M. Guy

Gain equalization of EDFA's with Bragg gratings

Flat-gain amplifiers are needed to ensure proper amplification of every channel in wavelength-division-multiplexed communication systems. Such amplifiers can be realized by combining a precisely tailored filter with an erbium-doped fiber amplifier (EDFA). In this letter, we show that Bragg gratings can lead to accurate EDFA gain equalization. Reflection and transmission gratings have been used to demonstrate gain equalization over 32 nm with excursion inferior to /spl plusmn/0.1 and /spl plusmn/0.3 dB, respectively. A maximum 0.04-dB noise-figure penalty results from this process. By extension, Bragg gratings could also equalize the gain of any arbitrary gain profile, over any arbitrary bandwidth.

1.6-b/s/Hz 160-Gb/s 230-km RZ-DQPSK polarization multiplex transmission with tunable dispersion compensation

A 160-Gb/s (4/spl times/40 Gb/s) return-to-zero differential quadrature phase-shift keying polarization-division multiplex transmission is demonstrated with Q>15.6 dB in one of eight 100-GHz-spaced wavelength-division-multiplex channels after 230 km of fiber. Residual chromatic dispersion (CD) is equalized by a thermally tunable CD compensator for the 192.5-THz channel. Polarizations, in-phase and quadrature data channels are demultiplexed using a LiNbO/sub 3/-based automatic polarization control and a 1-bit interferometer, respectively.

Group delay ripple of cascaded Bragg grating gain flattening filters

Chirped fiber Bragg gratings used as gain flattening filters were fabricated with peak-to-peak group delay ripple (GDR) less then 3 ps. It is shown that GDR of cascaded similar filters grows as the square root of their number. Group delay measurement is discussed and ripple quantifiers using peak-to-peak amplitude root-mean-square amplitude 100-pm window averaged amplitude and highest Fourier amplitude are compared. GDR of gain flattening filters based on chirped fiber Bragg gratings should not cause significant impairments in systems operating at 10 and 40 Gb/s.

Ultra-compact coherent receiver based on hybrid integration on silicon

A coherent receiver based on silicon photonics is presented. Its performance is confirmed by single-channel and WDM transmission tests with PM-QPSK modulation at 28 Gbaud up to 4800 km. The packaged core is very compact with dimensions of 6 mm × 8 mm.

Ultra-narrowband fiber Bragg gratings for laser linewidth reduction and RF filtering

We review the improved performances of a narrow linewidth laser using negative electrical feedback obtained through advances on narrowband FBG filters. Noteworthy, the tolerance of the laser to vibrations is significantly improved. As an extension of this work, these narrow filters are proposed for filtering optical signals in RF photonics systems.

Automatic tunable chromatic dispersion compensation at 40 gb/s in ASK and DPSK, NRZ, and CSRZ 263-km transmission experiments

Chromatic dispersion (CD) in single-mode optical fiber distorts pulses and is a big obstacle for the installation of long-haul dynamically routed transmission systems, especially at 40 Gb/s. Here the automatic residual CD compensation of a 263-km fiber link in the range -300 to -700 ps/nm is demonstrated for nonreturn-to-zero amplitude-shift keying (NRZ-ASK), carrier-suppressed return-to-zero (CSRZ)-ASK, NRZ differential phase-shift keying (DPSK), and CSRZ-DPSK modulation formats at 40 Gb/s. A thermally tunable dispersion compensator minimizes residual CD, which is measured by a synchronous arrival time detection scheme. The measured transmission penalty with online CD compensation is between /spl plusmn/1.2 dB for various link lengths and compensated CD values.

Silicon-based products and solutions

TeraXion started silicon photonics activities aiming at developing building blocks for new products and customized solutions. Passive and active devices have been developed including MMI couplers, power splitters, Bragg grating filters, high responsivity photodetectors, high speed modulators and variable optical attenuators. Packaging solutions including fiber attachment and hybrid integration using flip-chip were also developed. More specifically, a compact packaged integrated coherent receiver has been realized. Good performances were obtained as demonstrated by our system tests results showing transmission up to 4800 km with BER below hard FEC threshold. The package size is small but still limited by the electrical interface. Migrating to more compact RF interface would allow realizing the full benefit of this technology.

1.6-Tb/s (40/spl times/40 Gb/s) transmission over 44,...,94 km of SSMF with adaptive chromatic dispersion compensation

Full-band 1.6-Tb/s adaptive chromatic dispersion compensation is demonstrated for the first time. A multichannel tunable dispersion compensator is automatically controlled by arrival time detection on one out of 40 wavelength-division-multiplexed transmitted channels.

Bragg grating gain flattening filters with small group delay ripples

Group delay ripples less than 3 ps in amplitude were measured in chirped fiber Bragg gratings used as gain flattening filters. The delay ripples of cascaded filters increase as the square root of their number.

Polarisation mode dispersion compensation of chirped Bragg gratings

We demonstrate compensation of polarisation mode dispersion for a chirped Bragg grating. A short length of highly birefringent fiber improves the pulse reshaping action of a chirped Bragg dispersion compensator used in a recirculating loop.