Del Mar Photonics - Newsletter December 2010 - Newsletter April 2011

Question:

Can you do Raman spectroscopy or CARS with this setup? btw the carbon nanotubes are auto-fluorescence?

Answer:
No and yes. This particular setup is optimized for continuous imaging and spectroscopy of fluorescent nanotubes which emit between ~ 900 and 1600 nm. It uses tunable cw laser which excite resonance absorption peaks of selected nanotube structures and a set of filters to transmit near-infrared nanotube emission and stop laser light. To detect Raman signals from nanotubes one would need better optics, e.g. specialized notch filters, to reject excitation and detect signals very close to the excitation wavelength. Perhaps even CARS would be possible if the laser is used in femtosecond mode (+ specialized optics and detectors), but it has not been tried here. Both Raman and CARS spectroscopy of individual nanotubes have been demonstrated by other research groups already.

Regarding autofluorescence (and without deviating much into definitions) - everything emits some photons with certain probability after absorption of light. The question is - with what probability? For nanotubes this value is yet to be defined. Estimates show that for selected nanotube structures (and in good environment like some inert gas) this probability, or quantum yield, may reach 0.1-0.2

 

Del Mar Photonics featured customer Bruce Weisman. Professor Weisman ordered Trestles Ti:Sapphire laser with built-in DPSS pump laser.

Professor Weisman wrote: Our applications are for carbon nanotube excitation, mostly with a cw beam but in some experiments with mode-locked pulses.

Del Mar Photonics offered Trestles Ti:Sapphire model with both CW and femtosecond modes of operation.
Detailed laser specifications are as follows (request a quote):

Trestles Ti:Sapphire laser with built-in DPSS pump laser
Ti:Sapphire oscillator having a tuning range of 710-920 nm;
 Output power: 30mW (@3W pump, in the whole range);
Spatial mode: TEMoo;
Polarization: linear horizontal;
Repetition rate: 80 MHz;
Pulse duration: <100 fs
Electronic starter with TTL output for mode-locked mode
observation. Output mirrors included.
USB-controlled tuning slit for wavelength tuning

 3BRF-TM 3-plate BRF for CW lasers (step motor controlled tuning)
Provides CW tuning and 40 GHz linewidth of the Trestles fs
lasers in CW mode; output power @700 nm - >50 mW (3W pump)

3 W pump DPSS laser with control and power supply unit
Power: 3 W
Wavelength: 532 nm
Beam size: 2.0 mm
Spatial mode: TEM00
Bandwidth: 30 GHz
Divergence: 0.4 mrad
M squared: < 1.1
Power stability: < 0.4 % RMS
Noise: < 0.4% RMS
Noise bandwidth: 1 Hz - 6 MHz
Pointing stability: < 2 microrads/C
Polarization ratio: 100:1
Polarization direction: horizontal
Coherence length: < 1 cm
Beam angle: < 1 mrad
Umbilical length: 1.5 m
Warm-up time: 10 min

 

New models:

Trestles LH femtosecond lasers with integrated DPSS DMPLH laser pump - DPSS DMPLH lasers

We are looking forward to hear from you and help you with your optical and crystal components requirements. Need time to think about it? Drop us a line and we'll send you beautiful Del Mar Photonics mug (or two) so you can have a tea party with your colleagues and discuss your potential needs