We present squeezing and anti-squeezing spectra of the output from a degenerate optical parametric oscillator (OPO) network arranged in different coherent quantum feedback configurations. One OPO serves as a quantum plant, the other as a quantum controller. The addition of coherent feedback enables shaping of the output squeezing spectrum of the plant, and is found to be capable of pushing the frequency of maximum squeezing away from the optical driving frequency and broadening the spectrum over a wider frequency band. The experimental results are in excellent agreement with the developed theory, and illustrate the use of coherent quantum feedback to engineer the quantum-optical properties of the plant OPO output.

We report high performance infrared sensors that are based on intersubband transitions in nanoscale self-assembled quantum dots combined with a microcavity resonator made with a high-index-contrast two-dimensional photonic crystal. The addition of the photonic crystal cavity increases the photocurrent, conversion efficiency, and the signal to noise ratio ͑represented by the specific detectivity D * ͒ by more than an order of magnitude. The conversion efficiency of the detector at V b = −2.6 V increased from 7.5% for the control sample to 95% in the PhC detector. In principle, these photonic crystal resonators are technology agnostic and can be directly integrated into the manufacturing of present day infrared sensors using existing lithographic tools in the fabrication facility. © 2006 American Institute of Physics. ͓DOI: 10.1063/1.2194167͔ Infrared sensors in the wavelength range of 3 -25 m are of immense technological importance due to their application in medical diagnostics, fire-fighting equipment, and night vision systems. Quantum dot infrared photodetectors have been identified as an emerging technology for this wavelength regime due to their low dark current leading to a potentially higher operating temperature and normal incidence operation based on a mature GaAs technology. [1][2][3][4][5] Presently, high performance midinfrared detectors are based on mercury cadmium telluride ͑MCT͒. Due to a dramatic change of the band gap as a function of material composition, it is very challenging to reproducibly obtain large area homogeneous materials suitable for large area focal plane arrays ͑FPA͒ based on this material system. In contrast, mature materials growth technologies for III-V semiconductors can provide very accurate control of compositions and homogeneity. Therefore there is interest in developing IR photodetectors using III-V materials. One of the most promising III-V semiconductor long wavelenght infrared ͑LWIR͒ detectors is the quantum well infrared photodetector ͑QWIP͒, 6-9 which employs the intersubband or the subbandto-continuum transitions in quantum wells. One of the drawbacks of n-type QWIPs is that they cannot detect normally incident light due to the restriction of selection rules for the optical transition. In contrast, the intersubband optical transitions in quantum dots ͑QDs͒ do not have that restriction, due to the three-dimensional quantum confinement. Theoretically, quantum dot infrared photodetectors ͑QDIPs͒ and quantum dot-in well ͑DWELL͒ detectors ͑which is a combination of a quantum dot and quantum well detector͒ offer several advantages over QWIPs, including lower dark current ͑hence higher T operation͒, higher responsivity, normal incidence detection, and improved radiation hardness. 10,11 QDIPs with low dark current densities and high operating temperature have been reported. 2,3 Asymmetrically designed DWELL detectors have also been shown to have a biasdependent spectral response that is suitable for multispectral imagery. 12 Recently, a two color 320ϫ 256 FPA, based on a volt...

Abstract:We present the design of mid-infrared and THz quantum cascade laser cavities formed from planar photonic crystals with a complete in-plane photonic bandgap. The design is based on a honeycomb lattice, and achieves a full in-plane photonic gap for transverse-magnetic polarized light while preserving a connected pattern for efficient electrical injection. Candidate defects modes for lasing are identified. This lattice is then used as a model system to demonstrate a novel effect: under certain conditionsthat are typically satisfied in the THz range -a complete photonic gap can be obtained by the sole patterning of the top metal contact. This possibility greatly reduces the required fabrication complexity and avoids potential damage of the semiconductor active region. 328-332 (1993). 15. A similar phenomenon occurs in guided membrane PC structures, where it is known that the extent of the photonic gap depends on the membrane thickness. However, in the dielectric membrane structures, beyond a critical membrane thickness further reduction in thickness does not increase the bandgap due to a loss of mode localization in the dielectric membrane. The double-metal waveguide structure does not suffer from such a loss of confinement. 1957-1964 (2006

Abstract:We present the design of mid-infrared and THz quantum cascade laser cavities formed from planar photonic crystals with a complete in-plane photonic bandgap. The design is based on a honeycomb lattice, and achieves a full in-plane photonic gap for transverse-magnetic polarized light while preserving a connected pattern for efficient electrical injection. Candidate defects modes for lasing are identified. This lattice is then used as a model system to demonstrate a novel effect: under certain conditionsthat are typically satisfied in the THz range -a complete photonic gap can be obtained by the sole patterning of the top metal contact. This possibility greatly reduces the required fabrication complexity and avoids potential damage of the semiconductor active region. 328-332 (1993). 15. A similar phenomenon occurs in guided membrane PC structures, where it is known that the extent of the photonic gap depends on the membrane thickness. However, in the dielectric membrane structures, beyond a critical membrane thickness further reduction in thickness does not increase the bandgap due to a loss of mode localization in the dielectric membrane. The double-metal waveguide structure does not suffer from such a loss of confinement. 1957-1964 (2006

In this paper we report the use of a photonic crystal resonant cavity to increase the quantum efficiency, detectivity (D*) and the background limited infrared photodetector (BLIP) temperature of a quantum dot detector. The photonic crystal is incorporated in InAs/InGaAs/GaAs dots-in-well (DWELL) detector using Electron beam lithography. From calibrated blackbody measurements, the conversion efficiency of the detector with the photonic crystal (DWELL-PC) is found to be 58.5% at-2.5 V while the control DWELL detectors have quantum efficiency of 7.6% at the same bias. We observed no significant reduction in the dark current of the photonic crystal devices compared to the normal structure. The generation-recombination limited D* at 77K with a 300K F1.7 background, is estimated to be 6 x 10 10 cmHz 1/2 /W at-3V bias for the DWELL-PC which is a factor of 20 higher than that of the control sample. We also observed a 20% increase in the BLIP temperature for the DWELL-PCs.