Frequency comb swept lasers.
Frequency comb swept lasers.
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DOI：
10.1364/oe.17.021257
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发表时间：
2009-11-09
期刊：
影响因子：
3.8
通讯作者：
Fujimoto JG
中科院分区：
文献类型：
--
作者：
Tsai TH;Zhou C;Adler DC;Fujimoto JG
我们展示了一个频率梳（FC）扫频激光器和频率梳傅里叶域锁模（FC-FDML）激光器的应用在光学相干层析成像（OCT）。基于光纤的FC扫描激光器分别以1 kHz和120 kHz的扫描速率在以1310 nm为中心的135 nm调谐范围内工作，平均输出功率为50 mW。扫描激光器中的25 GHz自由光谱范围频率梳状滤波器使激光器产生一系列明确定义的频率阶跃。频率梳状滤波器的窄带宽（0.015nm）使其在~ 3 mm范围内的灵敏度滚降达到~−1.2dB，而传统的扫频光源和FDML激光器的灵敏度滚降分别为− 10 dB和−5dB。在非常长的范围内进行测量是可能的，灵敏度损失最小，但是来自0- 3 mm的主要测量范围之外的反射会出现混叠回到主要范围内。此外，从激光器输出的频率梳在频率上是等间隔的（在k空间中是线性的）。滤波后的激光输出可用于对OCT干涉信号采样进行自计时，从而实现条纹信号的直接快速傅立叶变换，而不需要条纹重新校准过程。讨论了FC扫频激光器的设计和工作原理，并提出了用于OCT和干涉测量应用的短腔激光器的设计。
We demonstrate a frequency comb (FC) swept laser and a frequency comb Fourier domain mode locked (FC-FDML) laser for applications in optical coherence tomography (OCT). The fiber-based FC swept lasers operate at a sweep rate of 1kHz and 120kHz, respectively over a 135nm tuning range centered at 1310nm with average output powers of 50mW. A 25GHz free spectral range frequency comb filter in the swept lasers causes the lasers to generate a series of well defined frequency steps. The narrow bandwidth (0.015nm) of the frequency comb filter enables a ~−1.2dB sensitivity roll off over ~3mm range, compared to conventional swept source and FDML lasers which have −10dB and −5dB roll offs, respectively. Measurements at very long ranges are possible with minimal sensitivity loss, however reflections from outside the principal measurement range of 0–3mm appear aliased back into the principal range. In addition, the frequency comb output from the lasers are equally spaced in frequency (linear in k-space). The filtered laser output can be used to self-clock the OCT interference signal sampling, enabling direct fast Fourier transformation of the fringe signals, without the need for fringe recalibration procedures. The design and operation principles of FC swept lasers are discussed and designs for short cavity lasers for OCT and interferometric measurement applications are proposed.