Richard P. Mirin

Detecting single infrared photons with 93% system efficiency

Researchers develop a fiber-coupled single-photon-detection system using amorphous tungsten silicide superconducting nanowire single-photon detectors. The system detection efficiency is higher than 90% in the wavelength range between 1520 nm and 1610 nm. The device dark-count rate, timing jitter and reset time are 1 cps, 150 ps and 40 ns, respectively.

Observing the Average Trajectories of Single Photons in a Two-Slit Interferometer

An experiment determined the trajectories of single photons through a two-slit interferometer. A consequence of the quantum mechanical uncertainty principle is that one may not discuss the path or “trajectory” that a quantum particle takes, because any measurement of position irrevocably disturbs the momentum, and vice versa. Using weak measurements, however, it is possible to operationally define a set of trajectories for an ensemble of quantum particles. We sent single photons emitted by a quantum dot through a double-slit interferometer and reconstructed these trajectories by performing a weak measurement of the photon momentum, postselected according to the result of a strong measurement of photon position in a series of planes. The results provide an observationally grounded description of the propagation of subensembles of quantum particles in a two-slit interferometer.

Strong Loophole-Free Test of Local Realism

We performed an loophole-free test of Bells inequalities. The probability that local realism is compatible with our results is less than 5.9×10^-9.

1.3 μm photoluminescence from InGaAs quantum dots on GaAs

We use molecular beam epitaxy to grown coherently strained InGaAs islands on (100) GaAs substrates. The islands show room‐temperature photoluminescence at 1.3 μm with a full width at half‐maximum of only 28 meV. The integrated photoluminescence intensity is comparable to that of a quantum well. The islands are formed by depositing 22 monolayers of In0.3Ga0.7As with alternating beams of In, Ga, and As2. Atomic force microscopy measurements show that the islands are ellipsoidal sections with an average peak height of 24 nm. The intersection of the islands with the (100) plane is an ellipse whose major axis is along [011] and has a mean length of 54 nm, and whose minor axis is along [011] and has a mean length of 36 nm. The islands form a dense array with an areal coverage of about 40%.

Room-temperature continuous-wave operation of 1.54-μm vertical-cavity lasers

We report on the room-temperature continuous-wave operation of vertical-cavity lasers operating at 1.54 /spl mu/m. The devices use a 7 strain-compensated quantum-well active layer sandwiched between two Al(Ga)As-GaAs quarter-wave mirrors joined by wafer fusion. Five device sizes between 8 and 20 /spl mu/m were found to operate continuously at room temperature (23/spl deg/C), The lowest room-temperature continuous-wave threshold current of 2.3 mA was measured on an 8-/spl mu/m diameter device, while the highest continuous-wave operating temperature of 33/spl deg/C was measured on a 12-/spl mu/m device.<<ETX>>

LOW THRESHOLD, WAFER FUSED LONG WAVELENGTH VERTICAL CAVITY LASERS

We demonstrate electrically injected InGaAsP (1.3 μm) vertical cavity lasers (VCLs) fabricated on GaAs substrates and employing GaAs/AlAs mirrors. The technique of wafer fusion allows for integration of GaAs/AlAs mirrors with InP double heterostructures without degradation of device performance, despite a 3.7% lattice mismatch between the wafers. The wafer fused VCLs have the lowest threshold current (9 mA) and lowest threshold current density (9.5 kA/cm2) and the highest characteristic temperature (T0=67 K) reported to date of any room‐temperature long wavelength VCL.

Travelling-wave photodetectors with 172-GHz bandwidth and 76-GHz bandwidth-efficiency product

Results of the first fabrication and measurement of travelling-wave photodetectors are reported. The devices have bandwidths as high as 172 GHz, the highest reported for a p-i-n photodetector, and bandwidth-efficiency products as large as 76 GHz, the largest reported for any photodetector without gain. Comparisons with vertically illuminated and waveguide photodetectors fabricated on the same wafer establish the superior performance of travelling-wave photodetectors. Microwave loss on the travelling-wave photodetector structure is identified as a bandwidth limitation.<<ETX>>

64/spl deg/C continuous-wave operation of 1.5-/spl mu/m vertical-cavity laser

We report on 64/spl deg/C continuous-wave (CW) operation of a 1.5-/spl mu/m vertical-cavity laser. This laser consists of two fused AlGaAs-GaAs mirrors with a strain-compensated InGaAsP-InP MQW active region. Selective lateral oxidation is used for current confinement. Minimum room-temperature threshold current is as low as 0.8 mA, and maximum CW output power is as high as 1 mW at 15/spl deg/C. Pulsed operation is achieved up to 100/spl deg/C. Current spreading losses and device heating are analyzed in detail. Dynamic parameters such as maximum 3-dB parameters such as maximum, 3-dB bandwidth (4.7 GHz), alpha factor (4.0), and linewidth (39 MHz) are also investigated.

Design and analysis of double-fused 1.55-/spl mu/m vertical-cavity lasers

Detailed design and experimental characterization of three generations of double-fused vertical-cavity lasers are described. The result of this design evolution is the first above-room-temperature continuous-wave operation of long-wavelength vertical-cavity lasers. Threshold currents of 2.3 mA and yields greater than 90% have been obtained.

Double‐fused 1.52‐μm vertical‐cavity lasers

We demonstrate a novel long‐wavelength vertical‐cavity laser structure employing two AlAs/GaAs mirrors and a strain‐compensated InGaAsP quantum‐well active region. The lasers have been fabricated by wafer fusion and have the lowest room‐temperature pulsed threshold current density of 3 kA/ cm2 at 1.52 μm. Eight laser sizes ranging from 9 to 60 μm were fabricated with threshold currents as low as 12 mA. Single transverse mode operation was observed on the 9 μm device, while other devices lased multimode. The maximum pulsed output power was 7 mW.