Val N. Morozov

VCSEL/CMOS smart pixel arrays for free-space optical interconnects

This paper describes a VCSEL-Si smart pixel array technology, developed at the University of Colorado, and reports on an optoelectronic processor that is based on these hybrid SPAs. This effort is unique in the processing complexity of the pixels, in the bidirectionary of the optical interconnects, and in the thermosonic bonding of the VCSEL and silicon chips.

Tolerance analysis for three‐dimensional optoelectronic systems packaging

A series of optoelectronic processing systems is under development at the Optoelectronic Computing System Center (OCSC) at the University of Colorado. The demonstrations consist of two facing optoelectronic modules that communicate with each other using bidirectional free-space optical channels. An analysis of the fabrication tolerances required for correct operation of these systems is presented. An overview of the system and the techniques used for fabrication is given, along with the tolerances achieved in practice. A comparison with theoretical results indicates the critical alignments within the system. Methods to obtain the alignments required for larger systems are discussed.

Waveguide holograms with white light illumination

Waveguide holography (WGH) as an improved technique for display holography is discussed. The feasibility of reconstruction of waveguide holograms with white light is presented. Experimental results and future applications for waveguide holograms are also given.

Toward a free-space parallel optoelectronic computer: a 300-MHz optoelectronic counter using holographic interconnects

We built and tested one of the key components of a free-space holographically interconnected stored-program optoelectronic computer: a counter. The counter is constructed with 1-ns-latency optoelectronic NOR gates and is interconnected with holographic optical elements. Two synchronization methods were also demonstrated: the gate-and-strobe method and the time-of-flight method. These counters represent prototypical optoelectronic finite-state controllers. They were developed to demonstrate the feasibility of providing optoelectronic controllers for optoelectronic processors.

A new paradigm for parallel optical interconnects

A highly redundant, self-routing architecture is described utilizing parallel optical interconnects. The fundamental hardware component is a monolithically integrated module consisting of an array of VCSELs, resonant detectors, and waveguide couplers. Different types of interconnect specific architectures, including a reconfigurable, non-blocking crossbar will be presented.

Demonstration of a massively parallel bidirectional crosspoint switch with optical control

We are assembling a crosspoint switch system to demonstrate the free-space interconnects based on the smart-pixel-array (SPA) technology. The hybrid SPA including VCSEL arrays, microlens array, hologram array, and CMOS detector array will be described. The whole system is packaged using a custom designed optomechanics component. The design, fabrication and performance of the system are discussed.

System analysis of massively parallel crosspoint switch with optical control

In this paper, the structure and design of a crosspoint switch using the bi-directional free-space optical interconnect system is presented. An optical model for design of the system parameters such as VCSEL beam diameter, size and apodization of the hologram, and size of the detector is given based on crosstalk analysis of the system. Impact of VCSEL wavelength variation on the system design is considered. The hologram array design and a way to improve the diffraction efficiency by a copying technique utilizing DuPont photopolymer are presented. Aberrations due to the Fourier lens in the system are calculated and ways for correction of the aberrations are discussed.

PRACTICAL SPEED LIMITS OF FREE-SPACE GLOBAL HOLOGRAPHIC INTERCONNECTS : TIME SKEW, JITTER AND TURN-ON DELAY

The speed limits imposed on free-space global interconnects are affected by factors that can be divided into three groups: geometric parameters of the optical system that determine the propagation time and time skew, emitter parameters (turn-on delay and timing jitter), and system requirements (fan-in in the detector and bit error rate). For 32 × 32 global interconnects, numerical estimations of light propagation time and timing skew are presented. Time delay and jitter in a diode laser are calculated. After evaluation of these parameters, the timing and synchronization methods (gate and strobe or time of flight) can be selected, and the ultimate clock frequency of the overall system can be determined. The decisive role of contrast ratio and fan-in in the detector plane in determining the practical modulation rate of the diode laser is discussed.

Tolerance analysis of packaging for free-space optical interconnects

A bi-directional free-space holographically interconnected crosspoint switch and FFT processor are under development at the Optoelectronic Computing Systems Center at the University of Colorado at Boulder. Both systems include two sets of optoelectronic modules which communicate with each other using free-space interconnects. The size of the detector array and the vertical-cavity surface-emitting laser (VCSEL) array on each module is 8 by 8. The packaging of such system is critical for the proper operation of the systems. The overview of the systems and the techniques used for fabrication are provided. A model f the tolerance analysis of the system is presented, in which the misalignments of the VCSEL array, microlens array, hologram array, Fourier lens, and the detector array are taken into account. The fabrication tolerances for each component required for correct system operation is given. Statistical analysis based on Monte Carlo simulation for the detection efficiency and signal-to-noise ratio is calculated given misalignment distribution of 17 misalignments of the components of the system. The methods used for the alignment of the system are discussed.

Wavefront reconstruction using self-referenced direct-drive adaptive optics

A global self-referencing system allows local adaptive optics to be used in a pure optical system for wavefront reconstruction. No conventional, discrete optical components are required.