Thermal Sensitivity of Birefringence in Polarization-Maintaining Hollow-Core Photonic Bandgap Fibers

Round 1

Reviewer 1 Report

    The manuscript reports the thermal sensitivity of birefringence in polarization-maintaining hollow-core photonic bandgap fibers. The thermal sensitivity of birefringence of PM HC-PBGFs is determined by the distortion of the fiber structure and can be two orders of magnitude smaller than that of the panda PM fibers.  I suggest to accept the manuscript with some improvements to the manuscript.

1. The thermal deformation induced by temperature variation is the key to TSB, can you give two quantitative relations, one is from temperature variation to thermal deformation, another is from thermal deformation to TSB?

2. The "FMs" in Line 108 should be deleted. The "CL" has no full name. The "10-5" in Line 123 is a clerical error. 

3. The thickness of the quartz fiber layer Dbare and tcoat should be shown in Fig. 1.

4. The description in Lines 113 to 115 is inaccurate and unnesscery because the CL is not the dominant loss in these fibers.

5. Considering the TSB might be change nonlinearly with temperature, as shown in Fig.4(c) , how to get the value of TSB in this paper? is it |B(-40℃)-B(60℃)|, TSB at 20℃, or mean of TSB between -40℃ and 60℃?

6.Because the contrast test of TSB is an important support for the conclusion of this paper, could the test data curve be provided in section 4?

Author Response

Dear reviewer:

Thanks for your commonts to my manuscript, and it is helpful for me. The following files include my response. Please check it.

Lidong

Author Response File: Author Response.docx

Reviewer 2 Report

The main focus of this study is on the use of polarization-maintaining (PM) hollow-core photonic bandgap fibers (HC-PBGFs) in fiber optic gyroscopes (FOGs). The authors investigate the effect of different fiber structure parameters on the thermal deformation and resulting birefringence variation of PM HC-PBGFs. They also compare the thermal sensitivity of birefringence (TSB) of PM HC-PBGFs with that of commonly used Panda PM fibers. The results show that for rhombic core fibers, the TSB is determined by the distortion of the cladding and can be two orders of magnitude smaller than that of Panda PM fibers. For hexagonal core fibers, the birefringence variation depends mainly on the drift of surface modes (SMs) caused by the deformation of the core, which can lead to a high TSB of up to 10^-4/100°C. This study provides important insights into the development of high-birefringence temperature-stable HC-PBGFs and their potential use in FOGs.

The authors claim that the confinement loss of the fiber structure is less than 0.1dB/Km, but no significant reason is present to support the study.

What is the point of mentioning coating thickness in lines 120 and 127.

 

The article may not fully address the limitations of the study or provide suggestions for future research.

 

The writing quality of the article may be somewhat lacking, with some sentences being poorly constructed or challenging to follow.

Serious proofreading must be done to correct typographical errors.

Author Response

Dear reviewer:

Thanks for your commonts to my manuscript, and it is helpful for me. The following files include my response. Please check it.

Lidong

Author Response File: Author Response.docx

Reviewer 3 Report

The authors investigated the thermal sensitivity of birefringence in PM HC-PBGFs, which is crucial and useful for the fiber optic gyroscope. This article is well organized and technically sound, the content is substantial, and the parameters are compared in detail. However, some phenomena may need more clarification and discussion to make them readable. Thus, a minor revision is suggested before accepting it for publication. The detailed comments and suggestions can be seen below:

1.        In the “Abstract” section, “To verify the application potential of PM HC-PBGFs in FOG, we compared their thermal sensitivity of birefringence (TSB) with that of the common used Panda PM fiber, which was tested to 5.07×10-5/100℃.” The test result of the TSB of the Panda PM fiber is given here, which one is not so important. However, the comparison result or the TSB of the PM HC-PBGF matters and should be given here in my opinion.

2.        In the same position, “common used” can be modified as “commonly used”.

3.        In line 160, “The curve of the fiber birefringence varies almost linearly with temperature.” here the words “almost linearly” are not admired for a research article, it is better to show the linearity value of the linear fitting cure.

4.        In line 162, “Birefringence should be reduced from an appearance point of view, but it has increased.” the authors just described the phenomenon without any clarification or reason for this phenomenon, worse the readability of the text.

5.        In line 183, “When the temperature gradually increased from 40℃ to 60℃, the curves of the two polarized modes show an increasing trend, while the slope of X-p neff curve decreases.” similarly, can you explain why the slope of X-p neff curve decreases with the temperature?

 

6.        In Fig. 5(b), the wavelength(μm) on x-axes should be d/Ʌ.

Author Response

Dear reviewer:

Thanks for your commonts to my manuscript, and it is helpful for me. The following files include my response. Please check it.

Lidong

Author Response File: Author Response.docx