2.0-/spl mu/m single-mode operation of InGaAs-InGaAsP distributed-feedback buried-heterostructure quantum-well lasers

Distributed-feedback (DFB) buried-heterostructure (BH) lasers with quantum-well active region emitting at 2.0 /spl mu/m have been fabricated and characterized. The lasers with four wells showed performance of practical use: threshold current as low as 15 mA for 600-/spl mu/m-long devices and CW single-mode output up to 5 mW at 2.03 /spl mu/m under operation current of 100 mA were observed. The current- and temperature-tuning rates of DFB mode wavelength are 0.004 nm/mA and 0.125 nm/K, respectively.     

In(Al)GaAs–AlGaAs Wafer Fused VCSELs Emitting at 2- μm Wavelength

We demonstrate 2-mum wavelength, wafer-fused In(Al)GaAs-InP-AlGaAs-GaAs vertical-cavity surface-emitting lasers (VCSELs) emitting single-mode power of 0.5 mW at room temperature with a threshold current of 4 mA and sidemode suppression ratio of over 30 dB. These devices can be continuously tuned with current by 5 nm without mode hopping, with a tuning rate of 0.31 nm/mA. These features demonstrate the potential of these long wavelength VCSELs for gas sensing and other optical spectroscopy applications.     

High output power single longitudinal mode graded index separateconfinement multiple quantum well InGaAs/InP distributed feedback (GRINSCH MQW DFB) lasers

A high continuous-wave (CW) output and high quantum efficiency of 1.5 μm-wavelength InGaAs/InP graded-index separate-confinement multiple-quantum-well DFB lasers were demonstrated. A threshold current of 45 mA with a maximum output power close to 100 mW and a quantum efficiency of 0.33 mW/mA was obtained. Single-frequency light output with power as high as 16 dBm (40 mW) was launched into a single-mode fiber     

High-efficiency GaInP-AlGaInP ridge waveguide single-mode lasersoperating at 650 nm

In this letter, the authors report a very high quantum efficiency of 91% for antireflection/high-reflection-coated GaInP-AlGaInP ridge waveguide laser diodes operating at 650 nm range. The laser structure was grown by solid-source molecular beam epitaxy. The laser diodes performed stable single-mode operation up to 60 mW. Threshold current as low as 50 mA was measured for 5.5×600 μm² laser diodes. To the authors' best knowledge, this is among the best ever reported efficiency for visible lasers     

A long-wavelength MEMS tunable VCSEL incorporating a tunnel junction

In this letter, we describe the performance of a microelectromechanical system tunable vertical-cavity surface-emitting laser operating at 1550 nm and incorporating a tunnel junction for improved current injection and reduced optical loss. These lasers exhibit single-mode powers greater than 0.28 mW over 10 nm of tuning. Peak single-mode powers are greater than 0.8 mW and minimum threshold currents are less than 1 mA.     

1.3-μm GaInAsN Vertical-Cavity Surface-Emitting Lasers by Oxide-Planarized and Surface-Relief Processes for Single-Mode Operation

In this letter, we investigate and characterize the 1.3-mum single-mode vertical-cavity surface-emitting lasers (VCSELs) with two GaInAsN strained multiple quantum wells as the active region. Surface relief technique and a thick silicon oxide were used for the spatial mode filtering and the planarization processing, respectively. The VCSELs with a 5-mum-diameter surface-relief aperture and a 12-mum-diameter oxide-confined aperture at room temperature exhibit a threshold current of 3 mA, a slope efficiency of 0.14 mW/mA, a maximum operation temperature of 90 degC, and a single-mode behavior. These VCSELs show a maximum light output power of 1 mW for the single fundamental mode with a transverse-mode suppression of more than 30 dB and also show a clear eye-opening feature operated at 2.488 Gb/s and 12.6 mA     

Low-chirp and high-power 1.55-/spl mu/m strained-quantum-well complex-coupled DFB laser

High-power, low-chirp, and low-threshold current characteristics of 1.55 /spl mu/m complex-coupled compressively strained InGaAsP quantum-well DFB laser with a loss grating are presented. Kink-free light-current characteristics with single-mode power over 40 mW are demonstrated for uncoated devices. A relatively low threshold current of 10 mA and a high slope efficiency of 0.23 W/A have been obtained even with the loss grating employed. Stable single-mode emission was demonstrated with a side mode suppression ratio up to 54 dB, a low chirp of less than 0.3 nm under 1 Gb/s pseudorandom digital modulation and a spectral linewidth of 8 MHz.     

High-efficiency resonant-cavity LEDs emitting at 650 nm

We fabricated resonant-cavity light-emitting diodes (LEDs) emitting at 650 nm. Compressively strained GaInP quantum wells were used as an active layer embedded between AlGaAs-AlAs Bragg mirrors. The Bragg mirrors formed a one-wavelength optical resonator. Two devices with different light-emitting areas were compared: 1) a large area chip (300 μm×300 μm) with a conventional LED contact and 2) a small area chip with an 80-μm light opening with an annular contact. Large devices are more suitable for high output power whereas the smaller devices might be useful for data transmission e.g., via plastic optical fibers. For epoxy-encapsulated large area devices, we achieved a maximum wall-plug efficiency of 10.2% and maximum output power of 12.2 mW at 100 mA. The small area LEDs yielded 2.9 mW at 20 mA and a maximum wall-plug efficiency of 9.5%     

80/spl deg/C continuous-wave operation of 2.01-/spl mu/m wavelength InGaAlAs-InP vertical-cavity surface-emitting lasers

Electrically pumped buried tunnel junction InGaAlAs-InP vertical-cavity surface-emitting lasers (VCSELs) with self-adjusted lateral current and optical confinement and record emission wavelengths beyond 2 /spl mu/m are presented. Front and back side mirrors are realized using 31.5 epitaxial layer pairs of alternating InGaAs-InAlAs and a dielectric 2.5 pair CaF/sub 2/-a-Si layer stack. The devices show single-mode continuous-wave operation up to heat sink temperatures over 80/spl deg/C. The maximum output power at 20/spl deg/C reaches 0.43 mW, threshold current and voltage are as low as 0.66 mA and 0.73 V, respectively. To reach the long emission wavelength, we use an optimized active region comprising heavily strained quantum wells. High-resolution X-ray diffraction and photoluminescence measurements reveal excellent material quality without relaxation in the quantum wells.     

Low degradation rate in strained InGaAs/AlGaAs single quantum welllasers

A 10000 h, 30°C constant-current lifetest performed on five strained In_0.2Ga_0.8As/AlGaAs single-quantum-well lasers, with λ~930 nm, is discussed. The devices are 90-μm×400-μm oxide-stripe lasers with facet coatings, grown by atmospheric pressure organometallic vapor-phase epitaxy. For each diode, the current was maintained at a constant value of ~300 mA, corresponding to approximately 100 mW of output power. After 10⁴ h, thresholds increased from an average of 84 mA to 108 mA, while quantum efficiencies were essentially unchanged. In relation to a typical 100-mW constant-power lifetest, this is equivalent to a degradation rate of less than 1%/kh     

1.3-μm GaInAsP/InP transverse-mode stabilized buried-crescentlasers by a new fabrication technique using a reactive ion beam etching

Transverse-mode-stabilized, 1.3-μm, GaInAsP/InP, buried-crescent (BC) lasers fabricated using a reactive ion beam etching (RIBE) technique are presented. Yields of single-transverse-mode operation as high as 95% are achieved with low threshold currents of 11-25 mA. Transverse-mode stability under both high-power and long-term operation (50°C, 20 mW, 1000 h) is demonstrated. A coupling efficiency into a single-mode fiber of 63% and a coupled power of 40 mW at 160 mA are achieved. Stable continuous-wave operation is also confirmed under a constant power of 5 mW (50 and 70°C) and 20 mW (50°C) in an aging test     

380‐nm Ultraviolet Light‐Emitting Diodes with InGaN/AlGaN MQW Structure

In this paper, we demonstrate the capabilities of 380‐nm ultraviolet (UV) light‐emitting diodes (LEDs) using metal organic chemical vapor deposition. The epi‐structure of these LEDs consists of InGaN/AlGaN multiple quantum wells on a patterned sapphire substrate, and the devices are fabricated using a conventional LED process. The LEDs are packaged with a type of surface mount device with Al‐metal. A UV LED can emit light at 383.3 nm, and its maximum output power is 118.4 mW at 350 mA.     

Performance and reliability of InGaAsP superluminescent diode

The performance and reliability of a 1.3-μm superluminescent diode (SLD) with a novel structure are reported. A window structure with a tapered active layer is applied to suppress lasing oscillation. A V-groove structure is introduced to achieve high coupling efficiency into a single-mode fiber. The design of optimized device dimensions allows SLD operation to be obtained even at 0°C. 1.3 mW is coupled into a single-mode fiber at 150 mA and 25°C. The spectral modulation depth is 15% over the entire emission spectral width of 32 nm. The operating life of a SLD has been estimated from the results of accelerated aging carried out for 5000 h at the ambient temperatures of 50 and 125°C. The activation energy of degradation is estimated to be 0.58 eV, and the extrapolated life is 10⁶ h at an ambient temperature of 25°C     

Single-spatial-mode semiconductor VCSELs with a nonplanar upper dielectric DBR

Single-spatial-mode semiconductor vertical-cavity surface-emitting lasers (VCSELs) with a non-planar upper (output) dielectric distributed Bragg reflector (DBR) for the 850 nm spectral region are fabricated. The suggested design provides stable single-mode generation in the entire range of working currents, limited by overheating of the active region. Devices with intracavity contacts and a comparatively large current-aperture diameter (5–6 μm) exhibit single-mode lasing at a wavelength of 840–845 nm in the continuous-wave mode at room temperature with threshold currents of 1.2–1.3 mA, a differential efficiency of 0.5–0.55 mW mA^?1, and anoutput power of up to 2 mW.     

1.55-/spl mu/m DFB lasers utilizing an automatically buried absorptive InAsP layer having a high single-mode yield

We describe 1.55-/spl mu/m distributed feedback laser diodes (DFB LDs) having a single-mode (SM) yield as high as 80% and 93% for as-cleaved and antireflection/high reflection (AR/HR=3%/95%) coated devices, respectively. The high SM yield was achieved by introducing an automatically buried InAsP layer between a concave of InP corrugations and an overgrown layer. The use of the automatically buried InAsP layer implemented by a single step growth makes the device fabrication process much easier than that of conventional loss-coupled DFB LDs. Fabricated DFB LDs with AR/HR-coated facets showed a low threshold current of 8 mA (34 mA) and a high slope efficiency of 0.32 mW/mA (0.22 mW/mA) at 25/spl deg/C (85/spl deg/C). A sidemode suppression ratio better than 40 dB was obtained for the temperature range between -20/spl deg/C and 85/spl deg/C and the injection current range between 20 and 100 mA.     

Design and fabrication of temperature-insensitive InGaP-InGaAlP resonant-cavity light-emitting diodes

Visible InGaP-InGaAlP resonant-cavity light-emitting diodes with low-temperature sensitivity output characteristics were demonstrated. By means of widening the resonant cavity to a thickness of three wavelength (3/spl lambda/), the degree of power variation between 25 /spl deg/C and 95 /spl deg/C for the devices biased at 20 mA was apparently reduced from -2.1 dB for the standard structure design (1-/spl lambda/ cavity) to -0.6 dB. An output power of 2.4 mW was achieved at 70 mA. The external quantum efficiency achieved a maximum of 3% at 13 mA and dropped slowly with increased current for the device. The external quantum efficiency at 20mA dropped only 14% with elevated temperature from 25 /spl deg/C to 95/spl deg/C. The current dependent far-field patterns also showed that the emission always took place perfectly in the normal direction, which was suitable for plastic fiber data transmission.     

2.05-μm wavelength InGaAs-InGaAs distributed-feedbackmultiquantum-well lasers with 10-mW output power

Single-mode operation beyond 2.05-μm wavelength has been achieved in InGaAs-InGaAs distributed-feedback (DFB) laser with four quantum wells. The continuous-wave output power is 10.5 mW at a drive current of 200 mA and 25°C, The tuning range of the wavelength is between 2.051-2.056 μm with a temperature tuning rate of +0.125 nm/°C     

1.95-μm strained InGaAs-InGaAsP-InP distributed-feedbackquantum-well lasers

Distributed-feedback emission from strained InGaAs-InGaAsP-InP quantum well lasers has been examined over a temperature range of 130 K to 300 K. Continuous single-mode output from 190 to 300 K with a side-mode-suppression ratio of about 10 dB was observed. The wavelength was 1.95 μm at 273 K and tuned at a rate of 0.13 nm/K. The current-tuning rate was 0.0043 nm/mA (-340 MHz/mA) at 273 and 283 K     

Widely tunable 850-nm metal-filled asymmetric cladding distributed Bragg reflector lasers

Broadly tunable distributed Bragg reflector (DBR) lasers utilizing metal-filled surface-etched diffraction gratings were fabricated on a GaAs-unstrained quantum well with AlGaAs core and cladding layers. Devices with 200- and 400-/spl mu/m gratings sections were fabricated. Single-mode devices are fabricated over a broad spectral range, exhibiting over 55 mW of single-facet output power. The optical properties of this structure are analyzed in terms of effective index step between the peak and valley of the grating and scattering loss in the DBR. Discrete devices were fabricated with lasing wavelengths between 846.6 and 862.9 nm at intervals of 1.44nm, representing a range of 16.3 nm. Wavelength tuning by current injection into the DBR section is explored, and a broad tuning range of over 18 nm is measured while single-mode performance is maintained. The spectral linewidth of these devices is measured. The temperature dependence of light versus current, threshold current values, and spectral characteristics are also examined.     

Room-temperature continuous-wave operation of type-I GaSb-based lasers at 3.1 μm

Type-I interband lasers on GaSb were grown by molecular beam epitaxy using 16 nm InGaAsSb compressively-strained quantum wells (QWs) with 30 nm AlInGaAsSb quinary barriers for improved hole confinement. The 3QW active regions were embedded in standard AlGaAsSb waveguides to limit the thickness of quinary material owing to its low growth temperature requirements. In continuous-wave operation, a typical ridge waveguide laser (width 10 mum, length 1214 mum) produced 6 mW total output power at 20degC with a threshold current of 140 mA. The temperature sensitivity of the devices remains a challenge, as evidenced by the dramatically improved performance at 0degC (16 mW total output power, threshold current 74 mA).