Felix Grawert

Generation of sub-10-fs pulses from a Kerr-lens mode-locked Cr 3+ :LiCAF laser oscillator by use of third-order dispersion-compensating double-chirped mirrors

Pulses as short as 9 fs at 220-mW average power and a 97-MHz repetition rate are generated from a cw Ti:sapphire-pumped Kerr-lens mode-locked Cr(3+)LiCAF laser oscillator employing broadband double-chirped mirrors for second- and third-order dispersion compensation. Fine adjustment of dispersion is accomplished with a fused-silica prism pair. The result demonstrates that Raman-induced self-frequency shifting of the pulse does not limit sub-10-fs pulse generation from colquiriite crystals.

Diode-pumped 10-fs Cr3+: LiCAF laser

We demonstrate 10-fs pulses from a diode-pumped, soft-aperture Kerr lens mode-locked Cr3+:LiCAF laser with a spectral bandwidth of 150 nm and 40 mW of output power at a repetition rate of 110 MHz. For dispersion compensation, double-chirped mirrors and prisms are used. The pulses are characterized by use of spectral shearing interferometry.

220-fs erbium-ytterbium:glass laser mode locked by a broadband low-loss silicon/germanium saturable absorber.

We demonstrate femtosecond performance of an ultrabroadband high-index-contrast saturable Bragg reflector consisting of a silicon/silicon dioxide/germanium structure that is fully compatible with CMOS processing. This device offers a reflectivity bandwidth of over 700 nm and subpicosecond recovery time of the saturable loss. It is used to achieve mode locking of an Er-Yb:glass laser centered at 1540 nm, generating 220-fs pulses, with what is to our knowledge the broadest output spectrum to date.

Electronic Photonic Integrated Circuits for High Speed, High Resolution, Analog to Digital Conversion

Progress in developing high speed ADCs occurs rather slowly - at a resolution increase of 1.8 bits per decade. This slow progress is mostly caused by the inherent jitter in electronic sampling - currently on the order of 250 femtoseconds in the most advanced CMOS circuitry. Advances in femtosecond lasers and laser stabilization have led to the development of sources of ultrafast optical pulse trains that show jitter on the level of a few femtoseconds over the time spans of typical sampling windows and can be made even smaller. The MIT-GHOST (GigaHertz High Resolution Optical Sampling Technology) Project funded under DARPAs Electronic Photonic Integrated Circuit (EPIC) Program is trying to harness the low noise properties of femtosecond laser sources to overcome the electronic bottleneck inherently present in pure electronic sampling systems. Within this program researchers from MIT Lincoln Laboratory and MIT Campus develop integrated optical components and optically enhanced electronic sampling circuits that enable the fabrication of an electronic-photonic A/D converter chip that surpasses currently available technology in speed and resolution and opens up a technology development roadmap for ADCs. This talk will give an overview on the planned activities within this program and the current status on some key devices such as wavelength-tunable filter banks, high-speed modulators, Ge photodetectors, miniature femtosecond-pulse lasers and advanced sampling techniques that are compatible with standard CMOS processing.

Design of all-optical switches based on carrier injection in Si/SiO/sub 2/ split-ridge waveguides (SRWs)

All-optical switches based on optical carrier injection in high-index-contrast Si/SiO2 split-ridge-waveguide (SRW) couplers are analyzed. The waveguide devices are suitable for the construction of low-loss optical switch matrices as well as fast optical switching. These devices exhibit robustness against fabrication tolerances, improved heat sinking, good carrier confinement, and high uniformity in transmission over the entire C-band of optical communications, in contrast to comparable devices based on buried or ridge waveguides. Reasonably low electrical switching power of 1-10 mW is predicted for switching frequencies of 1 MHz to 1 GHz. Carrier recombination measurements in thin Si layers passivated with different oxide layers confirm the feasibility of the designed switches and modulators

Stabilized Optical Fiber Links for the XFEL

The timing synchronization scheme for the European X-Ray free electron laser facility (XFEL) is based on the generation and distribution of sub-picosecond laser pulses with actively stabilized repetition rate which are used to synchronize local RF oscillators. An integral part of the scheme is the distribution of the optical pulse stream to parts of the facility via optical fiber links. The optical path length of the fiber has to be stabilized against short-term and long-term timing jitter due to environmental effects, such as temperature drifts and acoustic vibrations, to better than 10 fs for distances ranging from tens of meters to several kilometers. In this paper, we present first experimental results toward signal transmission through a 50 m-long fiber link with femtosecond stability.

Silicon-germanium saturable absorber mirrors

A silicon-germanium ultra-broadband saturable Bragg reflector with sub-picosecond recovery time is fabricated. Its performance is demonstrated by mode-locking an Er-Yb glass laser generating 220 fs pulses spanning the C-band of the optical communication range.

Automatic feedback control of an Er-doped fiber laser with an intracavity loss modulator

Saturable absorber mode-locking ofanEr-doped fiber laser isachieved overtheentire parameter range withautomatic gaincontrol andactive feedback stabilization using anintracavity loss modulator. ©2005 Optical Society ofAmerica OCIScodes: (320.7090) Ultrafast lasers, (140.4050) Mode-locked lasers, (140.3540) Lasers, Q-switched

Q-Switch Suppression in an Er-Doped Waveguide Laser with an Intracavity Loss Modulator

Suppression of Q-switch instabilities in an Er-doped waveguide laser, passively mode-locked with a saturable Bragg reflector, is demonstrated using an intracavity loss modulator, despite the strong pulse shaping per roundtrip and millisecond gain relaxation time.

Si/Ge Semiconductor Saturable Bragg Reflectors for Integrated Mode-Locked Lasers

Silicon-germanium saturable absorber mirrors at 1550 nm are demonstrated. The device is used to achieve stable, continuously mode-locked operation of an Er-Yb:glass laser centered at 1540 nm, generating 220 fs pulses