InAsSb/InAsSbP double-heterostructure lasers emitting at 3–4 µm: Part I

Previous publications concerned with the development and investigation of InAsSb/InAsSbP double heterostructure lasers emitting at 3–4 μm fabricated by liquid phase epitaxy are reviewed. In pulsed mode, the maximum operating temperature of the lasers is 203 K, the characteristic temperature is 35 K, and differential quantum efficiency is 20±5% at 77K. Mesa-stripe lasers with a 10-to 30-μm stripe width and a 200-to 500-μm cavity length can operate in CW mode up to 110 K. The total optical output power of more than 10 mW at λ=3.6 μm is obtained at T=82 K in CW mode. The output power per mode does not exceed 2 mW/facet. A single-mode lasing is achieved in the temperature range of 12–90 K. __________ Translated from Fizika i Tekhnika Poluprovodnikov, Vol. 34, No. 11, 2000, pp. 1396–1403. Original Russian Text Copyright ? 2000 by Danilova, Imenkov, Sherstnev, Yakovlev.     

High power InGaAsSb(Gd)/InAsSbP double heterostructure lasers (λ=3.3 µm)

InGaAsSb(Gd)/InAsSbP double heterostructure lasers (λ=3.3 μm, T=77 K) yield a multimode power of 1.56 W in pulsed operation (pulse width 30 μs, repetition frequency f=500 Hz) and 160 mW in the continuous-wave (CW) case. In the single-mode CW operation, the power is 18.7 mW. It is shown that heating of the active region is responsible for sublinear light-current characteristics in “long-cavity” lasers, whereas in “short-cavity” (L=140–300 μm) lasers the power is mainly limited by internal losses. __________ Translated from Fizika i Tekhnika Poluprovodnikov, Vol. 35, No. 10, 2001, pp. 1261–1265. Original Russian Text Copyright ? 2001 by Aydaraliev, Zotova, Karandashev, Matveev, Remennyi, Stus’, Talalakin.     

A spatially single-mode laser for a range of 1.25–1.28 μm on the basis of InAs quantum dots on a GaAs substrate

Spatially single-mode lasing in the wavelength range of 1.25–1.28 μm was accomplished in injection lasers on GaAs substrates. The peak output power is 110 mW at room temperature, and the differential quantum efficiency amounts to 37%. The active region of the laser is formed by an array of self-organizing InAs quantum dots. __________ Translated from Fizika i Tekhnika Poluprovodnikov, Vol. 34, No. 1, 2000, pp. 117–120. Original Russian Text Copyright ? 2000 by Mikhrin, Zhukov, Kovsh, Maleev, Ustinov, Shernyakov, Kayander, Kondrat’eva, Livshits, Tarasov, Maksimov, Tsatsul’nikov, Ledentsov, Kop’ev, Bimberg, Alferov.     

The shape of the signals of transient photoconductivity in silicon doped with gold or sulfur

Experimental results of studying the photoconductivity kinetics in silicon doped with either gold or sulfur are reported. The nonequilibrium charge-carrier concentration was generated by the effect of pulsed laser radiation. The time dependence of nonequilibrium conductivity was determined by contactless measurements from a variation in the reflected power of the microwave field. The long-term photoconductivity with the time constant of τ ≈ 1.6 ms at room temperature is observed in the silicon samples overcompensated with sulfur. Conventional short-term processes (τ ≈ 2–3 μs) characteristic of the centers with deep levels are observed in the silicon samples doped with gold. These differences are accounted for using the known data on the energy characteristics of the gold and sulfur levels in the silicon band gap and their charge states. Original Russian Text ? A.D. Kiryukhin, V.V. Grigor’ev, A.V. Zuev, V.V. Zuev, N.A. Korolev, 2007, published in Fizika i Tekhnika Poluprovodnikov, 2007, Vol. 41, No. 3, pp. 269–272.     

High-power 1.5 µm InAs-InGaAs quantum dot lasers on GaAs substrates

Light-current, spectral, and temperature characteristics of long-wavelength (1.46–1.5 μm) lasers grown on GaAs substrates, with an active area based on InAs-InGaAs quantum dots, are studied. To reach the required lasing wavelength, quantum dots were grown on top of a metamorphic InGaAs buffer layer with an In content of about 20%. The maximum output power in pulsed mode was 7 W at room temperature. The differential efficiency of the laser, which had a 1.5-mm-long cavity, was 50%. The temperature dependence of the threshold current is described by a characteristic temperature of 61 K in the temperature range 10–73°C. __________ Translated from Fizika i Tekhnika Poluprovodnikov, Vol. 38, No. 6, 2004, pp. 763–766. Original Russian Text Copyright ? 2004 by Maksimov, Shernyakov, Kryzhanovskaya, Gladyshev, Musikhin, Ledentsov, Zhukov, Vasil’ev, Kovsh, Mikhrin, Semenova, Maleev, Nikitina, Ustinov, Alferov.     

Design and technology of vertical-cavity surface-emitting lasers with nonconducting epitaxial mirrors

Design and technology problems in the fabrication of vertical-cavity surface-emitting lasers (VCSELs) equipped with nonconducting distributed Bragg reflectors (DBRs) and fabricated using molecular-beam epitaxy are considered. VCSELs with an active region were formed on the basis of InGaAs quantum wells and incorporated an AlGaAs/GaAs bottom DBR and an oxidized AlGaO/GaAs top DBR; the diameter of the oxidized aperture was equal to 7–12 μm. The devices exhibit a continuous-wave lasing at room temperature with threshold currents of 0.5–1.5 mA, a differential efficiency as high as 0.5 mW/mA, and a highest output power of 3 mW. __________ Translated from Fizika i Tekhnika Poluprovodnikov, Vol. 37, No. 10, 2003, pp. 1265–1269. Original Russian Text Copyright ? 2003 by Maleev, Kovsh, Zhukov, Vasil’ev, Mikhrin, Kuz’menkov, Bedarev, Zadiranov, Kulagina, Shernyakov, Shulenkov, Bykovskii, Solov’ev, M?ller, Ledentsov, Ustinov.     

Gain and internal losses in InGaAsSb/InAsSbP double-heterostructure lasers

We report on a study characterizing internal losses and the gain in InGaAsSb/InAsSbP diode-heterostructure lasers emitting in the mid-infrared (3–4 μm). Numerical simulations of the current dependence of the intensity of spontaneous emission above the laser threshold and of the differential quantum efficiency allowed us to determine the intraband absorption k ₀ ≈5.6×10⁻¹⁶ cm². The cavity-length dependence of the threshold current is used to estimate the internal losses at zero injection current α ₀≈5 cm⁻¹. Calculations of the internal losses at laser threshold showed that they increase more than fourfold when the cavity length is decreased from 500 μm to 100 μm. The temperature dependence of the differential quantum efficiency is explained on the assumption that intraband absorption with hole transitions into a split-off band occurs. It is shown that the maximum operating temperature of “short-cavity” lasers is determined by the intraband absorption rather than by Auger recombination. The internal losses are shown to have a linear current dependence. The separation of the quasi-Fermi levels as a function of current demonstrates an absence of voltage saturation of the p-n junction above threshold. Fiz. Tekh. Poluprovodn. 33, 759–763 (June 1999)     

垂直腔面发射激光器

The development and application of vertical-cavity surface-emitting lasers (VCSELs) are summarized in this paper. The emphasis is focused on the high power single and 2-D arrays bottom-emitting VCSELs with a wavelength of 980nm. A distinguished device performance is achieved. The maximum continuous-wave (CW) output power of large aperture single devices with active diameters up to 500μm is as high as 1.95W at room temperature, which is to our knowledge the highest value reported for a single device. Size dependence of the output power, the threshold current and the differential resistance are discussed. A 16 elements array with 200μm aperture size (250μm center spacing) of individual elements shows a CW output power of 1.32W at room temperature.     

An ionization-type Si:S-based semiconductor converter of infrared images with sensitivity in the spectral range of CO2-laser radiation

An ionization-type semiconductor converter of infrared images that operates in the pulsed mode at a temperature of 77 K was studied. It is shown that it is possible to control the spectral range of photoconverter’s photosensitivity (λ=5–10.6 μm) by short-wavelength illumination of photodetector included in the converter. The response time of the converter is ∼5×10⁻⁷ s. __________ Translated from Fizika i Tekhnika Poluprovodnikov, Vol. 35, No. 8, 2001, pp. 1009–1012. Original Russian Text Copyright ? 2001 by Tulanov, Siyabekov, Davletova, Ortaeva.     

Infrared light-emitting diodes based on GaInAsSb solid solutions grown from lead-containing solution-melts

Light-emitting diodes (LEDs) were fabricated on the basis of GaInAsSb alloys grown from lead-containing solution-melts. Electroluminescence characteristics and their current and temperature dependences were studied. The external photon yield at room temperature was 1.6 and 0.11% for LEDs with emission wavelengths λ=2.3 and 2.44 μm, respectively. For LEDs with emission wavelength λ=2.3 μm, the average emission power P=0.94 mW was attained in the quasi-continuous mode at room temperature. In the pulsed mode, the peak radiation power was P=126 mW at a current of 3 A, a pulse duration of 0.125 μs, and a frequency of 512 Hz. __________ Translated from Fizika i Tekhnika Poluprovodnikov, Vol. 38, No. 12, 2004, pp. 1466–1472. Original Russian Text Copyright ? 2004 by Astakhova, Grebenshchikova, Ivanov, Imenkov, Kunitsyna, Parkhomenko, Yakovlev.     

High-efficiency LEDs of 1.6–2.4 µm spectral range for medical diagnostics and environment monitoring

High efficient LED structures covering the spectral range of 1.6–2.4 μm have been developed on the basis of GaSb and its solid solutions. The electroluminescent characteristics and their temperature and current dependences have been studied. The radiative and nonradiative recombination mechanisms and their effect on the quantum efficiency have been investigated. A quantum efficiency of 40–60% has been obtained in the quasi-steady mode at room temperature. A short-pulse optical power of 170 mW was reached. __________ Translated from Fizika i Tekhnika Poluprovodnikov, Vol. 37, No. 8, 2003, pp. 996–1009. Original Russian Text Copyright ? 2003 by Stoyanov, Zhurtanov, Astakhova, Imenkov, Yakovlev.     

Asymmetric quantum well broadband thyristor laser

A broadband thyristor laser based on InGaAs/GaAs asymmetric quantum well (AQW) is fabricated by metal organic chemical vapor deposition (MOCVD). The 3-μm-wide Fabry-Perot (FP) ridge-waveguide laser shows an S-shape I-V characteristic and exhibits a flat-topped broadband optical spectrum coverage of ~27 nm (Δ_-10 dB) at a center wavelength of~1090 nm with a total output power of 137 mW under pulsed operation. The AQW structure was carefully designed to establish multiple energy states within, in order to broaden the gain spectrum. An obvious blue shift emission, which is not generally acquired in QW laser diodes, is observed in the broadening process of the optical spectrum as the injection current increases. This blue shift spectrum broadening is considered to result from the prominent band-filling effect enhanced by the multiple energy states of the AQW structure, as well as the optical feedback effect contributed by the thyristor laser structure.     

Frequency shift in a system of two laser diodes

An easily reproducible construction of two butt-joint laser diodes based on a GaAs/InGaAs/InGaP structure is fabricated and investigated. The construction forms a composite cavity in which about half of stimulated emissions of a long-wavelength diode transforms into emissions of a ground mode of a waveguide of a short-wavelength diode. It is found that the emission spectrum from the composite cavity is represented not only by fundamental (close) frequencies of two diodes with a power of ∼1 W, but also by their sum frequency and second harmonic with a power as high as 1 μW. The found nonlinear enrichment of the emission spectrum of a two-frequency heterolaser with a composite cavity is caused by a lattice nonlinearity of the semiconductor and allows one to plan equally effective intracavity generation of various frequencies in a far-IR range at room temperature. Original Russian Text ? A.A. Biryukov, B.N. Zvonkov, S.M. Nekorkin, V.Ya. Aleshkin, V.I. Gavrilenko, K.V. Marem’yanin, S.V. Morozov, V.V. Kocharovskii, Vl.V. Kocharovskii, 2007, published in Fizika i Tekhnika Poluprovodnikov, 2007, Vol. 41, No. 11, pp. 1384–1388.     

Difference mode generation in injection lasers

The nonlinear generation of a difference mode in an injection laser is considered. A new design based on the InGaP/GaAs/InGaAs heterostructure is suggested in order to generate two laser modes with a wavelength of about 1 μm and a difference mode at a wavelength of about 10 μm. In lasers with a 100-μm-wide waveguide, the power output of the difference mode can be as high as ∼10 mW at ∼10 W in the short-wavelength modes. __________ Translated from Fizika i Tekhnika Poluprovodnikov, Vol. 35, No. 10, 2001, pp. 1256–1260. Original Russian Text Copyright ? 2001 by Aleshkin, Afonenko, Zvonkov.     

Nature of the edge electroluminescence peak in the Si:(Er,O) diode breakdown mode

Electroluminescence (EL) of erbium-and oxygen-doped Si:(Er,O) diodes at λ=1.00–1.65 μm has been studied in the p-n junction breakdown and forward current modes. The EL was measured at room temperature from the front and back surfaces of the diodes. A peak corresponding to the absorption band edge of silicon was observed in the EL spectra of some diodes in the p-n junction breakdown mode. The peak is associated with the injection of minority carriers from the metal contact into silicon, with subsequent band-to-band radiative recombination. The band-to-band recombination intensity increases sharply on reaching a certain current density that depends on the fabrication technology. This threshold current density decreases with the temperature of post-implantation annealing of Si:(Er,O) diodes increasing in the range 900–1100°C. __________ Translated from Fizika i Tekhnika Poluprovodnikov, Vol. 36, No. 4, 2002, pp. 453–456. Original Russian Text Copyright ? 2002 by Emel’yanov, Nikolaev, Sobolev.     

Ultralow internal optical loss in separate-confinement quantum-well laser heterostructures

Internal optical loss in separate-confinement laser heterostructures with an ultrawide (>1 smm) waveguide has been studied theoretically and experimentally. It is found that an asymmetric position of the active region in an ultrawide waveguide reduces the optical confinement factor for higher-order modes and raises the threshold electron density for these modes by 10–20%. It is shown that broadening the waveguide to above 1 μm results in a reduction of the internal optical loss only in asymmetric separate-confinement laser heterostructures. The calculated internal optical loss reaches ∼0.2 cm⁻¹ (for λ≈1.08 μm) in an asymmetric waveguide 4 μm thick. The minimum internal optical loss has a fundamental limitation, which is determined by the loss from scattering on free carriers at the transparency carrier density in the active region. An internal optical loss of 0.34 cm⁻¹ was attained in asymmetric separate-confinement laser heterostructures with an ultrawide (1.7 μm) waveguide, produced by MOCVD. Lasing in the fundamental transverse mode has been obtained owing to the significant difference in the threshold densities for the fundamental mode and higher-order modes. The record-breaking CW output optical power of 16 W and wallplug efficiency of 72% is obtained in 100-μm aperture lasers with a Fabry-Perot cavity length of ∼3 mm on the basis of the heterostructures produced. __________ Translated from Fizika i Tekhnika Poluprovodnikov, Vol. 38, No. 12, 2004, pp. 1477–1486. Original Russian Text Copyright ? 2004 by Slipchenko, Vinokurov, Pikhtin, Sokolova, Stankevich, Tarasov, Alferov.     

Structural and optical properties of InAs quantum dots in AlGaAs matrix

Structural and optical properties of InAs quantum dots (QDs) grown in a wide-bandgap Al_0.3Ga_0.7As matrix is studied. It is shown that a high temperature stability of optical properties can be achieved owing to deep localization of carriers in a matrix whose band gap is wider than that in GaAs. Specific features of QD formation were studied for different amounts of deposited InAs. A steady red shift of the QD emission peak as far as ∼1.18 μm with the effective thickness of InAs in Al_0.3Ga_0.7As increasing was observed at room temperature. This made it possible to achieve a much higher energy of exciton localization than for QDs in a GaAs matrix. To obtain the maximum localization energy, the QD sheet was overgrown with an InGaAs layer. The possibility of reaching the emission wavelength of ~1.3 μm is demonstrated. __________ Translated from Fizika i Tekhnika Poluprovodnikov, Vol. 37, No. 5, 2003, pp. 578–582. Original Russian Text Copyright ? 2003 by Sizov, Samsonenko, Tsyrlin, Polyakov, Egorov, Tonkikh, Zhukov, Mikhrin, Vasil’ev, Musikhin, Tsatsul’nikov, Ustinov, Ledentsov.     

InAsSb/InAsSbP double-heterostructure lasers emitting in the 3–4 µm spectral range

Our earlier reports concerning the fabrication by liquid-phase epitaxy and investigation of InAsSbP/InAsSb/InAsSbP double heterostructure lasers emitting at 3–4 μm are reviewed. The dependences of spectral characteristics and the spatial distribution of the laser emission on temperature and current are discussed. Lasing modes are shifted by 0.5–1.0 cm⁻¹ to longer wavelengths with increasing temperature. The tuning of the lasing modes by means of current is very fast (10⁻⁸–10⁻¹² s). With increasing current, the modes are shifted to shorter wavelengths by 50–60 ? at 77 K. The maximum mode shift of 104 ? (10 cm⁻¹) is observed at 62 K. The spectral line width of the laser is as narrow as 10 MHz. Abnormally narrow directional patterns in the p-n junction plane are observed in some cases in the spatial distribution of laser emission. The current tuning of lasers, due to nonlinear optical effects, has been modeled mathematically in good agreement with the experiment. Transmittance spectra of OCS, NH₃, H₂O, CH₃Cl, and N₂O gases were recorded using current-tuned lasers. __________ Translated from Fizika i Tekhnika Poluprovodnikov, Vol. 35, No. 12, 2001, pp. 1466–1480. Original Russian Text Copyright ? 2001 by Danilova, Imenkov, Kolchanova, Yakovlev. See [1].     

Dual-wavelength all-fiber Q-switched fiber laser using bismuth-doped fiber as saturable absorber

A passively Q-switched all-fiber laser is demonstrated using a 10-cm-long bismuth-doped fiber (BDF) as a saturable absorber (SA). The dual-wavelength operation was obtained due to the nonlinear effect inside the fabricated BDF, which has a high germanium content. Stable Q-switched pulses were obtained at the dual synchronous wavelengths of 1 530.1 nm and 1 531.1 nm. When the pump power is tuned from 105.3 mW to 191.0 mW, the repetition rate can be varied from 82.6 kMz to 117.6 kHz. The maximum pulse energy and average output power were 83.4 nJ and 9.8 mW, respectively while the minimum pulse width was 8.5 μs at the maximum pump power of 191.0 mW. Our results indicate that BDF could be a promising alternative optical modulator for pulsed fiber laser application.     

InAsSb/InAsSbP diode lasers with separate electrical and optical confinement, emitting at 3–4 µm

Diode lasers based on InAsSb/InAsSbP with separate electrical and optical confinement, emitting in the wavelength interval 3–4 μm, are investigated. The lasers attain a higher operating temperature when electrical confinement is created by means of type-II heterojunctions. Interface Auger recombination is suppressed in lasers of this type, and the experimental current density is close to the theoretically calculated value for the case of predominant volume Auger recombination at a temperature of 180–220 K. Fiz. Tekh. Poluprovodn. 31, 976–979 (August 1997)