Niloy K. Dutta

Bio: Niloy K. Dutta is an academic researcher from University of Connecticut. The author has contributed to research in topics: Laser & Semiconductor laser theory. The author has an hindex of 38, co-authored 427 publications receiving 7153 citations. Previous affiliations of Niloy K. Dutta include Cornell University & Alcatel-Lucent.

Study of all-optical XOR using Mach-Zehnder Interferometer and differential scheme

Abstract: All-optical XOR functionality has been demonstrated experimentally using an integrated SOA-based Mach-Zehnder interferometer (SOA-MZI) at 20 and 40 Gb/s. The performance of the XOR results has been analyzed by solving the rate equation of the SOA numerically. The high-speed operation is limited by the carrier lifetime in the SOA. In order to solve the limitations imposed by carrier lifetime, a differential scheme for XOR operation has been experimentally investigated. This scheme is potentially capable of XOR operation to >100 Gb/s.

Performance of gain-guided surface emitting lasers with semiconductor distributed Bragg reflectors

Abstract: The performance limitations of gain-guided vertical cavity surface emitting lasers (VCSELs) which use epitaxially grown semiconductor distributed Bragg reflectors (DBRs) are discussed. The light-current (L-I) characteristics and emission wavelength of such lasers are examined as a function of temperature and time under continuous wave (CW) and pulsed operation. The authors observed a sharp roll-over in the CW L-I characteristics which limits the maximum output power. The threshold current under CW operation is found to be lower than that obtained under pulsed conditions. Several microseconds long delay in lasing turn-on is also observed. It is shown quantitatively that these anomalies are a consequence of severe heating effects. It is shown that reduction of the series resistance and threshold current density can lead to significant improvements in the power performance of VCSELs. >

Locking range and stability of injection locked 1.54 µm InGaAsp semiconductor lasers

Abstract: Measurements of the intensity of an injection locked 1.54 μm InGaAsP laser are reported. The change in intensity of the locked laser across the locking range is quite asymmetric, with a shape that agrees well with the theory of Lang. A linewidth parameter of \alpha = 6 \pm 1 was determined from the magnitude of the locking range. The injection locked laser was found to be unstable on the high frequency end of the locking range. The physical origin of this instability is explained in terms of a laser intensity change altering the phase of the laser field relative to that of the injected field.

Excellent uniformity and very low (<50 A/cm2) threshold current density strained InGaAs quantum well diode lasers on GaAs substrate

Abstract: We report the growth and fabrication of InGaAs/GaAs strained quantum well (QW) lasers with a very low threshold current density, Jth, of <50 A cm−2 emitting at 0.98 μm. The lasers, 1350 μm long, had two InGaAs 80 A quantum wells in the active region and Al0.6Ga0.4As in cladding layers, and were grown on 3° off (100) towards 〈111〉A GaAs substrate. Misorienting the substrate towards 〈111〉A improves the material quality and device performance substantially for x≊0.6 in the cladding layer, but degrades it somewhat for x≊0.35. The Jth increased about 25% with decreasing x from 0.6 to 0.35 due to decreased optical confinement. Single QW stripe lasers with x=0.35 tested on a 3.0 cm×1016 μm size bar, representative of the whole 5‐cm‐diam substrate, exhibited a yield of ≳90% and an excellent spatial uniformity of Jth and emission wavelengths which were 212±4 A cm−2 and 989±1 nm, respectively.

I and i

Abstract: There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality. Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

[서평]「Applied Cryptography」

Abstract: The objective of this paper is to give a comprehensive introduction to applied cryptography with an engineer or computer scientist in mind. The emphasis is on the knowledge needed to create practical systems which supports integrity, confidentiality, or authenticity. Topics covered includes an introduction to the concepts in cryptography, attacks against cryptographic systems, key use and handling, random bit generation, encryption modes, and message authentication codes. Recommendations on algorithms and further reading is given in the end of the paper. This paper should make the reader able to build, understand and evaluate system descriptions and designs based on the cryptographic components described in the paper.

Fiber Bragg gratings

Abstract: Since the discovery of photosensitivity in optical fibers there has been great interest in the fabrication of Bragg gratings within the core of a fiber. The ability to inscribe intracore Bragg gratings in these photosensitive fibers has revolutionized the field of telecommunications and optical fiber based sensor technology. Over the last few years, the number of researchers investigating fundamental, as well as application aspects of these gratings has increased dramatically. This article reviews the technology of Bragg gratings in optical fibers. It introduces the phenomenon of photosensitivity in optical fibers, examines the properties of Bragg gratings, and presents some of the important developments in devices and applications. The most common fabrication techniques (interferometric, phase mask, and point by point) are examined in detail with reference to the advantages and the disadvantages in utilizing them for inscribing Bragg gratings. Reflectivity, bandwidth, temperature, and strain sensitivity of the Bragg reflectors are examined and novel and special Bragg grating structures such as chirped gratings, blazed gratings, phase-shifted gratings, and superimposed multiple gratings are discussed. A formalism for calculating the spectral response of Bragg grating structures is described. Finally, devices and applications for telecommunication and fiber-optic sensors are described, and the impact of this technology on the future of the above areas is discussed.

Lasing in metallic-coated nanocavities

Abstract: Metallic cavities can confine light to volumes with dimensions considerably smaller than the wavelength of light. It is commonly believed, however, that the high losses in metals are prohibitive for laser operation in small metallic cavities. Here we report for the first time laser operation in an electrically pumped metallic-coated nanocavity formed by a semiconductor heterostructure encapsulated in a thin gold film. The demonstrated lasers show a low threshold current and their dimensions are smaller than the smallest electrically pumped lasers reported so far. With dimensions comparable to state-of-the-art electronic transistors and operating at low power and high speed, they are a strong contender as basic elements in digital photonic very large-scale integration. Furthermore we demonstrate that metallic-coated nanocavities with modal volumes smaller than dielectric cavities can have moderate quality factors.