1.5 μm InP/GaInAsP linear laser array with twelve individuallyaddressable elements

Linear arrays of twelve individually addressable InP/GaInAsP channelled-substrate buried-heterostructure lasers emitting at λ=1.5 μm were fabricated. Spacing between active elements (250 μm) was made to match the fibre spacing in a 12-fibre ribbon. Individual arrays were epoxy bonded, p-side up to metallised BeO carriers. Best case uniformity of laser characteristics within an array is indicated by tight distributions of lasing threshold (9.8±0.9 mA at 30°C) and output powers of (8.6±0.4 mW at 100 mA). While no significant optical crosstalk could be detected, small increases (≃10%) in device lasing thresholds were observed when two adjacent elements were operated CW simultaneously, probably due to the thermal impedance of the epoxy-bond employed and the resultant heating of operating nearest-neighbour devices. Such arrays offer the potential for reduced fibre alignment time per element thus reducing packaging costs per source. In addition, reduced space requirement per source is realised     

Room temperature pulsed operation of 1.5 μm GaInAsP/InPvertical-cavity surface-emitting laser

Room-temperature pulsed operation of a GaInAsP/InP vertical-cavity surface-emitting laser diode (VCSELD) with an emission wavelength near 1.55 μm is reported. A double heterostructure with a 34-pair GaInAsP (λ_g=1.4 μm)/InP distributed Bragg reflector (DBR) was grown by metalorganic chemical vapor deposition (MOCVD). The measured reflectivity of the semiconductor DBR is over 97% and threshold current is 260 mA for a 40-μmφ device with a 0.88-μm-thick active layer. Threshold current density is as low as 21 kA/cm² at room temperature     

A GaInAsP/InP tapered-waveguide semiconductor laser amplifierintegrated with a 1.5 μm distributed feedback laser

A GaInAsP/InP index-guided type tapered-waveguide traveling-wave semiconductor laser amplifier (TTW-SLA) with exponential taper structure was realized for the first time and its integration with a 1.5 μm wavelength phase adjusted DFB laser was demonstrated. A reasonable amount of the single-pass gain, which was limited by the residual reflectivity at the output end of the amplifier region, was obtained with no serious problem with the lasing spectrum. A narrow beam divergence of FWHM=5.5° and stable longitudinal mode operation were obtained with the output waveguide width of 20 μm by adopting both a window structure and 7° angled facets. This value agrees well with the theoretically calculated one and proves that single transverse-mode propagation can be attained by an exponentially tapered TTW-SLA with a very wide output end     

1.5 μm GaInAsP/InP distributed reflector (DR) lasers with SCHstructure

The large differential quantum efficiency η_df with one-directional output operation obtained in 1.5-μm distributed reflector (DR) lasers using a thin active layer of 50 nm and the separate-confinement heterostructure (SCH) structure is discussed. η _df of the DR laser was experimentally determined to be twice that of distributed-feedback (DFB) lasers cleaved from the same wafer, which indicates high efficiency and high power characteristics of DR lasers     

CW operation of 1.5 ?m GaInAsP/InP buried-heterostructure laser with a reactive-ion-etched facet

The reactive-ion-etching technique in forming facet mirrors for 1.5 ?m GaInAs/InP buried-heterostructure (BH) lasers is reported. Room-temperature CW operation has been achieved with BH lasers having one of the facets formed by RIE and metallic coating and the other by cleaving. The laser with 330 ?m long cavity has a 110 mA threshold.     

Narrow spectral linewidth 1.5 μm GaInAsP/InP distributed Braggreflector (DBR) lasers

The spectral linewidth of distributed Bragg reflector (DBR) lasers is discussed. The narrowest linewidth of 3.2 MHz was obtained at P =1.5 mW. It was found that narrow spectral linewidths can be obtained constantly for the DBR lasers with long and low optical loss corrugation regions, and with a small coupling coefficient. These results are explained by the external cavity model, which is used in the theoretical analysis. To increase the output power of the narrow-linewidth DBR lasers, AR (antireflection) coating was applied to the output facet. Improved quantum efficiency and submode suppression were achieved. Degradation of the linewidths by the AR coating was insignificant     

1.5 μm GaInAsP angled-facet flared-waveguide traveling-wavelaser amplifiers

A broadband laser amplifier requires extremely low facet reflectivity (<0.1%). Previously, a low effective facet reflectivity of 0.05% was realized by an angle-facet structure in the 1.3-μm wavelength band. Present work reports an improved structure for the 1.5-μm wavelength band by flaring the waveguide ends near the angled facets. With a conventional antireflection coating of ~1% reflectivity, the measured effective facet reflectivity is less than 0.01% and the resultant devices have a fiber-to-fiber gain of 15 dB centered at 1.49 μm     

Low threshold operation of 1.55 μm GaInAsP/InP DFB-BH LDsentirely grown by MOVPE on InP gratings

1.55 μm GaInAsP/InP DFB-BH LDs on corrugated InP substrates were fabricated by only two-stage MOVPE including burying layer growth. The 9 mA minimum threshold current was achieved with both facets cleaved, which the authors believe is the lowest among MOVPE grown DFB LDs with InP grating. Up to 20 mW maximum output power and 0.21 W/A differential quantum efficiency were also attained under single longitudinal mode operation     

AlGaInAs/InP 1.5 μm MQW DFB laser diodes exceeding 20 GHzbandwidth

Buried mushroom multiquantum well DFB laser diodes with compressively strained GaInAs quantum wells and asymmetric confinement layer design are fabricated with a combined MBE/MOCVD technology. Packaged devices exhibit high -3 dB IM bandwidths for very low bias levels and a record bandwidth for this material system of 21 GHz     

Very low threshold operation of 1.52 μm GaInAsP/InP DFB buriedridge structure laser diodes entirely grown by MOCVD

1.52 μm GaInAsP/InP DFB laser diodes with a buried ridge structure were fabricated entirely by MOCVD, with a second-order corrugation on the GaInAsP guiding layer. The 5 mA minimum threshold current achieved is believed to be the lowest yet reported for DFB lasers. Single longitudinal-mode operation with a side-mode suppression ratio greater than 35 dB was obtained from 20°C (up to 16 mW) to 90°C (up to 3 mW)     

Bistable operation of 0.8 μm GaInAsP/GaAs lasers

Quaternary GaInAsP prepared on GaAs is a very promising material for optoelectronic devices in alternating AlGaAs/GaAs systems. The authors report bistable operation in stripe geometry GaInAsP/GaAs DH lasers with gain region and absorbing region in the laser resonator. A hysteresis loop is observed in the I/L curve under pulsed operation at room temperature     

High output power GaInAsP/InP superluminescent diode at 1.3 μm

The authors have developed a 1.3 μm superluminescent diode using a revolutionary structure. A light diffusion surface is placed diagonally on the active layer within the device to suppress the lasing action. Superluminescent diode characteristics were achieved in the range 0-50°C, and the coupled power into a single-mode fibre reached 1 mW     

CW operation of DFB-BH GaInAsP/InP lasers in 1.5 ?m wavelength region

Distributed-feedback buried heterostructure (DFB-BH) GaInAsP/InP lasers in the 1.5 ?m wavelength region have been operated continuously at heat-sink temperatures as high as 310 K. A threshold current of 55 mA at 300 K and single longitudinal mode operation have been obtained.     

Extremely high power 1.48 μm GaInAsP/InP GRIN-SCH strained MQWlasers

A record CW output power of 360 mW at 25°C was achieved by investigating the structure of optical confinement layer in 1.48 μm GRIN-SCH MQW lasers. It is experimentally demonstrated that the use of a wide bandgap and thin SCH layer gives a high differential quantum efficiency without expense of threshold current. Low driving currents, 195 mA for 100 mW, 450 mA for 200 mW and 890 mA for 300 mW, were obtained in the optimized cavity lengths     

Extremely low threshold operation of 1.5 mu m GaInAsP/InP buried ridge stripe lasers

1.5 mu m Fabry-Perot lasers exhibiting extremely low threshold currents have been obtained with a buried ridge stripe (BRS) structure. Threshold currents are 5.7 and 15.5 mA for 300 mu m and 1 mm cavity lengths, respectively, in CW operation. The optical losses of the buried waveguide have been determined from the external quantum efficiency dependence with cavity length.<>     

CW operation of 1.5 ~ 1.6 ?m wavelength GaInAsP/InP buried-heterostructure integrated twin-guide laser with distributed Bragg reflector

A 1.5 ~ 1.6 ?m GaInAsP/InP buried-heterostructure integrated twin-guide laser with distributed Bragg reflector (BH-DBR-ITG laser) was realised, for the first time, and CW operation was achieved up to 255 K. Single-wavelength operation was obtained at temperatures between 228 K and 245 K with the temperature dependence of lasing wavelength of 10 ?/deg. At 233 K, the threshold current, the output power and the differential quantum efficiency were 110 mA, 2.2 mW and 4.8%/facet, respectively.     

1.5 ?m room-temperature pulsed operation of GaInAsP/InP double heterostructure grown by LP MOCVD

The letter reports the first successful room-temperature pulsed operation of a broad-area contact laser of GaInAsP/InP double heterostructure, grown by LP MOCVD, emitting at 1.5 ?m. Pulsed thresholds as low as 2.5 kA/cm2 have been obtained for 1.5 ?m, for an active layer thickness of 0.48 ?m. This is equal to a current density per micrometre of 5.2 kA cm?2 ?m?1. InxGa1?xAsyP1?y, III, III, V, V alloys are of great interest for use in infra-red devices. They can be grown lattice matched on InP over a wide range of compositions. The resulting bandgap (1.35?0.75 eV) covers a spectral range which contains the region of lowest losses and lowest dispersion in modern optical fibres. This property makes In1?xGaxASyP1?y, very attractive as a semiconductor laser and detector material for future fibre communication systems.     

Low-threshold-current CW operation of 1.5 ?m GaInAsP/InP bundle-integrated-guide distributed-Bragg-reflector (BIG-DBR) lasers

Low-threshold-current and high-power operation of 1.5 ?m GaInAsP/InP bundle-integrated-guide (BIG) DBR lasers were obtained. A single-mode operation temperature range of more than 70 deg was demonstrated around room temperature by shortening the active region to 100 ?m. The modulation characteristic was measured up to 2 GHz with a modulation depth of 100%. A maximum value of dynamic wavelength shift was 2 ? at 1.2 times threshold current.     

Tunable absolute-frequency laser at 1.5 μm

Frequency stabilisation of a two-frequency diode-pumped Er,Yb:glass laser is demonstrated using Doppler-broadened or saturated-absorption lines of ¹³C₂H₂. Continuous tunability in the 1530-1550 nm range is obtained. Beat note measurements lead to a frequency accuracy better than 10 kHz for a 10s response time     

Narrow-band vertically stacked filters in InGaAlAs/InP at 1.5 μm

A narrow-band wavelength filter in InGaAlAs/InP has been modeled, fabricated, and tested. A highly asymmetrical, vertically coupled directional coupler operating near the band-edge is formed by a narrow ridge and a wide strip-loaded waveguide. The results of numerical simulation, performed by employing the spectral index method, effective-index method, and a modified coupled-mode theory, are used to fabricate a filter structure with a prescribed filter response. Operation at a center wavelength around 1.5 μm with a bandwidth of 18 Å and transfer efficiency of ~46-68% is achieved. Excellent agreement between the. Designed and measured bandwidth is demonstrated. A multichannel filter device based on an array of individual filters that is capable of extending the usable spectral range is analyzed