R. Menzel

Direct Generation of 50 ps-Pulses from an External Cavity Diode Laser Yielding 200 mW Average Output Power

We present a broad area diode laser with a very simple external resonator which shows self-induced modelocking of about 10 longitudinal modes at a repetition rate of 1-3 GHz, resulting in short pulses.

ps-Pulse generation by self-induced modelocking of a high power broad area diode laser in an external resonator

Up to 250 mW of ps-pulses with a pulsewidth of 50 ps and a repetition rate of 1-3 GHz are generated by self-induced modelocking of a high-power diode-laser working in an external resonator.

Enhancement of the spectral width of a gain-switched Ti:sapphire laser up to 80 nm by nonlinear absorbers

Summary form only given. For white light interferometric measurements like coherence radar with large field-of-view or optical tomography light sources with short coherence lengths and high brightness are needed. These requirements can be fulfilled by gain-switched Ti:sapphire lasers. Further enhancement of the spectral bandwidth was achieved with an intracavity saturable absorber. We observed the maximum bandwidth with hexamethyldibenzoindotricarbocyaninine perchlorate (HDITCP) in ethanol to 80.3 nm.

Enhancing two-photon excited fluorescence by using thermal light

Two-photon excited fluorescence (TPEF) has become a standard technique in modern microscopy but it is still affected by photo-damage of the probe owed to high excitation intensities. This work reports on utilizing the photon bunching effect in thermal light to enhance the efficiency of TPEF under continuous wave excitation. A super-luminescence diode (SLD) was used as thermal light source and compared it to coherent excitation from a DFB diode laser emitting at the same wavelength. The degree of second order coherence g(2) of both sources was measured. The SLD showed photon bunching with g(2) = 1.90±0.2 as expected for thermal light, while the DFB diode laser emitted coherent light exhibiting no photon bunching at g(2) = 1.

Coupled ring resonator geometry for efficient second harmonic generation

Generation of visible light by second-harmonic generation (SHG) of diode laser radiation using enhancement cavities with a nonlinear crystal is a well established technique. The main problem is to lock the laser emission to the resonance frequency of the enhancement cavity or vice versa. The two common approaches are electronic or optical locking. In electronic locking, an error signal proportional to the frequency detuning is generated [1]. This signal can be applied, e. g., to the driving current of the diode laser or to a piezo-controlled mirror. In optical locking, light is injected into the laser to force the laser emission to the resonance frequency of the enhancement cavity. Therefore, the enhancement cavity itself can be used to filter out the appropriate frequency [2].

Principles and operation of a mode locked Nd: YAG laser using a nonlinear mirror based on stimulated Brillouin scattering

We report on a Q-switched and mode locked laser oscillator with phase conjugating mirror. It emits ps-pulses in a double burst structure with an adjustable pulse energy between 0.5 – 2 mJ

Layer-by-layer coated capsules for efficient and directed electron transfer

We present a concept, where this effect is used to implement a stepwise electron transfer with the direction given by a polarity gradient i.e. increasing solvatation. The layer-by-layer deposition of polyelectrolytes can be used to build such a structure if dye-doped polyelectrolytes with increasing polarity are deposited onto charged colloids. Finally the basic colloids are removed, providing the electron transfer (ET)-system on nanometer scale on capsules with a diameter of 2 /spl mu/m.

Tunable cw-diode laser for 940 to 990 nm with over 700 mW of near-diffraction limited light

In this paper, the setup for the tunable cw-GaAs diode laser chip in an external cavity, which consists of stripe-array, a fast axis collimator, a grating, and a /spl lambda//2-plate, has been explained.

Fs-pump-and-probe spectroscopy on squaraine dyes

In this paper we present our investigations on the first step of the optically induced multistep electron transfer in squarilic systems, i.e. we show the evolution of the transient intramolecular charge transfer state on a fs-timescale. For the chosen pump-and-probe setup a mode-locked Ti-sapphire laser in combination with a regenerative amplifier provides the used 100 fs-laserpulses. As probe light we use white light which is generated in a thin sapphire plate and which allows us to measure the excited state absorption in a wide spectral range (240 nm) simultaneously. When exciting the squaraine molecule with the frequency-doubled laser light at 400 nm, the local charge densities inside the squaraine vary. It can be noticed that an intramolecular electron transfer from the nitrogen towards the squaric acid has taken place.

High Brightness High Brilliance Tunable Broad Area Diode Laser with 1 W of Near Diffraction Limited Light

An unstable external cavity diode laser is presented with an AR-coated stripe-array diode as gain medium which yields up to 1 W with a bandwidth below 3 MHz and M2< 2 over the tuning range 940 nm through 980 nm.