Faezeh Gholami

Transmission of 640-Gb/s RZ-OOK Channel Over 100-km SSMF by Wavelength-Transparent Conjugation

We report the first demonstration of 640-Gb/s return-to-zero ON-OFF keying channel transmission over a 100-km standard single-mode fiber link employing midspan phase conjugation. A frequency-degenerate conjugate field spanning more than 20 nm is created in a low-birefringence parametric mixer for the first time. Physical separation of the conjugate field from the original field is enabled by utilizing pump polarization nondegeneracy. Rigorous link characterization using a high-quality 640-Gb/s transmitter and a high-sensitivity receiver revealed error-free (bit error ratio <;10-9) performance, eliminating the need for impractical fiber length control or electronic signal processing. The compatibility of wavelength-transparent conjugation with spectrally inefficient channel implies that channels with higher bit rates and better spectral efficiency can also be compensated.

Third-order nonlinearity in silicon beyond 2350 nm

Measurement of the Kerr nonlinearity in silicon is reported in the 2350 nm to 2750 nm wavelength range, where three-photon absorption effect is present. The measurements confirm that the Kerr interaction strength is comparable to that in the near-infrared. The measured dispersion trend for the Kerr coefficient is consistent with that obtained using Kramers-Kronig relations. Three-photon absorption was measured, and its effect on the nonlinear figure of merit in silicon appears not to be as restrictive as that of two-photon absorption. The results identify silicon as a promising platform for parametric processes in mid-infrared spectral region.

Short wavelength infrared frequency conversion in ultra-compact fiber device

Linear and nonlinear characteristics of devices using millimeter-scale spools of highly nonlinear fiber are experimentally investigated within 2000-2400nm spectral range. Coils with radius larger than 3.5 mm indicate that macro-bending induced radiation loss is negligible up to 2400nm. Devices with smaller diameter coiling resulted in macro-bending losses that dominate over micro-bending losses beyond 2200nm. A tunable short-wave infrared source was constructed using a coin-sized fiber module to demonstrate an efficient nonlinear conversion from 1.26 to 2.2 microm.

Phase-preserving parametric wavelength conversion to SWIR band in highly nonlinear dispersion stabilized fiber.

The first successful translation of a phase modulated optical signal over 80 THz, from the near infrared to the short-wave infrared (SWIR) band is demonstrated. A signal, phase-modulated at 10 Gbps, was received in an error-free manner in the SWIR(1.7-2.2 μm) band. A new class of highly nonlinear fiber with reduced dispersion fluctuation was utilized as the platform for this phase-preserving distant parametric conversion.

Mid-Infrared Wavelength Conversion in Silicon Waveguides Pumped by Silica-Fiber-Based Source

We discuss the potential of four-wave mixing (FWM) in a cascaded silica-silicon platform for generation of light in the midwave infrared (mid-IR) spectral domain. The motivation for developing light sources in mid-IR is supported by numerous applications, such as free-space communications, light detection and ranging (LIDAR), remote sensing, and medicine. These applications would greatly benefit from narrow linewidth and widely tunable laser sources with modulation capability. In this paper, a summary of existing light sources in mid-IR is given and the potential features that the proposed hybrid silica-silicon source can deliver to mid-IR applications are listed. Silica fiber is a well utilized platform at telecom wavelengths that is supported by an excellent infrastructure including tunable narrow linewidth laser sources, unsurpassed in the other spectral domains, high-bandwidth modulators, and detectors. The capability of this platform has recently been extended to the shortwave IR region (SWIR). On the other hand, silicon suffers from impairments imposed by nonlinear absorption at telecom wavelengths, but it possesses excellent linear and nonlinear optical properties in the SWIR (1.7-2.2 μm) and mid-IR (2.2-5 μm) regions. Therefore, in combination with a silica-based SWIR source, it can be utilized as an efficient FWM platform for mid-IR frequency generation.

Transmission of 640 Gbps RZ-OOK channel over 100 km of SSMF by wavelength-transparent conjugation

We demonstrate the first uncompensated transmission of a 640 Gbps RZ-OOK channel over 100 km of standard SMF. The error-free performance of the ultrafast link was achieved by a new, wavelength-transparent and polarization-invariant signal conjugation scheme for the first time.

All-Fiber Tunable SWIR Parametric Source at 2.4 µm

We report a record long-wavelength silica fiber optic source, capable of reaching 2.4µm, based on cascaded four-wave-mixing. The source is tunable over a spectral range of more than 130nm, with a peak power exceeding 10mW.

Kerr nonlinearity in silicon beyond 2.35μm

We present measurements of χ⁽³⁾ in silicon in the 2.35 to 2.75μm interval, showing Kerr coefficients close to 1×10⁻¹⁸ m²/W. The results clearly identify silicon as a promising platform for nonlinear processes in the mid-infrared.

40-GHz Analog-to-Digital Converter Based on Sampling Gate of Silicon Waveguide with Ultra-Low Loss and High Conversion Efficiency

An ultra-low loss and high conversion efficiency silicon waveguide is used as sampling gate via four waves mixing, and 5.2 effective number of bits of signal at 40-GHz is achieved by 2-GHz cavity-less pulse source.

Octave-wide characterization of highly nonlinear fiber dispersion

We demonstrate wide-band technique to characterize the dispersion properties of highly nonlinear fiber with record accuracy. The new method is based on processing of spectral fringes generated by the balanced interferometer transfer function when excited by parametric super-continuum source.