Nonlinear optical properties of photoresists for projection lithography

Optical beams are self-focused and self-trapped upon initiating crosslinking in photoresists. This nonlinear optical phenomenon is apparent only for low average optical intensities and produces index of refraction changes as large as 0.04. We propose using the self-focusing and self-trapping phenomenon in projection photolithography to enhance the resolution and depth of focus

Narrow-band optical filter through phase conjugation by nondegenerate four-wave mixing in sodium vapor

An ultrahigh-Q tunable optical filter with a FWHM bandwidth of 41 MHz is demonstrated. The filtering is produced by nondegenerate phase conjugation through four-wave mixing in atomic-sodium vapor. The filter is observed to have a maximum quantum efficiency of 4 x 10^-3. However, degenerate phase-conjugation experiments in sodium suggest that a quantum efficiency of greater than unity can be attained on a cw basis

Nonlinear dispersion in a coupled-resonator optical waveguide

The propagation of an optical pulse in a coupled-resonator optical waveguide may be calculated nonperturbatively to all orders of dispersion, in the conventional tight-binding approximation, even though the dispersion relationship is nonlinear. Working in this framework, we discuss limits of the physical parameters and approximations to the exact formulation that highlight the conditions under which pulse distortion can be minimized. The results are fundamental to the design of coupled-resonator optical waveguides and are also relevant to other applications of the tight-binding method

Coupled-mode analysis of fiber-optic add drop filters for dense wavelength-division multiplexing

We present a coupled-mode theory of fiber-optic add drop filters, which involve directional coupling between two fibers combined with fiber Bragg gratings defined inside the coupling region. The analysis self-consistently accounts for both the directional and the reflection coupling, and the propagation constants and structure of the supermodes of the combined structure are derived. We present a detailed analysis of a filter design based on identical fibers. The calculated device parameters satisfy the requirements for dense wavelength-division multiplexing applications

Optical bright and dark states in side-coupled resonator structures

We analyze side-coupled standing-wave cavity structures consisting of Fabry-Perot and photonic crystal resonators coupled to two waveguides. We show that optical bright and dark states, analogous to those observed in coherent light-matter interactions, can exist in these systems. These structures may be useful for variable, switchable delay lines

Mutual phase locking of a coupled laser diode-Gunn diode pair

Mutual phase locking has been achieved through series connection of a semiconductor laser and a Gunn diode oscillator. Experimental results obtained demonstrate a mutual interaction between the two oscillators which results in a short term Gunn diode oscillator stability and improved spectral purity of its output. We also observe a narrowing of laser pulses and an improvement in regularity

The intrinsic electrical equivalent circuit of a laser diode

The basic electrical equivalent circuit of a laser diode is derived. The effects of spontaneous emission and self-pulsations are included. It is found that self-pulsations are represented by a negative resistance in the model. Application of this model suggests purely electronic methods of suppressing relaxation oscillations in laser diodes

Designing coupled-resonator optical waveguide delay lines

We address the trade-offs among delay, loss, and bandwidth in the design of coupled-resonator optical waveguide (CROW) delay lines. We begin by showing the convergence of the transfer matrix, tight-binding, and time domain formalisms in the theoretical analysis of CROWs. From the analytical formalisms we obtain simple, analytical expressions for the achievable delay, loss, bandwidth, and a figure of merit to be used to compare delay line performance. We compare CROW delay lines composed of ring resonators, toroid resonators, Fabry-Perot resonators, and photonic crystal defect cavities based on recent experimental results reported in the literature

Active coupled-resonator optical waveguides. I. Gain enhancement and noise

We use a tight-binding formalism in the time domain to analyze the effect of resonant gain enhancement and spontaneous emission noise in amplifying coupled-resonator optical waveguides (CROWs). We find the net amplification of a wave propagating in a CROW does not always vary with the group velocity, and depends strongly on the termination and excitation of these structures. The signal-to-noise ratio and noise figure of CROW amplifiers are derived in the tight-binding formalism as well. The physical interpretations and practical consequences of the theoretical results are discussed