Neil D. Whitbread

Widely tunable DS-DBR laser with monolithically integrated SOA: design and performance

We report recent device characterization results for a fully packaged widely tunable digital supermode (DS) distributed Bragg reflector (DBR) laser which has been monolithically integrated with a semiconductor optical amplifier. This new device gives all of the wide tunability and high side-mode suppression ratio performance previously reported for the DS-DBR laser with the added feature of output powers in excess of 14 dBm in fiber. In addition to output power and basic tuning behavior, we report on linewidth and relative intensity noise measurements for this device in order to investigate the noise characteristics of this laser.

Dynamically controlled channel-to-channel switching in a full-band DS-DBR laser

This paper presents a detailed series of measurements and modeled results that demonstrate rugged switching in a full-band tunable laser between stable, wavelength locked ITU frequencies. During switching a monolithically integrated optical amplifier has been used as a shutter to achieve greater than 40 dB attenuation whilst the wavelength is being tuned. The interactions between the thermal distribution down the laser and the induced frequency deviations are investigated, and the residual frequency deviation of <5 GHz is shown to be predominately thermal.

InP Mach–Zehnder Modulator Platform for 10/40/100/200-Gb/s Operation

We describe the design and performance of a wavelength-flexible modulator platform based on multiple quantum well epitaxy on InP. The Mach-Zehnder modulator platform provides high levels of performance in a compact footprint, is suitable for high volume manufacturing, and is compatible with integration of a tunable laser source. Applications spanning 10-, 40-, 100-, and 200-Gb/s transmission are described.

A novel broadband DBR laser for DWDM networks with simplified quasi-digital wavelength selection

A surface ridge DBR laser has been fabricated using conventional InP processing techniques, with the Bragg gratings defined by e-beam lithography. For a phase grating comb spacing of 6.8 nm, a nine grating device is predicted to yield complete coverage over >45 nm, sufficient to cover C- or L-band.

Linewidth in Widely Tunable Digital Supermode Distributed Bragg Reflector Lasers: Comparison Between Theory and Measurement

A transfer-matrix-based model is presented for calculating the linewidth of a widely tunable distributed Bragg reflector (DBR) laser as a function of its tuning currents. This model is used to calculate the linewidth of a digital supermode (DS)-DBR laser across its tuning range and compared to linewidth measurements under the same conditions. Excellent agreement is obtained with all the fine structure seen in the measurement being reproduced by the model. This suggests that the dominant factors which determine the complex structure of the linewidth are simple ones such as loss, threshold gain and optical power rather than complex details of the carrier dynamics

Equivalent Performance in C - and L -Bands of Digital Supermode Distributed Bragg Reflector Lasers

New results on the design and performance of digital supermode distributed Bragg reflector lasers for L-band operation are presented. The L-band device, which is fabricated using the same InP-based process as its C-band equivalent is shown to give essentially the same performance. The design changes required are discussed and a detailed comparison presented between C- and L-band devices. Together, a two-chip solution can provide more than 200 consecutive 50-GHz spaced channels (82-nm bandwidth) with SMSR greater than 45 dB and fiber-coupled leveled powers of 13 dBm.

Dynamic control of wavelength switching and shuttering operations in a broadband tunable DS-DBR laser module

Dynamic control of channel switching is demonstrated in a DS-DBR laser module using an integrated optical amplifier as a shutter. Switching time between locked channels is less than 6 ms and frequency deviation less than 5 GHz.

Miniaturized InP dual I&Q mach Zehnder modulator with full monitoring functionality for CFP2

A compact InP modulator chip is presented for 32Gbaud coherent transmission having high efficiency and linear EO response V2π<;5V and ER>25dB; and a full set of integrated waveguide detectors and phase-controls for testing, set-up and monitoring.

Directly-modulated DS-DBR tunable laser for uncooled C-band WDM system

A tunable DS-DBR laser is demonstrated for uncooled WDM C-band channel generation with tight spacing (50 GHz) and low thermal drift (plusmn 2.5 GHz) up to 70degC. 2.5 Gb/s direct modulation with transmission over a 75 km link is achieved

Sidelobes in the response of arrayed waveguide gratings caused by polarization rotation

Earlier it was observed that polarization rotation in an AWG built from birefringent waveguides can result in sidelobes in its response. This effect was measured in a polarization sensitive AWG with an orthogonal layout. Now we investigate through detailed simulation whether this effect also exists in polarization desensitised AWGs. It is shown that a dispersion compensated AWG does not suffer from a polarization sidelobe. Alternatively, the AWG can be designed to minimize polarization rotation to suppress the sidelobe.