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We report an experimental observation of a blue shift in the n=1 heavy-hole exciton line of In0.53Ga0.47As/InP multiple quantum wells resulting from a picosecond photoexcitation in the transparent spectral region. The temporal response of this shift follows the excitation and it is attributed to the optical Stark effect. The shift was measured to be 0.19 meV for an incident light with a photon energy 20 meV below the exciton peak and with a 10-MW/cm2 intensity. [ABSTRACT FROM AUTHOR]

Near-band-gap optical nonlinearity in In0.53Ga0.47As/InP multiple quantum well (MQW) structures is studied by a combination of nonlinear absorption, pump-and-probe, and forward degenerate four-wave mixing experiments. Near complete saturation of the n=1 heavy-hole exciton is observed for the first time in In0.53Ga0.47As/InP MQW structures. Nonlinear susceptibility χ(3) is found to be 0.08 esu, which is about the same as that for GaAs/GaAlAs MQW structures. Saturation intensity is 200 W/cm2. [ABSTRACT FROM AUTHOR]

We have constructed all-optical logic étalons operating in the 1.55-μm wavelength region using InGaAs/InP multiple quantum well (MQW) structures. These étalons have low-energy requirements with several nanosecond recovery times, exhibit high on/off contrast (>20:1 if desired) with large on-state transmission (>40%), and have signal gain, thus making them possible to cascade. For example, we have performed gating using 6 pJ input energy with 5:1 contrast and gain about 2 at 100 MHz operating frequency. These étalons also show optical bistability. The nonlinear coefficients for the InGaAs/InP MQW’s deduced from experimental results are found to be on the same order as those for GaAs/GaAlAs MQW’s. [ABSTRACT FROM AUTHOR]

We report the generation of 0.5 ps full width at half-maximum optical pulses at >0.3 THz (tunable) repetition rate via an induced modulational instability in a single-mode fiber. A 1.319-μm neodymium:yttrium aluminum garnet laser is chosen as the carrier wave and the initial modulation on this carrier is introduced by mixing it with an external-grating-cavity InGaAsP laser. The use of this all-optical modulating scheme and the nonlinear optical propagation effect in fiber (i.e., modulational instability) allows one to reach into the terahertz regime, which is about two orders of magnitude beyond the fastest data limited by the finite response of electronics. [ABSTRACT FROM AUTHOR]

We report the first demonstration of two-stage optical fiber pulse compression using the grating pair technique and, successively, the soliton effect. Firstly, 100 ps pulses from a 1.319-μm mode-locked neodymium:yttrium aluminum garnet laser are chirped by a 2-km positive dispersion fiber (zero-dispersion wavelength λ0=1.59 μm) and compressed into 2 ps pulses by a grating pair. Subsequently, the resultant 2 ps pulses are coupled into a 40-m negative dispersion fiber (λ0=1.275 μm) and compressed further into 90 fs pulses via the pulse narrowing effect of high-order soliton propagation. The combined compression factor of 1100 is the largest reported to date using optical fibers. [ABSTRACT FROM AUTHOR]

We report a 50-fold fiber-grating pulse compression in the near-infrared region. 100 ps (FWHM) pulses from a mode-locked neodymium:yttrium aluminum garnet laser operated at 1.319 μm have been compressed into 2 ps pulses by using a 2-km dispersion-shifted fiber and a grating pair separated by 2.41 m in a double-pass configuration. The novel feature of this demonstration is the use of dispersion-shifted fiber (zero-dispersion wavelength at 1.59 μm) for producing a linear chirp over most of the pulse and, thus, almost all the input power appears in the compressed pulse. [ABSTRACT FROM AUTHOR]

Examines the chemical-beam epitaxial (CBE) growth of InP/InGaAsP Bragg mirrors around 1.55 micrometer wavelength region. Achievement of mirrors with nearly 100% reflectivity; Obtainment of a layer thickness uniformity in horizontal and vertical directions; Capability of CBE in maintaining uniformity of InP/InGaAsP.

Room-temperature continuous-wave oscillation with an emission power in excess of 1 mW was achieved in vertical-cavity surface-emitting lasers containing a 0.5-μm-thick GaAs active layer sandwiched between a distributed Bragg reflector (DBR) and a hybrid metal DBR. The devices have a cw threshold current of 40 mA in 15-μm-diam size and a T0 of 115 K. Fiber butt coupling and pseudorandom data modulation of these lasers with open eyes up to 500 Mbit/s were demonstrated. [ABSTRACT FROM AUTHOR]

We report room-temperature lasing at 0.94–1.002 μm in high-finesse Fabry– Perot resonators with Inx Ga1-x As/GaAs multiple quantum well active layers (x=0.18–0.2). The quantum wells and AlAs/GaAs quarter-wave stack mirrors were epitaxially grown on GaAs substrates. Optically pumping with 0.875 μm, 10 ps pulses yielded a threshold of 15 pJ incident pulse energy. The equivalent threshold current density is about 26 μA/μm2 (2.6 kA/cm2 ), suggesting ultralow thresholds in micrometer-size devices. At the lasing wavelengths the GaAs substrates are essentially transparent allowing the possibility of integrating micro-optic lenslets on the substrate backsides for light collection. Nonlinear optical gating of 1.064 μm light was also achieved in these structures. [ABSTRACT FROM AUTHOR]

Intense single-peak photoluminescences of free-exciton origin were observed in InxGa1-x As/GaAs strained-layer quantum wells with x ranging from 0.09 to 0.20. Band lineups in these strained-layer heterostructures were determined by the dependence of luminescence energy on the well thickness. The heterojunction discontinuity in the heavy hole valence bands was found to be about 30% of the gap difference and independent of x. Exciton-phonon coupling was determined by temperature-dependent absorption measurements and the coupling strength was found to be similar to that of unstrained GaAs/AlxGa1-x As quantum wells. [ABSTRACT FROM AUTHOR]

Optically pumped lasers emitting near 600 nm at room temperature have been fabricated for the first time in Cd0.25Zn0.75Te/ZnTe superlattices grown on GaAs substrates. The threshold pump intensity using pulsed 0.53 μm radiation increased from ∼7 kW/cm at 10 K to ∼60 kW/cm2 at room temperature with a threshold temperature dependence described by T0∼111 K. [ABSTRACT FROM AUTHOR]

A new technique using single-mode fibers as spatial filters for probing carrier dynamics such as diffusion and recombination is introduced. Diffusion coefficients of 5.5 and 5 cm2/s are obtained for optically excited electron-hole plasmas in a 1.9-μm-thick In0.6Ga0.4As0.85P0.15 bulk layer and in an In0.53Ga0.47As/InP quantum well sample with well thickness of 100 Å, respectively. [ABSTRACT FROM AUTHOR]

Examines the epitaxial growth of strained-layer InGaAs/InGaAsP multiquantum well distributed feedback (DFB) laser. Location of the DFB laser in the multiquantum well; Exhibition of defect-free indium phosphide regrowth; Operation of the buried-hererostructures 6-quantum well DFB lasers.

We have achieved room-temperature pulsed and cw lasing at 980 nm in an optically pumped vertical cavity structure grown by molecular beam epitaxy containing only a single quantum well (SQW) of In0.2Ga0.8As. Limited gain due to the extremely short active material length of 80 Å implies that losses due to absorption, scattering, and mirror transmission are extremely low. Using 10 ps pump pulses at 860 or 880 nm, the estimated energy density absorbed in the spacer was ∼12 fJ/μm2 at threshold, indicating a carrier density approximately four times that required for transparency. Continuous wave pumping yielded an estimated threshold absorbed intensity of ∼7 μW/μm2. [ABSTRACT FROM AUTHOR]

Superlattices of Ga0.47In0.53As/InP grown by chemical beam epitaxy (CBE) were studied in detail by transmission electron microscopy, absorption, photoluminescence (PL), photoluminescence excitation (PLE), and photocurrent (PC) spectroscopies. Results from all these characterization techniques independently confirmed the superior qualities of the CBE-grown Ga0.47In0.53As/InP superlattices over previously reported results. Photoluminescence linewidths were close to those obtained from CBE-grown single quantum wells. All of the observed excitonic absorption peaks in absorption, PLE, and PC spectra were well resolved and clearly assigned including the forbidden E13h transition for the first time. In fact, these excitonic structures were still observed in the PC spectra at temperatures as high as 102 °C. [ABSTRACT FROM AUTHOR]

Alterable temperature-dependent emission wavelength shifts were observed from (InP)[sub 2]/(GaP)[sub 2] short-period superlattices (SPSs) quantum wells grown with different interruption periods. Photoluminescence spectra showed that the peak energy of the SPS samples is inversely proportional to the interruption time conducted between the two consecutive binary growth sequences in the SPS regions. It is believed that a lateral composition modulation occurred during the interruption period which resulted in periodic In-rich and Ga-rich regions in the SPS quantum wells along the growth plane. With the lateral compositional variation, temperature variation can induce a multiaxial strain effect which can either amplify or reduce the temperature-dependent wavelength shift of the SPS quantum wells with different interruption periods. © 1998 American Institute of Physics. [ABSTRACT FROM AUTHOR]