For a graph $G$, let its Laplacian be $\Delta = I - D^{-1/2}AD^{-1/2}$, where $A$ is the adjacency matrix, $I$ is the identity matrix and $D$ is the diagonal matrix with vertex degrees. I'm interested in the spectral gap of $G$, i.e. the first nonzero eigenvalue of $\Delta$, denoted by $\lambda_{1}(G)$.

Is it true that a randomly chosen (with uniform distribution) $d$-regular bipartite graph on $(n, n)$ vertices (with multiple edges allowed) has, with probability approaching $1$ as $n \to \infty$, $\lambda_1$ arbitrarily close to $1$ (i.e. we can make arbitrarily close by taking $d$ large enough)?

If yes, is there a reference for this fact?

Proofs of expanding properties for random regular graphs which I have found in the literature usually give the probability only bounded from below by a constant, i. e. $1/2$, although I imagine that actually almost all random graphs have good spectral gap.

Note: by $d$-regular bipartite graph I mean a graph in which each vertex (on the left and on the right) has degree $d$.

3 deleted 133 characters in body

For a graph $G$, let its Laplacian be $\Delta = I - D^{-1/2}AD^{-1/2}$, where $A$ is the adjacency matrix, $I$ is the identity matrix and $D$ is the diagonal matrix with vertex degrees. I'm interested in the spectral gap of $G$, i.e. the first nonzero eigenvalue of $\Delta$, denoted by $\lambda_{1}(G)$.

Is it true that a randomly chosen (with uniform distribution) $d$-regular bipartite graph on $(n, n)$ vertices has, with probability approaching $1$ as $n \to \infty$, $\lambda_1$ arbitrarily close to $1$ (i.e. we can make arbitrarily close by taking $d$ large enough)?

If yes, is there a reference for this fact?

Proofs of expanding properties for random regular graphs which I have found in the literature usually give the probability only bounded from below by a constant, i. e. $1/2$, although I imagine that actually almost all random graphs have good spectral gap.

Note: by $d$-regular bipartite graph I mean a graph in which each vertex on one side has degree $d$ (and there are no restrictions on the vertices left and on the other side), although the standard notion of regularity (all vertices have right) has degree $d$) is also OK.d$. 2 added 86 characters in body For a graph$G$, let its Laplacian be$\Delta = I - D^{-1/2}AD^{-1/2}$, where$A$is the adjacency matrix,$I$is the identity matrix and$D$is the diagonal matrix with vertex degrees. I'm interested in the spectral gap of$G$, i.e. the first nonzero eigenvalue of$\Delta$, denoted by$\lambda_{1}(G)$. Is it true that a randomly chosen (with uniform distribution)$d$-regular bipartite graph on$(n, n)$vertices has, with probability approaching$1$as$n \to \infty$,$\lambda_1$arbitrarily close to$1$(i.e. we can make arbitrarily close by taking$d$large enough)? If yes, is there a reference for this fact? Proofs of expanding properties for random regular graphs which I have found in the literature usually give the probability only bounded from below by a constant, i. e.$1/2$, although I imagine that actually almost all random graphs have good spectral gap. Note: by$d$-regular bipartite graph I mean a graph in which each vertex on one side has degree$d$(and there are no restrictions on the vertices on the other side), although the standard notion of regularity (all vertices have degree$d\$) is also OK.

1