Multichannel Lasers Research Articles

Acoustic Streaming Tunnel Enables Particle Velocity Stretching in Multiplex Flow Cytometry.

Multiplexed flow cytometry, known for its powerful high-throughput identification capability, is widely applied across various biomedical and clinical fields. However, classical flow cytometry relies on multichannel lasers and detectors, which are significant in cost and size, limiting their application in miniaturized assays. Herein, we developed an acoustic streaming-based flow cytometry technique that focuses on multisized microbeads flowing sheathlessly. This method enables the discrimination of particle types and the quantification of target protein concentrations using only a single detector. Microbeads of different sizes exhibit distinct behaviors in the continuous acoustic streaming tunnel, leading to an increased velocity difference during their transition under the laser spot. Consequently, a size detection method based on "velocity stretching" has been established. A multiplex assay of three proteins: cardiac troponin I, creatine kinase-MB and myoglobin, in acute myocardial infarction is performed to validate the feasibility and evaluate the performance of the system. This new multiplexed flow cytometry strategy is expected to enable low-cost and onsite detection of multiple biomarkers.

Improvement of response bandwidth and sensitivity of Rydberg receiver using multi-channel excitations

We investigate the response bandwidth of a superheterodyne Rydberg receiver at a room-temperature vapor cell, and present an architecture of multi-channel lasers excitation to increase the response bandwidth and keep sensitivity, simultaneously. Two microwave fields, denoted as a local oscillator (LO) E_{text{LO}} and a signal field E_{text{SIG}}, couple two Rydberg states transition of |52D_{5/2}rangle to |53P_{3/2}rangle . In the presence of the LO field, the frequency difference between two fields can be read out as an intermediate frequency (IF) signal using Rydberg electromagnetically induced transparency (EIT) spectroscopy. The bandwidth of the Rydberg receiver is obtained by measuring the output power of IF signal versus the frequency difference between two fields. The bandwidth dependence on the Rabi frequency of excitation lasers is presented, which shows the bandwidth decrease with the probe Rabi frequency, while it is quadratic dependence on the coupling Rabi frequency. Meanwhile, we investigate the effect of probe laser waist on the bandwidth, showing that the bandwidth is inversely proportional to the laser waist. We achieve a maximum response bandwidth of the receiver about 6.8 MHz. Finally, we design an architecture of multi-channel lasers excitation for increasing the response and keeping the sensitivity, simultaneously. Our work has the potential to extend the applications of Rydberg atoms in communications.

Passive Phase Locking Coherent Combination of Solid-State Lasers through Stimulated Brillouin Scattering Effect

The stimulated Brillouin scattering (SBS) effect, a new approach to the combination of solid-state lasers, can be actualized via coherent synthesis. In this paper, a solid-state laser based on SBS passive phase locking, utilizing the master oscillator power amplifier (MOPA) structure at the front end of the lasers, provides the amplification of the Stokes light subsequently generated. In order to reduce the influence of thermal effects on beam quality, beam-split amplification has been adopted with the same phase locking used by the back injection of the Stokes pulse. With the advantage of the combined scheme, the energy extraction efficiency of SBS coherent combination can be reached at 91.8% with coherent fringe visibility of 83%. Therefore, it provides a new way to improve the brightness through realizing the coherent combination of multi-channel solid-state lasers.

Theoretical simulation of the selective stimulation of axons in different areas of a nerve bundle by multichannel near-infrared lasers.

Damaged nerve function can be repaired by applying external stimuli, and the selective stimulation of nerve fibers is the highest goal of nerve functional repair. This paper proposes a method of using multichannel near-infrared lasers to achieve the selective stimulation of axons in different areas in a mixed nerve bundle. An exposed bullfrog sciatic nerve was considered the object of study to realize the selective stimulation. A model was established by using COMSOL Multiphysics to simulate the temperature distribution of nerves under multichannel near-infrared laser stimulation. The results of this model showed that by changing the distance between the laser fiber and the nerve (d) or the power of the 4 lasers (P), the axons at different parts of the nerve bundle may be selectively stimulated. If only the axons located in the center are selected to be activated, it is necessary to set the d and P value in the four directions to the same value. If only axons on the nerve edge are selected for activation, we can reduce the d value of the nearest laser (or increase P) and increase the d value of lasers in other directions (or decrease P). If only axons in the shallow area below the surface between the two lasers are selected for activation, it is necessary to reduce the d value of the laser in two directions close there (or increase P) and increase the d value of the laser in the other two directions (or decrease P). If only the axons of the superficial region on the coordinate axis are activated, the d value of the laser in the farthest direction can be increased (or decrease P) and the d value of the other three lasers can be reduced (or increase P). Moreover, the results of animal experiments further verify the feasibility of our method to realize selective activation of the axons.

Design of a dual-channel modelocked fiber laser that avoids multi-pulsing.

Multi-channel modelocked lasers and their design have attracted much attention. Here, we use the Swift-Hohenberg equation to study dual-channel simultaneous modelocking (DSML) in a fiber laser. When a quartic filter is added to the laser cavity, the stable dual-channel simultaneous modelocking can be obtained for a given filter bandwidth when frequency separation, ωs, is less than a calculated threshold, ωth. When ωs>ωth, a multipulsing instability occurs. We use a linear stability analysis to determine the limit that the multi-pulsing instability imposes on DSML, and we propose a cavity design that avoids the multi-pulsing instability.

Research on laser interference lithography based on mutual injection dual-output laser

In this paper, a laser interference lithography technology which based on the mutual injection dual-output laser is innovatively developed. The experimental study of two beams of laser interference lithography on the material surface is carried out by using two beams of phase locking and the same frequency output. In order to solve the problems caused by beam splitter in laser interference lithography in the past, such as unequal energy, high loss and unsatisfactory interference pattern. U cavity structure is constructed by using two pump gain dielectric devices and two perpendicular 45° total reflection mirrors in the experiment. Outputing two parallel beams with pulse width of 8.2 ns and energy of 186 mJ after intracavity electro-optic Q-switching. Then using two other reflection mirrors to make the two beams of light reflection convergence onto the surface of the silicon material for interference lithography. When the angles of two beams are 12°, 9°and 6°, the clear interference fringes with periods of 5.1 μm, 6.9 μm and 10.4 μm are obtained. The interference photolithography using a dual-output laser with mutual injection has a positive significance for micromachining technology, and it can be extended to multi-channel laser interferometry processing using multi-channel mutual injection lasers.

TDM interrogation of intensity-modulated USFBGs network based on multichannel lasers.

We report a large-scale multi-channel fiber sensing network, where ultra-short FBGs (USFBGs) instead of conventional narrow-band ultra-weak FBGs are used as the sensors. In the time division multiplexing scheme of the network, each grating response is resolved as three adjacent discrete peaks. The central wavelengths of USFBGs are tracked with the differential detection, which is achieved by calculating the peak-to-peak ratio of two maximum peaks. Compared with previous large-scale hybrid multiplexing sensing networks (e.g., WDM/TDM) which typically have relatively low interrogation speed and very high complexity, the proposed system can achieve interrogation of all channel sensors through very fast and simple intensity measurements with a broad dynamic range. A proof-of-concept experiment with twenty USFBGs, at two wavelength channels, was performed and a fast static strain measurements were demonstrated, with a high average sensitivity of ~0.54dB/µƐ and wide dynamic range of over ~3000µƐ. The channel to channel switching time was 10ms and total network interrogation time was 50ms.

The stability of the stationary generation of a multichannel laser

Stable generation of multi-channel lasers that find application in optical communication systems with spectral multiplexing is studied theoretically. A computational model to determine the frequencies and increments of self-oscillating perturbations depending on the key laser parameters and the characteristics of the channels cross-saturation is proposed. It is shown that for typical conditions of an erbium-doped fiber laser, multichannel generation with a large number of channels (more than ten), although stable, is characterized by large fluctuations of channel power due to the very small decay increments of perturbations caused by small technical fluctuations of the laser parameters.

High-power high beam-quality multi-waveguide CO2 amplifiers

The results from modeling the energy characteristics of a multi-waveguide power amplifier are presented. The optical schemes and calculations for the most promising circuits of multichannel waveguide CO2 amplifiers are given. The amplifying system itself removes the problem of phase locking in individual channels of multichannel systems. The experimental results from the synchronization of arrays of multichannel waveguide CO2 lasers allow the production of high-power (up to 15 kW) high beam-quality multibeam lasers. Technological lasers with such properties have yet to be produced anywhere in the world.

基于功率合束器的多路光纤激光自组织相干合成

基于功率合束器的多路光纤激光自组织相干合成

多路光纤激光相干偏振合成技术研究

多路光纤激光相干偏振合成技术研究

Selection of optical modes in multichannel fibre lasers

The numerical simulation of radiation propagation in a multichannel fibre amplifier showed that the phases of input beams having the initial spread are equalised during the propagation of these beams due to the spatial filtration of the field by the structure of amplifying channels. The nonlinear part of the refractive index affects the phase matching process to a lesser extent. An increase in the coupling between the channels enhances the self-organisation of the beams.

Phenomenological model of multichannel solid-state lasers and its use in describing the stable operation of ring and linear lasers

A simple phenomenological model of multichannel solid-state lasers is proposed. This model describes the main relationships governing stable operation of such lasers. The conditions of validity of the proposed concepts are considered for various types of multichannel lasers. It is shown that the nature of the relaxation oscillation spectra is the same for ring lasers, linear two-frequency lasers, coupled-cavity lasers, and bichromatic lasers.

Interferometer for optical coupling and mode selection in a multichannel laser array

A theoretical consideration is presented of the optical coupling and selection of laser array modes by the use of a developed Lummer-Gehrcke interferometer as a resonator reflector. Control of the mirror reflection of the proposed interferometer permits laser power to be redistributed through channels on the outlet resonator mirror; in particular, it makes it possible to lead power out of the resonator by a single beam. In this way it is possible to diminish the sidelobes in the far-field radiation profile of multichannel lasers and to raise the efficiency of the optical coupling of the laser array with waveguides and fibers. This method may be used for the redistribution of laser power on the outlet mirror in striped lasers as well.

Fundamental limits for linearity of CATV lasers

We have considered nonlinear distortions in a subcarrier multiplexed optical transmission system arising from carrier heating effects in the source laser. We included two sources of carrier heating: free-carrier absorption of the coherent radiation in the cavity, and the power flux into the active layer, associated with the input current. Resulting from the very existence of modulated optical and electrical signals, these effects cannot be avoided in any laser structure. Simple analytic expressions have been derived for the intermodulation distortion in multichannel single-mode lasers. For an 80-channel 60-540 MHz system with 3% optical modulation depth per channel, the composite second-order (CSO) distortion brought about by the hot-carrier effects is near the tolerance limit for CATV systems.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

High speed and high density wavelength multichannel butt-jointed DBR lasers

A wavelength multichannel DBR laser exhibiting a −3dB 1M bandwidth up to 8 GHz has been demonstrated. By monitoring only one current in the DBR section, the highest number (18) ever reported of wavelength channels regular spaced has been obtained on a three section DBR structure which was optimised in terms of active-passive coupling efficiency and lengths.

Characteristics of the formation of a radiation structure by focusing a multichannel-laser beam

The positions of the planes with different states of the structure of the radiation in the far-field zone of focusing optical systems were determined theoretically and experimentally for multichannel lasers as a function of the focal lengths of the focusing systems and of the distance from the exit window of a laser resonator due to the focusing system. An analysis was made of the influence of the radiation structure on the formation of the zones of the laser interaction with steel under different laser processing conditions.

Influence of certain radiation parameters on wavefront reversal of a pump wave in a Brillouin mirror

A study was made of wavefront reversal, accompanying stimulated Brillouin scattering in various media, and of the way it was affected by the geometrical, temporal, and polarization characteristics of the exciting radiation. In an oscillator-amplifier system, practically complete compensation was achieved for phase distortions of the oscillator signal introduced by the amplifier components. The output energy of the light beam was then 3 J, its diameter was 4 mm, and its divergence (diffraction limited) was 0.3 mrad. The results of the experiments indicated a practical possibility of applying the wavefront reversal phenomenon in high-power multichannel lasers.