Franko Kueppers

Multichannel and rate all-optical clock recovery

We report on a new clock recovery scheme utilizing a birefringent fiber resonator and a polarizer that allows for parallel all-optical processing of multiple channels and rates. It is demonstrated for 21 simultaneous channels, 20 carrying data at 10 Gb/s and one at 40 Gb/s. Earlier demonstrations of multichannel operation have reported four recovered channels at only one single rate

50 nm continuously tunable MEMS VCSEL devices with surface micromachining operating at 1.95 µm emission wavelength

An investigation of micro-electro-mechanical-system vertical-cavity surface-emitting lasers at 1.95xa0µm emission wavelength grown on InP is presented. The top sided distributed Bragg reflector has been substituted by a dielectric SiOx/SiNy membrane. Its deflection causes a continuous change of emission wavelength due to cavity tuning. The membrane actuation can be achieved in two different ways: by electrostatic attraction and electrothermal expansion. The recently developed surface-micro-machining technique allows both tuning mechanisms on one and the same device. The maximum achieved continuous tuning range is 50xa0nm with side-mode-suppression-ratios beyond 50xa0dB over the entire tuning range. Peak optical output powers of 1.0 to 1.8 mW with threshold current densities of 2.2 kA cm−2xa0will be presented.

Direct DPSK modulation of chirp managed lasers for symmetrical 10-Gbit/s WDM-PONs

In this paper we propose the use of chirp managed lasers (CML) as cost-effective downstream transmitters in next generation access networks. The network simplicity and an optical power budget of 36 dB obtained with phase-shift-keying direct modulation of CML proves that the proposed solution could be a strong candidate for future WDM-PONs.

Ultra wide mode-hop free tuning around 1550-NM telecom wavelength using high-speed MEMS-VCSELS

We report ultra-wide tuning of a 1550 nm BCB based high-speed MEMS-VCSEL. The MEMS is electrothermally actuated for a continuous tuning of 101 nm. Maximum output power and minimum threshold current is 3.2 mW and 2.6 mA, respectively.

Ultrawideband signal generation based on directly modulated semiconductor laser and optical filtering

A novel optical ultrawideband (UWB) pulse generator, which is capable of generating both Gaussian monocycle and Gaussian doublet pulses, by using a directly modulated semiconductor laser, optical filtering and chromatic dispersion in fiber is proposed and experimentally demonstrated. The combination of directly modulated laser and optical filter performs an electro-optic derivative operation, which produces a monocycle pulse when Gaussian pulse driving current is applied. The transmission of the obtained signal in single mode fiber is also considered, the chromatic dispersion has strong influences on the laser chirped pulses. We exploit this accumulative dispersion in order to switch the pulse polarity and shape. The proposed system is implemented, and the generation of UWB monocycle and doublet pulses is experimentally demonstrated. Gaussian monocycle and doublet pulses with a fractional bandwidth of about 137% and 108% are experimentally generated.

Widely tunable singlemode surface micro-machined MEMS-VCSELs operating at 1.95-μm

We present surface micro-machined micro-electro mechanical-system (MEMS) tunable vertical-cavity surfaceemitting lasers (VCSEL) with rectangular and triangular shaped quantum wells (QWs) emitting around 1:95 μm predestined for broadband tunable diode laser absorption spectroscopy. The VCSELs show single-mode operation and high side-mode suppression-ratio SMSR < 50 dB within the whole tuning range of 50nm and 35 nm, the fibre-coupled optical power of 1:0mW and 1:76mW and the threshold current of 2:5mA and 2:0mA for the rectangular and triangular shaped QWs respectively. The 3 dB modulation frequency of the MEMS is 110 Hz.

1.55 μm high-speed MEMS-tunable VCSEL

We present a micro electro-mechanical system (MEMS) tunable vertical-cavity surface-emitting laser (VCSEL) emitting around 1.55 μm with single-mode output power of >2.5mW and high side-mode suppression-ratio (SMSR) of >50dB over the entire tuning range of >50nm. The small-signal modulation technique (S21) has been used to study intrinsic and parasitic influences on the modulation response of the device. Additionally, the static characteristics as well as electrical and thermal design of the device are discussed with respect to its high-speed modulation behavior. The tunable laser shows 3-dB direct modulation frequencies above 6.4 GHz.

Saturated collision amplifier for the extended reach Passive Optical Networks: The upstream challenge

In this paper we discuss about the extended reach 10-Gbit/s Passive Optical Network (XGPON) and the use of a Saturated Collision Amplifier (SCA) for the up- and downstream extension. Especially the upstream amplification is challenging because of the used (i.e. standardized) wavelength and the bursty nature of the traffic. In order to benefit the SCA scheme, the Optical Network Units (ONUs) have to be equipped with low-cost DPSK transmitters. The use of widely tunable direct modulated VCSELs are proposed and discussed.