailed characterization of a laboratory setup for photoacoustic NO2 trace gas detection at the ppb level. The signal generation is based on the excitation of electronic 2B2 and 2B1 states using a low-cost semiconductor laser emitting at 450nm. An acoustic resonator was used for signal amplification and the modulation frequency of the laser was determined to 3395Hz in order to gain maximum signal amplification. The quality of resonant amplification was determined to 7.9. The gas samples were NO2 calibration gases diluted with pure nitrogen. The signal-to-noise ratio (SNR) dependency on the flow rate Q and the lock-in time constant τLIA was investigated, respectively, and the optimum values were specified to Q=500mL/min and τLIA=2s. In case of ambient noise, increasing τLIA to 10s was evaluated as sufficient for SNR preservation. The noise level was measured in the absence of NO2 and it was determined to be composed of 51% electronic noise and 49% gas flow noise. With the analyte concentration ranging from 300ppbV to 100ppmV, the linear dependency of the photoacoustic amplitude on the NO2 concentration was specified, the sensitivity was determined to 110μV/ppmV and the maximum measurement error was calculated to ±0.8%. The detection limit was determined to 2.0ppbV. Furthermore, the stability of the signal was investigated and a maximum drift of ±1% was observed within a measuring period of 30 min. The response time τ90 was specified to 58s. All results considered, this photoacoustic measuring system, which is based on low-cost signal generation and detection units, provides an excellent basis in view of developing a portable device for photoacoustic trace gas detection.

Fabrication of a-C Semiconductor Nanoparticles for Quantum Dots Surface Emitting Laser Using High-Density Plasma in Localized Area

1. Introduction Everyone uses and always carries mobile terminals in these modern days, when the information level in a society has been highly developed. Since the devices are used on various scenes in a life, low power consumption and high-speed data communication at low cost are required. The semiconductor laser used in a terminal device has two problems: a high production cost and low velocity of light emitted from laser.Surface emitting laser has been developed as a low-cost semiconductor laser, but sufficient velocity of light has not been obtained.Lower velocity of light is caused by the process of energy calibration of light emitted from the semiconductor device.The size of conventional laser device is several micro meters at minimum, and multiple bonding orbitals are formed in electronic state of the semiconductors. In transition of highly-excited electrons to lower state, there is more than one state, which electrons can transit to. It results in a considerable variation in wavelength of light and energy of light must be calibrated. To homogenize emitted light, quantum size effect are tried to be employed. The reduction of device size to quantum size not having multiple energy levels can homogenize the emitting energy. With this method, calibration of energy is not necessary and the velocity of light can be improved. To realize low power consumption, high-speed communication, and low production cost, stack layer of semiconductor particles with a diameter of 10 nm in porous alumina was tried to be fabricated. We, however, found it hard to control the diameter of semiconductor particle under 10 nm and stack the particles .Moreover, rare metals such as Ga and In are commonly used as materials for semiconductor laser and increase costs. Thus, non-rare material semiconductor particle with a diameter of 10 nm should be developed. Our research group has reported that the method to fabricate nanoparticle of a-C semiconductor was established and particle diameter could freely be controlled in the range from 200 to 10 nm by using high-density plasma localize area. The objective of this study is to realize quantum dots surface emitting laser by stacking the a-C semiconductor particle in porous alumina template. Synthesis method which enhances the semiconductor properties of the nanoparticles up to the level applicable to a semiconductor laser was tried to be established. The a-C semiconductor nanoparticles of which optical gap are regulated by addition of Si atoms were synthesized by the plasma CVD method using hollow cathode electrodes. 2. Experiment Section Localized high-density plasma regions were formed by inserting aluminum porous plate between cathode and anode electrodes. Performance of a-C semiconductor mobilities and back ground current tends to be degraded by sp2 carbon impurities. In order to evaluate the content of sp2carbon in a-C semiconductor nanoparticle, carrier mobilities in Hall effect measurement, current in photo electrochemical measurement without photo irradiation, and onset potential in photo current under the exposure to UV lamp were employed. 3. Result and Discussion The average diameter of the synthesized semiconductor particles was approximately 15 nm. Semiconductor properties of nanoparticles could be controlled by RF power and flow rate of hydrogen gas during CVD synthesis. The amount of sp2 impurities can be reduced by lowering the plasma power from 32 to 20 W. As a result, carrier mobility was elevated from 3.4 to 5.4 cm2V-1S-1 because electron scattering was suppressed. Further, by increasing the flow rate of hydrogen gas from 50 to 200 sccm, sp2 defects on the surface were reduced by H2 plasma etching. It results in the decrease of leakage current from 1.3 to 0.5 μA/cm2, the positive shift of onset potential of photo current from -0.4 to 2.6 V, and clear rectification behavior. By reducing sp2 impurities, semiconductor properties of the nanoparticles can be improved. It is concluded that synthesize method of n-type semiconductor nanoparticles with a diameter of 15 nm and controllable semiconductor properties was successfully established. Figure 1

Orbital angular momentum vertical-cavity surface-emitting lasers

Harnessing the orbital angular momentum (OAM) of light is an appealing approach to developing photonic technologies for future applications in optical communications and high-dimensional quantum key distribution (QKD) systems. An outstanding challenge to the widespread uptake of the OAM resource is its efficient generation. In this work we design a new device that can directly emit an OAM-carrying light beam from a low-cost semiconductor laser. By fabricating micro-scale spiral phase plates within the aperture of a vertical-cavity surface-emitting laser (VCSEL), the linearly polarized Gaussian beam emitted by the VCSEL is converted into a beam carrying specific OAM modes and their superposition states, with high efficiency and high beam quality. This new approach to OAM generation may be particularly useful in the field of OAM-based optical and quantum communications, especially for short-reach data interconnects and QKD.

Compact, diode-pumped, solid-state lasers for next generation defence and security sensors

Low-cost semiconductor laser diode pump sources have made a dramatic impact in sectors such as advanced manufacturing. They are now disrupting other sectors, such as defence and security (D&S), where Thales UK is a manufacturer of sensor systems for application on land, sea, air and man portable. In this talk, we will first give an overview of the market trends and challenges in the D&S sector. Then we will illustrate how low cost pump diodes are enabling new directions in D&S sensors, by describing two diode pumped, solid- state laser products currently under development at Thales UK. The first is a new generation of Laser Target Designators (LTD) that are used to identify targets for the secure guiding of munitions. Current systems are bulky, expensive and require large battery packs to operate. The advent of low cost diode technology, merged with our novel solid-state laser design, has created a designator that will be the smallest, lowest cost, STANAG compatible laser designator on the market. The LTD delivers greater that 50mJ per pulse up to 20Hz, and has compact dimensions of 125×70×55mm. Secondly, we describe an ultra-compact, eye-safe, solid-state laser rangefinder (LRF) with reduced size, weight and power consumption compared to existing products. The LRF measures 100×55×34mm, weighs 200g, and can range to greater than 10km with a single laser shot and at a reprate of 1Hz. This also leverages off advances in laser pump diodes, but also utilises low cost, high reliability, packaging technology commonly found in the telecoms sector. As is common in the D&S sector, the products are designed to work in extreme environments, such as wide temperature range (-40 to +71°C) and high levels of shock and vibration. These disruptive products enable next- generation laser sensors such as rangefinders, target designators and active illuminated imagers.

Direct generation of 2-ps blue pulses from gain-switched InGaN VCSEL assessed by up-conversion technique.

Ultra-short pulses in blue region generated from compact and low-cost semiconductor lasers have attracted much attention for a wide variety of applications. Nitride-based vertical-cavity surface-emitting lasers (VCSELs), having intrinsic high material gain and short cavities, favor the generation of ultra-short blue pulses via a simple gain-switching technique. In this study, we fabricated a single-mode InGaN VCSEL consisting of 10-period InGaN/GaN quantum wells (QWs). The output pulses were evaluated accurately with an up-conversion measurement system having time resolution of 0.12 ps. We demonstrated that ultra-short blue pulses, as short as 2.2 ps at 3.4 K and 4.0 ps at room temperature, were generated from the gain-switched InGaN VCSEL via impulsive optical pumping, without any post-processing. The gain-switched pulses we obtained should greatly promote the development of ultra-short blue pulse generation. In addition, this successful assessment demonstrates the up-conversion technique's usefulness for characterizing ultra-short blue pulses from semiconductor lasers.

Spectral dynamics of picosecond gain-switched pulses from nitride-based vertical-cavity surface-emitting lasers

Short pulses generated from low-cost semiconductor lasers by a simple gain-switching technique have attracted enormous attention because of their potential usage in wide applications. Therein, reducing the durations of gain-switched pulses is a key technical point for promoting their applications. Therefore, understanding the dynamic characteristics of gain-switched pulses is highly desirable. Herein, we used streak camera to investigate the time- and spectral-resolved lasing characteristics of gain-switched pulses from optically pumped InGaN single-mode vertical-cavity surface-emitting lasers. We found that fast initial components with ultra-short durations far below our temporal resolution of 5.5 ps emerged on short-wavelength sides, while the entire pulses were down-chirped, resulting in the simultaneous broadening of the spectrum and pulse width. The measured chirp characteristics were quantitatively explained using a single-mode rate-equation model, combined with carrier-density-dependent gain and index models. The observed universal fast short-wavelength components can be useful in generating even shorter pulses from gain-switched semiconductor lasers.

Parameter design of a biaxial lidar ceilometer

This paper presents parameter design methodology and related optomechanical engineering of a 905-nm diode-laser biaxial, eye-safe lidar ceilometer prototype for cloud-height monitoring. Starting with a brief review of the state-of-the-art ceilometer technology, acceptable parameter ranges are identified for the key system parts. Parameter tuning is achieved by imposing goal criteria on the simulated signal-to-noise ratio and laser-telescope overlap factor. The system is based on a low-cost pulsed semiconductor laser, low-cost Fresnel-lens telescope, a low-noise-equivalent power avalanche-photodiode optoelectronic receiver, and collimating/focusing adjustable parts. Finally, preliminary test measurements are presented.

Single-heterostructure laser diode producing a &lt;inline-formula&gt;&lt;math display="inline" overflow="scroll"&gt;&lt;mrow&gt;&lt;mn mathvariant="bold"&gt;6&lt;/mn&gt;&lt;mrow&gt;&lt;mtext&gt; &lt;/mtext&gt;&lt;mtext&gt; &lt;/mtext&gt;&lt;mi mathvariant="normal"&gt;W&lt;/mi&gt;&lt;/mrow&gt;&lt;mo&gt;/&lt;/mo&gt;&lt;mn mathvariant="bold"&gt;40&lt;/mn&gt;&lt;mtext&gt; &lt;/mtext&gt;&lt;mtext&gt; &lt;/mtext&gt;&lt;mi&gt;ps&lt;/mi&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/inline-formula&gt; optical pulse from a &lt;inline-formula&gt;&lt;math display="inline" overflow="scroll"&gt;&lt;mrow&gt;&lt;mn mathvariant="bold"&gt;20&lt;/mn&gt;&lt;mrow&gt;&lt;mtext&gt; &lt;/mtext&gt;&lt;mo&gt;μ&lt;/mo&gt;&lt;mi mathvariant="bold"&gt;m&lt;/mi&gt;&lt;/mrow&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/inline-formula&gt; stripe width

A compact, low-cost semiconductor laser diode producing 40 ps full width at half maximum (FWHM) single-spike lasing pulses with 6 Watts peak power from a 20 μm stripe width is realized in the form of a simple single-heterostructure, grown by metal-organic chemical vapor deposition. The structure possesses a linearly graded doping profile extending from the p+ and n+ sides towards the p-n junction. This laser diode is operated under room temperature conditions and applies pumping current pulses (roughly 10 to 20 A/2 to 3 ns FWHM) achievable with a commercially available silicon avalanche transistor as an electrical switch.

Lasers in Communications

Low-cost semiconductor lasers power the shortest networks in the data center and the long-haul links that speed information around the globe. Today, lasers are integrated into photonic circuitry and even optical cables.

Automatic locking of a 633 nm semiconductor laser on iodine

The purpose of this paper is to develop a low-cost semiconductor laser frequency standard around 633 mm based on digital signal processing techniques. This standard sweeps the frequency of the laser by means of the injection current in order to measure some linear absorption transitions of iodine (/sup 127/I/sub 2/). It identifies those lines by using a reference table of known transitions of the iodine vapor and then automatically locks the frequency of the laser on a selected transition. A microcontroller and a digital signal processor are used to perform those functions. The effects of laser temperature, mode jumps, and transition linewidth are considered for successful operations. It is demonstrated that this system can automatically lock a 633 nm semiconductor laser on the P(33) 6-3 transition of iodine.

Infrared photorefractive polymers and their applications for imaging.

Photorefractive polymers with high diffraction efficiency in the visible and near-infrared regions of the electromagnetic spectrum have been developed. These polymers, which have a large dynamic range because of their high orientational birefringence, incorporate a dye designed to have a large dipole moment and a high linear polarizability anisotropy. Such polymers have enabled demonstrations of imaging through scattering media, using a holographic time-gating technique at a wavelength that is compatible with the transparency of biological tissues and with the emission of low-cost semiconductor laser diodes.

Use of laser diodes locked to atomic transitions in multiwavelength coherent communications

The possibility of building multiwavelength coherent communication systems based on low-cost semiconductor lasers in the 0.8µm range locked to rubidium linear absorption is investigated. The values of frequency offset between the resonances of both the D2 (780 nm) and D, (794.7 nm) lines are considered. A simple two-carrier FDM set-up using three resonances of the D2 line is presented and the optical frequency offsets are measured.