Sub-microsecond Switching Time Research Articles

Synthesis and Characterization of New Chiral Smectic Four-Ring Esters.

Orthoconic antiferroelectric liquid crystals (OAFLCs) represent unique self-organized materials with significant potential for applications in photonic devices due to their sub-microsecond switching times and high optical contrast in electro-optical effects. However, almost all known OALFCs suffer from low chemical stability and short helical pitch values. This paper presents the synthesis and study results of two chiral AFLCs, featuring a four-ring structure in the rigid core and high chemical stability. The mesomorphic properties of these compounds were investigated using polarizing optical microscopy and differential scanning calorimetry. Spectrometry and electro-optical studies were employed to estimate the helical pitch, tilt angle, and spontaneous polarization of the synthesized compounds and the prepared mixtures. All studied compounds exhibit enantiotropic chiral smectic mesophases including the SmA*, the SmC*, and a very broad temperature range of the SmCA* phase. Doping top-modern antiferroelectric mixture with synthesized compounds offers benefits such as increased helical pitch and tilt angle values without significantly influencing spontaneous polarization. This allows the prepared mixture to be regarded as an OAFLC with high optical contrast, characterized by an almost perfect dark state. These valuable physicochemical and optical properties suggest significant potential of studied materials for practical applications.

On-chip tunable quantum interference in a lithium niobate-on-insulator photonic integrated circuit

Programmable interferometric circuits are at the heart of integrated quantum photonic processors. While the lithium niobate-on-insulator platform has the potential to advance integrated quantum photonics due to its strong nonlinearity and tight mode confinement, the demonstration of reconfigurable two-photon interference has not yet been achieved. Here, we design, fabricate and characterize the building block of such interferometric networks in the form of a 2 × 2 Mach–Zehnder Interferometer. We use a thermo-optic phase shifter to achieve stable performance with a power consumption of Pπ=44.4 mW and sub-microsecond switching times. We demonstrate the effectiveness of our device for quantum applications by measuring single-photon routing with up to 34 dB extinction ratio. We show Hong-Ou-Mandel interference with fully tunable visibilities reaching a maximum value of 97.4±1.0% . As part of large scale quantum photonic circuits, this building block will facilitate reconfigurable and tunable photonic processing units integrated alongside non-classical light sources.

Thermo-optic phase shifter with sub-microsecond switching time and low power consumption

We propose a thermo-optic phase shifter utilizing multimode interference in a silicon waveguide. The electrodes were attached to the section where the multimode interference had the minimum optical electric field around the sidewalls. We designed the multimode waveguide width to reduce optical propagation loss in the C–L wavelength band (1.53–1.625 μm). We succeeded in developing a low optical loss thermo-optic phase shifter with less than 0.1 dB in the wavelength range of 1.5 to 1.6 μm. Moreover, wavelength dependence was reduced by adjusting the number of electrodes. An optical switch with the designed thermo-optic phase shifter was fabricated and used to estimate the optical switching time. Switching time of several microseconds was obtained by normal pulse operation, and ultrafast optical switching of about 500 ns was realized by overdrive control.

Silicon photonic wavelength cross-connect with integrated MEMS switching

We report on monolithically integrated wavelength cross-connects (WXCs) on an enhanced silicon photonic platform with integrated micro-electro-mechanical-system (MEMS) actuators. An 8 × 8 WXC with 8 wavelength channels comprising 16 echelle gratings and 512 silicon photonic MEMS switches is integrated on a 9.7 mm × 6.7 mm silicon chip. The WXC inherits the fundamental advantages of silicon photonic MEMS space switches, including low loss, broad optical bandwidth, large fabrication tolerance, and simple digital control. The WXC exhibits a low crosstalk of −30 dB, a submicrosecond switching time of 0.7 µs, and on-chip optical insertion losses varying from 8.8 dB to 16.4 dB. To our knowledge, it is the largest channel capacity (64 channels = 8 ports × 8 wavelengths) integrated WXC ever reported.

Digital electric field induced switching of plasmonic nanorods using an electro-optic fluid fiber

We demonstrate the digital electric field induced switching of plasmonic nanorods between “1” and “0” orthogonal aligned states using an electro-optic fluid fiber component. We show by digitally switching the nanorods that thermal rotational diffusion of the nanorods can be circumvented, demonstrating an approach to achieve submicrosecond switching times. We also show, from an initial unaligned state, that the nanorods can be aligned into the applied electric field direction in 110 ns. The high-speed digital switching of plasmonic nanorods integrated into an all-fiber optical component may provide opportunities for remote sensing and signaling applications.

Highly Scalable Digital Silicon Photonic MEMS Switches

Optical circuit switches with fast switching times can provide rapidly reconfigurable bandwidth in data center networks. Silicon photonic switches are attractive candidates with their fast response times and CMOS process compatibility. In this paper, we report on a 50 × 50 silicon photonic switch with MEMS-actuated vertical adiabatic couplers. The switch is monolithically integrated on a 7.6 × 7.6 mm2 chip. It has an on-chip insertion loss of 8.5 dB. Our switch exhibits a sub-microsecond switching time (0.85 μs), a broad spectral bandwidth (1400–1700 nm), and digital switching characteristic. The switch architecture is highly scalable as light passes through only one switching element irrespective of the switch size.

Coupled cavity InGaAsP/InP laser for synthetic optical coherence tomography and other applications

The authors describe widely tunable coupled cavity semiconductor lasers with sub-microsecond switching times between modes over the operating range of ∼100 nm. With appropriate modulation of injection currents and time averaging of the output, these devices provide short coherence lengths and can be an excellent source for synthesised optical coherence tomography (OCT). The depth resolution was found to be ∼15 μm for a 100 nm wavelength tuning range centred at 1580 nm. High-output power and brightness together with a short coherence length confers on these asymmetric multiple quantum well (AMQW) C 3 laser some advantages over conventional sources for OCT. Also, a rapid wavelength switching capability allows the AMQW C 3 lasers to be used in real-time OCT and other applications needing wavelength agile sources.

Two switching devices utilizing VO2

Vanadium dioxide undergoes a crystallographic phase transformation at 68°C which is accompanied by a large and abrupt change in resistivity. Two devices, a two-terminal threshold switch and a four-terminal thermal relay, based on this effect are investigated theoretically and experimentally with regard to switching applications. The formation of thermal filaments is found to have a strong influence on both the dc characteristics and on the switching properties. One consequence for both devices is that the power required to sustain the "on" condition is significantly less than that required for switching. It is shown that both devices should be capable of submicrosecond switching times at milliwatt power levels.

A high speed constant current switch for use with the National Physical Laboratory plasma-metal junction harmonic generator

The National Physical Laboratory plasma-metal junction harmonic generator is based on the nonlinear properties of the cathode spot of an arc established in a gas at high pressure. To inhibit transfer of metal from one electrode to the other the arc must be maintained by a source of constant current, of up to 0.5A, whose polarity is reversed at an audio frequency with a submicrosecond switching time. This paper describes a solid state device meeting the above requirements and having a switching time of less than 0.2 μsec.

A Slow Wave Digital Ferrite Strip Transmission Line Phase Shifter

This paper is concerned with the development of a nonreciprocal, digital, slow wave phase shifter which combines submicrosecond switching times with a compact strip transmission line structure. After a qualitative explanation of the operation of the phase shifter is given, an analysis of the dispersion characteristics of the meander line is presented. Impedance matching techniques are discussed along with the experimental results. Various design parameters, which affect the device performance, are examined