A novel high-speed optical reflectometry with high-reflectance-resolution is demonstrated by synthesis of optical coherence function for diagnosis of optical fiber assembly modules. In this new scheme, the optical frequency of a laser source is modulated doubly: one in sinusoidal wave to synthesize a coherence peak scanning along the fiber under test for distributed reflection/scattering measurement, the other in linear sweep to make the wavelength domain averaging optically for high reflectance resolution. Experimental results show that a reflection-distribution profile with reflectance-resolution better than 0.1dB can be obtained within 1 minute with this method.
We have fabricated an optically clocked transistor array (OCTA) in an optoelectronic integrated circuit (OEIC) technology incorporating 0.18-µm gate length high-electron-mobility transistors (HEMTs). As a result of its dual serial-to-parallel (SP) and parallel-to-serial (PS) conversion (time demux/mux) capability, the OCTA realizes a single-chip, low-power interface between input/output high-speed asynchronous burst optical packets and CMOS electronics, thus enabling a compact, low-power solution for label swapping of optical packets. Single channel measurements indicate an input bandwidth greater than 65Gb/s. An eight-channel array demonstrates SP and PS conversion at 40Gb/s.
The tuned corrugated surfaces and other corresponding structures can be labeled as soft and hard surface through an analogy acoustics and the concept has proven useful to many problems in electromagnetic theory. By use of the spectral-domain approach, the Weyl's identity and the technique of exponential-integral function, a simple and accurate closed-form expression is derived for dyadic Green's function of planar artificially soft and hard surface. The Green's function is expressed as the sum of three parts: primary field, image field reflected by a perfect electric conductor boundary and field created by a transmission-line current source. In addition, the expressions of related surface waves and the related power are derived and compared to the previous. The obtained result can serve as the foundation for the related practical electromagnetic problems in the presence of a soft and hard surface.
This paper presents a theoretical formulation on the stability criteria for non-linear oscillator circuits. We extend Kurokawa's discriminant to a general free-running oscillator employing an n-port active device. It is shown that the product of device admittance and passive circuit impedance matrices dominates the oscillation behavior. The frequency- and amplitude-partial derivatives of the matrix determinant play a key role in the stability analysis. The obtained results are especially effective for designing broadband micro- and millimeter-wave signal generators and frequency synthesizers.