Edgard Goobar

Single quantum dots emit single photons at a time : Antibunching experiments

We have studied the photoluminescence correlation from a single InAs/GaAs self-assembled Stranski–Krastanow quantum dot under continuous, as well as under pulsed excitation. Under weak continuous excitation, where the single dot luminescence is due primarily to single exciton recombinations, antibunching is observed in the single dot emission correlation. Under weak pulsed excitation, the number of photons emitted by the quantum dot per pulse is close to one. We present data obtained under both conditions and are able to show that devices based on single quantum dots can be used to generate single photons.

Relative intensity noise and linewidth measurements of a widely tunable GCSR laser

The intensity and frequency noise of a grating assisted codirectional coupler with rear sampled grating reflector laser with 40-nm tuning range and 35-dB sidemode suppression ratio (SMSR) have been measured. The linewidth varies from 430 kHz to 4 MHz as a function of tuning. The resonance frequency, intrinsic bandwidth and damping factor for this device were extracted from the relative intensity noise (RIN) measurements. At high bias, the RIN is -150 dB/Hz and the maximum resonance frequency is 4.5 GHz.

Experimental demonstration of the relative phase operator

We have experimentally demonstrated a realization of the two-mode relative phase operator introduced by Luis and Sanchez-Soto (Luis A and Sanchez-Soto L L 1993 Phys. Rev. A 48 4702). The relative phase distribution function was measured for a weakly excited relative phase eigenstate and weakly excited two-mode coherent states. The experiment is also (using the eigenstates) a demonstration of Heisenberg-limited interferometry.

Amplitude and frequency modulation characteristics of widely tunable GCSR lasers

The amplitude (AM) and frequency (FM) modulation responses of a grating assisted codirectional coupler with rear sampled grating reflector laser were measured over a 40-nm tuning range. The extracted modulation bandwidth varied between 3 and 4 GHz and parameters as parasitic cutoff, maximum relaxation frequency and K-factor were extracted from curve fittings to the AM response. The frequency modulation measurements revealed low chirp despite the large tunability of the device. The linewidth enhancement factor was calculated from the AM and FM measurements. The values ranges from three to nine for ten different operating wavelengths.

LOW NOISE PHOTON NUMBER MANIPULATION USING SEMICONDUCTOR LIGHT EMITTERS AND RECEIVERS

The photon number (intensity) of a light beam can be read out and amplified essentially without adding any noise. In this article we will describe recent proof-of-principle experiments using simple optoelectronic circuits. We also discuss the significance of these results with respects to applications in communication and quantum optics. The relation to quantum non-demolition measurement (QND) strategies is also discussed.

Studies of self-assembled InP quantum dots in planar microcavities

Abstract Self-assembled InP quantum dots have been grown in planar microcavities. The dots were embedded in a Ga 0.52 In 0.48 P spacer grown on top of a high reflectance epitaxial Al 0.29 Ga 0.71 As/AlAs distributed Bragg reflector (DBR) to obtain a 3λ/4 cavity. The Fabry–Perot microcavity is formed between the AlGaAs/AlAs DBR and a dielectric SiN x /SiO 2 DBR deposited on top of the GaInP spacer. The quantum dot emission is centered at 1.62 eV at 7 K. The microcavity resonance is centered at 1.65 eV, with a linewidth of 2 meV. Micro-photoluminescence (PL) studies using different objectives with different numerical apertures enable the collection of transversal modes.

High performance narrow linewidth thermally tuned semiconductor laser

A high performance narrow linewidth tunable semiconductor laser, with a novel airgap process is presented. Total tuning power less than 100mW is achieved for the whole C-band. Spectral linewidth between 80 and 120 kHz, and SMSR >49dB are also shown.

High speed modulation characteristics of long wavelength vertical cavity lasers based on an integrated InP Bragg reflector

The high-speed performance of 1.55 /spl mu/m GaInAsP MQW vertical cavity lasers based on a 50-period GaInAsP-InP bottom mirror operating continuous-wave at low temperature is presented. The maximum small-signal modulation bandwidth was limited by parasitics to 3.4 GHz.

Low-noise optoelectronic photon number amplifier and quantum-optical tap

The properties of a photon number amplifier and quantum-optical tap have been experimentally investigated. The device consists of a high-quantum-efficiency photodetector that drives eight series-coupled light emitters. The light from the series-coupled emitters is detected by parallel coupled photodetectors, which drive a new light emitter. It is shown that the light reaching the first photodetector can be measured, amplified by the series-coupled emitters, and regenerated by means of the last emitter without the introduction of significant noise. Hence the input light can be quantum correlated with the amplified photocurrent as well as with the output light.

Measurement of amplitude and frequency modulation responses of widely tunable GCSR lasers

The amplitude and frequency modulation responses of a grating assisted codirectional coupler (GCSR) semiconductor laser were measured over 40 nm tuning range. The extracted modulation bandwidth varied between 3 and 4 GHz and the linewidth enhancement factors range from 3 to 9.