Backlink indexing is crucial in SEO as it helps search engines discover and index the backlinks to your site, which can improve your site's visibility and ranking. Here are some unique and effective techniques to ensure your backlinks are indexed:
Use high-quality content on your site. Search engines prioritize indexing sites that offer value to users. Ensure your content is high-quality, relevant, and provides a good user experience. This makes it more likely that search engines will index your backlinks quickly.

Social Media Engagement: Share your content, including pages where you've gained backlinks, on social media platforms. Social signals can prompt search engines to index your content faster. Engagement through likes, shares, and comments can further enhance visibility.

Submit to Web Directories: Submitting your website to reputable web directories can help in getting your backlinks indexed. Choose directories that are relevant to your industry and have a high domain authority.

Use Ping Services: Ping services like Ping-O-Matic can notify search engines about your new content or backlinks. While its effectiveness may vary, it's a straightforward method to signal search engines about updates on your site.

Create Internal Links: If you have control over a site where you've acquired a backlink, ensure that the page with the backlink is well-integrated into the site through internal linking. This helps search engine crawlers find and index the page.

Google Search Console: Use Google Search Console to submit sitemaps and individual URLs for indexing. This doesn't guarantee immediate indexing of your backlinks, but it alerts Google to their existence.

Quality Over Quantity: Focus on getting backlinks from high-authority, reputable sites within your niche. A few high-quality backlinks can be more beneficial than numerous low-quality ones.

Engage in Forums and Comment Sections: Participating in forums and comment sections related to your niche can help. Leave thoughtful comments and include a link back to your site when relevant and allowed. This can drive both traffic and search engine attention.

Leverage Blogging Platforms: Guest posting on reputable blogging platforms or sites related to your niche can help get your backlinks indexed. Ensure the content is valuable and relevant to the audience of those platforms.

Monitor Your Backlinks: Use tools like Ahrefs, SEMrush, or Moz to monitor your backlinks and their indexing status. This will help you identify which techniques are working best for your site.
Remember, the goal is not just to have your backlinks indexed but to ensure they contribute positively to your site's SEO. Focus on strategies that align with white hat SEO practices to avoid penalties from search engines.