Pulsed Semiconductor Laser Research Articles

The Optical Nonlinearities of Zinc Semiconductor Crystals under Different Laser Pulse Width

Based on Z-scan technique, the nonlinear absorption characteristics and nonlinear refraction characteristics of ZnO crystal, ZnS crystal and ZnSe crystal were studied under the picosecond (ps) laser pulses and the femtosecond (fs) laser pulses respectively. The experimental results show that the nonlinear absorption characteristics of the three kinds of crystals are reverse saturable absorption mainly due to two-photon absorption under the ps laser pulses. The nonlinear refraction characteristics are self-defocusing and the nonlinear refractive indexes are positive because of free carrier. The nonlinear absorption characteristics of the ZnO crystal and ZnS crystal are reverse saturable absorption mainly due to three-photon absorption under the fs laser pulses, and the ZnSe crystal is two-photon absorption. The nonlinear refraction characteristics of the three kinds of crystals are self-focusing because of bound electron. The experimental results show that zinc semiconductor crystals materials and laser pulse width can influence the optical nonlinear characteristics of materials.

Terahertz Time-Domain Spectroscopy System Driven by a Monolithic Semiconductor Laser

A fiber coupled terahertz time-domain spectroscopy (THz TDS) system which is driven by a pulsed monolithic semiconductor laser is presented. A bandwidth of over 0.6 THz with a signal to noise ratio (SNR) of 45 dB has been achieved at a wavelength of 1550 nm. This concept could pave the way towards ultra-compact and low-cost THz TDS systems.

A New Optical UWB Modulation Technique for 250Mbps Wireless Link in Implantable Biotelemetry Systems

We propose an optical UWB modulation based on a new pulsed coding technique for wireless implantable biotelemetry. The solution employs sub-nanosecond laser pulses allowing for both high data rates and reduction of the power consumption compared to the state-of-the-art. Thus, the proposed approach is suitable for upcoming biomedical systems like autonomous implantable neural devices. The developed architecture consists of a transmitter and a receiver employing a pulsed semiconductor laser and a small sensitive area photodiode, respectively, and includes coding and decoding digital systems, biasing and driving analogue circuits for laser pulse generation and photodiode signal conditioning. Experimental findings, obtained by employing discrete components prototype PCBs and FPGA implementations, validate the novel technique showing the capabilities to achieve a BER less than 10-9 with data rates up to 250Mbps and an estimated power consumption lower than 5mW. These results enable, for example, the transmission of a 1000-channel neural recording system sampled at 16 kHz with 16-bit resolution.

Investigation the bit rate of quantum key using Si single photon detectors

This work reports on the results of experimental investigations bit rate of quantum key distribution on a setup designed for quantum cryptography with single photons. Silicon avalanche photodiodes (C30902S) serve as single-photon detectors. The quantum key is transmitted with pulsed semiconductor lasers by coding polarization states of photons in two alternative nonorthogonal bases over free spase.

Microscopic analysis of non-equilibrium dynamics in the semiconductor-laser gain medium

Fully microscopic many-body calculations are used to analyze the carrier dynamics in situations where a strong sub-picosecond pulse interacts with an inverted semiconductor quantum well. Electron-electron and electron-phonon scatterings are calculated on a second Born-Markov level. Intra-subband scatterings on a scale of tens of femtoseconds are shown to quickly re-fill the kinetic holes created in the carrier distributions during the pulse amplification. Even for sub-100 fs pulses, this significantly influences the pulse amplification as well as its spectral dependence. Interband scatterings on a few picosecond timescale limit the possibly achievable repetition rate in pulsed semiconductor lasers.

Beam forming optic aberrations’ impact on maximum range of semiconductor laser based rangefinders

AbstractMiniature rangefinding modules based on pulsed semiconductor laser technology are becoming more and more popular components of a variety of modern optoelectronics devices where precise, fast and eye-safe range estimation is needed. Current trends associated with minimization of both physical dimensions and cost of such modules lead to the design approach relying on exact meeting the requirements of a given application, concerning the spatial resolution and especially the maximum range. Optical components of a rangefinder cover a substantial part of its cost and determine its overall dimensions, but primarily — the indigenous parameters of the transmitter and receiver trains are crucial for the maximum measurable range. The quantitative analysis of transmitter optics aberrational characteristics impact on signal-to-noise ratio range dependence and thus the maximum range of a laser rangefinder is presented in the paper. Modern optical fabrication technology offers a huge range of solutions, changing in imaging/projecting characteristics which implies the price level as well. Rangefinder optics has a very specific task which sometimes makes it unreasonable to fight for the diffraction limited performance. The article provides the approach how to determine the acceptable level of optical aberrations which still does not degrade the measurable range significantly.

Portable optical-resolution photoacoustic microscopy with a pulsed laser diode excitation

Optical-resolution photoacoustic microscopy (OR-PAM) has been significantly improved in terms of spatial resolution, detection sensitivity, imaging speed, and penetration depth. However, the popular producibility of OR-PAM system is still limited by the size and cost of solid-state laser excitation. Here, we developed a portable laser-diode-based OR-PAM (LD-OR-PAM) system using a pulsed semiconductor laser source, which was operated at 905 ± 15 nm with a pulse energy as low as 4.9 μJ. The measured lateral resolution has been improved to ∼1.5 μm from hundreds of microns. The compact and inexpensive natures of LD-OR-PAM would promote the potential clinical applications such as in dermatology.

Светочувствительная метаболическая сеть в клеткахEscherichia coli: спектральная селективность и репаративные функции глобиновых фоторецепторов

The influence of He-Ne laser radiation (632.8), incoherent monochromatic red light (601-685 nm), as well as pulsed radiation semiconductor laser (660 nm) on the growth of the culture of wild type or uvrA strain of E. coli WP2 and on the DNA transformation of plasmid pDick (Amp, Km) in E. coli NM522 was investigated. After light signal, photoenhancement of the quantity of cells in culture retains during several generations, while the enhancement of the transformation efficiency was observed only for the kanamycin marker. This makes it possible to suppose that metabolic signaling network acts as a red light receptor. The observed spectral selectivity suggests that flavohemoglobin fatty acid peroxidase works as a photosensitive component in the reparative network. It is proposed that the enhanced effectiveness of light in the uvrA strain results from photoactivation ofglobin EcDOS phosphodiesterase as an O2 provider for AlkB demethylase.

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.

Investigation of the arbitrary waveform semiconductor laser as seed light source for high energy laser

A pulse semiconductor laser modulated by arbitrary shaping electrical waveform is produced and the generated optical pulse can be taken as the seed resource for high-power laser facilities.Based on ultrawide band microwave device and microstrip line transmission delay application, an all-solid-state circuit for generating arbitrary modulation pulse to modulate the semiconductor laser is fabricated. For improving the semiconductor laser power, the output laser pulse is sent into erbium-doped fiber master oscillator power amplifier architecture for amplification. In the experiment, the output laser pulse can be arbitrarily adjusted at 1547.9 nm center wavelength, less than 10 ns duration, lower than 100 kHz repetition rate, and 330 ps time domain adjustment.

3D-visual laser-diode-based photoacoustic imaging

We present a 3D-visual laser-diode-based photoacoustic imaging (LD-PAI) system with a pulsed semiconductor laser source, which has the properties of being inexpensive, portable, and durable. The laser source was operated at a wavelength of 905 nm with a repetition rate of 0.8 KHz. The energy density on the sample surface is about 2.35 mJ/cm(2) with a pulse energy as low as 5.6 μJ. By raster-scanning, preliminary 3D volumetric renderings of the knotted and helical blood vessel phantoms have been visualized integrally with an axial resolution of 1.1 mm and a lateral resolution of 0.5 mm, and typical 2D photoacoustic image slices with different thickness and orientation were produced with clarity for detailed comparison and analysis in 3D diagnostic visualization. In addition, the pulsed laser source was integrated with the optical lens group and the 3D adjustable rotational stage, with the result that the compact volume of the total radiation source is only 10 × 3 × 3 cm(3). Our goal is to significantly reduce the costs and sizes of the deep 3D-visual PAI system for future producibility.

Electron-beam pumped pulsed IR semiconductor laser based on a quantum-size InGaAs/AlGaAs structure

The characteristics of the radiation of a 890-nm laser based on a quantum-size InGaAs/AlGaAs structure, pumped by a (15–26)-keV electron beam, have been studied. An output pulsed power up to 90 W with an efficiency of 3.5% is obtained from each laser end face at room temperature of the active element and a cavity length of 0.5 mm.

脉冲式半导体激光器端面抽运主振荡功率放大器及腔外倍频系统

脉冲式半导体激光器端面抽运主振荡功率放大器及腔外倍频系统

Pulsed semiconductor lasers with higher optical strength of cavity output mirrors

Asymmetric heterostructures with an ultrathick waveguide based on an AlGaAs/GaAs alloy system that allow lasing at a wavelength of 905 nm have been developed and fabricated by hydride metalorganic vapor-phase epitaxy. The internal optical loss and internal quantum efficiency of semiconductor lasers based on such structures were 0.7 cm-1 and 97%, respectively. It is shown that the highest output optical power of laser diodes with antireflecting (SiO2) and reflecting (Si/SiO2) coatings deposited on untreated Fabry-Perot cavity facets obtained by cleaving in an oxygen atmosphere reached 67 W in the pulsed mode and is limited by mirror damage. Treatment of Fabry-Perot cavity facets by etching in argon plasma and the formation of coatings with passivating and oxygen-blocking GaN and Si3N4 layers allowed an increase in the maximum output optical power to 120 W. Mirror damage was not observed at the attained output optical power.

Design of high-peak current and narrow pulse driver of laser diode

This paper presents a laser diode (LD) pulse driving circuit that can generate current pulses of amplitudes range from 6 to 30A, with pulse widths varying from 5 to 100 ns and frequencies varying from 500 Hz to 50 kHz. It is with monostabillity trigger used as pulse shaping component, with power metal-oxide-semiconductor field effect transistors (MOSFETs) as fast switches and power inverter devices, with low voltage power supply that the circuit generates high-peak pulse current. As its structure is simple and easy to understoand and realize, the circuit is of great value to be used to drive pulsed semiconductor laser.

Using single-photon detectors for quantum key distribution in an experimental fiber-optic communication system

This paper gives experimental results of quantum key distribution on a fiber-optic setup at a telecom wavelength of 1555 nm. A self-compensated two-channel optical circuit is used. Quantum key distribution was performed by coding the phase states of single photons radiated by a pulsed semiconductor laser in two alternative nonorthogonal bases. Specially developed single photon counters based on InGaAs: InP avalanche photodiodes were employed as high-sensitivity photodetectors. The results of investigation of the quantum efficiency, probability of afterpulses, and noise level for various operating modes of the detectors at temperatures from −40 to −60°C are given. A key distribution rate of 450 bit/s was obtained for a single-mode fiber-optic quantum communication channel between the receiver and sender 25 km long at a laser pulse clock frequency of 5 MHz and an average number of photons per pulse of about 0.2. For the achieved photodetector characteristics, the average number of errors in the quantum key did not exceed 3.7%.

Development of laser rangefinder-binoculars at S A Zverev Krasnogorsk Factory

This paper presents data on laser rangefinder-binoculars developed and produced at OAO S. A. Zverev Krasnogorsk Factory. The illuminator of the rangefinder is a pulsed semiconductor laser, and the detector is a silicon avalanche photodiode. The main parameters and characteristics of the items are presented, and a functional diagram of the rangefinder channel is considered. Ways of improving the rangefinder-binoculars are pointed out: increasing the maximum measurable distance, enhancing the measurement accuracy, and creating modifications with a set of additional options.

Peak equalization of rational-harmonic-mode-locking fiberized semiconductor laser pulse via optical injection induced gain modulation

Optical injection induced gain modulation of a semiconductor optical amplifier (SOA) is demonstrated to equalize the peak intensity of pulses generating from the rational-harmonic-mode-locking (RHML) SOA based fiberized semiconductor laser. This is achieved by adjusting the temporal shape of the injected optical signal generated from a Mach-Zehnder intensity modulator, in which the DC biased level exceeding Vpi and the electrical pulse amplitude of 1.5Vpi are concurrently employed. Numerical simulation on the injected optical signal profile and the SOA gain during the inverse-optical-pulse injection induced gain modulation process are also demonstrated. After a peculiar inverse-optical-pulse injection, each pulse in the 5th-order RHML pulse-train experiences different gain from temporally varied SOA gain profile, leading the pulse peak to equalize one another with a minimum standard deviation of 2.5% on the peak intensity variation. The optimized 5th-order RHML pulse exhibits a signal-to-noise suppression ratio of 20 dB and a reduced variation on temporal spacing from 11 to 4 ps. The clock amplitude jitter is compress from 35.3% to 7.3%, which is less than the limitation up to 10% for 5th order RHML generation.

On the distribution of 1550-nm photon pairs efficiently generated using a periodically poled lithium niobate waveguide

We report on efficient generation of 1550-nm photon pairs in a periodically poled lithium niobate waveguide using the spontaneous parametric down-conversion process. Such photon pairs are expected to find applications in fiber-based long-distance quantum communication. Pumping the waveguide with a pulsed semiconductor laser with a pulse rate of 800 kHz and a maximum average pump power of 50 μW, we obtain a coincidence rate of 600 s −1. Despite only two single-photon detectors are used, we gain some information about the photon-number distribution. Our measurements are found to be in agreement with a Poissonian photon-pair distribution, but clearly differ from the expected outcomes for both conventional and two-mode squeezed states, the latter corresponding to a thermal photon-pair distribution. The Poissonian photon-pair distribution is also explained by comparing the coherence time of the pump light and of the detected photons. An average of 0.9 generated photon pairs per pulse can thus be inferred.

Experimental setup for quantum cryptography by means of single polarized photons

Pioneering experiments on single-photon quantum cryptography that are performed with a tailored setup are reported. The key is transferred by pulsed semiconductor lasers, which encode the polarization state of the photons in two mutually nonorthogonal bases. Photon detectors are based on C30902S silicon avalanche photodiodes. For a laser pulse repetition rate of 100 kHz and a mean number of photons per pulse of about 0.2, the key generation rate reaches ≈4 kbit/s. The error rate in the key does not exceed 1%.