| Company | Contact | Home |
MOGlaser ECD-003 Options
Headboard and cable US$240 and $50
These are normally included with the MOGLabs DLC controllers. If
the laser is purchased separately, without controller, these are
almost certainly required.
Fold mirror US$260
When tuning the laser by rotating the grating, the output beam
direction will change. This can be corrected with a "fold
mirror"; see for example Rev. Sci. Inst.
72(2): 4477 (2001). However, for most applications,
the laser will be operated within a very small frequency range
such that the grating is not rotated enough to matter. The fold
mirror is then only useful when setting up the laser and after
that point degrades the performance (increases susceptibility to
vibration). If you will be working at one wavelength (e.g. Rb D2
line) then we recommend against this option.
Hermetic seal US$260
The laser cavity can be hermetically sealed with addition of cavity
exit windows and o-ring seal. The sensitivity to the effects of drafts and noise will
be reduced. Condensation due to operation at low temperatures will
also be minimised inside the cavity. Note that the seal is not vacuum tight.
Water cooling connections US$50
The laser base has a water cooling channel. Water cooling is
normally not required, but we offer quick-fit connectors to allow
easy water connection if required, for example to cool the laser
substantially below room temperature.
Faraday isolator US$1610
External cavity diode lasers are extremely susceptible to optical
feedback, and require some form of optical isolation for stable
single-frequency operation. We offer an internal Faraday isolator
from EOT with 4mm diameter
aperture, typically 37dB isolation and 85% transmission.
Anti-reflection coated diodes
Our standard 780/795/850nm diodes have a low-reflectivity coating on the external
facets, for example about 0.25% for the 780/150mW diodes (net output power 100 to 120mW). The
injection current must be adjusted so that the internal diode
cavity frequency and external cavity mode frequency are matched. For a given frequency the choices of
current and temperature are limited and the output power cannot be
arbitrarily varied. If the diode injection current
(or the temperature) is adjusted, the laser is likely to
mode-hop, usually by about 40 GHz, the internal diode cavity spacing. The mode-hop free
tuning range is 10 GHz or more, with current bias
enabled. Current bias refers to varying the laser injection current
automatically as the frequency is adjusted or swept.
With our standard coatings, the linewidth of the laser varies substantially with injection current. When the internal diode and external cavity frequencies, and grating angle, are all matched, the combined effective feedback is optimised and the linewidth will be narrow. If the cavities are not matched, the feedback is reduced and the linewidth consequently degraded; see Appl. Opt. 48(35): 6961 (2009) and Appl. Opt. 48(35): 6692 (2009) for further discussion.
Ultra-low reflectivity coatings on the diode allow continuous frequency tuning without mode-hops, or continuous variation of the output power, over a larger range. Such diodes are available at a range of wavelengths and power ratings. We usually have stock of 780nm and 850nm, 100mW net laser output power, at US$1070.
With our standard coatings, the linewidth of the laser varies substantially with injection current. When the internal diode and external cavity frequencies, and grating angle, are all matched, the combined effective feedback is optimised and the linewidth will be narrow. If the cavities are not matched, the feedback is reduced and the linewidth consequently degraded; see Appl. Opt. 48(35): 6961 (2009) and Appl. Opt. 48(35): 6692 (2009) for further discussion.
Ultra-low reflectivity coatings on the diode allow continuous frequency tuning without mode-hops, or continuous variation of the output power, over a larger range. Such diodes are available at a range of wavelengths and power ratings. We usually have stock of 780nm and 850nm, 100mW net laser output power, at US$1070.
Diffraction gratings
We use gold-coated, sinusoidal holographic gratings, with diffraction
efficiency specified for reasonable compromise between frequency
stability and output power. Lower diffraction efficiency gratings can
be used to increase the output power by up to 20%, provided the
operating wavelength will be close to the diode gain peak wavelength,
and at the expense of reduced modehop-free scan range. Alternately,
even higher diffraction efficiency may be needed to pull the lasing
wavelength far from the gain peak of the diode. Non-standard grating
options are usually US$300.