Journal: Nature Communications

Article Title: The optical frequency comb fibre spectrometer

doi: 10.1038/ncomms12995

Figure Lengend Snippet: The repetition frequency f r and offset frequency f o of the Er:fibre OFC are locked to an Rb standard disciplined by a GPS. The OFC output beam passes through the gas cell filled with 12 C 2 H 2 at 10 mbar and is multiplexed with the SF laser output beam inside the PM fibre; both beams are coupled into the MM fibre held in the temperature-stabilized aluminium chamber. The speckle pattern emerging from the MM fibre is finally imaged onto the InGaAs camera and processed by a laptop pc. DDS, Direct Digital Synthesizer; ECDL, extended cavity diode laser; PD, photodiode; PZT, piezoelectric transducer; SC, supercontinuum.

Article Snippet: An objective with a NA of 0.5 is used to image the speckle patterns onto a 320 × 256 InGaAs camera (HighFinesse, LC320).

Techniques:

Journal: Nature Communications

Article Title: The optical frequency comb fibre spectrometer

doi: 10.1038/ncomms12995

Figure Lengend Snippet: ( a , c ) Speckle patterns of the narrow-linewidth SF laser and OFC at 1,535.3 nm emerging from the output of the MM fibre and imaged onto the InGaAs camera. Typical values for the speckle contrast (see ‘Methods' section for definitions) of the SF laser and OFC are 0.710 and 0.078, respectively. ( b , d ) Autocorrelation coefficient of the speckle patterns and temperature of the MM fibre as a function of time. To avoid frequency drift, the speckle patterns of the SF laser and OFC have been acquired with the laser locked to the OFC which is in turn locked to a Rb standard disciplined by a GPS. A speckle pattern has been stored every Δ t =10 s and correlated to the pattern acquired at t =0 s; a degradation of nearly 1% and 0.01% after 3 h is observed in the autocorrelation trace of the SF laser and OFC, respectively.

Article Snippet: An objective with a NA of 0.5 is used to image the speckle patterns onto a 320 × 256 InGaAs camera (HighFinesse, LC320).

Techniques:

Journal: Nature Communications

Article Title: The optical frequency comb fibre spectrometer

doi: 10.1038/ncomms12995

Figure Lengend Snippet: ( a ) A sequence of transmission spectra by a 142-mm cell filled with pure 12 C 2 H 2 at pressure of 10 mbar acquired with the MM fibre spectrometer. The sequence has been measured by setting a tunable filter (−10 dB band of 0.6 nm) at the desired central wavelength and imaging the speckle patterns at the MM fibre output onto an InGaAs camera (40-μs exposure time, 10 frames averaged). Each spectrum spans 1 nm and is sampled by ∼500 comb lines. ( b ) Transmission spectrum of the 12 C 2 H 2 cell, as calculated by fitting the experimental data corresponding to the main absorptions (red line, bottom) and retrieved from the HITRAN database (blue line, top). The standard error on the centre wavelength of the fitted absorption lines is better than 0.028 pm (±3.5 MHz at 1.53 μm).

Article Snippet: An objective with a NA of 0.5 is used to image the speckle patterns onto a 320 × 256 InGaAs camera (HighFinesse, LC320).

Techniques: Sequencing, Transmission Assay, Imaging