Room-temperature Laser Operation Research Articles

661.7 nm room-temperature CW operation of AlGaInP double-heterostructure lasers with aluminium-containing quaternary active layer

We report for the first time on room-temperature (25°C) continuous-wave (CW) operation of AlGaInP double-heterostructure lasers with an aluminium-containing quaternary active layer. The active layer is (Al0.1Ga0.9)0.5In0.5P. The lasing wavelength is 661.7 nm, which is the shortest ever reported for semiconductor lasers. The threshold current is 120 mA (6.7 kA/cm2).

626.2-nm pulsed operation (300 K) of an AlGaInP double heterostructure laser grown by metalorganic chemical vapor deposition

Room-temperature pulsed laser operation of (Al0.55Ga0.45)0.5In0.5P /(Al0.17Ga0.83)0.5In0.5P / (Al0.55Ga0.45)0.5In0.5P double heterostructure laser diodes grown by metalorganic chemical vapor deposition has been achieved. The lasing wavelength is 626.2 nm, which is the shortest ever reported for an AlGaInP double heterostructure laser. Threshold current density is 50 kA/cm2 for a diode with a 20-μm-wide and 200-μm-long stripe.

Dual wavelength room temperature laser operation of colour centres in lithium fluoride

Tunable room-temperature laser operation has been achieved on two spectral bands from colour centres in a slab of LiF crystal pumped by the frequency-doubled output of a Q-switched Nd : YAG laser. An initial build-up of laser action in the red (∼715 nm) has been observed to be followed by a period during which the intensity of the red emission reached a peak and as it decreased a near infra-red (∼940 nm) lasing component evolved. The output at this longer wavelength emission increased to a relatively constant value and long-term stable laser operation was maintained.

Room-temperature pulsed operation of AlGaInP/GaInP/AlGaInP double heterostructure visible light laser diodes grown by metalorganic chemical vapor deposition

Room-temperature pulsed laser operation of (Al0.3Ga0.7)0.5In0.5P/ Ga0.5In0.5P/ (Al0.3Ga0.7)0.5In0.5P double heterostructure laser diodes grown by metalorganic chemical vapor deposition has been achieved for the first time. The lowest threshold current density was 26 kA/cm2 for a diode with a 22-μm-wide and 160-μm-long stripe. The lasing wavelength was 0.683 μm.

Cw room-temperature operation of GaAlAs single quantum well visible (7300 Å) diode lasers at 100 mW

100-mW room-temperature cw laser operation at 7300 Å has been achieved in a Ga1−xAlxAs (x∼0.22), ∼300 Å thick, single quantum well double heterostructure diode grown by organometallic vapor phase epitaxy. The proton-delineated stripe contact is 6 μm wide, and the front and rear laser facets are coated for antireflection and high reflection respectively. The cw threshold current is 86 mA for a 250-μm-long device, and linear output power versus current characteristics are observed up to 100 mW with an external differential quantum efficiency of 1 W/A (59%). cw output power exceeds 13 mW at 100 °C. Between 25–55 °C, the pulsed threshold current varies exponentially with temperature T as exp(T/T0), where T0∼187 K.

CW room-temperature visible single quantum well Ga0.73Al0.27As diode lasers grown by metalorganic chemical vapour deposition

Room-temperature CW laser operation at 7125 Å has been achieved in a (Ga1−xAlxAs, x̃0.27) single quantum well double heterostructure (SQW-DH) diode laser. The laser consists of a 9 μm-wide delineated shallow proton stripe. The pulsed threshold current for a 250 μm long device is 115 mA whereas the CW threshold current is 140 mA. The CW external differential quantum efficiency is 60%.

Quantum-well Al<inf>x</inf>Ga<inf>1 - x</inf>As-GaAs heterostructure lasers grown by metalorganic chemical vapor deposition

Data are presented on photopumped single- and multiple-quantum-well Al x Ga 1-x As-GaAs heterostructures grown by metalorganic chemical vapor deposition (MO-CVD) showing that continuous room-temperature (CW 300 K) laser operation of such structures is possible in the range 0-150 meV above the GaAs active region band edge ( \Delta E \equiv \hbar \omega - E_{g} = 0-150 meV). Optically pumped multiple-quantum-well heterostructure lasers of short cavity length ( l \lsim 20 \mu m), and thus high edge-to-edge cavity end losses, are shown to operate at photo-excitation threshold levels as low as 900 W/cm2( J_{th} \sim 375 A/cm2). As the quantum-well dimension is reduced to L_{z} \lsim 100 A, single-active-layer heterostructures shift their laser operation to higher confined-particle states, or fail to operate altogether, whereas multiple-active-layer heterostructures continue to operate as lasers on the lowest confined-particle states n = 1 e \rightarrow hh and n' = 1' e \rightarrow lh transitions). For a multiple-quantum-well heterostructure of small enough GaAs active region size, L_{z} A, recombination radiation at the energy gap is cut off, and as expected, laser operation on the lowest confined-particle states (1 - 1') is shifted to high energy ( \hbar \omega - E_{g} > 50 meV).

Cw room-temperature laser operation of Nd : CAMGAR at 0.941 and 1.059 μ

Continuous-wave laser operation at 300 °K at 941 and 1059 nm has beeen demonstrated using Nd : CAMGAR. Discrimination against the 1059-nm line required only tuned dielectric mirrors because of the strong 941-nm fluorescence. Gain and loss coefficients at 1059 nm were determined.

Room-temperature operation of Ga(1−x)AlxAs/GaAs double-heterostructure lasers grown by metalorganic chemical vapor deposition

Room-temperature pulsed laser operation of Ga(1−x)AlxAs/GaAs double-heterostructure lasers grown by metalorganic chemical vapor deposition (MO-CVD) has been achieved. Threshold current densities as low as 1.2 kA/cm2 have been attained in totally internally reflecting devices. In broad-area Fabry-Perot diodes, threshold current densities as low as 3 kA/cm2 have been attained. These lasers are fabricated from five-layer epitaxial structures grown entirely by the MO-CVD process.

Low threshold CW room temperature laser operation of Nd:CAMGAR at 0.941 µm

Low threshold CW room temperature laser operation of Nd:CAMGAR at 0.941 µm

Multicomponent solid-solution semiconductor lasers

Properties of a new hetetrostructure based on quaternary alloys are presented in application to semiconductor lasers. Room temperature laser operation is obtained near 1.06 and 1.8 μm with injection pumping and near 2 μm with electron-beam pumping.

Cw room-temperature InxGa1−xAs/InyGa1−yP 1.06-μm lasers

Room-temperature cw laser operation at wavelengths between 1.06 and 1.12 μm has been obtained from double-heterojunction structures of InxGa1−xAs/InyGa1−yP prepared by vapor-phase epitaxy. These devices have pulsed threshold current densities as low as 1000 A/cm2 and external differential quantum efficiencies as high as 55%. Their active laser cavities are between 0.14 and 0.36 μm thick, providing fundamental transverse-mode operation with far-field patterns 50 to 60° wide.

Room-temperature operation of GaAs Bragg-mirror lasers

Room-temperature operation of GaAs distributed Bragg reflector lasers is reported. The diodes are fabricated from conventional double heterostructures involving only a single step of liquid-phase epitaxy. For gratings with a period of 3700 Å, the diodes lased at 8770 Å, which corresponds to the high-absorption side of the spontaneous emission spectrum. Thresholds as low as 6 kA/cm2 have been realized.

Nd-glass laser with three-dimensional optical waveguide

Room-temperature laser operation in a three-dimensional Nd-glass waveguide is reported. The waveguide was fabricated by a double-diffusion process with ion migration. A Nd-glass laser, 4 mm in length, was end-pumped at 590-nm wavelength with a pulsed Rhodamine 6G dye laser. The threshold power for the Nd-glass waveguide laser was about 18 μJ, which was nearly one-half of that for a conventional Nd-glass laser without guiding structure. The measured value of the threshold for a waveguide laser agrees with the theoretical calculation.

Room-temperature laser operation of InxGa1−xAs p-n junctions

Room-temperature laser diodes which emit coherent infrared radiation near 1.1 μm have been prepared from InxGa1−xAs (x [inverted lazy s]0.23) vapor-grown p-n junction structures. At 77°K, laser threshold current densities as low as 1210 A/cm2 and external differential quantum efficiencies as high as 50% have been obtained at 1.08 μm. At 300°K, the threshold current densities are between 70 000 and 98 000 A/cm2 for emission at 1.145 μm.

Optically Pumped Volume-Excited cw Room-Temperature In1−x Gax P (x ≤ 0.60) Platelet Lasers

Room-temperature cw laser operation well into the visible spectrum (λ ∼ 6000 Å) is reported for In1−xGaxP (x ≤ 0.60). Thin (1–5-μ) experimental samples are compressed into In, under a thick (∼ 250-μ) high-index (η > 2. 6) SiC window, with a thin (10–50-μ) narrow SiC platelet under part of the In1−xGaxP sample. The thin In1−xGaxP samples, in the compound cavity, are volume excited in a small spot with an argon laser so that the heat is easily removed by the SiC windows and nearby In heat sink.