Semiconductor Laser Arrays Research Articles

高功率准连续半导体激光阵列中应变对独立发光点性能的影响

高功率准连续半导体激光阵列中应变对独立发光点性能的影响

Analysis on High Temperature Characteristic of High Power Semiconductor Laser Array

Analysis on High Temperature Characteristic of High Power Semiconductor Laser Array

Low-Voltage AlGaAs/GaAs Thyristors as High-Peak-Current Pulse Switches for High-Power Semiconductor Laser Pumping

The dynamic characteristics of a low-voltage thyristor based on an AlGaAs/GaAs heterostructure have been studied in the mode of generation of high-amplitude pulses with width of tens of nanoseconds in a circuit with low-impedance load based on an array of high-power AlGaAs/GaAs semiconductor lasers. The presented approach uses thyristors and diode laser arrays as discrete components, so it can be extended to other (not AlGaAs/GaAs-based) semiconductor lasers. It is demonstrated that a current pulse can be generated with an amplitude of 69 A and a width of 40 ns in a vertically assembled stack of an array of semiconductor lasers and thyristors. It was shown that raising the number of single thyristors does not lead to pulse broadening and makes it possible to raise several-fold the peak current amplitude to 208 A, with the peak laser emission power reaching a value of 78 W.

Tunable single-frequency source based on a DFB laser array for the spectral region of 1.55 μm

A technology of arrays of distributed-feedback semiconductor lasers for the spectral region of 1.55 μm and their characteristics are presented. Stable single-frequency lasing with a side mode suppression ratio higher than 25 dB is demonstrated. The possibility of continuous wavelength tuning in a range of up to 7 nm is shown.

Experiment demonstration of DFB semiconductor laser array based on S-bent waveguide with sampled grating

A four-wavelength DFB laser array based on S-bent waveguide and sampled grating is experimentally demonstrated. The laser array shows good single mode operation and uniform wavelength spacing. Since the fabrication for multi-wavelength of the gratings only requires conventional sampled grating combined with s-bent waveguides, the whole laser chip fabrication is very simple.

Thermal management of a semiconductor laser array based on a graphite heat sink.

Thermal analysis of a semiconductor laser array is carried out by establishing a packaging structure model of the array based on the use of copper as the base heat sink. A novel composite heat sink structure for a high-power semiconductor laser array with copper-implanted graphite microholes is proposed. The relationship between the location and quantity of microholes and the junction temperature of the semiconductor laser array is analyzed by numerical simulation. The packaging structure is found to effectively reduce the temperature generated by the semiconductor laser array in the process of operation, and the highest temperature is reduced by 4.52K. Since the laser diode bar is composed of multiple emitters, the temperature of the intermediate emitters is higher than that of the edge emitters. The structure of the graphite heat sink is optimized to improve the temperature uniformity of the semiconductor laser array emitter. Without changing the parameters of the semiconductor laser array device, the temperature difference is calculated, and a reduction from 7.68 to 2K is shown.

Evanescently Coupled DBR Laser Arrays in the 760–770 nm Wavelength Range

In this letter, we present evanescently coupled semiconductor laser arrays designed with a distributed Bragg reflector section for spectrally narrow emission and a combined waveguide section for high optical output powers. These devices were designed and fabricated in the AlGaAs material system with an InGaAsP quantum well providing emission in the 760–770 nm wavelength range. Measurements of the light-current characteristics reveal high optical output powers of 600 mW at 20 °C and 700 mW at 5 °C limited by thermal rollover without any signs of a catastrophic optical mirror damage or rapid power degradation. Spectrally narrow emission of 0.2 nm at −3 dB and a high wavelength stability with a small current tuning coefficient of 0.7 pm/mA were found. Far-field investigations reveal pre-dominant coupling of lowest order in-phase supermode emission without any sections for adjusting the phase of the electrical field vector for adjacent elements.

Stability through symmetry

Lasers A common route to get more light out of a laser system is to couple multiple lasers to form an array. However, instabilities owing to cross-talk and interference between different modes of individual cavities is generally detrimental to performance and could ultimately be damaging to the laser cavities. Hokmabadi et al. applied notions derived from supersymmetry, a theory developed in high-energy physics to describe the make-up and properties of particles, to design a stable array of semiconductor lasers (see the Perspective by Kottos). Based on symmetry arguments, the method is scalable and could provide a practical platform to design and develop complex photonic systems. Science , this issue p. [623][1]; see also p. [586][2] [1]: /lookup/doi/10.1126/science.aav5103 [2]: /lookup/doi/10.1126/science.aaw1203

Reduced relative intensity noise of a coherently combined single-mode semiconductor laser array under injection locking

A scheme for reducing the relative intensity noise (RIN) of laser source by an injection locked single-mode semiconductor laser array is proposed and demonstrated. Intensity and phase noise of the slave laser under injection locking are first analyzed by rate equations, and the RIN of the injection locked laser array after coherent combining is then estimated. The RIN of the injection-locked $N$-element laser array can be reduced by a factor about $1/N$ over the entire frequency range in the ideal case. Measurements with a two-element distributed feedback laser array confirm the main theoretical predictions and a nearly 3 dB reduction in RIN is obtained. The effect of the key parameters on the RIN of the injection locked array is investigated as well.

Non‐Hermitian Gauged Topological Laser Arrays

AbstractStable and phase‐locked emission in an extended topological supermode of coupled laser arrays, based on concepts of non‐Hermitian and topological photonics, is theoretically suggested. A non‐Hermitian Su–Schrieffer–Heeger chain of coupled microring resonators is considered, and it is shown that application of a synthetic imaginary gauge field via auxiliary passive microrings leads to all supermodes of the chain, except one, to become edge states. The only extended supermode, that retains some topological protection, can stably oscillate suppressing all other non‐topological edge supermodes. Numerical simulations based on a rate equation model of the semiconductor laser arrays confirm stable anti‐phase laser emission in the extended topological supermode and the role of the synthetic gauge field to enhance laser stability.

Rate equation analysis and non-Hermiticity in coupled semiconductor laser arrays

Optically coupled semiconductor laser arrays are described by coupled rate equations. The coupled mode equations and carrier densities are included in the analysis, which inherently incorporate the carrier-induced nonlinearities including gain saturation and amplitude-phase coupling. We solve the steady-state coupled rate equations and consider the cavity frequency detuning and the individual laser pump rates as the experimentally controlled variables. We show that the carrier-induced nonlinearities play a critical role in the mode control, and we identify gain contrast induced by cavity frequency detuning as a unique mechanism for mode control. Photon-mediated energy transfer between cavities is also discussed. Parity-time symmetry and exceptional points in this system are studied. Unbroken parity-time symmetry can be achieved by judiciously combining cavity detuning and unequal pump rates, while broken symmetry lies on the boundary of the optical locking region. Exceptional points are identified at the intersection between broken symmetry and unbroken parity-time symmetry.

Method to improve near-field nonlinearity of a high-power diode laser array on a microchannel cooler

Due to thermal stress, each emitter in a semiconductor laser bar or array is vertically displaced along the p-n junction; the result is that each emitter is not in a line, called near-field nonlinearity. Near-field nonlinearity along a laser bar (also known as “SMILE” effect) degrades the laser beam brightness, which causes an adverse effect on optical coupling and beam shaping. A large SMILE value causes a large divergence angle after collimation and a wider line after collimation and focusing. We simulate the factors affecting the SMILE value of a high-power diode laser array on a microchannel cooler (MCC). According to the simulation results, we have fabricated a series of laser bars bonded on MCCs with lower SMILE value. After simulation and experiment analysis, we found the key factor to affect SMILE is the deformation of the thin MCC because of the distribution of strain and stress in it. We also decreased the SMILE value of 1-cm-wide full bar AuSn bonded on MCCs from 12 to 1 μm by balancing force on MCC to minimize the deformation.

封装对大功率半导体激光器阵列热应力及Smile的影响

封装对大功率半导体激光器阵列热应力及Smile的影响

Phased Array Tracking of Semiconductor Laser Arrays With Complex Coupling Coefficients

In this paper, it is shown that a ring structure coupled diode-injection laser stripe array with complex coupling coefficients can be controlled in such a fashion as to perform agile beam tracking by use of a phased array. The controller uses measurements of the power of the individual laser stripes. The symmetry of the array is exploited to obtain a control law of a simple form.

Multiclustered chimeras in large semiconductor laser arrays with nonlocal interactions.

The dynamics of a large array of coupled semiconductor lasers is studied numerically for a nonlocal coupling scheme. Our focus is on chimera states, a self-organized spatiotemporal pattern of coexisting coherence and incoherence. In laser systems, such states have been previously found for global and nearest-neighbor coupling, mainly in small networks. The technological advantage of large arrays has motivated us to study a system of 200 nonlocally coupled lasers with respect to the emerging collective dynamics. Moreover, the nonlocal nature of the coupling allows us to obtain robust chimera states with multiple (in)coherent domains. The crucial parameters are the coupling strength, the coupling phase and the range of the nonlocal interaction. We find that multiclustered chimera states exist in a wide region of the parameter space and we provide quantitative characterization for the obtained spatiotemporal patterns. By proposing two different experimental setups for the realization of the nonlocal coupling scheme, we are confident that our results can be confirmed in the laboratory.

Multiple-wavelength distributed-feedback laser arrays with high coupling coefficients and precise channel spacing.

Special designs of sampled Bragg gratings have been used to fabricate distributed-feedback semiconductor laser arrays with very precise wavelength spacing and strong coupling coefficients. By dividing one sampling period into two equal sections, each with a grating but with a π-phase shift between the sections, the ±1st-order channels are enhanced while eliminating the zeroth-order reflection. By using multiple phase-shifted sections, only the -1st-order channel is enhanced. Using a single electron beam lithography step and two π-phase-shifted sections, we have fabricated an eight-channel laser array with a channel spacing of 100GHz.

High-temperature operation of 640 nm wavelength high-power laser diode arrays

We realized the fabrication of a red semiconductor laser array with high optical power and reliability using an AlGaInP-based compound semiconductor. To obtain a high optical output, the semiconductor laser requires high-quality quantum wells. In this work, we improved quantum well layer abruptness by applying high-temperature growth condition to quantum wells. We obtained a very high optical power of 20.1 W with a wavelength of 644 nm under this growth condition using magnesium as a dopant for a p-type layer. As a results, we achieved a high characteristic temperature of 68 K and a high electrical-to-optical (E–O) conversion efficiency 37% at 15 W optical output. When the laser lifetime at a temperature of 35 °C and an optical output power of 6.6 W for operation is defined as the time when the output power decreases to 50%, which is usually used for defining the lifetime of ultra high-pressure (UHP) lamps in projection display, we can estimate the lifetime of this laser to be longer than 10000 h or more.

Turbulent chimeras in large semiconductor laser arrays

Semiconductor laser arrays have been investigated experimentally and theoretically from the viewpoint of temporal and spatial coherence for the past forty years. In this work, we are focusing on a rather novel complex collective behavior, namely chimera states, where synchronized clusters of emitters coexist with unsynchronized ones. For the first time, we find such states exist in large diode arrays based on quantum well gain media with nearest-neighbor interactions. The crucial parameters are the evanescent coupling strength and the relative optical frequency detuning between the emitters of the array. By employing a recently proposed figure of merit for classifying chimera states, we provide quantitative and qualitative evidence for the observed dynamics. The corresponding chimeras are identified as turbulent according to the irregular temporal behavior of the classification measure.

DFB laser arrays based on the REC technique and their applications in radio-over-fiber systems (Invited Paper)

We review the recent work of distributed-feedback (DFB) multi-wavelength semiconductor laser arrays (MWLAs) based on the reconstruction equivalent chirp (REC) technique. The experimental results show that the proposed MWLA has very high wavelength precision (<±0.1 nm), while the fabrication cost is low. Only one step of holographic exposure and another step of photolithography are required for grating fabrication. The packaging technique for a high-bandwidth analog DFB laser and laser array was developed. A directly modulated MWLA transmitter module was achieved. In addition, an improved MWLA with an integrated reflector was proposed and successfully applied in a radio-over-fiber system.

千瓦级传导冷却半导体激光器阵列热特性

千瓦级传导冷却半导体激光器阵列热特性