求助光纤耦合

jack_0711 · 发表于 2009-7-15 14:49:42

大家好！
我现在用光纤耦合的光斑,，中心光斑比较暗，虽然整体效率在85%以上，但是在中心光斑比较暗，不清楚是怎么回事
直接光纤耦合，LD+柱透镜+光纤

laserfan · 发表于 2009-7-15 14:55:46

调整一下,可能和光纤直径\长度\弯曲角度,以及聚焦透镜参数有关.

jack_0711 · 发表于 2009-7-15 21:39:56

2# laserfan
光纤长度3米、直径200um、孔径0.22的，那主要还是耦合的问题，对吧！要是光纤耦合好了，整个光斑是不是就是均匀的；
在SC插芯的和光纤的连接处衔接时不是很牢靠，我在稍微晃动插芯与光纤衔接处时，输出光斑形状会发生变化，光斑就不均匀而是一圈一圈的

badan · 发表于 2009-7-15 21:49:57

即使是你现在这种情况，近场光斑应该还是均匀的，不知道你是不是真的需要远场光斑也同样均匀！

liang · 发表于 2009-7-16 08:35:56

我也遇到类似的情况
我们800um芯径的光纤

关注中！！！！！！！！！！！！

jack_0711 · 发表于 2009-7-16 22:22:03

4# badan
近场时，光强度影响，视觉上光斑很均匀，在远场中，光斑比较大，相对来说光能能分散，这时看见光斑的噪点就比较大，在光斑中心有暗区；

badan · 发表于 2009-7-17 07:56:47

以我的经验，从阶跃型多模光纤直接出来的激光，只要光纤的长度足够，近场光版一定是均匀的，而要直接在远场得到均匀的光斑，基本上是不现实的，真的有必要的话，可以采取其他的方法。
以下结果供你参考：

Waveguide Modes

Waveguide structures are spatially inhomogeneous structures which can guide waves. For light propagating in a waveguide, the self-consistency condition for a mode is more strict than for free-space modes: the shape of the complex amplitude profile in the transverse dimensions must remain exactly constant. Any re-scaling is not allowed, only an overall phase change (described by the propagation constant) and a loss or gain of total optical power. The phase change per unit length is called the propagation constant, and is generally different for different modes.

A waveguide has only a finite number of guided propagation modes, the intensity distributions of which have a finite extent around the waveguide core. The number of guided modes, their transverse amplitude profiles and their propagation constants depend on the details of the waveguide structure and on the optical frequency. A single-mode waveguide (e.g. a single-mode fiber) has only a single guided mode per polarization direction. As an example of a multimode waveguide, Figure 3 shows the transverse profiles of all the modes of a multimode fiber.

modes of a fiber

Figure 3: Electric field amplitude profiles for all the guided modes of a fiber with a top-hat refractive index profile (→ step index fiber). The two colors indicate different signs of electric field values.

A waveguide also has cladding modes, the intensity distributions of which essentially fill the whole cladding (and core) region. Optical fibers (even single-mode fibers) have a large number of cladding modes, which often exhibit substantial propagation losses at the outer interface of the cladding.

badan · 发表于 2009-7-17 08:10:33

这里还有个计算光线模式的matlab程序。

Fiber modes.zip (12.15 KB, 下载次数: 48)

liang · 发表于 2009-7-17 08:55:59

没软件
打不开啊！
汗！！！！！！！！！！！！！！

litwei · 发表于 2009-7-17 09:04:43

感谢badan分享.

jack_0711 · 发表于 2009-7-17 13:14:51

谢谢你，badan，辛苦了

toobug · 发表于 2009-7-20 13:16:16

无语。。。还是缺金钱

求助光纤耦合

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