Stefan Hammerfeldt

Design of a widely tunable modulated grating Y-branch laser using the additive Vernier effect for improved super-mode selection

We present the design of a modulated grating Y-branch semiconductor laser containing a splitter and two multi-peak reflectors. High selectivity is achieved using the additive Vernier effect.

Monolithically Integrated 100 GHz DFB-TWEAM

A monolithically integrated distributed feedback (DFB) laser and traveling-wave electro-absorption modulator (TWEAM) with ges 100 GHz -3 dBe bandwidth suitable for Non-return-to-zero (NRZ) operation with on-off keying (OOK) is presented. The steady-state, small-signal modulation response, microwave reflection, chirp characteristic, and both data operation and transmission were investigated. The DFB-TWEAM was found to be an attractive candidate for future short distance communication in high bitrates systems.

High performance narrow linewidth thermally tuned semiconductor laser

A high performance narrow linewidth tunable semiconductor laser, with a novel airgap process is presented. Total tuning power less than 100mW is achieved for the whole C-band. Spectral linewidth between 80 and 120 kHz, and SMSR >49dB are also shown.

New widely tunable edge-emitting laser diodes at 1.55 μm developed in the European IST-project NEWTON

Widely tunable lasers are generally considered as the transmitters of future WDM optical communications. Electronically tunable edge-emitting laser diodes are of particular interest as they can switch the wavelength in tens of nanoseconds and thus offer great potential for new networking concepts such as optical packet or burst switching, label switching, bandwidth on demand, ... In this paper we discuss new concepts for such widely tunable laser diodes which are studied in the framework of the European IST project NEWTON (NEw Widely Tunable laser diodes for Optical Networks).

Narrow linewidth tunable semiconductor laser

A full-C band tunable laser equipped with an air-gap suspended waveguide structure for efficient thermal heater tuning is described. It is shown that the monolithic tunable laser can simultaneously meet the requirements for the output power, side-mode suppression ratio, and spectral linewidth for 16-QAM coherent communication system. Together with an optimized design for the Bragg grating and a reduced optical loss for thermally-tuned un-doped waveguide, a high SMSR of 54.5 dB, an output power of 19 dBm, and 80 kHz linewidth over 103 channels across the C-band were achieved. A possibility for further reduction of the heater tuning power is also discussed.

Silicon optical bench for flip-chip integration of high speed widely tunable lasers

A silicon optical bench for flip chip mounted widely tunable modulated-grating Y-branch lasers is presented. Its impact on the static and dynamic performance of the laser device is evaluated and compared with a conventional aluminium nitride carrier. The carriers exhibited similar thermal and static performance but the dynamic performance was limited by the electrode layout and the higher microwave losses of the silicon optical bench. With improved microwave design of the electrodes, flip-chip mounting on a silicon optical bench is promising for low cost assembly of high-speed multi-electrode devices.

A silicon optical bench for flip chip mounting of widely tunable modulated grating Y-branch lasers

A silicon optical bench for flip chip mounted widely tunable lasers is presented. Its impact on the static and dynamic characteristics of the laser device is evaluated and compared with a conventional aluminium nitride carrier.